8724E

MAX1908_05 MAXIM | Alldatasheet

Document overview

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Technical content

Features

♦ ±0.5% Output Voltage Accuracy Using Internal Reference (0°C to +85°C) ♦ ±4% Accurate Input Current Limiting ♦ ±5% Accurate Charge Current ♦ Analog Inputs Control Charge Current and Charge Voltage ♦ Outputs for Monitoring Current Drawn from AC Adapter Charging Current AC Adapter Presence ♦ Up to 17.6V Battery-Voltage Set Point ♦ Maximum 28V Input Voltage ♦ > 95% Efficiency ♦ Shutdown Control Input ♦ Charge Any Battery Chemistry Li+, NiCd, NiMH, Lead Acid, etc. MAX1908/MAX8724/MAX8765 Low-Cost Multichemistry Battery Chargers IINP CSSP CSSN DHI BST LX DLOV SHDN ICHG ACIN ACOK REFIN ICTL GND 15161718192021 VCTL BATT CELLS CSIN CSIP PGND DLO 7654321 CCV CCI CCS REF CLS LDO DCIN MAX1908 MAX8724 MAX8765 THIN QFN TOP VIEW Pin Configuration

Ordering Information

FROM HOST μP 10μH 0.015Ω BATT+ DCIN REFIN VCTL ICTL ACIN ACOK SHDN ICHG IINP CCV CCI CCS CELLS LDO BST DLOV DHI LX DLO PGND CSIP CSIN BATT REF CLS GND CSSP CSSN 0.01Ω Minimum Operating Circuit 19-2764; Rev 4; 7/05 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. EVALUATION KIT AVAILABLE PART TEMP RANGE PIN- PACKAGE PKG CODE MAX1908ETI -40°C to +85°C 28 Thin QFN T2855-6 MAX8724ETI -40°C to +85°C 28 Thin QFN T2855-6 MAX8765ETI -40°C to +85°C 28 Thin QFN T2855-6

Low-Cost Multichemistry Battery Chargers ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x V REFIN, CELLS = float, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25°C.) Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. CSIP to CSIN or CSSP to CSSN or CCI, CCS, CCV, DLO, ICHG, DLOV, VCTL, ICTL, REFIN, CELLS, CLS, Continuous Power Dissipation (TA = +70°C) 28-Pin Thin QFN (5mm × 5mm) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CHARGE-VOLTAGE REGULATION VVCTL = VREFIN (2, 3, or 4 cells) -0.5 +0.5 VVCTL = VREFIN / 20 (2, 3, or 4 cells) -0.5 +0.5 Battery-Regulation Voltage Accuracy VVCTL = VLDO (2, 3, or 4 cells) -0.5 +0.5 VCTL Default Threshold VVCTL rising 4.0 4.1 4.2 V REFIN Range (Note 1) 2.5 3.6 V REFIN Undervoltage Lockout VREFIN falling 1.20 1.92 V CHARGE-CURRENT REGULATION CSIP-to-CSIN Full-Scale Current- Sense Voltage VICTL = VREFIN 71.25 75 78.75 mV VICTL = VREFIN -5 +5 VICTL = VREFIN x 0.6 -5 +5 VICTL = VLDO -6 +6 MAX8765 only; VICTL = VREFIN x 0.036 -45 +45 Charging-Current Accuracy MAX8724 only; VICTL = VREFIN x 0.058 -33 +33 Charge-Current Gain Error (MAX8765 Only) -2 +2 % Charge-Current Offset (MAX8765 Only) -2 +2 mV ICTL Default Threshold VICTL rising 4.0 4.1 4.2 V BATT/CSIP/CSIN Input Voltage Range 0 19 V VDCIN = 0 or VICTL = 0 or SHDN = 0 1 CSIP/CSIN Input Current Charging 400 650 µA

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x V REFIN, CELLS = float, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Cycle-by-Cycle Maximum Current Limit IMAX RS2 = 0.015Ω 6.0 6.8 7.5 A ICTL Power-Down Mode Threshold Voltage (MAX1908/MAX8724 Only) VICTL rising REFIN / 100 REFIN / REFIN / 33 V VVCTL = VICTL = 0 or 3V -1 +1 ICTL, VCTL Input Bias Current VDCIN = 0, VVCTL = VICTL = VREFIN = 5V -1 +1 µA VDCIN = 5V, VREFIN = 3V -1 +1 REFIN Input Bias Current VREFIN = 5V -1 +1 µA ICHG Transconductance (MAX1908/MAX8724 Only) GICHG VCSIP - VCSIN = 45mV 2.7 3 3.3 µA/mV ICHG Transconductance (MAX8765 Only) GICHG VCSIP - VCSIN = 45mV 2.85 3 3.15 µA/mV ICHG Transconductance Error (MAX8765 Only) -5 +5 % ICHG Transconductance Offset (MAX8765 Only) -5 +5 µA VCSIP - VCSIN = 75mV -6 +6 VCSIP - VCSIN = 45mV -5 +5 ICHG Accuracy VCSIP - VCSIN = 5mV -40 +40 ICHG Output Current VCSIP - VCSIN = 150mV, VICHG = 0 350 µA ICHG Output Voltage VCSIP - VCSIN = 150mV, ICHG = float 3.5 V INPUT-CURRENT REGULATION CSSP-to-CSSN Full-Scale Current-Sense Voltage 72 75 78 mV VCLS = VREF -4 +4 VCLS = VREF / 2 -7.5 +7.5 Input Current-Limit Accuracy VCLS = 1.1V (MAX8765 only) -10 +10 Input Current-Limit Gain Error (MAX8765 Only) -2 +2 % Input Current-Limit Offset (MAX8765 Only) -2 +2 mV CSSP, CSSN Input Voltage Range 8 28 V VDCIN = 0 0.1 1 CSSP, CSSN Input Current (MAX1908/MAX8724 Only) VCSSP = VCSSN = VDCIN > 8V 350 600 µA VDCIN = 0V 0.1 1 CSSP Input Current (MAX8765 Only) VCSSP = VCSSN = 28V VDCIN = 28V 400 650 µA

