ANALOG DEVICES ADM1176 Service Manual

V

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Hot Swap Controller and

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

2

C® fast mode-compliant interface (400 kHz maximum)

I
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

2

I

C interface.

An internal current sense amplifier senses voltage across the sense
resistor in the power path via the VCC pin and the SENSE pin.

I2C® Power Monitor with Convert Pin

ADM1176

FUNCTIONAL BLOCK DIAGRAM

ADM1176

MUX

VCC

SENSE

3.15V TO 16.5

AMPLIFIER

ON

1.3V
UV COMPARATOR

CURRENT

SENSE

V

0

I

R

GND

1

SENSE

SENSEVCC

GATE

SDA

SCL

A

GND

ADM1176

ON

Figure 2. Applications Diagram

12-BIT

ADC

FET DRIVE

CONTROLLER

TIMER

Figure 1.

N-CHANNEL FET

A1TIMER
A0

2

C

I

CONTROLLER

P = VI

SDA
SCL

SDA
SCL
A1
A0

GATE

06046-001

06046-002

The ADM1176 limits the current through this resistor by control­ling 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.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.

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 I

2

C interface allows a controller to read
current and voltage data from the ADC. Measurements can be
initiated by an I

2

C command. Alternatively, the ADC can run
continuously, and the user can read the latest conversion data
whenever it is required. Up to 16 unique I

2

C addresses can be

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

The ADM1176 is packaged in a 10-lead MSOP.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2006 Analog Devices, Inc. All rights reserved.

ADM1176

TABLE OF CONTENTS

Features.............................................................................................. 1

Initial Timing Cycle ................................................................... 14

Applications....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Descriptions............................. 7

Typical Performance Characteristics ............................................. 8

Overview of the Hot Swap Function............................................ 13

Undervoltage Lockout ............................................................... 13

ON Function ............................................................................... 13

TIMER Function ........................................................................13

GATE and TIMER Functions During a Hot Swap ................ 14

Calculating Current Limits and Fault Current Limit Time.. 14

Hot Swap Retry on the ADM1176-1 ....................................... 15

Voltage and Current Readback..................................................... 16

Serial Bus Interface..................................................................... 16

Identifying the ADM1176 on the I

General I

Write and Read Operations ...................................................... 18

Quick Command........................................................................ 18

Write Command Byte................................................................ 18

Write Extended Byte .................................................................. 19

Read Voltage and/or Current Data Bytes................................ 20

Applications Waveforms................................................................ 22

Kelvin Sense Resistor Connection ........................................... 23

Outline Dimensions....................................................................... 24

Ordering Guide .......................................................................... 24

2

C Timing.................................................................... 16

2

C Bus............................... 16

REVISION HISTORY

9/06—Revision 0: Initial Version

Rev. 0 | Page 2 of 24

ADM1176

SPECIFICATIONS

VCC = 3.15 V to 16.5 V; TA = −40°C to +85°C; typical values at TA = 25°C, unless otherwise noted.

Table 1.

Parameter Min Typ Max Unit Conditions

VCC PIN

Operating Voltage Range, V
Supply Current, ICC 1.7 2.5 mA
Undervoltage Lockout, V
Undervoltage Lockout Hysteresis, V

ON PIN

Input Current, I

INON

−2 +2 μA
Rising Threshold, V

ONTH

Trip Threshold Hysteresis, V
Glitch Filter Time 3 μs

SENSE PIN

Input Leakage, I

−1 +1 μA V

SENSE

Overcurrent Fault Timing Threshold, V

Overcurrent Limit Threshold, V

Fast Overcurrent Trip Threshold, V

GATE PIN

Drive Voltage, V

3 6 9 V V

GATE

Pull-Up Current 8 12.5 17 μA V
Pull-Down Current 1.5 mA V
5 mA V
7 mA V

TIMER PIN

Pull-Up Current (Power On Reset), I
Pull-Up Current (Fault Mode), I
Pull-Down Current (Retry Mode), I

