Hot Swap Controller and 2 I C Power Monitor Data Sheet ADM1176 FEATURES FUNCTIONAL BLOCK DIAGRAM Allows safe board insertion and removal from a live backplane ADM1176 Controls supply voltages from 3.15 V to 16.5 V MUX Precision current sense amplifier V VCC 0 Precision voltage input SDA 12-BIT 2 I C ADC 12-bit ADC for current and voltage readback I SCL A 1 Charge-pumped gate drive for external N-channel FET A1 SENSE A0 Adjustable analog current limit with circuit breaker CURRENT SENSE 3% accurate hot swap current limit level AMPLIFIER Fast response limits peak fault current Automatic retry or latch-off on current fault FET DRIVE ON GATE CONTROLLER Programmable hot swap timing via TIMER pin 1.3V Active high ON pin UNDERVOLTAGE 2 COMPARATOR I C fast mode-compliant interface (400 kHz maximum) 2 address pins allow 16 devices on the same bus GND TIMER 10-lead MSOP Figure 1. APPLICATIONS 3.15V TO 16.5V R N-CHANNEL FET Power monitoring/power budgeting SENSE Central office equipment Telecommunications and data communications equipment VCC SENSE PCs/servers CONTROLLER GATE GENERAL DESCRIPTION ADM1176 P = VI The ADM1176 is an integrated hot swap controller that offers SDA SDA ON SCL SCL digital current and voltage monitoring via an on-chip 12-bit analog-to-digital converter (ADC), communicated through an TIMER A1 2 I C interface. GND A0 An internal current sense amplifier measures voltage across the sense resistor in the power path via the VCC pin and the SENSE pin. Figure 2. Applications Diagram The ADM1176 limits the current through this resistor by control- ling the gate voltage (via the GATE pin) of an external N- A 12-bit ADC can measure the current seen in the sense channel FET in the power path. The voltage across the sense resistor, as well as the supply voltage on the VCC pin. An resistor (and therefore the inrush current) is kept below a preset 2 industry-standard I C interface allows a controller to read maximum. current and voltage data from the ADC. Measurements can be The ADM1176 protects the external FET by limiting the time that 2 initiated by an I C command. Alternatively, the ADC can run the maximum current runs through it. This current limit period continuously, and the user can read the latest conversion data is set by the value of the capacitor attached to the TIMER pin. 2 whenever it is required. Up to 16 unique I C addresses can be Additionally, the device provides protection from overcurrent created, depending on how the A0 and A1 pins are connected. events that may occur after the hot swap event is complete. In The ADM1176 is packaged in a 10-lead MSOP. 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. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com 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. Fax: 781.461.3113 20062012 Analog Devices, Inc. All rights reserved. 06046-002 06046-001ADM1176 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Calculating Current Limits and Fault Current Limit Time .. 14 Applications ....................................................................................... 1 Initial Timing Cycle ................................................................... 14 General Description ......................................................................... 1 Hot Swap Retry on the ADM1176-1 ....................................... 15 Functional Block Diagram .............................................................. 1 Voltage and Current Readback ..................................................... 16 Revision History ............................................................................... 2 Serial Bus Interface ..................................................................... 16 2 Specif icat ions ..................................................................................... 3 Identifying the ADM1176 on the I C Bus ............................... 16 2 Absolute Maximum Ratings ............................................................ 6 General I C Timing .................................................................... 16 Thermal Characteristics .............................................................. 6 Write and Read Operations ........................................................... 18 ESD Caution .................................................................................. 6 Quick Command ........................................................................ 18 Pin Configuration and Function Descriptions ............................. 7 Write Command Byte ................................................................ 18 Typical Performance Characteristics ............................................. 8 Write Extended Command Byte .............................................. 19 Overview of the Hot Swap Function ............................................ 13 Read Voltage and/or Current Data Bytes ................................ 20 Undervoltage Lockout ............................................................... 13 Applications Information .............................................................. 22 ON Function ............................................................................... 13 Applications Waveforms ............................................................ 22 TIMER Function ........................................................................ 13 Kelvin Sense Resistor Connection ........................................... 22 Outline Dimensions ....................................................................... 23 GATE and TIMER Functions During a Hot Swap O p erat ion ..................................................................................... 14 Ordering Guide .......................................................................... 23 REVISION HISTORY 5/12Rev. B to Rev. C 4/07Rev. 0 to Rev. A Added VBUS = 3.0 V to 5.5 V Condition to VIL and VIH, Table 1 ..... 4 Changes to GATE and TIMER Functions During Changes to Kelvin Sense Resistor Connection Section ............. 22 a Hot Swap Section ......................................................................... 14 Deleted Figure 46 ............................................................................ 23 Changes to Calculating Current Limits and Updated Outline Dimensions ....................................................... 23 Fault Current Limit Time Section ................................................ 14 Changes to Initial Timing Cycle Section ..................................... 14 2/08Rev. A to Rev. B Changes to Table 5 .......................................................................... 16 Changed V to V Throughout ................................................. 3 VCC CC Changes to Figure 32 and Figure 33............................................. 17 Changes to Input Current for 00 Decode, I , Parameter ... 3 ADRLOW Changes to Figure 37 ...................................................................... 19 Changes to Input Current for 11 Decode, IADRHIGH, Parameter ... 3 Changes to Figure 39 and Figure 40............................................. 20 Added ADC Conversion Time Parameter .................................... 5 Added Applications Information Heading ................................. 22 Added Fast Overcurrent Response Time Parameter ................... 5 9/06Revision 0: Initial Version Added Endnote 2 and Endnote 3 ................................................... 5 Change to Figure 14 ......................................................................... 9 Changes to Figure 15 Caption ......................................................... 9 Changes to Figure 24 ...................................................................... 11 Changes to TIMER Function Section .......................................... 13 2 Changes to General I C Timing Section, Step 3 ......................... 16 Changes to Table 5 .......................................................................... 16 Changes to Figure 32 and Figure 33 ............................................. 17 Changes to Quick Command Section ......................................... 18 Changes to Figure 35 ...................................................................... 18 Changes to Table 7 .......................................................................... 18 Changes to Write Extended Command Byte Section ................ 19 Changes to Figure 37 ...................................................................... 19 Changes to Table 9 and Table 11 ................................................... 19 Changes to Converting ADC Codes to Voltage and Current Readings Section ......................................................... 20 Rev. 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