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x V REFIN, CELLS = float, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS VDCIN = 0 0.1 1 CSSN Input Current (MAX8765 Only) VCSSP = VCSSN = 28V VDCIN = 28V 0.1 1 µA CLS Input Range (MAX1908/MAX8724 Only)

1.6 REF V

(MAX8765 Only) 1.1 REF V CLS Input Bias Current VCLS = 2V -1 +1 µA IINP Transconductance (MAX1908/MAX8724 Only) GIINP VCSSP - VCSSN = 75mV 2.7 3 3.3 µA/mV VCSSP - VCSSN = 75mV -5 +5 IINP Accuracy VCSSP - VCSSN = 37.5mV -7.5 +7.5 % IINP Transconductance (MAX8765 Only) GIINP VCSSP - VCCSN = 75mV 2.82 3 3.18 µA/mV IINP Transconductance Error (MAX8765 Only) -6 +6 % IINP Transconductance Offset (MAX8765 Only) -10 +10 µA IINP Output Current VCSSP - VCSSN = 150mV, VIINP = 0 350 µA IINP Output Voltage VCSSP - VCSSN = 150mV, VIINP = float 3.5 V SUPPLY AND LDO REGULATOR DCIN Input Voltage Range VDCIN 8 28 V VDCIN falling 7 7.4 DCIN Undervoltage-Lockout Trip Point VDCIN rising 7.5 7.85 V DCIN Quiescent Current IDCIN 8.0V < VDCIN < 28V 3.2 6 mA VBATT = 19V, VDCIN = 0 1 BATT Input Current IBATT VBATT = 2V to 19V, VDCIN = 19.3V 200 500 µA LDO Output Voltage 8V < VDCIN < 28V, no load 5.25 5.4 5.55 V LDO Load Regulation 0 < ILDO < 10mA 34 100 mV LDO Undervoltage-Lockout Trip Point VDCIN = 8V 3.20 4 5.15 V REFERENCE REF Output Voltage 0 < IREF < 500µA 4.072 4.096 4.120 V REF Undervoltage-Lockout Trip Point VREF falling 3.1 3.9 V

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x V REFIN, CELLS = float, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS TRIP POINTS VDCIN falling, referred to VCSIN (MAX1908/MAX8724 only) 50 100 150 BATT Power-Fail Threshold VCSSP falling, referred to VCSIN (MAX8765 only) 50 100 150 mV BATT Power-Fail Threshold Hysteresis 200 mV ACIN Threshold Hysteresis 0.5% of REF 20 mV ACIN Input Bias Current VACIN = 2.048V -1 +1 µA SWITCHING REGULATOR DHI Off-Time VBATT = 16V, VDCIN = 19V, VCELLS = VREFIN 0.36 0.4 0.44 µs DHI Minimum Off-Time VBATT = 16V, VDCIN = 17V, VCELLS = VREFIN 0.24 0.28 0.33 µs DHI Maximum On-Time 2.5 5 7.5 ms DLOV Supply Current IDLOV DLO low 5 10 µA BST Supply Current IBST DHI high 6 15 µA BST Input Quiescent Current VDCIN = 0, VBST = 24.5V, VBATT = VLX = 20V 0.3 1 µA LX Input Bias Current VDCIN = 28V, VBATT = VLX = 20V 150 500 µA LX Input Quiescent Current VDCIN = 0, VBATT = VLX = 20V 0.3 1 µA DHI Maximum Duty Cycle 99 99.9 % Minimum Discontinuous-Mode Ripple Current 0.5 A Battery Undervoltage Charge Current VBATT = 3V per cell (RS2 = 15mΩ), MAX1908 only, VBATT rising 150 300 450 mA CELLS = GND, MAX1908 only, VBATT rising 6.1 6.2 6.3 CELLS = float, MAX1908 only, VBATT rising 9.15 9.3 9.45 Battery Undervoltage Current Threshold CELLS = VREFIN, MAX1908 only, VBATT rising 12.2 12.4 12.6 V DHI On-Resistance High VBST - VLX = 4.5V, IDHI = +100mA 4 7 Ω DHI On-Resistance Low VBST - VLX = 4.5V, IDHI = -100mA 1 3.5 Ω DLO On-Resistance High VDLOV = 4.5V, IDLO = +100mA 4 7 Ω DLO On-Resistance Low VDLOV = 4.5V, IDLO = -100mA 1 3.5 Ω

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x V REFIN, CELLS = float, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C , unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ERROR AMPLIFIERS GMV Amplifier Transconductance GMV V V C T L = V LD O, V BAT T = 16.8V , C E LLS = V RE F IN 0.0625 0.125 0.2500 µA/mV GMI Amplifier Transconductance GMI VICTL = V RE F IN , VCSIP - VCSIN = 75mV 0.5 1 2.0 µA/mV GMS Amplifier Transconductance GMS VCLS = VREF, VCSSP - VCSSN = 75mV 0.5 1 2.0 µA/mV CCI, CCS, CCV Clamp Voltage 0.25V < VCCV,CCS,CCI < 2V 150 300 600 mV LOGIC LEVELS CELLS Input Low Voltage 0.4 V CELLS Input Float Voltage CELLS = float (VREFIN / 2) - 0.2V VREFIN / 2 ( V R E F IN / 2) + 0.2V V CELLS Input High Voltage VREFIN - 0.4V V CELLS Input Bias Current CELLS = 0 or VREFIN -2 +2 µA ACOK AND SHDN ACOK Input Voltage Range 0 28 V ACOK Sink Current V ACOK = 0.4V, VACIN = 3V 1 mA ACOK Leakage Current V ACOK = 28V, VACIN = 0 1 µA SHDN Input Voltage Range 0 LDO V V SHDN = 0 or VLDO -1 +1 SHDN Input Bias Current VDCIN = 0, V SHDN = 5V -1 +1 µA SHDN Threshold V SHDN falling 22 23.5 25 % of VREFIN SHDN Threshold Hysteresis 1 % of VREFIN

