LTC4271 datasheet(14/30 Pages) LINER

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LTC4266A/LTC4266C

4266acfc

PIN FUNCTIONS

GATE4: Port 4 Gate Drive. GATE4 should be connected

to the gate of the external MOSFET for port 4. When the

MOSFET is turned on, the gate voltage is driven to 12V

(typ) above VEE. During a current limit condition, the

voltage at GATE4 will be reduced to maintain constant

current through the external MOSFET. If the fault timer

expires, GATE4 is pulled down, turning the MOSFET off

and recording a tCUT or tSTART event. If the port is unused,

float the GATE4 pin.

OUT4: Port 4 Output Voltage Monitor. OUT4 should be

connected to the output port. A current limit foldback

circuit limits the power dissipation in the external MOSFET

by reducing the current limit threshold when the drain-to-

source voltage exceeds 10V. The port 4 Power Good bit is

set when the voltage from OUT4 to VEE drops below 2.4V

(typ). A 500k resistor is connected internally from OUT4

to AGND when the port is idle. If the port is unused, OUT4

pin must be floated.

SENSE3: Port 3 Current Sense Input. See SENSE4.

GATE3: Port 3 Gate Drive. See GATE4.

OUT3: Port 3 Output Voltage Monitor. See OUT4.

VEE: Main Supply Input. Connect to a –45V to –57V

supply, relative to AGND.

SENSE2: Port 2 Current Sense Input. See SENSE4.

GATE2: Port 2 Gate Drive. See GATE4.

OUT2: Port 2 Output Voltage Monitor. See OUT4.

SENSE1: Port 1 Current Sense Input. See SENSE4.

GATE1: Port 1 Gate Drive. See GATE 4.

OUT1: Port 1 Output Voltage Monitor. See OUT4.

AUTO: AUTO Pin Mode Input. AUTO pin mode allows the

LTC4266A/LTC4266C to detect and power up a PD even

if there is no host controller present on the I2C bus. The

voltage of the AUTO pin determines the state of the internal

registers when the LTC4266A/LTC4266C is reset or comes

out of VDD UVLO (see the LTC4266A/LTC4266C Software

Programming documentation). The states of these register

bits can subsequently be changed via the I2C interface.

The real-time state of the AUTO pin is read at bit 0 in the

Pin Status register (11h). Internally pulled down to DGND.

Must be tied locally to either VDD or DGND.

MSD: Maskable Shutdown Input. Active low. When pulled

low, all ports that have their corresponding mask bit set

in the Misc Config register (17h) will be reset, equivalent

to pulling the SHDN pin low. Internal filtering of the MSD

pin prevents glitches less than 1μs wide from resetting

ports. Internally pulled up to VDD.

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