Features: Wide Output Voltage Range: 0.8V £ VOUT £ 14V
Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
OPTI-LOOP® Compensation Minimizes COUT
±1% Output Voltage Accuracy
Power Good Output Voltage Monitor
Phase-Lockable Fixed Frequency 250kHz to 550kHz
Latched Short-Circuit Shutdown (LTC3727 Only)
Dual N-Channel MOSFET Synchronous Drive
Wide VIN Range: 4V to 36V Operation
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Soft-Start Current Ramping
Foldback Output Current Limiting
Output Overvoltage Protection
Low Shutdown IQ: 20mA
Small 28-Lead SSOP Package
LTC3727-1 Also Available in the 5mm ´ 5mm QFN Package
Selectable Constant Frequency or Burst Mode® OperationApplication Telecom Systems
Automotive Systems
Battery-Operated Digital DevicesPinout
SpecificationsInput Supply Voltage (VIN)............................36V to 0.3V
Top Side Driver Voltages
(BOOST1, BOOST2) .......................................42V to 0.3V
Switch Voltage (SW1, SW2) ............................36V to 5V
INTVCC, EXTVCC, (BOOST1-SW1),
(BOOST2-SW2) ...........................................8.5V to 0.3V
RUN/SS1, RUN/SS2, PGOOD ..................... ....7V to 0.3V
SENSE1+, SENSE2 +, SENSE1,
SENSE2 Voltages .....................................14V to 0.3V
PLLIN, PLLFLTR, FCB, Voltage ............ ..INTVCC to 0.3V
ITH1, ITH2, VOSENSE1, VOSENSE2 Voltages .....2.7V to 0.3V
Peak Output Current <10ms (TG1, TG2, BG1, BG2) ... .3A
INTVCC Peak Output Current ............................... .50mA
Operating Temperature Range (Note 2)40°C to 85°C
Junction Temperature (Note 3) ........................... 125°C
Storage Temperature Range ..............65°C to 150°C
Storage Temperature Range
(UH Package) .....................................65°C to 125°C
Lead Temperature (Soldering, 10 sec).................300°C
DescriptionThe LTC®3727/LTC3727-1 are high performance dual step-down switching regulator controllers that drive all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows phaselockable frequency of up to 550kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out of phase.
OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. There is a precision 0.8V reference and a power good output indicator. A wide 4V to 30V (36V maximum) input supply range encompasses all battery chemistries.
A RUN/SS pin for each controller provides soft-start, and on the LTC3727GN, optional timed, short-circuit shutdown. Current foldback limits MOSFET heat dissipation during short-circuit conditions when overcurrent latchoff is disabled. Output overvoltage protection circuitry latches on the bottom MOSFET until VOUT returns to normal. The FCB mode pin can select among Burst Mode, constant frequency mode and continuous inductor current mode or regulate a secondary winding. The LTC3727/LTC3727-1 include a power good output pin that indicates when both outputs are within 7.5% of their designed set point.
LTC3727 Data Sheet
