LT1510

LT1510 LINER | Alldatasheet

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Technical content

Constant-Current Battery Charger Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)

• NiCd and NiMH batteries require charge termination circuitry (not shown in Figure 1).

, LTC and LT are registered trademarks of Linear Technology Corporation. ing requirement for lithium cells. The LT1510 can charge batteries ranging from 2V to 20V. 50°C/W, an 8-pin SO and a 16-pin PDIP.

FEATURES

n Charges NiCd, NiMH and Lithium-Ion Batteries –– Only One 1/10W Resistor Is Needed to Program Charging Current n High Efficiency Current Mode PWM with 1.5A Internal Switch and Sense Resistor n 3% Typical Charging Current Accuracy n Precision 0.5% Voltage Reference for Voltage Mode Charging or Overvoltage Protection n Current Sensing Can Be at Either Terminal of the Battery n Low Reverse Battery Drain Current: 3µA n Charging Current Soft Start n Shutdown Control n 500kHz Version Uses Small Inductor With switching frequency as high as 500kHz, The LT 1510 current mode PWM battery charger is the smallest, sim- APPLICATIONSU DESCRIPTIONU n Chargers for NiCd, NiMH and Lithium Batteries n Step-Down Switching Regulator with Precision Adjustable Current Limit Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)

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ABSOLUTE MAXIMUM RATINGSW WW U Operating Ambient Temperature Range Operating Junction Temperature Range PACKAGE/ORDER INFORMATIONW UU Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted. (Notes 7, 8) PARAMETER CONDITIONS MIN TYP MAX UNITS Overall Supply Current V PROG = 2.7V, VCC ≤ 20V l 2.90 4.3 mA VPROG = 2.7V, 20V < VCC ≤ VMAX l 2.91 4.5 mA DC Battery Current, IBAT (Note 1) 8V ≤ VCC ≤ 25V, 0V ≤ VBAT ≤ 20V, TJ < 0°C l 0.91 1.09 A RPROG = 4.93k l 0.93 1.0 1.07 A RPROG = 3.28k (Note 4) l 1.35 1.5 1.65 A RPROG = 49.3k l 75 100 125 mA TJ < 0°C l 70 130 mA VCC = 28V, VBAT = 20V RPROG = 4.93k l 0.93 1.0 1.07 A RPROG = 49.3k l 75 100 125 mA LT1510CN LT1510CS LT1510IN LT1510IS ORDER PART NUMBER TJMAX = 125°C, θJA = 125°C/ W ORDER PART NUMBER GN PART MARKING *V CC1 AND VCC2 SHOULD BE CONNECTED TOGETHER CLOSE TO THE PINS. FOUR CORNER PINS ARE FUSED TO INTERNAL DIE ATTACH PADDLE FOR HEAT SINKING. CONNECT THESE FOUR PINS TO EXPANDED PC LANDS FOR PROPER HEAT SINKING. TOP VIEW N PACKAGE 16-LEAD PDIP GND SW BOOST GND OVP SENSE GND GND GND V CC2 VCC1 PROG V C BAT GND GND** S PACKAGE* 16-LEAD PLASTIC SO TJMAX = 125°C, θJA = 75°C/ W (N) TJMAX = 125°C, θJA = 50°C/ W (S)* TOP VIEW SW BOOST GND SENSE V CC PROG V C BAT S8 PACKAGE 8-LEAD PLASTIC SO LT1510CS8 LT1510IS8 1510 1510I ORDER PART NUMBER S8 PART MARKING TOP VIEW GND SW BOOST GND OVP NC SENSE GND GND V CC2 VCC1 PROG V C NC BAT GND GN PACKAGE (0.015 IN) 16-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 75°C/ W ** FOUR CORNER PINS ARE FUSED TO INTERNAL DIE ATTACH PADDLE FOR HEAT SINKING. CONNECT THESE FOUR PINS TO EXPANDED PC LANDS FOR PROPER HEAT SINKING. LT1510CGN LT1510IGN LT1510-5CGN LT1510-5IGN 1510 1510I 15105 15105I

VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Overall Minimum Input Operating Voltage Undervoltage Lockout l 6.2 7 7.8 V Reverse Current from Battery (When VCC Is Not V BAT ≤ 20V, 0°C ≤ TJ ≤ 70°C l 31 5 µA Connected, VSW Is Floating) Boost Pin Current V CC – VBOOST ≤ 20V l 0.10 20 µA 20V < VCC – VBOOST ≤ 28V l 0.25 30 µA 2V ≤ VBOOST – VCC ≤ 8V (Switch ON) l 61 1 m A 8V < VBOOST – VCC ≤ 25V (Switch ON) l 81 4 m A Switch Switch ON Resistance V CC = 10V ISW = 1.5A, VBOOST – VSW ≥ 2V (Note 4) l 0.3 0.5 Ω ISW = 1A, VBOOST – VSW < 2V (Unboosted) l 2.0 Ω ΔIBOOST/ΔISW During Switch ON V BOOST = 24V, ISW ≤ 1A 20 35 mA/A Switch OFF Leakage Current V SW = 0V, VCC ≤ 20V l 2 100 µA 20V < VCC ≤ 28V l 4 200 µA Maximum VBAT with Switch ON l VCC – 2 V Minimum IPROG for Switch ON 24 2 0 µA Minimum IPROG for Switch OFF at VPROG ≤ 1V l 1 2.4 mA Current Sense Amplifier Inputs (SENSE, BAT) Sense Resistance (RS1) 0.08 0.12 Ω Total Resistance from SENSE to BAT (Note 3) 0.2 0.25 Ω BAT Bias Current (Note 5) V C < 0.3V –200 –375 µA VC > 0.6V 700 1300 µA Input Common Mode Limit (Low) l –0.25 V Input Common Mode Limit (High) l VCC – 2 V Reference Reference Voltage (Note 1) S8 Package R PROG = 4.93k, Measured at PROG Pin l 2.415 2.465 2.515 V Reference Voltage (Note 2) 16-Pin R PROG = 3.28k, Measured at OVP with 2.453 2.465 2.477 V VA Supplying IPROG and Switch OFF Reference Voltage Tolerance, 16-Pin Only 8V ≤ VCC ≤ 28V, 0°C ≤ TJ ≤ 70°C l 2.446 2.465 2.480 V 8V ≤ VCC ≤ 28V, 0°C ≤ TJ ≤ 125°C l 2.441 2.489 V 8V ≤ VCC ≤ 28V, TJ < 0°C l 2.430 2.489 V Oscillator Switching Frequency LT1510 180 200 220 kHz LT1510-5 440 500 550 kHz Switching Frequency Tolerance All Conditions of V CC, Temperature, LT1510 l 170 200 230 kHz LT1510, TJ < 0°C l 160 230 kHz LT1510-5 l 425 500 575 kHz LT1510-5, TJ < 0°C l 400 575 kHz Maximum Duty Cycle LT1510 l 87 % LT1510, TA = 25°C (Note 8) 90 93 % LT1510-5 (Note 9) l 77 81 %

VCC = 16V, VBAT = 8V, VMAX (maximum operating VCC) = 28V, no load on any outputs, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Current Amplifier (CA2) Transconductance V C = 1V, IVC = ±1µA 150 250 550 µmho Maximum VC for Switch OFF l 0.6 V IVC Current (Out of Pin) V C ≥ 0.6V 100 µA VC < 0.45V 3 mA Voltage Amplifier (VA), 16-Pin Only Transconductance (Note 2) Output Current from 100 µA to 500µA 0.5 1.2 2.5 mho Output Source Current, VCC = 10V V PROG = VOVP = VREF + 10mV 1.3 mA OVP Input Bias Current At 0.75mA VA Output Current l 50 150 nA The l denotes specifications which apply over the specified temperature range. Note 1: Tested with Test Circuit 1. Note 2: Tested with Test Circuit 2. Note 3: Sense resistor RS1 and package bond wires. Note 4: Applies to 16-pin only. 8-pin packages are guaranteed but not tested at –40 °C. Note 5: Current (≈ 700µA) flows into the pins during normal operation and also when an external shutdown signal on the VC pin is greater than 0.3V. Current decreases to ≈ 200µA and flows out of the pins when external shutdown holds the VC pin below 0.3V. Current drops to near zero when input voltage collapses. See external Shutdown in Applications Information section. Note 6: A linear interpolation can be used for reference voltage specification between 0°C and –40 °C. Note 7: Commercial grade device specifications are guaranteed over the 0°C to 70°C temperature range. In addition, commercial grade device specifications are assured over the –40°C to 85°C temperature range by design or correlation, but are not production tested. Maximum allowable ambient temperature may be limited by power dissipation. Parts may not necessarily be operated simultaneously at maximum power dissipation and maximum ambient temperature. Temperature rise calculations must be done as shown in the Applications Information section to ensure that maximum junction temperature does not exceed the 125°C limit. With high power dissipation, maximum ambient temperature may be less than 70°C. Note 8: Industrial grade device specifications are guaranteed over the –40 °C to 85°C temperature range. Note 9: 91% maximum duty cycle is guaranteed by design if V BAT or VX (see Figure 8 in Application Information) is kept between 3V and 5V. Note 10: VBAT = 4.2V. Thermally Limited Maximum Charging Current, 8-Pin SO INPUT VOLTAGE (V) MAXIMUM CHARGING CURRENT (A) 1.3 1.1 0.9 0.7 0.5 0.3

