特点
Wide Output Voltage Range:
0.8V < or = V
OUT
< or = 14V
Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
OPTI-LOOP? Compensation Minimizes C
OUT
±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 V
IN
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 I
Q
: 20μA
Selectable Constant Frequency or Burst Mode? Operation
Small 28-Lead SSOP Package
LTC3727-1 Also Available in the 5mm x 5mm QFN Package
典型应用
描述
The 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 phase-lockable 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 V OUT 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.