Low-Cost Multichemistry Battery Chargers (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = FLOAT, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C , unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CHARGE-VOLTAGE REGULATION VVCTL = VREFIN (2, 3, or 4 cells) -0.6 +0.6 VVCTL = VREFIN / 20 (2, 3, or 4 cells) -0.6 +0.6 Battery Regulation Voltage Accuracy VVCTL = VLDO (2, 3, or 4 cells) -0.6 +0.6 REFIN Range (Note 1) 2.5 3.6 V REFIN Undervoltage Lockout VREFIN falling 1.92 V CHARGE CURRENT REGULATION CSIP-to-CSIN Full-Scale Current- Sense Voltage VICTL = VREFIN 70.5 79.5 mV VICTL = VREFIN -6 +6 VICTL = VREFIN x 0.6 -7.5 +7.5 VICTL = VLDO -7.5 +7.5 MAX8765 only; VICTL = VREFIN x 0.036 -50 +50 Charging-Current Accuracy MAX8724 only; VICTL = VREFIN x 0.058 -33 +33 Charge-Current Gain Error (MAX8765 Only) -2 +2 % Charge-Current Offset (MAX8765 Only) -2 +2 mV BATT/CSIP/CSIN Input Voltage Range 0 19 V VDCIN = 0 or VICTL = 0 or SHDN = 0 1 CSIP/CSIN Input Current Charging 650 µA Cycle-by-Cycle Maximum Current Limit IMAX RS2 = 0.015Ω 6.0 7.5 A ICTL Power-Down Mode Threshold Voltage (MAX1908/MAX8724 Only) VICTL rising REFIN /

100 REFIN /

(MAX1908/MAX8724 Only) GICHG VCSIP - VCSIN = 45mV 2.7 3.3 µA/mV ICHG Transconductance (MAX8765 Only) GICHG VCSIP - VCSIN = 45mV 2.785 3.225 µA/mV ICHG Transconductance Error (MAX8765 Only) -7.5 +7.5 % ICHG Transconductance Offset (MAX8765 Only) -6.5 +6.5 µA

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = FLOAT, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C , unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS VCSIP - VCSIN = 75mV -7.5 +7.5 VCSIP - VCSIN = 45mV -7.5 +7.5 ICHG Accuracy VCSIP - VCSIN = 5mV -40 +40 INPUT-CURRENT REGULATION CSSP-to-CSSN Full-Scale Current-Sense Voltage 71.25 78.75 mV VCLS = VREF -5 +5 VCLS = VREF / 2 -7.5 +7.5 Input Current-Limit Accuracy VCLS = 1.1V (MAX8765 only) -10 +10 Input Current-Limit Gain Error (MAX8765 Only) -2 +2 % Input Current-Limit Offset (MAX8765 Only) -2 +2 mV CSSP, CSSN Input Voltage Range 8 28 V VDCIN = 0 1 CSSP, CSSN Input Current (MAX1908/MAX8724 Only) VCSSP = VCSSN = VDCIN > 8V 600 µA VDCIN = 0V 1 CSSP Input Current (MAX8765 Only) VCSSP = VCSSN = 28V VDCIN = 28V 650 µA VDCIN = 0V 1 CSSN Input Current (MAX8765 Only) VCSSP = VCSSN = 28V VDCIN = 28V 1 µA CLS Input Range (MAX1908/MAX8724 Only) (MAX8765 Only) 1.1 REF V IINP Transconductance (MAX1908/MAX8724 Only) GIINP VCSSP - VCSSN = 75mV 2.7 3.3 µA/mV IINP Transconductance (MAX8765 Only) GIINP VCSSP - VCCSN = 75mV 2.785 3.225 µA/mV IINP Transconductance Error (MAX8765 Only) -7.5 +7.5 % IINP Transconductance Offset (MAX8765 Only) -12 +12 µA

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = FLOAT, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C , unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SUPPLY AND LDO REGULATOR DCIN Input Voltage Range VDCIN 8 28 V DCIN Quiescent Current IDCIN 8V < VDCIN < 28V 6 mA VBATT = 19V, VDCIN = 0 1 BATT Input Current IBATT VBATT = 2V to 19V, VDCIN = 19.3V 500 µA LDO Output Voltage 8V < VDCIN < 28V, no load 5.25 5.55 V LDO Load Regulation 0 < ILDO < 10mA 100 mV REFERENCE REF Output Voltage 0 < IREF < 500µA 4.065 4.120 V TRIP POINTS VDCIN falling, referred to VCSIN (MAX1908/MAX8724 only) 50 150 BATT Power-Fail Threshold VCSSP falling, referred to VCSIN (MAX8765 only) 50 150 mV ACIN rising (MAX8765 only) 2.028 2.068 ACIN Threshold ACIN rising (MAX1908/MAX8724 only) 2.007 2.089 V SWITCHING REGULATOR DHI Off-Time VBATT = 16V, VDCIN = 19V, VCELLS = VREFIN 0.35 0.45 µs DHI Minimum Off-Time VBATT = 16V, VDCIN = 17V, VCELLS = VREFIN 0.24 0.33 µs DHI Maximum On-Time 2.5 7.5 ms DHI Maximum Duty Cycle 99 % Battery Undervoltage Charge Current VBATT = 3V per cell (RS2 = 15mΩ), MAX1908 only, VBATT rising 150 450 mA CELLS = GND, MAX1908 only, VBATT rising 6.09 6.30 CELLS = float, MAX1908 only, VBATT rising 9.12 9.45 Battery Undervoltage Current Threshold CELLS = VREFIN, MAX1908 only, VBATT rising 12.18 12.60 V DHI On-Resistance High VBST - VLX = 4.5V, IDHI = +100mA 7 Ω DHI On-Resistance Low VBST - VLX = 4.5V, IDHI = -100mA 3.5 Ω DLO On-Resistance High VDLOV = 4.5V, IDLO = +100mA 7 Ω DLO On-Resistance Low VDLOV = 4.5V, IDLO = -100mA 3.5 Ω

Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = FLOAT, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, C LDO = 1µF, LDO = DLOV, C REF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C , unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ERROR AMPLIFIERS GMV Amplifier Transconductance GMV V V C T L = V LD O, V BAT T = 16.8V , C E LLS = V RE F IN 0.0625 0.250 µA/mV GMI Amplifier Transconductance GMI VICTL = V RE F IN , VCSIP - VCSIN = 75mV 0.5 2.0 µA/mV GMS Amplifier Transconductance GMS VCLS = VREF, VCSSP - VCSSN = 75mV 0.5 2.0 µA/mV CCI, CCS, CCV Clamp Voltage 0.25V < VCCV,CCS,CCI < 2V 150 600 mV LOGIC LEVELS CELLS Input Low Voltage 0.4 V CELLS Input Float Voltage CELLS = float (VREFIN / 2) - 0.2V ( V R E F IN / 2) + 0.2V V CELLS Input High Voltage VREFIN - 0.4V V ACOK AND SHDN ACOK Input Voltage Range 0 28 V ACOK Sink Current V A COK = 0.4V, VACIN = 3V 1 mA SHDN Input Voltage Range 0 LDO V SHDN Threshold V S HDN falling 22 25 % of VREFIN Note 1: If both ICTL and VCTL use default mode (connected to LDO), REFIN is not used and can be connected to LDO. Note 2: Specifications to -40°C are guaranteed by design and not production tested. LOAD-TRANSIENT RESPONSE (BATTERY INSERTION AND REMOVAL) MAX1908 toc01 1ms/div IBATT 2A/div VBATT 5V/div VCCI 500mV/div VCCV 500mV/div ICTL = LDO VCTL = LDO CCV CCI LOAD-TRANSIENT RESPONSE (STEP IN-LOAD CURRENT) MAX1908 toc02 1ms/div VBATT 2V/div VCCI 500mV/div VCCS 500mV/div 16.8V 0LOAD CURRENT 5A/div ADAPTER CURRENT 5A/div ICTL = LDO CHARGING CURRENT = 3A V BATT = 16.8V LOAD STEP = 0 TO 4A ISOURCE LIMIT = 5A CCS CCS CCICCI VBATT 2V/div CHARGE CURRENT 2A/div LOAD CURRENT 5A/div ADAPTER CURRENT 5A/div LOAD-TRANSIENT RESPONSE (STEP IN-LOAD CURRENT) MAX1908 toc03 1ms/divICTL = LDO CHARGING CURRENT = 3A V BATT = 16.8V LOAD STEP = 0 TO 4A I SOURCE LIMIT = 5A Typical Operating Characteristics (Circuit of Figure 1, VDCIN = 20V, TA = +25°C, unless otherwise noted.)

Low-Cost Multichemistry Battery Chargers INDUCTOR CURRENT 500mA/div VDCIN 10V/div VBATT 500mV/div LINE-TRANSIENT RESPONSE MAX1908 toc04 10ms/divICTL = LDO VCTL = LDO ICHARGE = 3A LINE STEP 18.5V TO 27.5V -1.0 -0.8 -0.9 -0.6 -0.7 -0.4 -0.5 -0.3 -0.1 -0.2 0 2341 567 9 81 0 LDO LOAD REGULATION MAX1908 toc05 LDO CURRENT (mA) VLDO ERROR (%) VLDO = 5.4V -0.05 -0.03 -0.04 -0.01 -0.02 0.01 0.02 0.04 0.03 0.05 8 1 21 41 610 18 20 22 26 24 28 LDO LINE REGULATION MAX1908 toc06 VIN (V) VLDO ERROR (%) ILDO = 0 VLDO = 5.4V -0.10 -0.07 -0.08 -0.09 -0.06 -0.05 -0.04 -0.03 -0.02 -0.01 0 200 100 300 400 500 REF VOLTAGE LOAD REGULATION MAX1908 toc07 REF CURRENT (μA) VREF ERROR (%) -0.10 -0.04 -0.06 -0.08 -0.02 0.02 0.04 0.06 0.08 0.10 -40 10 -15 35 60 85REF VOLTAGE ERROR vs. TEMPERATURE MAX1908 toc08 TEMPERATURE (°C) VREF ERROR (%) 0.01 10 10.1 EFFICIENCY vs. CHARGE CURRENT 100 MAX1908 toc09 CHARGE CURRENT (A) EFFICIENCY (%) VBATT = 16V VBATT = 8V VBATT = 12V 100 250 200 150 300 350 450 400 500 04 62 8 10 12 14 16 18 20 22 FREQUENCY vs. VIN - VBATT MAX1908 toc10 (VIN - VBATT) (V) FREQUENCY (kHz) ICHARGE = 3A VCTL = ICTL = LDO

3 CELLS

4 CELLS

-0.4 -0.1 -0.3 -0.5 0.2 0.3 0.4 0.5 01234 OUTPUT V/I CHARACTERISTICS MAX1908 toc11 BATT CURRENT (A) BATT VOLTAGE ERROR (%) 0.1 -0.2

2 CELLS

0.02 0.01 0.03 0.06 0.07 0.05 0.04 0.08 BATT VOLTAGE ERROR vs. VCTL MAX1908 toc12 VCTL/REFIN (%) BATT VOLTAGE ERROR (%) 4 CELLS REFIN = 3.3V NO LOAD Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 20V, TA = +25°C, unless otherwise noted.)