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(θJA=125°C/W) TAMAX=60°C TJMAX=125°C Thermally Limited Maximum Charging Current, 16-Pin SO INPUT VOLTAGE (V) MAXIMUM CHARGING CURRENT (A) 1.5 1.3 1.1 0.9 0.7 0.5

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(θJA=50°C/W) TAMAX=60°C TJMAX=125°C 16V BATTERY 12V BATTERY 8V BATTERY 4V BATTERY Thermally Limited Maximum Charging Current, 16-Pin GN INPUT VOLTAGE (V) MAXIMUM CHARGING CURRENT (A) 1.5 1.3 1.1 0.9 0.7 0.5 LT1510 • TPC14 5 10 15 25 θJA = 80°C/W TAMAX = 60°C TJMAX = 125°C 4V BATTERY 8V BATTERY 12V BATTERY 16V BATTERY TYPICAL PERFORMANCE CHARACTERISTICS UW

TYPICAL PERFORMANCE CHARACTERISTICS UW Switching Frequency vs Temperature DUTY CYCLE (%) 0 1 03 05 07 0 ICC (mA)

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125°C 0°C 25°C VCC = 16V ICC vs Duty Cycle TEMPERATURE (°C) –20 FREQUENCY (kHz) 200 40 80 120 60 100 140

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IBAT (A) 0.1 EFFICIENCY (%) 100

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0.3 0.7 VCC = 15V (EXCLUDING DISSIPATION ON INPUT DIODE D3) V BAT = 8.4V Efficiency of Figure 2 Circuit ICC vs VCC VCC (V) ICC (mA) 7.0 6.5 6.0 5.5 5.0 4.5 5 10 15 20

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125°C 25°C 0°C MAXIMUM DUTY CYCLE IVA (mA) ∆VOVP (mV) 0.8

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125°C 25°C IVA vs ΔVOVP (Voltage Amplifier) VCC (V) ∆VREF (V) 0.003 0.002 0.001 –0.001 –0.002 –0.003 5 10 15 20

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TEMPERATURE (°C) DUTY CYCLE (%) 120

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VPROG (V) 0123 54 IPROG (mA)

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125°C 25°C PROG Pin Characteristic VC (V) IVC (mA) –1.20 –1.08 –0.96 –0.84 –0.72 –0.60 –0.48 –0.36 –0.24 –0.12 0.12 1.6

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0.4 0.8 1.2 2.0 VC Pin Characteristic

TYPICAL PERFORMANCE CHARACTERISTICS UW SWITCH CURRENT (A) BOOST CURRENT (mA)

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VCC = 16V VBOOST = 38V 28V 18V Switch Current vs Boost Current vs Boost Voltage TEMPERATURE (°C) REFERENCE VOLTAGE (V) 2.470 2.468 2.466 2.464 2.462 2.460 2.458 25 50 75 100

