TEA1762T_2

© NXP B.V. 2007. All rights reserved.

Product data sheet

Rev. 02 — 25 April 2007

5 of 15

NXP Semiconductors

TEA1762T

GreenChip synchronous rectifier controller

7.3 SMPS output voltage and current regulation

The output voltage of the flyback Switched Mode Power Supply (SMPS) can be controlled

by sensing the output voltage via the VSENSE pin. The feedback loop via the primary

controller can regulate the output voltage of the switched mode power supply by

regulating the voltage on the VSENSE pin to 2.5 V above the voltage on pin SENSEGND.

Also the output current of the flyback SMPS can be controlled or limited. The voltage on

the ISENSE pin is regulated or limited to 50 mV above the voltage on pin POWERGND.

7.4 Opto outputs

The opto output is intended to drive an opto coupler (see Figure 5). The opto outputs have

an open drain output configuration. The maximum sink current is internally limited to 5 mA

(typical). The outputs are linearly controlled via the VSENSE and ISENSE input pins. An

over-temperature situation will switch the protection opto output (OPTOPROT) to its

maximum sink current.

7.5 Protection input

The PROTECT pin is a general purpose input pin which can be used for additional

protection of the switched mode power supply. With a Negative Temperature Coefficient

(NTC) thermistor external temperature protection can be provided, e.g. the external power

switches and transformer can be protected against high temperatures. With a Zener diode

a secondary overvoltage protection can be made.

7.6 Reference voltage output

The reference voltage output pin can be used for supplying external circuitry. The

maximum output current must be limited to 1 mA.

7.7 Supply management

All (internal) reference voltages are derived from a temperature compensated, on-chip

band gap circuit. The reference voltage is trimmed to an accuracy within 1 %.

7.8 OverTemperature Protection (OTP)

The IC provides an accurate internal overtemperature protection of 150

°C (typical). The

IC will maximize the current of pin OPTOPROT as soon as the internal temperature limit is

reached. The opto signal can be used on the primary side of the flyback controller to

activate the SMPS protection or limit the output power. As soon as the overtemperature

condition is solved, normal operation will resume.