Hot Swap Controller and

Digital Power Monitor with Convert Pin

ADM1175

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 and active-low ON/ONB pin options

Convert start pin (CONV)

10-lead MSOP

APPLICATIONS

Power monitoring/power budgeting

Central office equipment

Telecommunication and data communication equipment

PCs/servers

GENERAL DESCRIPTION

The ADM1175 is an integrated hot swap controller and current

sense amplifier that offers digital current and voltage monitoring

via an on-chip, 12-bit analog-to-digital converter (ADC),

An internal current sense amplifier senses voltage across the sense

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

The ADM1175 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 ADM1175 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

ADM1175-1

SENSE

ON

VCC

CONV

1.3V

MUX

12-BIT

ADC

FET DRIVE

CONTROLLER

GND

CURRENT

SENSE

AMPLIFIER

UV COMPARATOR

A

SDA

SCL

ADR

GATE

TIMER

Figure 1.

N-CHANNEL FET

P = VI

CONTROLLER

ADM1175-1

SENSE

VCC

SDA

SCL

SDA

SCL

GND

GATE

CONV

CONV

ADR

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 industry-standard

or via the convert (CONV) pin. The CONV pin is especially

useful for synchronizing reads on multiple ADM1175 devices.

Alternatively, the ADC can run continuously, and the user can

read the latest conversion data whenever it is required. Up to four

ADR pin is connected.

The ADM1175 is packaged in a 10-lead MSOP.