Low-Cost Multichemistry Battery Chargers 01 . 0 0.5 1.5 2.0 CURRENT-SETTING ERROR vs. ICTL MAX1908 toc13 VICTL (V) CURRENT-SETTING ERROR (%) VREFIN = 3.3V 1.5 1.0 0.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 ICHG ERROR vs. CHARGE CURRENT MAX1908 toc14 IBATT (A) ICHG (%) VBATT = 16V VBATT = 12V VBATT = 8V VREFIN = 3.3V -40 -30 -20 -10 01234 IINP ERROR vs. SYSTEM LOAD CURRENT MAX1908 toc15 SYSTEM LOAD CURRENT (A) IINP ERROR (%) IBATT = 0 -80 -60 -40 -20 0 0.5 1.0 1.5 2.0 IINP ERROR vs. INPUT CURRENT MAX1908 toc16 INPUT CURRENT (A) IINP ERROR (%) SYSTEM LOAD = 0 ERROR DUE TO SWITCHING NOISE Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 20V, TA = +25°C, unless otherwise noted.)

Low-Cost Multichemistry Battery Chargers Pin Description PIN NAME FUNCTION 1 DCIN Charging Voltage Input. Bypass DCIN with a 1µF capacitor to PGND. 2 LDO D evi ce P ow er S up p l y. Outp ut of the 5.4V l i near r eg ul ator sup p l i ed fr om D C IN . Byp ass w i th a 1µF cap aci tor to GN D . 3 CLS Source Current-Limit Input. Voltage input for setting the current limit of the input source. 4 REF 4.096V Voltage Reference. Bypass REF with a 1µF capacitor to GND. 5 CCS Input-Current Regulation Loop-Compensation Point. Connect a 0.01µF capacitor to GND. 6 CCI Output-Current Regulation Loop-Compensation Point. Connect a 0.01µF capacitor to GND. 7 CCV Voltage Regulation Loop-Compensation Point. Connect 1kΩ in series with a 0.1µF capacitor to GND. 8 SHDN Shutdown Control Input. Drive SHDN logic low to shut down the MAX1908/MAX8724/MAX8765. Use with a thermistor to detect a hot battery and suspend charging.

9 ICHG

Charge-Current Monitor Output. ICHG is a scaled-down replica of the charger output current. Use ICHG to monitor the charging current and detect when the chip changes from constant-current mode to constant- voltage mode. The transconductance of (CSIP - CSIN) to ICHG is 3µA/mV. 10 ACIN AC Detect Input. Input to an uncommitted comparator. ACIN can be used to detect AC-adapter presence. 11 ACOK AC Detect Output. High-voltage open-drain output is high impedance when VACIN is less than VREF / 2. 12 REFIN Reference Input. Allows the ICTL and VCTL inputs to have ratiometric ranges for increased accuracy.

13 ICTL

Output Current-Limit Set Input. ICTL input voltage range is VREFIN / 32 to VREFIN. The MAX1908/MAX8724 shut down if ICTL is forced below VREFIN / 100 while the MAX8765 does not. When ICTL is equal to LDO, the set point for CSIP - CSIN is 45mV.

14 GND Analog Ground

15 VCTL Output Voltage-Limit Set Input. VCTL input voltage range is 0 to VREFIN. When VCTL is equal to LDO, the set point is (4.2 x CELLS)V.

16 BATT Battery Voltage Input

17 CELLS Cell Count Input. Tri-level input for setting number of cells. GND = 2 cells, float = 3 cells, REFIN = 4 cells.

18 CSIN Output Current-Sense Negative Input

19 CSIP Output Current-Sense Positive Input. Connect a current-sense resistor from CSIP to CSIN.

20 PGND Power Ground

21 DLO Low-Side Power MOSFET Driver Output. Connect to low-side nMOS gate. 22 DLOV Low-Side Driver Supply. Bypass DLOV with a 1µF capacitor to GND. 23 LX High-Side Power MOSFET Driver Power-Return Connection. Connect to the source of the high-side nMOS. 24 BST High-Side Power MOSFET Driver Power-Supply Connection. Connect a 0.1µF capacitor from LX to BST. 25 DHI High-Side Power MOSFET Driver Output. Connect to high-side nMOS gate.

26 CSSN Input Current-Sense Negative Input

27 CSSP Input Current-Sense Positive Input. Connect a current-sense resistor from CSSP to CSSN. 28 IINP Input-Current Monitor Output. IINP is a scaled-down replica of the input current. IINP monitors the total system current. The transconductance of (CSSP - CSSN) to IINP is 3µA/mV.

for setting the charge current and charge voltage. allows shutdown from a microcontroller or thermistor. tion voltage is a function of the battery chemistry. CELLS is the programming input for selecting cell count. CELLS to select an output voltage range for the charger. compensation (see the Compensationsection). Table 2. Cell-Count Programming Table 1. Versions Comparison

