Datasheet LT3740 (Analog Devices)
| Fabricante | Analog Devices |
| Descripción | Wide Operating Range, Valley Mode, No RSENSE Synchronous Step-Down Controller |
| Páginas / Página | 20 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 2.2V to 22V. Internal Boost … |
| Formato / tamaño de archivo | PDF / 244 Kb |
| Idioma del documento | Inglés |
FEATURES. DESCRIPTION. Wide VIN Range: 2.2V to 22V. Internal Boost Provides 6V Gate Drive. For VIN Down to 2.2V
Línea de modelo para esta hoja de datos
Versión de texto del documento
LT3740 Wide Operating Range, Valley Mode, No RSENSE™ Synchronous Step-Down Controller
FEATURES DESCRIPTION
n
Wide VIN Range: 2.2V to 22V
The LT®3740 is a synchronous step-down switching n
Internal Boost Provides 6V Gate Drive
regulator controller that drives N-channel power MOSFET
For VIN Down to 2.2V
stages. The controller uses valley current mode architecture n
No Sensing Resistor Required
to achieve very low duty cycles with excellent transient n
Dual N-Channel MOSFET Synchronous Drive
response without requiring a sense resistor. n Valley Current Mode Control The LT3740 includes an internal step-up converter to n Optimized for High Step-Down Ratio provide a bias 7.8V higher than the input voltage for the n Power Good Output Voltage Monitor drive. This enables the part to work from an input voltage n 0.8V Reference as low as 2.2V. n Three Pin-Selected Current Limit Levels n Constant Switching Frequency: 300kHz The XREF pin is an external reference input that allows the n Programmable Soft-Start user to override the internal 0.8V feedback reference with n Output Voltage Tracking any lower value, allowing full control of the output voltage n Available in 16-Pin 5mm × 3mm DFN during operation, output voltage tracking or soft-start. The LT3740 has three current limit levels that can be
APPLICATIONS
chosen by connecting the RANGE pin to ground, open, and input respectively. n Notebook and Palmtop Computers, PDA L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Portable Instruments No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Distributed Power Systems
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency vs Load Current
VIN 94 3V to 12V 22μH LT3740 1μF SWB BGDP 10μF 92 V V IN = 5V V BIAS IN = 3V IN 90 1Ω M1 SHDN TGATE HAT2168H 0.9μH 88 1Ω VOUT SW 1.8V 15k 10A 86 VIN = 12V XREF SN+ D1 EFFICIENCY (%) 100μF 1Ω M2 B320A 84 s 3 BGATE 0.22μF HAT2165H 82 39pF VOUT = 1.8V 15k SN– 80 V 105k C 0 2 4 6 PGND 8 10 20k LOAD CURRENT (A) RANGE GND FB 3740 TA01b 1nF 22pF 80.6k 3740 TA01a 3740fc 1
FEATURES DESCRIPTION
n
Wide VIN Range: 2.2V to 22V
The LT®3740 is a synchronous step-down switching n
Internal Boost Provides 6V Gate Drive
regulator controller that drives N-channel power MOSFET
For VIN Down to 2.2V
stages. The controller uses valley current mode architecture n
No Sensing Resistor Required
to achieve very low duty cycles with excellent transient n
Dual N-Channel MOSFET Synchronous Drive
response without requiring a sense resistor. n Valley Current Mode Control The LT3740 includes an internal step-up converter to n Optimized for High Step-Down Ratio provide a bias 7.8V higher than the input voltage for the n Power Good Output Voltage Monitor drive. This enables the part to work from an input voltage n 0.8V Reference as low as 2.2V. n Three Pin-Selected Current Limit Levels n Constant Switching Frequency: 300kHz The XREF pin is an external reference input that allows the n Programmable Soft-Start user to override the internal 0.8V feedback reference with n Output Voltage Tracking any lower value, allowing full control of the output voltage n Available in 16-Pin 5mm × 3mm DFN during operation, output voltage tracking or soft-start. The LT3740 has three current limit levels that can be
APPLICATIONS
chosen by connecting the RANGE pin to ground, open, and input respectively. n Notebook and Palmtop Computers, PDA L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Portable Instruments No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Distributed Power Systems
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency vs Load Current
VIN 94 3V to 12V 22μH LT3740 1μF SWB BGDP 10μF 92 V V IN = 5V V BIAS IN = 3V IN 90 1Ω M1 SHDN TGATE HAT2168H 0.9μH 88 1Ω VOUT SW 1.8V 15k 10A 86 VIN = 12V XREF SN+ D1 EFFICIENCY (%) 100μF 1Ω M2 B320A 84 s 3 BGATE 0.22μF HAT2165H 82 39pF VOUT = 1.8V 15k SN– 80 V 105k C 0 2 4 6 PGND 8 10 20k LOAD CURRENT (A) RANGE GND FB 3740 TA01b 1nF 22pF 80.6k 3740 TA01a 3740fc 1