Features: Sense Resistor Optional
Out-of-Phase Controllers Reduce Required Input Capacitance
Programmable Output Voltage Tracking
Constant Frequency Current Mode Architecture
Wide VIN Range: 2.75V to 9.8V
Wide VOUT Range: 0.6V to VIN
0.6V ±1.5% Reference
Low Dropout Operation: 100% Duty Cycle
True PLL for Frequency Locking or Adjustment(Frequency Range 250kHz to 850kHz)
Selectable Burst Mode® or Pulse Skipping Operation at Light Loads
Internal Soft-Start Circuitry
Selectable Maximum Peak Current Sense Threshold
Power Good Output Voltage Monitor
Output Overvoltage Protection
Micropower Shutdown: IQ = 9mA
Tiny 4mm ´ 4mm QFN and 24-Lead SSOP PackagesApplicationOne or Two Lithium-Ion Powered Devices
Notebook and Palmtop Computers, PDAs
Portable Instruments
Distributed DC Power SystemsPinout
SpecificationsInput Supply Voltage (VIN), PVIN1, PVIN2,
SENSE1+, SENSE2+ .................................... 0.3V to 10V
PGATE1, PGATE2, PLLLPF, RUN/SS, SYNC/MODE,
TRACK, IPRG1, IPRG2 Voltages .... ... 0.3V to (VIN + 0.3V)
VFB1, VFB2, ITH1, ITH2 Voltages .................. 0.3V to 2.4V
SW1, SW2 Voltages ..................2V to VIN + 1V or 10V Max
PGOOD ........................................................ 0.3V to 10V
PGATE1, PGATE2 Peak Output Current (<10µs) ............ 1A
Operating Temperature Range (Note 2) ...40°C to 85°C
Storage Ambient Temperature Range
QFN Package ......................................... 65°C to 125°C
SSOP Package .................................. .... 65°C to 150°C
Junction Temperature (Note 3) .............................. 125°C
Lead Temperature (Soldering, 10sec)
LTC3737EGN ......................................................... 300°C
DescriptionThe LTC®3737 is a 2-phase dual step-down switchingregulator controller that requires few external compo-nents. The constant frequency current mode architecture provides excellent AC and DC load and line regulation.MOSFET VDS sensing eliminates the need for current sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are mini-mized by operating the two controllers out of phase.
Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation and extends battery operating time.
Switching frequency can be programmed up to 750kHz,allowing the use of small surface mount inductors and capacitors. For noise sensitive applications, the LTC3737 can be externally synchronized from 250kHz to 850kHz.
Other features include a power good output voltage moni-tor, a tracking input and internal soft-start.
The LTC3737 is available in the low profile thermally enhanced (4mm × 4mm) QFN package or a 24-lead SSOP narrow package.
LTC3737 Data Sheet
