Rainbow Electronics MAX5943 - Manual (Page 9)

MAX5943
FireWire Current Limiter and Low-Drop
ORing Switch Controller
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Pin Description
PIN NAME FUNCTION
1 ON
On/Off-Control Input. ON sets the undervoltage lockout threshold and resets the part after a fault latch.
Drive ON high to enable the device. Drive ON low to disable the device. Connect ON to IN for the default
undervoltage lockout threshold. Connect a resistor-divider from IN to ON and GND to program the desired
undervoltage lockout threshold.
2 FAULT
Current-Fault, Active-Low, Open-Drain Output. FAULT asserts and latches low after a current-limit/circuit-
breaker fault has exceeded the current-limit/circuit-breaker timeout period (see the FAULT section).
3 TIM
Current-Limit/Circuit-Breaker Timeout Adjustment Input. Connect TIM to IN for the default timeout period or
connect a resistor from TIM to GND to program the current-limit/circuit-breaker timeout period.
4 ILIM
Current-Limit/Circuit-Breaker Threshold Input. Leave ILIM open for a 40mV circuit-breaker threshold,
connect to GND for a 50mV circuit-breaker threshold, or connect to IN for a 60mV circuit-breaker threshold
(see the Current Limiting section).
5 LATCH
Latch or Autoretry Fault Management Selection Input. Connect LATCH to IN to select latch-off mode
after a current-limit/circuit-breaker timeout. Connect LATCH to GND for autorestart mode after a current-
limit/circuit-breaker timeout.
6 OR_ADJ
ORing Switch Turn-On Current Threshold Adjustment Input. Select one of three ORing switch turn-on
threshold settings: connect OR_ADJ to GND, connect OR_ADJ to IN, or leave OR_ADJ floating (see the
Power-Supply ORing section).
7, 10, 13 N.C. No Connection. Not internally connected.
8 ONQ1
ORing Switch Manual Turn-On Input. Drive ONQ1 low to enable power-supply ORing. Drive ONQ1 high
to set GATE1 high to allow reverse current flow. ONQ1 is disabled when V
IN is below the UVLO threshold,
V ON is below the V ON_REF threshold, and after a current/circuit-breaker fault.
9 GND Ground
11 OUT Output Voltage Sense. Connect to the output.
12 GATE2
Current-Limiter Switch Gate Drive Output. Connect GATE2 to the gate of the 2nd n-channel MOSFET.
GATE2 is a charge pump with a 45µA pullup current to 5.5V (typ) above OUT when active (see the Typical
Operating Circuit).
14 GATE1
ORing Switch Gate-Drive Output. Connect GATE1 to the gate of the 1st n-channel MOSFET. GATE1 is a
charge pump with a 45µA pullup current to 5.5V (typ) above SENSE when active (see the Typical
Operating Circuit).
15 SENSE
Current-Sense Negative Input. Connect a current-sense resistor, R SENSE, from IN to SENSE (see the
Typical Operating Circuit).
16 IN
Input Power and Current-Sense Positive Input. Connect IN to the positive terminal of the current-sense
resistor and to the power source (see the Typical Operating Circuit).