LT1944-1

LT1944-1_15 LINER | Alldatasheet

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Technical content

1944-1 is a dual micropower step-up DC/DC converter in a 10-pin MSOP package. One converter is designed with a 100mA current limit and a 400ns off-time; the other with a 175mA current limit and a 1.5ms off-time. The 1.5ms off-time converter is ideal for generating an output voltage that is close to the input voltage (i.e. a Li- Ion to 5V converter, or a two-cell to 3.3V converter). With an input voltage range of 1.2V to 15V, the LT1944-1 is ideal for a wide variety of applications. Both converters feature a quiescent current of only 20mA at no load, which further reduces to 0.5mA in shutdown. A current limited, fixed off- time control scheme conserves operating current, result- ing in high efficiency over a broad range of load current. Tiny, low profile inductors and capacitors can be used to minimize footprint and cost in space-conscious portable applications. n Low Quiescent Current: 20mA in Active Mode <1mA in Shutdown Mode n Operates with VIN as Low as 1.2V n Low VCESAT Switches: 85mV at 70mA n Uses Small Surface Mount Components n High Output Voltage: Up to 34V n Tiny 10-Pin MSOP Package n Small TFT LCD Panels n Handheld Computers n Battery Backup n Digital Cameras , LTC and LT are registered trademarks of Linear Technology Corporation. VIN SW2 FB1 LT1944-1 22µH D1 SHDN1 324k 4.7µF 40mA 15V 2.5mA –10V 1mA VIN 2.7V TO 4.2V 1944-1 TA01 GND PGND PGND SW1 4.7pF 4.7µF FB24 5SHDN2 22µH D2 178k 1µF 4.7pF C1, C2: TAIYO YUDEN JMK212BJ475 C3, C4: TAIYO YUDEN EMK212BJ105 C5: TAIYO YUDEN EMK107BJ104 D1, D2, D3, D4: CENTRAL SEMI CMDSH3 L1, L2: MURATA LQH3C220 0.1µF 1µF5V LOAD CURRENT (mA) 0.1 EFFICIENCY (%) 1 10 100 1944-1 TA01a VIN = 4.2V VIN = 2.7V Triple Output Power Supply (5V, 15V, –10V) for LCD Displays 5V Output Efficiency

ABSOLUTE AXI U RATI GSW WW U PACKAGE/ORDER I FOR ATIOUU W (Note 1) Operating Temperature Range (Note 2) .. –40°C to 85°C ORDER PART NUMBER LT1944-1EMS MS10 PART MARKING ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage 1.2 V Quiescent Current, Each Switcher Not Switching 20 30 mA VSHDN = 0V 1 mA FB Comparator Trip Point l 1.205 1.23 1.255 V FB Comparator Hysteresis 8m V FB Voltage Line Regulation 1.2V < V IN < 12V 0.05 0.1 %/V FB Pin Bias Current (Note 3) V FB = 1.23V l 30 80 nA Switch Off Time, Switcher 1 (Note 4) V FB > 1V 400 ns VFB < 0.6V 1.5 ms Switch Off Time, Switcher 2 (Note 4) V FB > 1V 1.5 ms VFB < 0.6V 1.5 ms Switch VCESAT ISW = 70mA 85 120 mV Switch Current Limit, Switcher 1 65 100 125 mA Switch Current Limit, Switcher 2 130 175 225 mA SHDN Pin Current V SHDN = 1.2V 2 3 mA VSHDN = 5V 8 12 mA SHDN Input Voltage High 0.9 V SHDN Input Voltage Low 0.25 V Switch Leakage Current Switch Off, V SW = 5V 0.01 5 mA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1944-1E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40 °C to 85°C operating TJMAX = 125°C, qJA = 160°C/W temperature range, otherwise specifications are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted. LTTU Consult LTC Marketing for parts specified with wider operating temperature ranges. FB1 SHDN1 GND SHDN2 FB2 SW1 PGND V IN PGND SW2 TOP VIEW MS10 PACKAGE 10-LEAD PLASTIC MSOP temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Bias current flows into the FB pin. Note 4: See Figure 1 for Switcher 1 and Switcher 2 locations.

TYPICAL PERFOR A CE CHARACTERISTICSUW Switch Saturation Voltage (VCESAT) Quiescent Current Feedback Pin Voltage and Bias Current TEMPERATURE (°C) –50 FEEDBACK VOLTAGE (V) 1944-1 G02 1.25 1.24 1.23 1.22 1.21 1.20 BIAS CURRENT (nA) CURRENT VOLTAGE –25 0 25 50 75 100 TEMPERATURE (°C) QUIESCENT CURRENT (µA) 1944-1 G03 –50 –25 0 25 50 75 100 VIN = 12V VIN = 1.2V VFB = 1.23V NOT SWITCHING PI FU CTIO S UU U FB1 (Pin 1): Feedback Pin for Switcher 1. Set the output voltage by selecting values for R1 and R2. SHDN1 (Pin 2): Shutdown Pin for Switcher 1. Tie this pin to 0.9V or higher to enable device. Tie below 0.25V to turn it off. GND (Pin 3): Ground. Tie this pin directly to the local ground plane. SHDN2 (Pin 4): Shutdown Pin for Switcher 2. Tie this pin to 0.9V or higher to enable device. Tie below 0.25V to turn it off. FB2 (Pin 5): Feedback Pin for Switcher 2. Set the output voltage by selecting values for R1B and R2B. SW2 (Pin 6): Switch Pin for Switcher 2. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to the pin to minimize EMI. PGND (Pins 7, 9): Power Ground. Tie these pins directly to the local ground plane. Both pins must be tied. V IN (Pin 8): Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible. SW1 (Pin 10): Switch Pin for Switcher 1. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to the pin to minimize EMI. SHUTDOWN PIN VOLTAGE (V) SHUTDOWN PIN CURRENT (µA) 1944-1 G03 0 5 10 15 25°C 100°C Switch Off Time Shutdown Pin Current Switch Current Limit TEMPERATURE (°C) –50 SWITCH VOLTAGE (V) 0.15 0.13 0.10 0.08 0.05 0.03 –25 02 5 5 0 1944-1 G01 75 100 ISWITCH = 100mA ISWITCH = 70mA TEMPERATURE (°C) –50 SWITCH OFF TIME (ns) –25 0 25 50 75 2000 1800 1600 1400 1200 1000 800 600 400 200 100 SWITCHER 2 SWITCHER 1 1944-1 G04 TEMPERATURE (°C) –50 PEAK CURRENT (mA) 200 175 150 125 100 –25 02 5 5 0 1944-1 G05 75 100 VIN = 12V VIN = 1.2V VIN = 12V VIN = 1.2V SWITCHER 1 SWITCHER 2

