PI2161-EVAL1 Datasheet, PDF (6/8 Pages) Vicor Corporation – PI2161-EVAL1 60V/12A High Side High Voltage Load Disconnect Switch

current is sourced from the power supply and
its output voltage will drop, but when the
MOSFET disconnects the load (shorted) from
the source, the bench power supply may
produce high output voltage with high current
capability that may damage the device under
test.
If a bench power supply has to be used, or there
is some wiring inter connection between PI2161-
EVAL1 input (Vin+ and Vin-) and the power
source, add a large electrolytic capacitor
between Vin+ and Vin- terminals to reduce
power source high voltage transient after load
disconnect.
6.2. Place the scope probes very close to PI2161 D
pin and SH pin to measure Vout and Vin, and
make sure that the scope ground leads are very
short.
6.3. Current trip point:
To find the exact current trip level, repeat steps
5.1 to 5.9 and then increment the load current
slowly. The current can be monitored by a
current probe placed at the unit input or by
reading the current display at the power supply
(PS1) or at the electronic load display. The
actual trip current is the current right before the
PI2161 turns the output off, VO output will go to
0V to indicate that the output is disconnect from
the source.
After PI2161 turns the output off by pulling the
MOSFET gate low, it will hold the MOSFET in an
off condition until it is reset.
6.4. Device Reset:
To reset PI2161 after a fault (high load current),
recycle PI2161 by sliding SW1 knob to Off
position and then slide the knob back to On
position.
6.5. Output short test
Enable PS1 and then apply a short at the load
(Vout). The short can be applied electronically
using the electronic load, a MOSFET connected
between Vout+ and Vout- or simply by connecting
Vout+ to Vout-. Then measure the response time
between when the output current reached the
set trip point and when PI2161 disconnect the
load. An example for PI2161 response time to an
output short circuit is shown in Figure 5.
Output Voltage [SH] (5V/div)
PG pin (5V/div)
Input Current (5A/div)
Turn off
& latch
Input Voltage [D] (5V/div)
Input Voltage [D] (5V/div)
PG pin (5V/div)
Set Trip Current
at 10.5A
(Rs=200mΩ)
94.4ns
MOSFET
Avalanche
At 69V
Output Voltage [SH] (5V/div)
Start Turn
off & latch
Input Current (5A/div)
120.4ns
Figure 5: Plot of PI2161 response time to a forward over-current condition
Test Setup:
DUT: PI2161-EVAL1
Vin = 45V
Output Load = 1.5A
Rs (R1) = 200mΩ
First applied slow ramping load
current and determined the trip
current: 10.5A
Test: Apply output short
PI2161 was enabled and load
current is at 1.5A, then shorted
Vout+ to Vout- with a MOSFET.
The current ramped at 230A/μs.
PI2161 turned the output off at
load current of 33A, by pulling
the MOSFET gate low and latch
it low.
PI2161 internal MOSFET starts to
turn off 94ns after the current
reach the trip point (10.5A). And
current reached 0A within 120ns.
Picor Corporation • picorpower.com
PI2161-EVAL1 User Guide Rev. 1.0 Page 6 of 8