SPS SECONDARY-SIDE CC/CV CONTROLLER

DESCRIPTION

The UTC UM612/A is a secondary-side CC/CV controller for

SPS applications.

It integrates a Constant Current (CC) regulating amplifier, a

Constant Voltage (CV) regulating amplifier, and 2 precision

reference voltages.

An internal 2.5V reference voltage is generated from VCC input

power. The UTC UM612/A can be used to monitor the

transformer secondary-side output voltage by the CV control loop

and regulate the output current by the CC control loop at the

same time.

The transformer secondary-side output voltage can be

monitored by the FB pin voltage. The sensed FB pin voltage is

compared with the 2.5V internal reference. When the FB pin

voltage is higher than 2.5V, the OUT pin will sink more current at

the external opto-coupler and instruct the controller at

primary-side to adjust the output voltage.

The output current can be regulated by the voltage across the

CN and CP pins through the current sense resistor connected

between the CN and CP pins. The voltage difference between CN

and CP pins is compared with the 60mV / 30mV internal

reference. When the voltage difference between CN and CP pins

is greater than 60mV / 30mV, the OUT pin will sink more current

at the external opto-coupler and instruct the controller at

primary-side to adjust the output current.

FEATURES

* Secondary-Side Constant Voltage (CV) and Constant Current (CC) Control

* 4.75V to 50V Operation Voltage Range

* 0.6mA Quiescent Current

* ±1% Output Voltage Accuracy at Full Temperature Range

* Smooth Transition Between CC and CV Control Loops

* -5V Negative Voltage Tolerance at CP pin