Figure 1. µC-Controlled Typical Application Circuit

Figure 2. Typical Application Circuit with Fixed Charging Parameters

Figure 3. Functional Diagram

Low-Cost Multichemistry Battery Chargers MAX1908/MAX8724/MAX8765 Setting the Charging-Current Limit The ICTL input sets the maximum charging current. The current is set by current-sense resistor RS2, connected between CSIP and CSIN. The full-scale differential voltage between CSIP and CSIN is 75mV; thus, for a 0.015Ω sense resistor, the maximum charging current is 5A. Battery-charging current is programmed with ICTL using the equation: The input voltage range for ICTL is V REFIN / 32 to VREFIN. The MAX1908/MAX8724 shut down if ICTL is forced below V REFIN / 100 (min), while the MAX8765 does not. Connect ICTL to LDO to select the internal default full- scale, charge-current sense voltage of 45mV. The charge current when ICTL = LDO is: where RS2 is 0.015 Ω, providing a charge-current set point of 3A. The current at the ICHG output is a scaled-down replica of the battery output current being sensed across CSIP and CSIN (see the Current Measurement section). When choosing the current-sense resistor, note that the voltage drop across this resistor causes further power loss, reducing efficiency. However, adjusting ICTL to reduce the voltage across the current-sense resistor can degrade accuracy due to the smaller signal to the input of the current-sense amplifier. The charging- current-error amplifier (GMI) is compensated at CCI (see the Compensation section). Setting the Input Current Limit The total input current (from an AC adapter or other DC source) is a function of the system supply current and the battery-charging current. The input current regulator limits the input current by reducing the charging current when the input current exceeds the input current-limit set point. System current normally fluc- tuates as portions of the system are powered up or down. Without input current regulation, the source must be able to supply the maximum system current and the maximum charger input current simultaneously. By using the input current limiter, the current capability of the AC adapter can be lowered, reducing system cost. The MAX1908/MAX8724/MAX8765 limit the battery charge current when the input current-limit threshold is exceeded, ensuring the battery charger does not load down the AC adapter voltage. An internal amplifier compares the voltage between CSSP and CSSN to the voltage at CLS. V CLS can be set by a resistive divider between REF and GND. Connect CLS to REF for the full-scale input current limit. The CLS voltage range for the MAX1908/MAX8724 is from 1.6V to REF, while the MAX8765 CLS voltage is from 1.1V to REF. The input current is the sum of the device current, the charger input current, and the load current. The device current is minimal (3.8mA) in comparison to the charge and load currents. Determine the actual input current required as follows: where η is the efficiency of the DC-DC converter. V CLS determines the reference voltage of the GMS error amplifier. Sense resistor RS1 and V CLS determine the maximum allowable input current. Calculate the input current limit as follows: Once the input current limit is reached, the charging current is reduced until the input current is at the desired threshold. When choosing the current-sense resistor, note that the voltage drop across this resistor causes further power loss, reducing efficiency. Choose the smallest value for RS1 that achieves the accuracy requirement for the input current-limit set point. Conditioning Charge The MAX1908 includes a battery-voltage comparator that allows a conditioning charge of overdischarged Li+ battery packs. If the battery-pack voltage is less than 3.1V × number of cells programmed by CELLS, the MAX1908 charges the battery with 300mA current when using sense resistor RS2 = 0.015 Ω. After the battery voltage exceeds the conditioning charge threshold, the MAX1908 resumes full-charge mode, charging to the programmed voltage and current limits. The MAX8724/MAX8765 do not offer this feature. AC Adapter Detection Connect the AC adapter voltage through a resistive divider to ACIN to detect when AC power is available, as shown in Figure 1. ACIN voltage rising trip point is V REF / 2 with 20mV hysteresis. ACOK is an open-drain output and is high impedance when ACIN is less than V REF / 2. Since ACOK can withstand 30V (max), ACOK I V VR SINPUT CLS REF =× 0 075 II IV VINPUT LOAD CHG BATT IN =+ × ⎠⎟η I V RSCHG = 0 045 I V VR SCHG ICTL REFIN =× 0 075

Low-Cost Multichemistry Battery Chargers can drive a p-channel MOSFET directly at the charger input, providing a lower dropout voltage than a Schottky diode (Figure 2). In the MAX1908/MAX8724 the ACOK comparator is enabled after REFIN is ready. In the MAX8765, the ACOK comparator is independent of REFIN. Current Measurement Use ICHG to monitor the battery-charging current being sensed across CSIP and CSIN. The ICHG voltage is proportional to the output current by the equation: V ICHG = ICHG x RS2 x GICHG x R9 where I CHG is the battery-charging current, G ICHG is the transconductance of ICHG (3µA/mV typ), and R9 is the resistor connected between ICHG and ground. Leave ICHG unconnected if not used. Use IINP to monitor the system input current being sensed across CSSP and CSSN. The voltage of IINP is proportional to the input current by the equation: V IINP = IINPUT x RS1 x GIINP x R10 where IINPUT is the DC current being supplied by the AC adapter power, G IINP is the transconductance of IINP (3µA/mV typ), and R10 is the resistor connected between IINP and ground. ICHG and IINP have a 0 to 3.5V output voltage range. Leave IINP unconnected if not used. LDO Regulator LDO provides a 5.4V supply derived from DCIN and can deliver up to 10mA of load current. The MOSFET drivers are powered by DLOV and BST, which must be connected to LDO as shown in Figure 1. LDO supplies the 4.096V reference (REF) and most of the control cir- cuitry. Bypass LDO with a 1µF capacitor to GND. Shutdown The MAX1908/MAX8724/MAX8765 feature a low-power shutdown mode. Driving SHDN low shuts down the MAX1908/MAX8724/MAX8765. In shutdown, the DC- DC converter is disabled and CCI, CCS, and CCV are pulled to ground. The IINP and ACOK outputs continue to function. SHDN can be driven by a thermistor to allow automatic shutdown of the MAX1908/MAX8724/MAX8765 when the battery pack is hot. The shutdown falling threshold is 23.5% (typ) of V REFIN with 1% V REFIN hysteresis to provide smooth shutdown when driven by a thermistor. DC-DC Converter The MAX1908/MAX8724/MAX8765 employ a buck reg- ulator with a bootstrapped nMOS high-side switch and a low-side nMOS synchronous rectifier. CCV, CCI, CCS, and LVC Control Blocks The MAX1908/MAX8724/MAX8765 control input current (CCS control loop), charge current (CCI control loop), or charge voltage (CCV control loop), depending on the operating condition. The three control loops, CCV, CCI, and CCS are brought together internally at the LVC amplifier (lowest voltage clamp). The output of the LVC amplifier is the feedback control signal for the DC-DC controller. The output of the G M amplifier that is the lowest sets the output of the LVC amplifier and also clamps the other two control loops to within 0.3V above the control point. Clamping the other two control loops close to the lowest control loop ensures fast transition with minimal overshoot when switching between different control loops. DC-DC Controller The MAX1908/MAX8724/MAX8765 feature a variable off- time, cycle-by-cycle current-mode control scheme. Depending upon the conditions, the MAX1908/MAX8724/ MAX8765 work in continuous or discontinuous-conduc- tion mode. Continuous-Conduction Mode With sufficient charger loading, the MAX1908/MAX8724/ MAX8765 operate in continuous-conduction mode (inductor current never reaches zero) switching at 400kHz if the BATT voltage is within the following range: 3.1V x (number of cells) < V BATT < (0.88 x VDCIN ) The operation of the DC-DC controller is controlled by the following four comparators as shown in Figure 4:

