LT1610

LT1610 LINER

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converter that operates from an input voltage as low as 1V. 1.7MHz, allowing the use of tiny capacitors and inductors. 300mA current with a voltage drop of 300mV. The LT1610 is available in 8-lead MSOP and SO packages. Burst Mode is a trademark of Linear Technology Corporation. Figure 1. 1-Cell to 3V Step-Up Converter , LTC and LT are registered trademarks of Linear Technology Corporation.

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ABSOLUTE MAXIMUM RATINGSW WW U PACKAGE/ORDER INFORMATIONW UU TJMAX = 125°C, qJA = 160°C/W TJMAX = 125°C, qJA = 120°C/W (Note 1) Consult factory for Military grade parts. Operating Temperature Range (Note 1) ORDER PART NUMBER LT1610CS8 LT1610IS8 S8 PART MARKING 1610 1610I ORDER PART NUMBER LT1610CMS8 MS8 PART MARKING LTDT V C FB SHDN PGND COMP GND V IN SW TOP VIEW MS8 PACKAGE 8-LEAD PLASTIC MSOP TOP VIEW VC FB SHDN PGND COMP GND V IN SW S8 PACKAGE 8-LEAD PLASTIC SO PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage 0.9 1 V Maximum Operating Voltage 8V Feedback Voltage l 1.20 1.23 1.26 V Quiescent Current V SHDN = 1.5V, Not Switching 30 60 mA Quiescent Current in Shutdown V SHDN = 0V, VIN = 2V 0.01 0.5 mA VSHDN = 0V, VIN = 5V 0.01 1.0 mA FB Pin Bias Current l 27 80 nA Reference Line Regulation 1V £ VIN £ 2V (25°C, 0°C) 0.6 1 %/V 1V £ VIN £ 2V (70°C) 2 %/V 2V £ VIN £ 8V (70°C) 0.2 %/V Error Amp Transconductance DI = 2mA2 5 mmhos Error Amp Voltage Gain 100 V/V Switching Frequency l 1.4 1.7 2 MHz Maximum Duty Cycle 77 80 95 % l 75 95 % ELECTRICAL C CHARA TERISTICS The l denotes specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. Commercial grade 0°C to 70°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted. (Note 2)

ELECTRICAL C CHARA TERISTICS The l denotes specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. Commercial grade 0°C to 70°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Switch Current Limit (Note 3) 450 600 900 mA Switch VCESAT ISW = 300mA 300 350 mV l 400 mV Switch Leakage Current V SW = 5V 0.01 1 mA SHDN Input Voltage High 1V SHDN Input Voltage Low 0.3 V SHDN Pin Bias Current V SHDN = 3V 10 mA VSHDN = 0V 0.01 0.1 mA The l denotes specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. Industrial grade – 40°C to 85°C, VIN = 1.5V, VSHDN = VIN, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage T A = 85°C 0.9 1 V TA = –40 °C 1.25 V Maximum Operating Voltage 8V Feedback Voltage l 1.20 1.23 1.26 V Quiescent Current 30 60 mA Quiescent Current in Shutdown V SHDN = 0V, VIN = 2V 0.01 0.5 mA VSHDN = 0V, VIN = 5V 0.01 1.0 mA FB Pin Bias Current l 27 80 nA Reference Line Regulation 2V £ VIN £ 8V (–40 °C) 0.03 0.15 %/V 2V £ VIN £ 8V (85°C) 0.2 %/V Error Amp Transconductance DI = 2mA2 5 mmhos Error Amp Voltage Gain 100 V/V Switching Frequency (Note 4) l 1.4 1.7 2 MHz Maximum Duty Cycle (Note 4) 77 80 95 % l 75 95 % Switch Current Limit 450 600 900 mA Switch VCESAT ISW = 300mA 300 350 mV l 400 mV Switch Leakage Current V SW = 5V 0.01 1 mA SHDN Input Voltage High 1V SHDN Input Voltage Low 0.3 V SHDN Pin Bias Current V SHDN = 3V 10 mA VSHDN = 0V 0.01 0.1 mA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1610C is guaranteed to meet specified performance from 0°C to 70°C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at –40 °C and 85°C. The LT1610I is guaranteed to meet the extended temperature limits. Note 3: Current limit guaranteed by design and/or correlation to static test. Current limit is affected by duty cycle due to ramp generator. See Block Diagram. Note 4: Not 100% tested at 85°C.

