ADM1270

Data Sheet

Rev. A | Page 6 of 21

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

12 PWRGD

NOTES

1. THE EXPOSED PAD IS LOCATED ON THE UNDERSIDE

OF THE LFCSP PACKAGE. SOLDER THE EXPOSED PAD

TO THE PRINTED CIRCUIT BOARD (PCB) TO IMPROVE

THERMAL DISSIPATION. THE EXPOSED PAD CAN BE

CONNECTED TO GROUND.

11 FLB

10 FB_PG

9

TIMER_OFF

VCAP 1

UV 3

OV 4

ISET 2

ADM1270

TOP VIEW

Figure 2. 16-Lead LFCSP Pin Configuration

Table 4. 16-Lead LFCSP Pin Function Descriptions

Pin No.

Mnemonic

Description

1

VCAP

Internal Regulated Supply. Place a capacitor with a 1 µF or greater value on this pin to maintain good accuracy.

This pin can be used as a reference to program the ISET pin voltage.

2

ISET

Current Limit. This pin allows the current-limit threshold to be programmed. The default limit is set when this pin

is connected directly to VCAP. To achieve a user defined sense voltage, the current limit can be adjusted using a

resistor divider from VCAP. An external reference can also be used.

3

UV

Undervoltage Input Pin. An external resistor divider is connected from the supply to this pin to allow an internal

comparator to detect whether the supply is under the UV limit.

4

OV

Overvoltage Input Pin. An external resistor divider is connected from the supply to this pin to allow an internal

comparator to detect whether the supply is above the OV limit.

5

ENABLE

Enable Pin. This pin is a digital logic input. This input must be high to allow the ADM1270 controller to begin a

power-up sequence. If this pin is held low, the ADM1270 is prevented from powering up. There is no internal pull-

up on this pin.

6

FAULT

Fault Output. This pin indicates that the device has shut down due to an overcurrent fault condition. The device

can be configured for automatic retry after shutdown by connecting this pin directly to the ENABLE pin.

7

GND

Ground Pin.

8

TIMER

voltage on the TIMER pin exceeds the upper threshold.

9

TIMER_OFF

SOA overcurrent fault has occurred, the GATE pin is pulled off until the voltage on the TIMER_OFF pin exceeds the

threshold.

10

FB_PG

PWRGD Feedback Input Pin. An external resistor divider is connected from the output voltage to this pin to allow

an internal comparator to detect when the output voltage is above the PWRGD threshold.

11

FLB

Foldback Pin. A foldback resistor divider is placed from the source of the FET to this pin. Foldback reduces the

current limit when the source voltage drops. The foldback feature ensures that the power through the FET is not

increased beyond the SOA limits.

12

PWRGD

Power-Good Signal. This signal indicates that the supply is within tolerance. This signal is based on the voltage

present on the FB_PG pin.

13

GATE

Gate Output Pin. This pin is the gate drive of an external P-channel FET. This pin is driven by the FET drive

controller, which provides a pull-down current to charge the FET gate pin. The FET drive controller regulates to a

maximum load current by regulating the GATE pin. GATE is held off when the supply is below the undervoltage

lockout (UVLO).

14

SENSE−

Negative Current Sense Input Pin. A sense resistor between the VCC/SENSE+ pin and the SENSE− pin sets the

analog current limit. The hot swap operation of the ADM1270 controls the external FET gate to maintain the sense