Features:
No Current Sense Resistors Required
Out-of-Phase Controllers Reduce Required
Input Capacitance
Tracking Function
Wide VIN Range: 2.75V to 9.8V
Constant Frequency Current Mode Operation
0.6V 1.5% Voltage Reference
Low Dropout Operation: 100% Duty Cycle
True PLL for Frequency Locking or Adjustment
Selectable Burst Mode (R)/Forced Continuous Operation
Auxiliary Winding Regulation
Internal Soft-Start Circuitry
Power Good Output Voltage Monitor
Output Overvoltage Protection
Micropower Shutdown: IQ = 9 Am
Tiny Low Profile (4mm ` 4mm) QFN and Narrow
SSOP Packages
Application
One or Two Lithium-Ion Powered Devices
Notebook and Palmtop Computers, PDAs
Portable Instruments
Distributed DC Power SystemsPinout
SpecificationsInput Supply Voltage (V IN) ....................... 0.3V to 10V
PLLLPF, RUN/SS, SYNC/FCB,
TRACK, SENSE1 + , SENSE2 + ,
IPRG1, IPRG2 Voltages.................. 0.3V to (V IN + 0.3V)
VFB1 , V FB2, I TH1, I TH2 Voltage............... 0.3V to 2.4V
SW1, SW2 Voltages............ 2V to V IN + 1V or 10V Max
PGOOD ...................................................... 0.3V to 10V
TG1, TG2, BG1, BG2 Peak Output Current (<10 s) ..... 1Am
Operating Temperature Range (Note 2).... 40 C to 85 C
Storage Temperature Range ....................65 C to 125 C
Junction Temperature (Note 3) ............................... 125 C
Lead Temperature (Soldering, 10 sec)
(LTC3736EGN) .........................................................300 C
Description
The LTC(R) 3736 is a 2-phase dual synchronous step-down switching regulator controller with tracking that drives external complementary power MOSFETs using few exter- nal components. The constant frequency current mode architecture with MOSFET V DS sensing eliminates the need for sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.
Burst Mode operation provides high efficiency at light loads. 100% duty cycle capability provides low dropout operation, extending operating time in battery-powered systems.
The switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and ca- pacitors. For noise sensitive applications, the LTC3736 switching frequency can be externally synchronized from 250kHz to 850kHz. Burst Mode operation is inhibited dur- ing synchronization or when the SYNC/FCB pin is pulled low in order to reduce noise and RF interference. Automatic soft- start is internally controlled.
The LTC3736 is available in the tiny thermally enhanced (4mm · 4mm) QFN package or 24-lead SSOP narrow package.
LTC3736 Data Sheet