Figure 1. LT1944-1 Block Diagram shot, again allowing L1 to deliver current to the output. tion during start-up and under short-circuit conditions. switch and in the external inductor and diode.

correct inductance value for your design. Table 1. Recommended Inductors performance. Pick a standard inductor close to this value. used (see Current Limit Overshoot section). without excessive reduction in maximum output current. value to be used for a SEPIC regulator using the LT1944-1. by the inductor (and the diode) during normal operation.

tained when IPEAK is kept below 400mA for the LT1944-1. be used at the output to minimize the output ripple voltage. a capacitor with a sufficient voltage rating. Table 2. Recommended Capacitors nent is rated to handle at least 100mA. inductor current, then delivering that current to the load.

Dual Output (5V, 24V) Boost Converter PACKAGE DESCRIPTIO U MSOP (MS10) 1100 * 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) 0.043 (1.10) MAX 0.007 – 0.011 (0.17 – 0.27) 0.005 – 0.002 (0.13 – 0.05) 0.034 (0.86) REF 0.0197 (0.50) BSC 12 3 45 0.193 – 0.006 (4.90 – 0.15) 8910 7 6 0.118 – 0.004* (3.00 – 0.102) 0.118 – 0.004** (3.00 – 0.102) 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) VIN SW1 FB2 LT1944-1 22µH D1 SHDN2 53.6k 1µF 24V 1mA 40mA VIN 2.7V TO 4.2V C1, C3: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN TMK316BJ105 D1, D2: CENTRAL SEMI CMDSH-3 L1, L2: MURATA LQH3C220 (408) 573-4150 (408) 573-4150 (631) 435-1110 (814) 237-1431 1944-1 TA02 GND PGND PGND 81 0 SW2 4.7pF 4.7µF FB12 1SHDN1 22µH D2 324k 4.7pF 4.7µF Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com ª LINEAR TECHNOLOGY CORPORATION 2001 19441f LT/TP 0801 2K • PRINTED IN USA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1307 Single-Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 75mA from One Cell, MSOP Package LT1316 Burst Mode TM Operation DC/DC with Programmable Current Limit 1.5V Minimum, Precise Control of Peak Current Limit LT1317 2-Cell Micropower DC/DC with Low-Battery Detector 3.3V at 200mA from Two Cells, 600kHz Fixed Frequency LT1610 Single-Cell Micropower DC/DC Converter 3V at 30mA from 1V, 1.7MHz Fixed Frequency LT1611 1.4MHz Inverting Switching Regulator in 5-Lead ThinSOT –5V at 150mA from 5V Input, Tiny ThinSOT Package LT1613 1.4MHz Switching Regulator in 5-Lead ThinSOT 5V at 200mA from 3.3V Input, Tiny ThinSOT Package LT1615 Micropower DC/DC Converter in 5-Lead ThinSOT 20V at 12mA from 2.5V Input, Tiny ThinSOT Package LT1617 Micropower Inverting DC/DC Converter in 5-Lead ThinSOT –15V at 12mA from 2.5V Input, Tiny ThinSOT Package LT1930A 2.2MHz Boost DC/DC Converter in ThinSOT 5V at 450mA from 3.3V, Tiny ThinSOT Package LT1944 Dual Micropower Step-Up DC/DC Converter 5V at 80mA and 30V at 8mA, MSOP Package Burst Mode is a trademark of Linear Technology Corporation Four Output Power Supply (–5V, –15V) VIN SW2 FB1 LT1944-1 22µH D1 SHDN1 324k 4.7µF 20mA 15V 2mA –15V 2mA –5V 20mA VIN 2.7V TO 4.2V 1944-1 TA03 GND PGND PGND SW1 4.7pF 4.7µF FB24 5SHDN2 22µH D2 178k 1µF 4.7pF C1, C2, C7: TAIYO YUDEN JMK212BJ475 C3, C4: TAIYO YUDEN EMK212BJ105 C5, C6: TAIYO YUDEN EMK107BJ104 D1, D2, D3, D4, D5, D6: CENTRAL SEMI CMDSH3 L1, L2: MURATA LQH3C220 0.1µF 0.1µF 4.7µF 1µF UTYPICAL APPLICATIO