3
dc1886bfa
DEMO MANUAL DC1886B
QUICK START PROCEDURE
Demonstration circuit 1886B is easy to set up to evaluate
the performance of the LTC4232 or LTC4232-1. Refer to
Figure 1 for the proper measurement equipment setup
and follow the procedure below.
1. Place jumpers in the following positions:
JP1
TIMER DURATION
FIXED 2ms
JP2
AUTORETRY
OFF
2. With power off, connect 12V power supply terminals
to the VDD (E1) and GND (E3) turrets.
3. Turn on the 12V power supply and verify the output
voltage between the V
OUT
(E2) and GND (E4) turrets.
Two green LEDs, D2 and D4 should light up.
4. Check the current limit using an electronic or resis-
tive load. It should be in the range of 5A to 6.1A if an
overcurrent condition occurs while the output is high
(after powering up properly). If the output is shorted
initially, the load current will be limited in the range of
1.2A to 1.8A due to the foldback characteristic. Current
may be monitored on the IMON turret. The IMON signal
scale is 0.4V/A.
An overcurrent condition is indicated by the red LED
FLT(D3) and red LED PG (D5).
5. Check the output voltage slew rate with an oscilloscope,
without a load connected. It should take from 22ms
to 80ms for LTC4232, and from 3.0ms to 7.0ms for
LTC4232-1.
6. For DC1886B-A (LTC4232) use a 2000μF capacitive
load to demonstrate that power up mode completes
successfully. Use a current probe to verify that inrush
current is limited initially by the foldback characteristic
and later by the low output voltage slew rate.
7. For DC1886B-A use a 6000μF capacitive load to dem-
onstrate that the part not only enters into the current
limit state but operates in this state until the timer period
expires. It is not a successful power up.
8. For DC18886B-B use a 800μF capacitive load to demon-
strate a successful power up mode. The controller will
operate in current limit almost all of the timer period.
9. For DC1886B-B use a 3000μF capacitive load to
demonstrate an unsuccessful power up transient. The
operating point does not leave current limit during the
whole timer period. It will then time out and turn off.
