Datasheet LTC3736-2 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual 2-Phase, No RSENSE , Synchronous Controller with Output Tracking |
| Pages / Page | 28 / 1 — FEATURES. DESCRIPTION. No Current Sense Resistors Required. Out-of-Phase … |
| File Format / Size | PDF / 357 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. No Current Sense Resistors Required. Out-of-Phase Controllers Reduce Required. Input. Capacitance
Model Line for this Datasheet
Text Version of Document
LTC3736-2 Dual 2-Phase, No R TM SENSE , Synchronous Controller with Output Tracking
FEATURES DESCRIPTION
n
No Current Sense Resistors Required
The LTC®3736-2 is a 2-phase dual synchronous step-down n
Out-of-Phase Controllers Reduce Required
switching regulator controller with tracking that drives
Input Capacitance
external complementary power MOSFETs using few ex- n
Tracking Function
ternal components. The constant-frequency current mode n
Wide VIN Range: 2.75V to 9.8V
architecture with MOSFET VDS sensing eliminates the need n
0.6V ±1% Voltage Reference
for sense resistors and improves effi ciency. Power loss and n
High Current Limit
noise due to the ESR of the input capacitance are minimized n Constant-Frequency Current Mode Operation by operating the two controllers out-of-phase. n Low Dropout Operation: 100% Duty Cycle Pulse-skipping operation provides high effi ciency at light n True PLL for Frequency Locking or Adjustment loads. 100% duty cycle capability provides low dropout n Selectable Pulse-Skipping/Forced Continuous operation, extending operating time in battery-powered Operation systems. n Auxiliary Winding Regulation n Internal Soft-Start Circuitry The switching frequency can be programmed up to 750kHz, n Power Good Output Voltage Monitor allowing the use of small surface mount inductors and n Output Overvoltage Protection capacitors. For noise sensitive applications, the LTC3736-2 n Micropower Shutdown: I switching frequency can be externally synchronized from Q = 9μA n Tiny Low Profi le (4mm × 4mm) QFN and Narrow 250kHz to 850kHz. An internal soft-start, which can be SSOP Packages lengthened externally, smoothly ramps the output voltage during start-up.
APPLICATIONS
The LTC3736-2 is available in the tiny thermally enhanced n One or Two Lithium-Ion Powered Devices (4mm × 4mm) QFN and 24-lead narrow SSOP packages. n Notebook and Palmtop Computers, PDAs , 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. Protected by U.S. Patents, including 5481178, n Distributed DC Power Systems 5929620, 6144194, 6580258, 6304066, 6611131, 6498466.
TYPICAL APPLICATION Effi ciency and Power Loss High Effi ciency, 2-Phase, Dual Synchronous DC/DC Step-Down Converter vs Load Current (Figure 15 Circuit)
VIN 2.75V TO 9.8V 100 10 VOUT = 2.5V V 10μF IN 95 s2 SENSE1+ SENSE2+ 90 EFFICIENCY 1 TG1 TG2 85 POWER LOSS (W) 2.2μH 2.2μH SW1 SW2 80 LTC3736-2 75 0.1 BG1 BG2 POWER LOSS 70 PGND PGND EFFICIENCY (%) 187k 118k 65 VOUT1 V V OUT2 0.01 FB1 VFB2 2.5V 1.8V 60 ITH1 ITH2 220pF 55 SGND 220pF 47μF 47μF 50 0.001 59k 15k 15k 59k 1 10 100 1000 10000 LOAD CURRENT (mA) 37362 TA01b 37362 TA01a 37362fb 1
FEATURES DESCRIPTION
n
No Current Sense Resistors Required
The LTC®3736-2 is a 2-phase dual synchronous step-down n
Out-of-Phase Controllers Reduce Required
switching regulator controller with tracking that drives
Input Capacitance
external complementary power MOSFETs using few ex- n
Tracking Function
ternal components. The constant-frequency current mode n
Wide VIN Range: 2.75V to 9.8V
architecture with MOSFET VDS sensing eliminates the need n
0.6V ±1% Voltage Reference
for sense resistors and improves effi ciency. Power loss and n
High Current Limit
noise due to the ESR of the input capacitance are minimized n Constant-Frequency Current Mode Operation by operating the two controllers out-of-phase. n Low Dropout Operation: 100% Duty Cycle Pulse-skipping operation provides high effi ciency at light n True PLL for Frequency Locking or Adjustment loads. 100% duty cycle capability provides low dropout n Selectable Pulse-Skipping/Forced Continuous operation, extending operating time in battery-powered Operation systems. n Auxiliary Winding Regulation n Internal Soft-Start Circuitry The switching frequency can be programmed up to 750kHz, n Power Good Output Voltage Monitor allowing the use of small surface mount inductors and n Output Overvoltage Protection capacitors. For noise sensitive applications, the LTC3736-2 n Micropower Shutdown: I switching frequency can be externally synchronized from Q = 9μA n Tiny Low Profi le (4mm × 4mm) QFN and Narrow 250kHz to 850kHz. An internal soft-start, which can be SSOP Packages lengthened externally, smoothly ramps the output voltage during start-up.
APPLICATIONS
The LTC3736-2 is available in the tiny thermally enhanced n One or Two Lithium-Ion Powered Devices (4mm × 4mm) QFN and 24-lead narrow SSOP packages. n Notebook and Palmtop Computers, PDAs , 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. Protected by U.S. Patents, including 5481178, n Distributed DC Power Systems 5929620, 6144194, 6580258, 6304066, 6611131, 6498466.
TYPICAL APPLICATION Effi ciency and Power Loss High Effi ciency, 2-Phase, Dual Synchronous DC/DC Step-Down Converter vs Load Current (Figure 15 Circuit)
VIN 2.75V TO 9.8V 100 10 VOUT = 2.5V V 10μF IN 95 s2 SENSE1+ SENSE2+ 90 EFFICIENCY 1 TG1 TG2 85 POWER LOSS (W) 2.2μH 2.2μH SW1 SW2 80 LTC3736-2 75 0.1 BG1 BG2 POWER LOSS 70 PGND PGND EFFICIENCY (%) 187k 118k 65 VOUT1 V V OUT2 0.01 FB1 VFB2 2.5V 1.8V 60 ITH1 ITH2 220pF 55 SGND 220pF 47μF 47μF 50 0.001 59k 15k 15k 59k 1 10 100 1000 10000 LOAD CURRENT (mA) 37362 TA01b 37362 TA01a 37362fb 1