TYPICAL PERFOR A CE CHARACTERISTICS UW Current Limit vs Duty CycleVCESAT vs Current SWITCH CURRENT (mA)

100 VCESAT (mV)

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TA = 85°C TA = – 40°C TA = 25°C Current Limit (DC = 30%) vs Temperature TEMPERATURE (°C) –50

200 SWITCH CURRENT LIMIT (mA)300

–25 02 5 5 0

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vs Input Voltage Feedback Voltage SHDN Pin Current vs SHDN Pin Voltage Transient Response, Circuit of Figure 1 SHDN VOLTAGE (V) SHDN CURRENT (µA) 35 8

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VIN = 1.25V 500 ms/DIV VOUT = 3V

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DUTY CYCLE (%) CURRENT LIMIT (mA) 800 700 600 500 400 300 200 100

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20 40 60 100 7010 30 50 90 TA = 25°C INPUT VOLTAGE (V) SWITCHING FREQUENCY (MHz) 0.25 0.75 1.00 1.25 2.50 1.75 2 4 5

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0.50 2.00 2.25 1.50 13 6 7 8 TA = 25°C TEMPERATURE (°C) –50

1.210 FEEDBACK VOLTAGE (V)

1.215 1.220 1.225 1.230 1.240 –25 02 5 5 0

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1.235 Quiescent Current vs Temperature TEMPERATURE (°C) –5 0 QUIESCENT CURRENT (µA) 25 75

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–2 5 0 5 0 100 Burst Mode Operation, Circuit of Figure 1 VOUT 20mV/DIV AC COUPLED SWITCH VOLTAGE 2V/DIV VIN = 1.25V 20 ms/DIV VOUT = 3V ILOAD = 3mA

FB (Pin 2): Feedback Pin. Reference voltage is 1.23V. OUT according to VOUT = 1.23V (1 + R1/R2). device. Tie to 1V or more to enable. SW (Pin 5): Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to keep EMI down. VIN (Pin 6): Input Supply Pin. Must be locally bypassed. current except switch current. Tie to local ground plane.

• 10 PGND

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Figure 2. LT1610 Block Diagram

Figure 2. Q1 and Q2 form a bandgap reference core whose crease, A1’s output goes high, enabling the rest of the IC. high efficiency even at load currents of 1mA or less. divider, appears at the FB pin, closing the overall loop. 8). The typical values for the internal RC are 50k and 50pF. introducing dI/dt induced noise into the ground plane.

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Figure 3. Recommended Component Placement for Boost Converter. Note Direct High Current Paths Using

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Figure 5. Recommended Component Placement for SEPIC

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Figure 4. Li-Ion to 3.3V SEPIC DC/DC Converter that spans (i.e., can be higher or lower than) the output.

APPLICATIONS INFORMATIONWU UU COMPONENT SELECTION Inductors Inductors used with the LT1610 should have a saturation current rating (–30% of zero current inductance) of ap- proximately 0.5A or greater. DCR should be 0.5W or less. The value of the inductor should be matched to the power requirements and operating voltages of the application. In most cases a value of 4.7mH or 10mH is suitable. The Murata LQH3C inductors specified throughout the data sheet are small and inexpensive, and are a good fit for the LT1610. Alternatives are the CD43 series from Sumida and the DO1608 series from Coilcraft. These inductors are slightly larger but will result in slightly higher circuit efficiency. Chip inductors, although tempting to use because of their small size and low cost, generally do not have enough energy storage capacity or low enough DCR to be used successfully with the LT1610. Diodes The Motorola MBR0520 is a 0.5 amp, 20V Schottky diode. This is a good choice for nearly any LT1610 application, unless the output voltage or the circuit topology require a diode rated for higher reverse voltages. Motorola also offers the MBR0530 (30V) and MBR0540 (40V) versions. Most one-half amp and one amp Schottky diodes are suitable; these are available from many manufacturers. If you use a silicon diode, it must be an ultrafast recovery type. Efficiency will be lower due to the silicon diode’s higher forward voltage drop. Capacitors The input capacitor must be placed physically close to the LT1610. ESR is not critical for the input. In most cases inexpensive tantalum can be used. The choice of output capacitor is far more important. The quality of this capacitor is the greatest determinant of the output voltage ripple. The output capacitor performs two major functions. It must have enough capacitance to satisfy the load under transient conditions and it must shunt the AC component of the current coming through the diode from the inductor. The ripple on the output results when this AC current passes through the finite impedance of the output capacitor. The capacitor should have low impedance at the 1.7MHz switching frequency of the LT1610. At this frequency, the impedance is usually dominated by the capacitor’s equivalent series resistance (ESR). Choosing a capacitor with lower ESR will result in lower output ripple. Perhaps the best way to decrease ripple is to add a 1 mF ceramic capacitor in parallel with the bulk output capaci- tor. Ceramic capacitors have very low ESR and 1 mF is enough capacitance to result in low impedance at the switching frequency. The low impedance can have a dramatic effect on output ripple voltage. To illustrate, examine Figure 6’s circuit, a 4-cell to 5V/100mA SEPIC DC/DC converter. This design uses inexpensive aluminum electrolytic capacitors at input and output to keep cost down. Figure 7 details converter operation at a 100mA load, without ceramic capacitor C5. Note the 400mV spikes on V OUT. After C5 is installed, output ripple decreases by a factor of 8 to about 50mV P-P. The addition of C5 also improves efficiency by 1 to 2 percent. Low ESR and the required bulk output capacitance can be obtained using a single larger output capacitor. Larger tantalum capacitors, newer capacitor technologies (for example the POSCAP from Sanyo and SPCAP from Panasonic) or large value ceramic capacitors will reduce the output ripple. Note, however, that the stability of the circuit depends on both the value of the output capacitor and its ESR. When using low value capacitors or capaci- tors with very low ESR, circuit stability should be evalu- ated carefully, as described below. Loop Compensation The LT1610 is a current mode PWM switching regulator that achieves regulation with a linear control loop. The LT1610 provides the designer with two methods of com- pensating this loop. First, you can use an internal compen- sation network by tying the COMP pin to the V C pin. This results in a very small solution and reduces the circuit’s total part count. The second option is to tie a resistor RC and a capacitor CC in series from the VC pin to ground. This allows optimization of the transient response for a wide variety of operating conditions and power components.

