概要

The device is a highly integrated solution for SMPS applications, with an LED pilot-lamp requiring a dual control loop to perform CV (constant voltage) and CC (constant current) regulation. The IC allows very efficient LED pilot-lamp driving which helps to reduce the standby consumption of the SMPS. It integrates a voltage reference, two op-amps (with OR-ed open-drain outputs), a low-side current sensing circuit and an LED pilot-lamp driver pin implemented with an open-drain mosfet driven by square waveform with 12.5% duty cycle at 1 kHz that allows reducing LED consumption.
The voltage reference, along with one op-amp, is the core of the voltage control loop. The current sensing circuit and the other op-amp make up the current control loop.
The external components needed to complete the two control loops are:
- a resistor divider that senses the output of the power supply and fixes the voltage regulation setpoint at the specified value
- a sense resistor that feeds the current sensing circuit with a voltage proportional to the DC output current; this resistor determines the current regulation setpoint and must be adequately rated in terms of power dissipation
- the frequency compensation components (R-C networks) for both loops.
The device is ideal for space-critical applications.