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VBOOST (V) 426 8 MAXIMUM DUTY CYCLE (%) 16 18 20 LT1510 • TPC15 10 12 14 22 VBOOST vs Maximum Duty Cycle PIN FUNCTIONSUU U GND: Ground Pin. SW: Switch Output. The Schottky catch diode must be placed with very short lead length in close proximity to SW pin and GND. VCC: Supply for the Chip. For good bypass, a low ESR capacitor of 10µF or higher is required, with the lead length kept to a minimum. VCC should be between 8V and 28V and at least 2V higher than VBAT for VBAT less than 10V, and 2.5V higher than VBAT for VBAT greater than 10V. Under- voltage lockout starts and switching stops when VCC goes below 7V. Note that there is a parasitic diode inside from SW pin to VCC pin. Do not force VCC below SW by more than 0.7V with battery present. All V CC pins should be shorted together close to the pins. BOOST: This pin is used to bootstrap and drive the switch power NPN transistor to a low on-voltage for low power dissipation. In normal operation, V BOOST = V CC + V BAT when switch is on. Maximum allowable VBOOST is 55V. SENSE: Current Amplifier CA1 Input. Sensing can be at either terminal of the battery. Note that current sense resistor RS1 (0.08Ω ) is between Sense and BAT pins. BAT: Current Amplifier CA1 Input. PROG: This pin is for programming the charging current and for system loop compensation. During normal opera- tion, VPROG stays close to 2.465V. If it is shorted to GND the switching will stop. When a microprocessor-controlled DAC is used to program charging current, it must be capable of sinking current at a compliance up to 2.465V. VC: This is the control signal of the inner loop of the current mode PWM. Switching starts at 0.7V and higher V C corresponds to higher charging current in normal opera- tion. A capacitor of at least 0.1µF to GND filters out noise and controls the rate of soft start. To shut down switching, pull this pin low. Typical output current is 30µA. OVP: This is the input to the amplifier VA with a threshold of 2.465V. Typical input current is about 50nA into pin. For charging lithium-ion batteries, VA monitors the battery voltage and reduces charging current when battery volt- age reaches the preset value. If it is not used, the OVP pin should be grounded.

≈ 0.65V VBAT VC 2N3055 LT1010 CA2 – CA1 3.3k 20k RS1 IBAT BAT SENSE

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0.047µF LT1510 0.22µF 56µF60k LT1006 – + VSW 0.7V 1.5V VBAT VREF VC GND SLOPE COMPENSATION PWM B1 CA2 CA1 VA VREF 2.465V SHUTDOWN 200kHz OSCILLATOR S R R RS1IBAT IPROG IPROG VCC VCC BOOST SW SENSE BAT 0VP 1510 BD PROG RPROG CPROG 60k IPROG IBAT = 500µA/A QSW gm = 0.64Ω CHARGING CURRENT IBAT = (IPROG)(2000) = 2.465V RPROG (2000)()

2.465V VA 10k 10k OVP

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0.47µF Test Circuit 2 OPERATIOU The LT1510 is a current mode PWM step-down (buck) switcher. The battery DC charging current is programmed by a resistor RPROG (or a DAC output current) at the PROG pin (see Block Diagram). Amplifier CA1 converts the charging current through R S1 to a much lower current IPROG (500µA/A) fed into the PROG pin. Amplifier CA2 compares the output of CA1 with the programmed current and drives the PWM loop to force them to be equal. High DC accuracy is achieved with averaging capacitor C PROG. Note that IPROG has both AC and DC components. IPROG goes through R1 and generates a ramp signal that is fed to the PWM control comparator C1 through buffer B1 and level shift resistors R2 and R3, forming the current mode inner loop. The Boost pin drives the switch NPN QSW into saturation and reduces power loss. For batteries like lithium-ion that require both constant-current and con- stant-voltage charging, the 0.5%, 2.465V reference and the amplifier VA reduce the charging current when battery voltage reaches the preset level. For NiMH and NiCd, VA can be used for overvoltage protection. When input volt- age is not present, the charger goes into low current (3µA typically) sleep mode as input drops down to 0.7V below battery voltage. To shut down the charger, simply pull the V C pin low with a transistor. APPLICATIONS INFORMATIONWU UU more in depth appications examples. Input and Output Capacitors In the chargers in Figures 1 and 2 on the first page of this data sheet, the input capacitor CIN is assumed to absorb all input switching ripple current in the converter, so it must have adequate ripple current rating. Worst-case RMS ripple current will be equal to one half of output charging current. Actual capacitance value is not critical. Solid tantalum capacitors such as the AVX TPS and Sprague 593D series have high ripple current rating in a relatively small surface mount package, but caution must be used when tantalum capacitors are used for input bypass. High input surge currents can be created when the adapter is hot-plugged to the charger and solid tantalum capacitors have a known failure mechanism when subjected to very high turn-on surge currents. Highest possible voltage rating on the capacitor will minimize problems. Consult with the manufacturer before use. Alternatives include new high