Figure 7. Switching Waveforms Without Ceramic Capacitor C5 Figure 8. Switching Waveforms with Ceramic Capacitor C5. Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC DC/DC Converter sation network is modified to achieve stable operation. fore offer very low output ripple in a small package. the X5R is less expensive and is available in higher values.

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4 CELLS

10 AVX TAJA226M006 Tantalum Internal

11 Taiyo Yuden JMK316BJ106 Internal

12 Taiyo Yuden JMK316BJ106 220pF/220k

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Figure 9. 2.5V to 5V Boost Converter Can Operate with a Figure 10. Tantalum Output Capacitor Figure 11. 10mF X5R-Type Ceramic Output Capacitor Figure 12. Ceramic Output Capacitor with 220pF/220k

4.7mH D1 VOUT 50mA

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C1, C2: AVX TAJA156M010R D1: MOTOROLA MBR0520 L1: SUMIDA CD43-4R7 MURATA LQH1C4R7 VIN SW PGND FBSHDN GNDCOMP LT1610 VC LOAD CURRENT (mA) 0.1 EFFICIENCY (%) 11 0

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VIN = 1.5V VIN = 3V VIN = 2V Efficiency2-Cell to 5V Converter 33mF 10mF2 CELLS 4.7mH D1 VOUT 3.3V 70mA

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C1: AVX TAJA106M010R C2: AVX TAJB336M006R D1: MBR0520 L1: MURATA LQH3C4R7 VIN SW PGND FBVC SHDNCOMP LT1610 SHUTDOWN GND LOAD (mA) EFFICIENCY (%) 0.1 10 100 1000

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3.3VOUT 3VIN 1.5VIN 2VIN Efficiency2-Cell to 3.3V Converter Efficiency5V to 12V/100mA Boost Converter LOAD CURRENT (mA) 0.1 EFFICIENCY (%) 1 10 100

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+C1 15mF 115k C1: AVX TAJA156M010 C2: AVX TAJB156M016 D1: MOTOROLA MBR0520 L1: MURATA LQH3C100M24 VIN SW PGND FBVC SHDNCOMP LT1610 SHUTDOWN GND

+C1 15mF 158k C1: AVX TAJA156M010 C2: AVX TAJB156M016 D1: MOTOROLA MBR0520 L1: MURATA LQH3C100M24 VIN SW PGND FBVC SHDNCOMP LT1610 SHUTDOWN GND 5V to 9V/150mA Boost Converter Efficiency LOAD CURRENT (mA) EFFICIENCY (%) 10 100 300

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5V to 9V Boost Converter Transient Response

3.3V TO 8V/70mA, – 8V/5mA, 24V/5mA TFT LCD Bias Supply Uses All Ceramic Capacitors 0.22µF 5.4µH VIN SW LT1610 PGND COMP VC FB SHDN GND 0.22µF 100k 48.7k

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4.7µF VIN 3.3V 4.7µF 1µF 1µF 1µF 0.22µF AVDD 70mA 0.22µF: TAIYO YUDEN EMK212BJ224MG 1µF: TAIYO YUDEN LMK212BJ105MG 4.7µF: TAIYO YUDEN LMK316BJ475ML D1: MOTOROLA MBRO520 D2, D3, D4: BAT54S L1: SUMIDA CDRH5D185R4 VON 24V 5mA VOFF –8 V 5mA 51pF TFT LCD Bias Supply Transient Response AVDD 200mV/DIV VON 500mV/DIV VOFF 200mV/DIV 70mA 25mAAVDD LOAD 200ms/DIV 1610 TA19VON LOAD = 5mA VOFF LOAD = 5mA

