Hot Swap Controller and

ADM1176

Rev. 0

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FEATURES

Allows safe board insertion and removal from a live backplane

Controls supply voltages from 3.15 V to 16.5 V

Precision current sense amplifier

Precision voltage input

12-bit ADC for current and voltage readback

Charge pumped gate drive for external N-channel FET

Adjustable analog current limit with circuit breaker

±3% accurate hot swap current limit level

Fast response limits peak fault current

Automatic retry or latch-off on current fault

Programmable hot swap timing via TIMER pin

Active-high ON pin

Two address pins allow 16 devices on the same bus

10-lead MSOP

APPLICATIONS

Power monitoring/power budgeting

Central office equipment

Telecommunication and data communication equipment

PCs/servers

GENERAL DESCRIPTION

The ADM1176 is an integrated hot swap controller that offers

digital current and voltage monitoring via an on-chip, 12-bit

analog-to-digital converter (ADC), communicated through an

An internal current sense amplifier senses voltage across the sense

resistor in the power path via the VCC pin and the SENSE pin.

The ADM1176 limits the current through this resistor by control-

ling the gate voltage of an external N-channel FET in the power

path, via the GATE pin. The sense voltage (and, therefore, the

inrush current) is kept below a preset maximum.

The ADM1176 protects the external FET by limiting the time

that it spends with maximum current running through it. This

current limit period is set by the choice of capacitor attached to

the TIMER pin. Additionally, the device provides protection from

overcurrent events that may occur once the hot swap event is

complete. In the case of a short-circuit event, the current in the

sense resistor exceeds an overcurrent trip threshold, and the FET

is switched off immediately by pulling down the GATE pin.

FUNCTIONAL BLOCK DIAGRAM

V

I

0

1

ADM1176

SENSE

ON

VCC

1.3V

MUX

12-BIT

ADC

FET DRIVE

CONTROLLER

GND

CURRENT

SENSE

AMPLIFIER

UV COMPARATOR

A

SDA

SCL

A1

A0

GATE

TIMER

Figure 1.

N-CHANNEL FET

P = VI

CONTROLLER

ADM1176

SENSE

VCC

SDA

SCL

SDA

SCL

GND

GATE

A0

A1

TIMER

3.15V TO 16.5V

ON

Figure 2. Applications Diagram

A 12-bit ADC can measure the current seen in the sense

resistor, as well as the supply voltage on the VCC pin. An

current and voltage data from the ADC. Measurements can be

continuously, and the user can read the latest conversion data

created, depending on the way the A0 and A1 pins are connected.

The ADM1176 is packaged in a 10-lead MSOP.