• IMIN —Compares the control point (LVC) against 0.15V (typ). If IMIN output is low, then a new cycle cannot begin.
• CCMP—Compares the control point (LVC) against the charging current (CSI). The high-side MOSFET on- time is terminated if the CCMP output is high.
• IMAX—Compares the charging current (CSI) to 6A (RS2 = 0.015 Ω). The high-side MOSFET on-time is terminated if the IMAX output is high and a new cycle cannot begin until IMAX goes low.
• ZCMP —Compares the charging current (CSI) to 333mA (RS2 = 0.015 Ω). If ZCMP output is high, then both MOSFETs are turned off. MAX1908/MAX8724/MAX8765

Figure 4. DC-DC Functional Diagram

Low-Cost Multichemistry Battery Chargers In normal operation, the controller starts a new cycle by turning on the high-side n-channel MOSFET and turning off the low-side n-channel MOSFET. When the charge current is greater than the control point (LVC), CCMP goes high and the off-time is started. The off-time turns off the high-side n-channel MOSFET and turns on the low-side n-channel MOSFET. The opera- tional frequency is governed by the off-time and is dependent upon V DCIN and VBATT. The off-time is set by the following equations: where: These equations result in fixed-frequency operation over the most common operating conditions. At the end of the fixed off-time, another cycle begins if the control point (LVC) is greater than 0.15V, IMIN = high, and the peak charge current is less than 6A (RS2 = 0.015Ω), IMAX = high. If the charge current exceeds IMAX, the on-time is terminated by the IMAX compara- tor. IMAX governs the maximum cycle-by-cycle current limit and is internally set to 6A (RS2 = 0.015 Ω). IMAX protects against sudden overcurrent faults. If, during the off-time, the inductor current goes to zero, ZCMP = high, both the high- and low-side MOSFETs are turned off until another cycle is ready to begin. There is a minimum 0.3µs off-time when the (V DCIN - VBATT) differential becomes too small. If VBATT ≥ 0.88 × VDCIN , then the threshold for minimum off-time is reached and the t OFF is fixed at 0.3µs. A maximum on- time of 5ms allows the controller to achieve > 99% duty cycle in continuous-conduction mode. The switching frequency in this mode varies according to the equation: Discontinuous Conduction The MAX1908/MAX8724/MAX8765 enter discontinuous- conduction mode when the output of the LVC control point falls below 0.15V. For RS2 = 0.015 Ω, this corre- sponds to 0.5A: for RS2 = 0.015Ω. In discontinuous mode, a new cycle is not started until the LVC voltage rises above 0.15V. Discontinuous- mode operation can occur during conditioning charge of overdischarged battery packs, when the charge cur- rent has been reduced sufficiently by the CCS control loop, or when the battery pack is near full charge (con- stant-voltage-charging mode). MOSFET Drivers The low-side driver output DLO switches between PGND and DLOV. DLOV is usually connected through a filter to LDO. The high-side driver output DHI is boot- strapped off LX and switches between V LX and VBST. When the low-side driver turns on, BST rises to one diode voltage below DLOV. Filter DLOV with a lowpass filter whose cutoff frequency is approximately 5kHz (Figure 1): Dropout Operation The MAX1908/MAX8724/MAX8765 have 99% duty-cycle capability with a 5ms (max) on-time and 0.3µs (min) off- time. This allows the charger to achieve dropout perfor- mance limited only by resistive losses in the DC-DC converter components (D1, N1, RS1, and RS2, Figure 1). Replacing diode D1 with a p-channel MOSFET driven by ACOK improves dropout performance (Figure 2). The dropout voltage is set by the difference between DCIN and CSIN. When the dropout voltage falls below 100mV, the charger is disabled; 200mV hysteresis ensures that the charger does not turn back on until the dropout volt- age rises to 300mV. Compensation Each of the three regulation loops—input current limit, charging current limit, and charging voltage limit—are compensated separately using CCS, CCI, and CCV, respectively. f RC F kHzC == ×× =1 23 31 48ππ μ Ω . IMIN V RS A= × =01 5 20 2 05. . f LI VV sRIPPLE CSSN BATT = × −() 03. μ f ttON OFF = + I Vt LRIPPLE BATT OFF= × t LI VVON RIPPLE CSSN BATT = × ts VV VOFF DCIN BATT DCIN =× −25. μ MAX1908/MAX8724/MAX8765

sense resistor in the Typical Application Circuits. L varies with load according to RL = VBATT / ICHG. Figure 5. CCV Loop Diagram

0.003Ω, which sets the output zero at 2.412MHz. lent output impedance of the GMI amplifier ≥ 10MΩ. Figure 6. CCV Loop Gain/Phase vs. Frequency

describe how to select these components. Figure 11 illustrates the variation of ripple current vs. Higher inductor values decrease the ripple current. good balance between inductor size and efficiency. C1 = input capacitor ripple current. D = DC-DC converter duty ratio. CHG = battery-charging current. occurs where the duty cycle is nearest 50%. Figure 11. Ripple Current vs. Battery Voltage