4.7mH D1 VOUT 4.5V C1, C2: AVX TAJA156M010 D1: MOTOROLA MBR0530T1 L1: MURATA LQH1C4R7 Q1: 2N3906

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+C2 15mF 200k 20Ω 845k 3.3nF VIN SW PGND COMPSHDN FBVC LT1610 GND Single Cell Super Cap Charger OUTPUT VOLTAGE (V) 2.0 OUTPUT CURRENT (mA) 2.5 3.0 3.5 4.0

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4.5 5.0 OUTPUT VOLTAGE (V) 2.0 OUTPUT POWER (mW) 2.5 3.0 3.5 4.0

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4.5 5.0 Super Cap Charger Output Current vs Output Voltage Super Cap Charger Output Power vs Output Voltage

Dimensions in inches (millimeters) unless otherwise noted. 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) MSOP (MS8) 1197 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 0.021 – 0.006 (0.53 – 0.015) 0° – 6° TYP SEATING PLANE 0.007 (0.18) 0.040 – 0.006 (1.02 – 0.15) 0.012 (0.30) REF 0.006 – 0.004 (0.15 – 0.102) 0.034 – 0.004 (0.86 – 0.102) 0.0256 (0.65) TYP 12 3 4 0.192 – 0.004 (4.88 – 0.10) 8 7 6 5 0.118 – 0.004* (3.00 – 0.102) 0.118 – 0.004 (3.00 – 0.102) 1 2 3 4 0.150 – 0.157 (3.810 – 3.988) 8 7 6 5 0.189 – 0.197* (4.801 – 5.004) 0.228 – 0.244 (5.791 – 6.197) 0.016 – 0.050 (0.406 – 1.270) 0.010 – 0.020 0°– 8° TYP 0.008 – 0.010 (0.203 – 0.254) SO8 0996 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

1610f LT/TP 0699 4K • PRINTED IN USA ª LINEAR TECHNOLOGY CORPORATION 1 998 TYPICAL APPLICATIONS N U Li-Ion to 3.3V SEPIC DC/DC Converter PART NUMBER DESCRIPTION COMMENTS LTC®1474 Micropower Step-Down DC/DC Converter 94% Efficiency, 10 mA IQ, 9V to 5V at 250mA LT1307 Single Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 75mA from 1 Cell, MSOP Package LTC1440/1/2 Ultralow Power Single/Dual Comparators with Reference 2.8 mA IQ, Adjustable Hysteresis LTC1502-3.3 Single Cell to 3.3V Regulated Charge Pump 40 mA IQ, No Inductors, 3.3V at 10mA from 1V Input LT1521 Micropower Low Dropout Linear Regulator 500mV Dropout, 300mA Current, 12 mA IQ LT1611 Inverting 1.4MHz DC/DC Converter 5V to –5V at 150mA, Tiny SOT-23 Package LT1613 Step-Up 1.4MHz DC/DC Converter 3.3V to 5V at 200mA, Tiny SOT-23 Package LTC1682 Doubler Charge Pump with Low Noise Linear Regulator Fixed 3.3V and 5V Outputs, 1.8V to 4.4V Input Range, 50mA Output RELATED PARTS Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear-tech.com SHUTDOWN 22mF 6.3V 22mF 6.3V 22mH 22mH 1µF CERAMIC D1INPUT Li-ION 3V to 4.2V VOUT 3.3V 120mA

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C1, C2: AVX TAJB226M006 C3: AVX 1206YC105 (X7R) D1: MOTOROLA MBR0520 L1, L2: MURATA LQH3C220 (UNCOUPLED) OR SUMIDA CLS62-220 (COUPLED) VIN SW PGND FB SHDN GND COMP LT1610 VC Efficiency LOAD CURRENT (mA) 0.1 EFFICIENCY (%) 1 10 100

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VIN = 2.7V VIN = 3.6V VIN = 4.2V SHUTDOWN 22mF 6.3V 22mF 6.3V 22mH 22mH 1µF CERAMIC D1 V OUT 120mA

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C1, C2: AVX TAJB226M006 C3: AVX 1206YC105 (X7R) D1: MOTOROLA MBR0520 L1, L2: MURATA LQH3C220 (UNCOUPLED) OR SUMIDA CLS62-220 (COUPLED) VIN SW PGND FB SHDN GND COMP LT1610 VC 4-Cell to 5V/120mA SEPIC DC/DC Converter LOAD CURRENT (mA) 0.1 EFFICIENCY (%) 1 10 100

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VIN = 3.6V VIN = 4.2V VIN = 5V VIN = 6.5V 4-Cell to 5V Efficiency