Pull-Down Current, I
Trip Threshold Hig h, V
Trip Thresho ld Low, V

TIMERDN

TIMERH

TIMERL

A0 PIN, A1 PIN

Set Address to 00, V
Set Address to 01, R

Set Address to 10, I

Set Address to 11, V

ADRLOWV

ADRLOWZ

ADRHIGHZ

ADRHIGHV

Input Current for 11 Decode, I
Input Current for 00 Decode, I

3.15 16.5 V

VCC

2.8 V VCC rising

UVLO

80 mV

UVLOHYST

−100

+100 nA ON < 1.5 V

1.26 1.3 1.34 V ON rising
35 50 65 mV

ONHYST

= V

92 mV

OCTIM

V

SENSE

OCTRIM

= (V

VCC

VCC

TIMER pin

97 100 103 mV

LIM

V

= (V

VCC

− V

LIM

current limit

115 mV

OCFAST

V

OCFAST

= (V

VCC

turned on

− V

VCC

− V

VCC

− V

VCC

= 0 V
= 3 V, V
= 3 V, V
= 3 V, V

, V
, V
, V

TIMERUPPOR

TIMERUPFAULT

TIMERDNRETRY

GATE

9 11 13 V V
7 10 13 V V

GATE

GATE

GATE

GATE

GATE

GATE

−3.5 −5 −6.5 μA Initial cycle, V

−40 −60 −80 μA During current fault, V
2 3 μA

After current fault and during a cool-down
period on a retry device, V

100 μA Normal operation, V

1.26 1.3 1.34 V TIMER rising

0.175 0.2 0.225 V TIMER falling

0 0.8 V Low state

135 150 165 kΩ

Resistor to ground state, load pin with specified
resistance for 01 decode

−1 +1 μA

Open state, maximum load allowed on the A0
pin and the A1 pin for 10 decode

2 5.5 V High state

3 10 μA V

ADRLOW

−40 −22 μA V

ADRHIGH

= 2.0 V to 5.5 V

ADR

= 0 V to 0.8 V

ADR

− V

), fault timing starts on the

SENSE

), closed-loop regulation to a

SENSE

− V

), gate pull-down current

SENSE

= 3.15 V

VCC

= 5 V

VCC

= 16.5 V

VCC

= 3.15 V

VCC

= 5 V

VCC

= 16.5 V

VCC

= 1 V

TIMER

= 1 V

TIMER

= 1 V

TIMER

= 1 V

TIMER

Rev. 0 | Page 3 of 24

ADM1176

Parameter Min Typ Max Unit Conditions

MONITORING ACCURACY

Current Sense Absolute Accuracy −1.45

−1.8

−2.8

−5.7

−1.5

−1.8

−2.95

−6.1

−1.95

−2.45

−3.85

−6.7

V

for ADC Full Scale 105.84 mV

SENSE

Voltage Sense Accuracy −0.85

−0.9 +0.9 %

−0.85

−0.9 +0.9 %

−0.9

−1.15 +1.15 %

VCC for ADC Full Scale,
Low Range (VRANGE = 1)

VCC for ADC Full Scale,
High Range (VRANGE = 0)

I2C TIMING

Low Level Input Voltage, V
High Level Input Voltage, V
Low Level Output Voltage on SDA, V
Output Fall Time on SDA from V

Maximum Width of Spikes Suppressed by
Input Filtering on SDA and SCL Pins

Input Current, II, on SDA/SCL When Not
Driving Out a Logic Low

Input Capacitance on SDA/SCL 5 pF

SCL Clock Frequency, f

Low Period of the SCL Clock 600 ns
High Period of the SCL Clock 1300 ns

1

+1.45 % V

+1.8 % V

+2.8 % V

+5.7 % V

+1.5 % V

+1.8 % V

+2.95 % V

+6.1 % V

+1.95 % V

+2.45 % V

+3.85 % V

+6.7 % V

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

SENSE

This is an absolute value to be used when
converting ADC codes to current readings;
any inaccuracy in this value is factored into
absolute current accuracy values (see specs
for Current Sense Absolute Accuracy)

+0.85 %

V

= 3.0 V to 5.5 V

VCC

(low range)

= 10.8 V to 16.5 V

V

VCC

(high range)

+0.85 %

V

= 3.0 V to 5.5 V

VCC

(low range)

= 10.8 V to 16.5 V

V

VCC

(high range)

+0.9 %

V

= 3.0 V to 5.5 V

VCC

(low range)

= 10.8 V to 16.5 V

V

VCC

(high range)

6.65

V

These are absolute values to be used when
converting ADC codes to current readings;

26.52

V

any inaccuracy in these values is factored into
voltage accuracy values (see specs for Current
Sense Absolute Accuracy)

0.3 V

IL

0.7 V

IH

0.4 V I

OL

to V

IHMIN

ILMAX

V

BUS

20 +

0.1 C

250 ns CB = bus capacitance from SDA to GND

B

V

BUS

= 3 mA

OL

50 250 ns

−10 +10 μA

400 kHz

SCL

= 75 mV 0°C to +70°C

= 50 mV 0°C to +70°C

= 25 mV 0°C to +70°C

= 12.5 mV 0°C to +70°C

= 75 mV 0°C to +85°C

= 50 mV 0°C to +85°C

= 25 mV 0°C to +85°C

= 12.5 mV 0°C to +85°C

= 75 mV −40°C to +85°C

= 50 mV −40°C to +85°C

= 25 mV −40°C to +85°C

= 12.5 mV −40°C to +85°C

0°C to +70°C

0°C to +70°C

0°C to +85°C

0°C to +85°C

−40°C to +85°C

−40°C to +85°C

Rev. 0 | Page 4 of 24

ADM1176

Parameter Min Typ Max Unit Conditions

Setup Time for a Repeated Start Condition,
t

SU;STA

SDA Output Data Hold Time, t
Setup Time for a Stop Condition, t

100 900 ns

HD;DAT

600 ns

SU;STO

Bus Free Time Between a Stop and a Start
Condition, t

Capacitive Load for Each Bus Line 400 pF

1

Monitoring accuracy is a measure of the error in a code that is read back for a particular voltage/current. This is a combination of amplifier error, reference error, ADC

error, and error in ADC full-scale code conversion factor.