to achieve adequate ripple rating. OS-CON can also be used. the ESR of the output capacitor and the battery impedance. ripple will flow in the battery. longer input start-up times are needed. adapter voltage where full power can be achieved. A fixed undervoltage lockout of 7V is built into the VCC pin. Internal lockout is performed by clamping the VC pin low. Zener diode (see Figure 3 circuit). Figure 3. Undervoltage Lockout

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The lockout voltage will be VIN = VZ + 1V.

For example, 1A charging current is needed. that the gate is pulled to ground. to drop to ≈ 200µA and reverse, flowing out of the BAT pin. causes all currents to drop to near zero. Figure 4. PWM Current Programming

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pulling the V C pin low with an open collector or drain. level to avoid multiple comparator transitions. of 0.5A when Q1 is on and 50mA when Q1 is off. input power applied for very long periods of time. Figure 5. Disconnecting Voltage Divider Figure 6. Charging NiMH or NiCd Batteries

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Figure 7. Current Comparator for Initiating Float Time-Out

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lower value and maintained as a constant trickle charge. time period to reduce 100% charge time. Performance Characteristics section.

BAT) instead of VBAT (see Figure 8). readings to other situations. Vias should be used to connect board layers together.

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Figure 9. LT1510 Thermal Resistance

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during normal operation (see Figure 11). Figure 12. High Speed Switching Path

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Figure 10. LT1510 Lead temperature the input is only a volt or two above the battery voltage. Figure 11. Replacing the Input Diode

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connected to expand traces for low thermal resistance. high current switching path.

Information furnished by Linear Technology Corporation is believed to be accurate and reliable. tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

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Figure 13. Critical Electrical and Thermal Path Layer *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

1510fc LT/GP 1197 REV C 4K • PRINTED IN USA  LINEAR TECHNOLOGY CORPORA TION 1995 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 l (408) 432-1900 FAX: (408) 434-0507 l TELEX: 499-3977 l www.linear-tech.com PART NUMBER DESCRIPTION COMMENTS LTC 1325 Microprocessor-Controlled Battery Management Can Charge, Discharge and Gas Gauge NiCd, NiMH and Pb-Acid System Batteries with Software Charging Profiles LT1372/LT1377 500kHz/1MHz Step-Up Switching Regulators High Frequency, Small Inductor, High Efficiency Switchers, 1.5A Switch LT1373 250kHz Step-Up Switching Regulator High Efficiency, Low Quiescent Current, 1.5A Switch LT1376 500kHz Step-Down Switching Regulator High Frequency, Small Inductor, High Efficiency Switcher, 1.5A Switch LT1511 3A Constant-Voltage/Constant-Current Battery Charger High Efficiency, Minimal External Components to Fast Charge Lithium, NiMH and NiCd Batteries LT1512 SEPIC Battery Charger V IN Can Be Higher or Lower Than Battery Voltage RELATED PARTS TYPICAL APPLICATIONU Dimensions in inches (millimeters) unless otherwise noted.PACKAGE DESCRIPTIONU S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.016 – 0.050 0.406 – 1.270 0.010 – 0.020 0° – 8° TYP 0.008 – 0.010 (0.203 – 0.254) 1 2 3 4 5 6 7 8 0.150 – 0.157** (3.810 – 3.988) 16 15 14 13 0.386 – 0.394* (9.804 – 10.008) 0.228 – 0.244 (5.791 – 6.197) 12 11 10 9 S16 0695 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) TYP DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE Adjustable Voltage Regulator with Precision Adjustable Current Limit SW BOOST VCC2 VIN 18V TO 25V VOUT 2.5V TO 15V CURRENT LIMIT LEVEL 50mA TO 1A

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0.22µF 0.1µF 100µF 30µH LT1510 1N5819 1N914 +POT POT 100k R PROG 4.93k0.01µF 500µF 1µF GND CURRENT LIMIT LEVEL = (2000) 2.465V RPROG VCC1 PROG BAT OVP SENSE VC