特点
Step-Down Controller
Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
Power Good Output Voltage Indicator
OPTI-LOOP? Compensation Minimizes C
OUT
DC Programmed Fixed Frequency 150kHz to 300kHz
Wide V
IN
Range: 3.5V to 36V Operation
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Soft-Start Current Ramping
Latched Short-Circuit Shutdown with Defeat Option
Remote Output Voltage Sense and OV Protection
5V and 3.3V Standby Regulators
Selectable Const. Freq. or Burst Mode? Operation
Step-Up Regulator
High Operating Switching Frequency of 1.2MHz
Low Internal V
CESAT
Switch: 400mV @ 1A, V
IN
= 3V
Wide V
IN
Range: 2.6V to 16V Operation
High Output Voltage: Up to 34V
典型应用
描述
The LTC?1876 is a high performance triple output switching regulator. It incorporates a dual step-down switching controller that drives all N-channel synchronous power MOSFET stages. A step-up regulator with an internal 1A, 36V switch provides the third output.
The step-down controllers minimize power loss and noise by operating the output stage of each controller out of phase. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. A RUN/SS pin for each controller provides both soft-start and an optional timed, short-circuit shutdown that can be configured to latch offone or both controllers. Current foldback provides additional short-circuit protection. In an overvoltage condition, the bottom MOSFET is latched on until V OUT returns to normal. The FCB pin can be used to inhibit Burst Mode operation or to enable regulation of a secondary output voltage.
The step-up regulator operates at 1.2MHz, allowing the use of tiny low cost capacitors and inductors. In addition,its internal 1A switch allows high current outputs to be generated. Its current mode control scheme provides excellent line and load regulation.