BUF

600 ns

1300 ns

Rev. 0 | Page 5 of 24

ADM1176

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

VCC Pin 20 V
SENSE Pin 20 V
TIMER Pin −0.3 V to +6 V
ON Pin −0.3 V to +20 V
GATE Pin 30 V
SDA Pin, SCL Pin −0.3 V to +7 V
A0 Pin, A1 Pin −0.3 V to +6 V
Storage Temperature Range −65°C to +125°C
Operating Temperature Range −40°C to +85°C
Lead Temperature (Soldering, 10 sec) 300°C
Junction Temperature 150°C

Table 3. Thermal Resistance

Package Type θJA Unit

10-Lead MSOP 137.5 °C/W

ESD CAUTION

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

Rev. 0 | Page 6 of 24

ADM1176

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

1

VCC

SENSE

2

ADM1176

ON

3

TOP VIEW

(Not to Scale)

GND

4
5

TIMER

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 VCC

Positive Supply Input Pin. The operating supply voltage range is from 3.15 V to 16.5 V. An undervoltage
lockout (UVLO) circuit resets the ADM1176 when a low supply voltage is detected.

2 SENSE

Current Sense Input Pin. A sense resistor between the VCC pin and the SENSE pin sets the analog current
limit. The hot swap operation of the ADM1176 controls the external FET gate to maintain the (V
voltage at 100 mV or below.

3 ON

Undervoltage Input Pin. Active-high pin. An internal ON comparator has a trip threshold of 1.3 V, and the
output of this comparator is used as an enable for the hot swap operation. With an external resistor divider
from VCC to GND, this pin can be used to enable the hot swap operation on a specific voltage on VCC, giving

an undervoltage function.
4 GND Chip Ground Pin.
5 TIMER

Timer Pin. An external capacitor, C

TIMER

The GATE pin turns off when the TIMER pin is pulled beyond the upper threshold. An overvoltage detection

with an external Zener can be used to force this pin high.
6 SCL I2C Clock Pin. Open-drain input requires an external resistive pull-up.
7 SDA I2C Data I/O Pin. Open-drain input/output. Requires an external resistive pull-up.
8 A0

9 A1

10 GATE

2

C Address Pin. This pin can be tied low, tied high, left floating, or tied low through a resistor. Sixteen different

I

2

I

C address options are available, depending on the external configuration of the A0 pin and A1 pin.

2

C Address Pin. This pin can be tied low, tied high, left floating or tied low through a resistor. Sixteen different

I

2

C address options are available, depending on the external configuration of the A0 pin and the A1 pin.

I

GATE Output Pin. This pin is the high-side gate drive of an external N-channel FET. This pin is driven by the

FET drive controller, which utilizes a charge pump to provide a 12.5 μA pull-up current to charge the FET

GATE pin. The FET drive controller regulates to a maximum load current (100 mV through the sense resistor)

by modulating the GATE pin.

10

GATE
A1

9

A0

8

SDA

7
6

SCL

06046-003

− V

SENSE

)

VCC

, sets a 270 ms/μF initial timing cycle delay and a 21.7 ms/μF fault delay.

Rev. 0 | Page 7 of 24

ADM1176

TYPICAL PERFORMANCE CHARACTERISTICS

2.0

1.8

1.6

1.4

1.2

1.0

(mA)

CC

I

0.8

0.6

0.4

0.2

0

024681014112 16

VCC (V)

Figure 4. Supply Current vs. Supply Voltage

8

06046-021

2.0

1.8

1.6

1.4

1.2

1.0

(mA)

CC

I

0.8

0.6

0.4

0.2

0

–40 806040200–20

TEMPERATURE (°C)

Figure 7. Supply Current vs. Temperature (Gate On)

06046-022

12

10

8

6

DRIVE VOLTAGE (V)

4

2

0

01

Figure 5. Drive Voltage (V

0

–2

–4

–6

(µA)

–8

GATE

I

–10

VCC (V)

− VCC) vs. Supply Voltage

GATE

8161412108642

06046-029

12

10

8

6

DRIVE VOLTAGE ( V)

4

2

0

–40 806040200–20

Figure 8. Drive Voltage (V

0

–2

–4

–6

(µA)

–8

GATE

I

–10

5V V

3.15V V

TEMPERATURE (°C)

− VCC) vs. Temperature

GATE

CC

CC

06046-030

–12

–14

01

VCC (V)

10 12 16148642

8

06046-027

Figure 6. Gate Pull-Up Current vs. Supply Voltage

–12

–14

–40 806040200–20

Figure 9. Gate Pull-Up Current vs. Temperature

Rev. 0 | Page 8 of 24

TEMPERATURE (°C)

06046-028