NXP Semiconductors
TEA1993TS
GreenChip synchronous rectifier controller
TEA1993TS All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2016. All rights reserved.
Product data sheet Rev. 1.1 — 14 September 2016
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12 Application information
A flyback switched mode power supply with the TEA1993TS consists of a primary
side controller with a primary switch, a transformer, and an output stage. To obtain
low conduction loss rectification, an SR MOSFET is used in the output stage. The SR
MOSFET can be placed low-side (see Figure 3) or can be placed high-side
(see Figure 11). In the high-side application, the TEA1993TS is self-supplying. The
capacitor on the CAP pin supplies the TEA1993TS. When the drain voltage is positive, it
is charged via the DRAIN pin.
The gate drive voltage for the synchronous rectifier switch is derived from the voltage
difference between the corresponding drain sense and source sense pins.
Special attention must be paid to the connection of the drain sense and source sense
pins. The voltages measured on these pins are used for the gate drive voltage. Wrong
measurement results in a less efficient gate drive because a gate voltage that is either
too low or too high. The connections to these pins must not interfere with the power
wiring.
The power wiring conducts currents with high dI/dt values. It can easily cause
measurement errors resulting from induced voltages due to parasitic inductances. The
separate source sense pins make it possible to sense the source voltage of the external
MOSFETs directly. So, the current carrying power ground tracks are not required.
DRIVER
PRIMARY
CONTROLLER
SECONDARY
CONTROLLER
S1
CAP
XV
OPTO
GND
GATE
DRAIN
XV
GND
SOURCE
TEA1993
ISENSE
AUX
VCC
HV
CTRL
GND
PROTECT
8
6
2
7
3
5
4
1
aaa-021216
SR high side
Figure 11. TEA1993TS configuration with high-side rectification
