TEA1791AT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 01 — 7 June 2010 7 of 13
NXP Semiconductors
TEA1791AT
GreenChip synchronous rectifier controller
11. Application information
A switched mode power supply with the TEA1791AT consists of a primary side
discontinuous conduction mode flyback controller, a transformer, and an output stage with
a feedback circuit. A MOSFET (Q
sec
) is used for low conduction losses in the output
stage. This MOSFET is controlled by the TEA1791AT.
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
TEA1791AT from excessive voltages. The R
SRSENSE
resistor should typically be 1 kΩ.
Higher values might impair correct timing and lower values may not provide sufficient
protection.
Fig 4. Application diagram high side rectification
Fig 5. Application diagram low side rectification
V
in
TR
PRIMARY
SIDE
CONTROLLER
Q
prim
V
CC
GND DRIVER
TEA1791AT
SRSENSE
Q
sec
R
SRSENSE
V
out
C
out
DRIVER
SRSENSE
V
CC
V
out
GND
TEA1791AT
PRIMARY
SIDE
CONTROLLER
V
in
Q
sec
C
out
R
SRSENSE
Q
prim
TR
014aaa897
