Datasheet LT1931, LT1931A (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 1.2MHz/2.2MHz Inverting DC/DC Converters in ThinSOT |
| Pages / Page | 12 / 1 — FEATURES. DESCRIPTIO. Fixed Frequency 1.2MHz/2.2MHz Operation. Very Low … |
| File Format / Size | PDF / 459 Kb |
| Document Language | English |
FEATURES. DESCRIPTIO. Fixed Frequency 1.2MHz/2.2MHz Operation. Very Low Noise: 1mVP-P Output Ripple. APPLICATIO S
Model Line for this Datasheet
Text Version of Document
LT1931/LT1931A 1.2MHz/2.2MHz Inverting DC/DC Converters in ThinSOT
U FEATURES DESCRIPTIO
■
Fixed Frequency 1.2MHz/2.2MHz Operation
The LT®1931/LT1931A are the industry’s highest power ■
Very Low Noise: 1mVP-P Output Ripple
inverting SOT-23 current mode DC/DC converters. Both ■ – 5V at 350mA from 5V Input parts include a 1A integrated switch allowing high current ■ –12V at 150mA from 5V Input outputs to be generated in a small footprint. The LT1931 ■ Uses Small Surface Mount Components switches at 1.2MHz while the LT1931A switches at 2.2MHz. ■ Wide Input Range: 2.6V to 16V These high speeds enable the use of tiny, low cost ■ Low Shutdown Current: <1µA capacitors and inductors 2mm or less in height. The ■ Low VCESAT Switch: 400mV at 1A LT1931 is capable of generating – 5V at 350mA or –12V ■ Pin-for-Pin Compatible with the LT1611 at 150mA from a 5V supply, while the LT1931A can ■ Low Profile (1mm) ThinSOTTM Package generate –5V at 300mA using significantly smaller induc- tors. Both parts are easy pin-for-pin upgrades for higher
U
power LT1611 applications.
APPLICATIO S
The LT1931/LT1931A operate in a dual inductor inverting ■ Disk Drive MR Head Bias topology that filters both the input side and output side ■ Digital Camera CCD Bias current. Very low output voltage ripple approaching 1mVP-P ■ LCD Bias can be achieved when ceramic output capacitors are used. ■ GaAs FET Bias Fixed frequency switching ensures a clean output free ■ Local Low Noise/Low Impedance Negative Supply from low frequency noise typically present with charge pump solutions. The low impedance output remains within 1% of nominal during large load steps. The 36V switch allows VIN to VOUT differential of up to 34V. The LT1931/LT1931A are available in the 5-lead ThinSOT package. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO
C2
Efficiency
L1A L1B 1µF 10µH 10µH VIN 100 5V 95 D1 V 90 IN SW VOUT –5V SHDN 85 R1 350mA C4 C1 LT1931 29.4k 220pF 80 4.7µF C3 NFB 22µF 75 GND R2 10k 70 EFFICIENCY (%) 65 60 C1: TAIYO YUDEN X5R JMK212BJ475MG 1931 F01 C2: TAIYO YUDEN X5R LMK212BJ105MG 55 C3: TAIYO YUDEN X5R JMK325BJ226MM 50 D1: ON SEMICONDUCTOR MBR0520 0 50 100 150 200 250 300 350 L1: SUMIDA CLS62-100 LOAD CURRENT (mA)
Figure 1. 5V to –5V, 350mA Inverting DC/DC Converter
1931 TA01 1931fa 1
U FEATURES DESCRIPTIO
■
Fixed Frequency 1.2MHz/2.2MHz Operation
The LT®1931/LT1931A are the industry’s highest power ■
Very Low Noise: 1mVP-P Output Ripple
inverting SOT-23 current mode DC/DC converters. Both ■ – 5V at 350mA from 5V Input parts include a 1A integrated switch allowing high current ■ –12V at 150mA from 5V Input outputs to be generated in a small footprint. The LT1931 ■ Uses Small Surface Mount Components switches at 1.2MHz while the LT1931A switches at 2.2MHz. ■ Wide Input Range: 2.6V to 16V These high speeds enable the use of tiny, low cost ■ Low Shutdown Current: <1µA capacitors and inductors 2mm or less in height. The ■ Low VCESAT Switch: 400mV at 1A LT1931 is capable of generating – 5V at 350mA or –12V ■ Pin-for-Pin Compatible with the LT1611 at 150mA from a 5V supply, while the LT1931A can ■ Low Profile (1mm) ThinSOTTM Package generate –5V at 300mA using significantly smaller induc- tors. Both parts are easy pin-for-pin upgrades for higher
U
power LT1611 applications.
APPLICATIO S
The LT1931/LT1931A operate in a dual inductor inverting ■ Disk Drive MR Head Bias topology that filters both the input side and output side ■ Digital Camera CCD Bias current. Very low output voltage ripple approaching 1mVP-P ■ LCD Bias can be achieved when ceramic output capacitors are used. ■ GaAs FET Bias Fixed frequency switching ensures a clean output free ■ Local Low Noise/Low Impedance Negative Supply from low frequency noise typically present with charge pump solutions. The low impedance output remains within 1% of nominal during large load steps. The 36V switch allows VIN to VOUT differential of up to 34V. The LT1931/LT1931A are available in the 5-lead ThinSOT package. , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO
C2
Efficiency
L1A L1B 1µF 10µH 10µH VIN 100 5V 95 D1 V 90 IN SW VOUT –5V SHDN 85 R1 350mA C4 C1 LT1931 29.4k 220pF 80 4.7µF C3 NFB 22µF 75 GND R2 10k 70 EFFICIENCY (%) 65 60 C1: TAIYO YUDEN X5R JMK212BJ475MG 1931 F01 C2: TAIYO YUDEN X5R LMK212BJ105MG 55 C3: TAIYO YUDEN X5R JMK325BJ226MM 50 D1: ON SEMICONDUCTOR MBR0520 0 50 100 150 200 250 300 350 L1: SUMIDA CLS62-100 LOAD CURRENT (mA)
Figure 1. 5V to –5V, 350mA Inverting DC/DC Converter
1931 TA01 1931fa 1
