TEA1761T_2 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 02 — 25 April 2007 3 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
6. Pinning information
6.1 Pinning
6.2 Pin description
7. Functional description
The TEA1761T is the controller for synchronous rectification to be used in discontinuous
conduction mode and quasi resonant flyback converters. Besides controlling the
SR MOSFET, the TEA1761T contains the voltage reference and amplifiers to regulate and
control the output voltage and current of the power supply.
7.1 Start-up and undervoltage lock out
The IC leaves the under-voltage lock-out state and activates the synchronous rectifier
circuitry and also the voltage/current sense circuitry as soon as the voltage on the V
CC
pin
is above 8.6 V (typical). As soon as the voltage drops below 8.1 V (typical), the
under-voltage lock-out state is re-entered and the SR driver output is actively kept low and
also the opto driver output is disabled.
7.2 Synchronous rectification
After a negative voltage (−310 mV typical) is sensed on the SRSENSE pin, the driver
output voltage is made high and the external MOSFET is switched on. As soon as the
SRSENSE voltage rises to −55 mV, the driver output voltage is regulated to maintain the
−55 mV on the SRSENSE pin. As soon as the SRSENSE voltage is above −12 mV, the
Fig 2. Pin configuration for TEA1761T
TEA1761T
SRSENSE V
CC
GND ISENSE
n.c. VSENSE
DRIVER OPTO
001aae772
1
2
3
4
6
5
8
7
Table 2. Pin description
Symbol Pin Description
SRSENSE 1 synchronous timing input
GND 2 ground
n.c. 3 not connected
DRIVER 4 driver output for SR MOSFET
OPTO 5 opto coupler driver output
VSENSE 6 sense input for voltage control
ISENSE 7 sense input for current control
V
CC
8 supply voltage
