TEA1791T_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 February 2009

7 of 11

NXP Semiconductors

TEA1791T

GreenChip synchronous rectifier controller

11. Application information

A switched mode power supply with the TEA1791T consists of a primary side

discontinuous conduction mode flyback controller, a transformer, and an output stage with

a feedback circuit. In the output stage a MOSFET (Qsec) is used for low conduction

losses. The MOSFET is controlled by the TEA1791T.

The timing for the synchronous rectifier switch is derived from the voltage sensed on the

SRSENSE pin. The resistor in the SRSENSE connection is needed to protect the

TEA1791T from excessive voltages. The SRSENSE resistor should typically be 1 k

Ω.

Higher values might impair correct timing, lower values may not provide sufficient

protection.

Fig 4.

Application diagram

TR

PRIMARY

SIDE

CONTROLLER

Qprim

GND

DRIVER

TEA1791T

SRSENSE

Qsec

RSRSENSE

Cout

014aaa702