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dc1886bfa
DEMO MANUAL DC1886B
JUMPERS AND LEDS
Figure 1. Proper Measurement Equipment Setup
Two demo board jumpers, JP1 and JP2, allow selection
of controller operation:
• JP1 TIMER DURATION: Set to FIXED 2ms position for
the internal 2ms timer period (FIXED 2ms not recom-
mended for LTC4232-1 during auto-retry) or ADJUST-
ABLE determined by TIMER capacitor C1 (12ms for
LTC4232 and 1.2ms for LTC4232-1). (Default position:
ADJUSTABLE)
• JP2 AUTORETRY: Set to ON for auto-retry or OFF for
latchoff on overcurrent fault. (Default position: OFF)
When selecting AUTORETRY option for the circuit with a
predominantly resistive load, particularly for LTC4232-1,
pay special attention to the power MOSFET thermal con-
dition. The initial low current limit (due to the foldback
characteristic) can power the load only during a very short
time, and the MOSFET will experience the maximum cur-
rent limit for almost all of the remaining power up period.
This may exceed the MOSFET SOA, if allowed to autoretry.
Four LEDs indicate the state of the hot swap circuit. Red
LEDs, D3 and D5, provide fault status and low output
voltage (it is a NOT power good signal). Two green LEDs,
D2 and D4, signal the presence of valid input and output
voltages.
