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T
P
3
T
P
5
T
P
8
J4
H12
RTN BIAS +
J6
Test Setup
5.3
Power-Up/Power-Down Procedure: Self Bias Mode
The following test procedure is recommended primarily for power up and shutting down the evaluation
Module in Self Bias mode. Never leave a powered EVM unattended for any length of time. Also, the unit
should never be handled while power is applied to it.
WARNING
There are very high voltages present on the EVM. Some
components reach temperatures above 50°C. Precautions must be
taken when handling the board. Never operate the UCC29950EVM-
631 without the fan running. Always make certain the bulk
capacitor (C6) has completely discharged prior to handling the
EVM.
1. Working at an ESD workstation, make sure that the ionizer is on before the EVM is removed from the
protective packaging. Electrostatic smock and safety glasses should also be worn. Because voltages in
excess of 400 V may be present on the EVM, do not connect the ground strap from the smock to the
bench. If testing with a load, set the electronic load to Constant Current Mode.
2. Power Up: in Self Bias Mode
(a) Connect the equipment as shown in
(b) Set the electronic load to 2 A.
(c) S1 to the ‘off’ position, switch toggle pointed to the heatsink as shown in
(d) Set S2 to the 'on' position, switch toggle pointed away from the heatsink as shown in
.
(e) Use the link to connect pin 2 to pin 3 of J4.
(f) Turn on the fan.
(g) Set the AC source voltage between 90 V
AC
and 264 V
AC
.
(h) Turn the AC source on.
(i) Verify that the output of the module is within regulation. Startup time may be several seconds.
Figure 5. J4 Link Setting for Self Bias Mode
12
Using the UCC29950EVM-631 300-W PFC/LLC Off-Line PSU Module
SLUUB69A – March 2015 – Revised March 2015
Copyright © 2015, Texas Instruments Incorporated