Low-Cost Multichemistry Battery Chargers MAX1908/MAX8724/MAX8765where dV is the maximum voltage sag of 0.5V while delivering energy to the inductor during the high-side MOSFET on-time, and dt is the period at highest oper- ating frequency (400kHz): Both tantalum and ceramic capacitors are suitable in most applications. For equivalent size and voltage rating, tantalum capacitors have higher capacitance, but also higher ESR than ceramic capacitors. This makes it more critical to consider ripple current and power-dissipation ratings when using tantalum capaci- tors. A single ceramic capacitor often can replace two tantalum capacitors in parallel. Output Capacitor The output capacitor absorbs the inductor ripple cur- rent. The output capacitor impedance must be signifi- cantly less than that of the battery to ensure that it absorbs the ripple current. Both the capacitance and ESR rating of the capacitor are important for its effec- tiveness as a filter and to ensure stability of the DC-DC converter (see the Compensation section). Either tanta- lum or ceramic capacitors can be used for the output filter capacitor. MOSFETs and Diodes Schottky diode D1 provides power to the load when the AC adapter is inserted. This diode must be able to deliver the maximum current as set by RS1. For reduced power dissipation and improved dropout per- formance, replace D1 with a p-channel MOSFET (P1) as shown in Figure 2. Take caution not to exceed the maximum V GS of P1. Choose resistors R11 and R12 to limit the VGS. The n-channel MOSFETs (N1a, N1b) are the switching devices for the buck controller. High-side switch N1a should have a current rating of at least the maximum charge current plus one-half the ripple current and have an on-resistance (R DS(ON)) that meets the power dissipation requirements of the MOSFET. The driver for N1a is powered by BST. The gate-drive requirement for N1a should be less than 10mA. Select a MOSFET with a low total gate charge (Q GATE ) and determine the required drive current by IGATE = QGATE × f (where f is the DC-DC converter’s maximum switching frequency). The low-side switch (N1b) has the same current rating and power dissipation requirements as N1a, and should have a total gate charge less than 10nC. N2 is used to provide the starting charge to the BST capacitor (C15). During the dead time (50ns, typ) between N1a and N1b, the current is carried by the body diode of the MOSFET. Choose N1b with either an internal Schottky diode or body diode capable of carrying the maximum charging current during the dead time. The Schottky diode D3 provides the supply current to the high-side MOSFET driver. Layout and Bypassing Bypass DCIN with a 1µF capacitor to power ground (Figure 1). D2 protects the MAX1908/MAX8724/ MAX8765 when the DC power source input is reversed. A signal diode for D2 is adequate because DCIN only powers the internal circuitry. Bypass LDO, REF, CCV, CCI, CCS, ICHG, and IINP to analog ground. Bypass DLOV to power ground. Good PC board layout is required to achieve specified noise, efficiency, and stable performance. The PC board layout artist must be given explicit instructions— preferably, a pencil sketch showing the placement of the power-switching components and high-current rout- ing. Refer to the PC board layout in the MAX1908 eval- uation kit for examples. Separate analog and power grounds are essential for optimum performance. Use the following step-by-step guide: 1) Place the high-power connections first, with their grounds adjacent: a) Minimize the current-sense resistor trace lengths, and ensure accurate current sensing with Kelvin connections. b) Minimize ground trace lengths in the high-current paths. c) Minimize other trace lengths in the high-current paths. d) Use > 5mm wide traces. e) Connect C1 to high-side MOSFET (10mm max length). f) LX node (MOSFETs, inductor (15mm max length)). Ideally, surface-mount power components are flush against one another with their ground terminals almost touching. These high-current grounds are then connected to each other with a wide, filled zone of top-layer copper, so they do not go through vias. The resulting top-layer power ground plane is connected to the normal ground plane at the MAX1908/MAX8724/MAX8765s’ backside exposed pad. Other high-current paths should also be mini- mized, but focusing primarily on short ground and current-sense connections eliminates most PC board layout problems. C I s V C1 2 1>× . μ

Table 3. Component List for Circuit of Figure 2 than 10mm from the current-sense resistors. itors can be placed further away. ground and normal ground to this node.

Low-Cost Multichemistry Battery Chargers MAX1908/MAX8724/MAX8765 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu it patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 29 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) QFN THIN.EPS (ND-1) X e e D C PIN # 1 I.D. (NE-1) X e E/2 E 0.08 C 0.10 C A A1 A3 DETAIL A E2/2

0.10 M C A B

PIN # 1 I.D. b 0.35x45° D/2 D2/2 LC LC e e LCCL k LL DETAIL B LL1 e AAAAA MARKING I 1 221-0140 PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm -DRAWING NOT TO SCALE- L e/2 COMMON DIMENSIONS MAX. EXPOSED PAD VARIATIONS NOM.MIN. MIN. NOM. MAX. NE ND PKG. CODES 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR T2855-3 AND T2855-6. NOTES: SYMBOL PKG. N e E D b A k 10. WARPAGE SHALL NOT EXCEED 0.10 mm. JEDEC 0.70 0.800.75 4.90 4.90 0.25 0.25 WHHB 0.350.30 5.10 5.105.00 0.80 BSC. 5.00 0.05 0.20 REF. 0.02 MIN. MAX.NOM. 16L 5x5 L 0.30 0.500.40 -- - -- - WHHC 5.00 5.00 0.30 0.55 0.65 BSC. 0.45 0.25 4.90 4.90 0.25 0.65 5.10 5.10 0.35 20L 5x5 0.20 REF. 0.75 0.02 NOM. 0.70 MIN. 0.05 0.80 MAX. -- - WHHD-1 5.00 5.00 0.25 0.55 0.50 BSC. 0.45 0.25 4.90 4.90 0.20 0.65 5.10 5.10 0.30 28L 5x5 0.20 REF. 0.75 0.02 NOM. 0.70 MIN. 0.05 0.80 MAX. -- - WHHD-2 5.00 5.00 0.40 0.50 BSC. 0.30 0.25 4.90 4.90 0.50 5.10 5.10 32L 5x5 0.20 REF. 0.75 0.02 NOM. 0.70 MIN. 0.05 0.80 MAX. 0.20 0.25 0.30 DOWN BONDS ALLOWED NO NO NO NO YES YES YES YES L 0.40 0.40 ** SEE COMMON DIMENSIONS TABLE ±0.15 11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. I 2 221-0140 PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm -DRAWING NOT TO SCALE- 12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. 0.050 0.02 0.600.40 0.50 ----- 0.30 0.40 0.50 5.104.90 5.00 0.25 0.35 0.45 0.40 BSC. 0.15 4.90 0.250.20 5.00 5.10 0.20 REF. 0.70 MIN. 0.75 0.80 NOM. 40L 5x5 MAX. 13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", ±0.05. exceptions