Dual FireWire Current Limiter and Low-Drop

ORing Switch Controller

8

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Pin Description

PIN

NAME

FUNCTION

1

INA

Channel A Input Power and Current-Sense Positive Input. Connect INA to the other end of the current-

sense resistor and to the power source (see the Typical Operating Circuit).

2

ONA

Channel A On/Off Control Input. ONA sets the undervoltage lockout threshold and resets the part after a

fault latch. Drive ONA high to enable the device. Drive ON_ low to disable the device. Connect ONA to INA

for the default undervoltage lockout threshold. Connect a resistor-divider from INA to ONA and to GND to

program the desired undervoltage lockout threshold.

3

FAULTA

Channel A Current-Fault Status Output. FAULTA is an open-drain output. FAULTA goes low after a current-

limit fault has exceeded the 2ms (typ) current-limit timeout period (see the FAULT_ section).

4

ONQ1

ORing Switch Manual Turn-On Input. Drive ONQ1 low to enable power-supply ORing for channels A and B.

Drive ONQ1 high to set GATE1A to GATE1B high to allow reverse-current flow. ONQ1 is disabled for the

threshold and after a current-limit fault.

5

OUTB

Channel B Output-Voltage Sense. Connect to the output.

6

GATE2B

Channel B Current-Limiter Switch Gate-Drive Output. Referenced to OUTB. Connect GATE2B to the gate of

the 2nd n-channel MOSFET. GATE2B is a charge pump with a 50µA pullup current to 5.5V (typ) above

OUTB when active (see the Typical Operating Circuit).

7

GATE1B

Channel B ORing Switch Gate-Drive Output. Referenced to SENSEB. Connect GATE1B to the gate of the

1st n-channel MOSFET. GATE1B is a charge pump with a 50µA pullup current to 5.5V (typ) above SENSEB

when active (see the Typical Operating Circuit).

8

SENSEB

9

INB

Channel B Input Power and Current-Sense Positive Input. Connect INB to the other end of the current-

sense resistor and to the power source.

10

ONB

Channel B On/Off Control Input. ONB sets the undervoltage lockout threshold and resets the part after a

fault latch. Drive ONB high to enable the device. Drive ON_ low to disable the device. Connect ONB to INB

for the default undervoltage lockout threshold. Connect a resistor-divider from INB to ONB and to GND to

program the desired undervoltage lockout threshold.

11

FAULTB

Channel B Current-Fault Status Output. FAULTB is an open-drain output. FAULTB goes low after a current-

limit fault has exceeded the 2ms (typ) current-limit timeout period (see the FAULT_ section).

12

GND

Ground

13

OUTA

Channel A Output-Voltage Sense. Connect to the output.

14

GATE2A

Channel A Current-Limiter Switch Gate-Drive Output. Referenced to OUTA. Connect GATE2A to the gate of

the 2nd n-channel MOSFET. GATE2A is a charge pump with a 50µA pullup current to 5.5V (typ) above

OUTA when active.

15

GATE1A

Channel A ORing Switch Gate-Drive Output. Referenced to SENSEA. Connect GATE1A to the gate of the

1st n-channel MOSFET. GATE1A is a charge pump with a 50µA pullup current to 5.5V (typ) above SENSEA

when active.

16

SENSEA

(see the Typical Operating Circuit).