Datasheet

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3.4 Enable
4 Test Set Up
4.1 Equipment
4.1.1 Voltage Source
4.1.2 Meters
4.1.3 Loads
4.1.3.1 LOAD1
4.1.4 Recommended Wire Gauge
4.1.4.1 V
12V_IN
to J1
4.1.4.2 J2 to LOAD1 (Power)
4.1.4.3 J3 to LOAD1 (Remote Sense)
Test Set Up
To operate with a 5-V input, two resistors need to be changed. R10 (R
KFF
) sets the voltage ramp
amplitude and needs to be reduced to 53.6 k Ω to lower the UVLO to 3.9 V for 5 V operation. In addition, a
330-k Ω resistor should be added at R15 to prevent an internal race condition during soft-start.
To disable the output and force the power MOSFETs into a high-impedance tri-state, connect TP21 to
TP19. This drives the base of Q3 and discharges the soft-start capacitor and shuts down the TPS40075
Controller.
V
12V_IN
The input voltage source (V
12V_IN
) should be a variable DC source between 0 V and 15 V, and capable of
5 A
DC
. Connect V
12V_IN
to J1 as shown in Figure 3 .
• A1: 0 A to 5 A
DC
, ammeter
• V1: V
12V_IN
, 0 V to 15 V voltmeter
• V2: V
1V5_OUT
0 V to 5 V voltmeter
The Output Load (LOAD1) should be an electronic constant current mode load capable of 0–15Adc at
1.5V.
The connection between the source voltage, V12V_IN and J1 of HPA187 can carry as much as 3 Adc.
The minimum recommended wire size is AWG #16 with the total length of wire less than 4 feet (2 feet
input, 2 feet return).
The power connection between J2 of HPA187 and LOAD1 can carry as much as 15 A
DC
. The minimum
recommended wire size is 2 × AWG #16, with the total length of wire less than 4 feet (2 feet output, 2 feet
return).
If remote sense is used, the remote sense connection between J3 of HPA187 and LOAD1 can carry less
than 1 A
DC
. The minimum recommended wire size is AWG #22, with the total length of wire less and 4
feet (2 feet output, 2 feet return).
Using the TPS40075: A 12-V to 1.5-V @ 15-A Synchronous Buck Converter6 SLUU254 – DECEMBER 2006
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