TEA1762T_2 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 02 — 25 April 2007 10 of 15
NXP Semiconductors
TEA1762T
GreenChip synchronous rectifier controller
11. Application information
A switched mode power supply with the TEA1762T 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 TEA1762T. The output voltage and/or current is
also controlled by the TEA1762T via the opto coupler connection to the primary side. See
Figure 5.
The output voltage is set by resistors R
fb1
and R
fb2
. The output current is controlled by the
resistor R
isense
. 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 TEA1762T from excessive voltages. The SRSENSE resistor should typically
be 1 kΩ. Higher values might impair correct timing, lower values may not provide sufficient
protection.
During output short circuit or load connection, the limiting values on pin SENSEGND must
not be exceeded.
Fig 5. Application example TEA1762T
014aaa058
DRIVER
SRSENSE
OPTOPROT
V
CC
OPTOREG
VSENSE
V
out
ISENSEPOWERGND
TEA1762T
PRIMARY
SIDE
CONTROLLER
OPTO1
OPTO2
V
in
Q
prim
Q
sec
R
opto
R
fb1
−t
R
fb2
C
out
C
fb
TR
R
srsense
R
isense
SENSEGND
PROTECT
VREF
