General Configurations
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SLVUA44B – June 2014 – Revised July 2017
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TPS25940EVM-635: Evaluation Module for TPS25940X
4.4.1
Preliminary Tests
4.4.1.1
For CH1 (J3-J2)
•
With the power supply set to 12 V on CH1, verify that the green PG LED (D3) is on. Press the EVM
RST switch, S1 and verify that the voltage at VOUT1 (TP2) starts falling slowly below 12 V and that the
green PG LED (D3) turns off and FLTb1 red LED (D2) turns ON. Release S1.
•
Reduce the input voltage on VIN1 and monitor VOUT1, Verify that VOUT1 (TP2) starts falling and is
fully turned off when VIN1 (TP3) reaches 9.5 V (±0.5 V). Verify that the PG1 green LED (D3) turns off
and FLTb1 red LED (D2) turns ON.
•
Increase the input voltage on VIN1 and monitor VOUT1, Verify that VOUT1 (TP2) starts increasing and
is fully turned off when VIN1 (TP3) reaches 16.5 V (±1 V). Verify that the PG1 green LED (D3) turns off
and FLTb1 red LED (D2) turns ON.
4.4.1.2
For CH2 (J8-J7)
•
With the power supply set to 12 V on CH2, verify that the green PG LED (D7) is on. Depress the EVM
RST switch, S2 and verify that the voltage at VOUT2 (TP16) starts falling slowly below 12 V and that
the green PG LED (D7) turns off and red FLTb2 LED (D6) turns ON. Release S2.
•
Reduce the input voltage on VIN2 and monitor VOUT2, verify that VOUT2 (TP16) starts falling and is
fully turned off when VIN2 (TP15) reaches 2.1 V (±0.3 V). Verify that the PG2 green LED (D7) turns off
and FLTb2 red LED (D6) turns ON.
•
Increase the input voltage on VIN2 and monitor VOUT2, verify that VOUT2 (TP16) starts increasing
and is fully turned off when VIN2 (TP15) reaches 15.5 V (±1 V). Verify that the PG2 green LED (D7)
turns off and FLTb2 red LED (D6) turns ON.
•
Turn off both the power supplies.
4.4.1.3
Ramp up Time Test (CH1 and CH2)
•
Verify ramp up time (CH1 and CH2,
with only 1 channel powered at a time
). Set up the oscilloscope
as shown in
Table 8
.
Table 8. PWR635 Oscilloscope Setting for Ramp Up Voltage Test
Oscilloscope setting
CH1 Probe Points
CH2 Probe Points
Channel 1 = 5 V/div
TP2 = VOUT1
TP16 = VOUT2
Channel 2 = 5 V/div
TP3 = VIN1
TP15 = VIN2
Channel 3 = 2 V/div
TP8 = EN/UVLO1
TP17 = EN/UVLO2
Trigger source = Channel 1
Trigger level = 6.0 ±0.5 V
Trigger polarity = Positive
Trigger Mode = Single Sequence
Time base = 1 ms/div
