Hot Swap Controller and Digital Power Monitor with ALERTB Output Data Sheet ADM1178 FEATURES FUNCTIONAL BLOCK DIAGRAM Allows safe board insertion and removal from a live ADM1178 backplane MUX Controls supply voltages from 3.15 V to 16.5 V V VCC 0 Precision current sense amplifier SDA 12-BIT 2 I C ADC Precision voltage input I SCL A 1 12-bit ADC for current and voltage readback ADR SENSE Charge-pumped gate drive for external N-channel FET CURRENT SENSE Adjustable analog current limit with circuit breaker AMPLIFIER ALERT ALERTB 3% accurate hot swap current limit level Fast response limits peak fault current FET DRIVE ON GATE CONTROLLER Automatic retry or latch-off on current fault 1.3V Programmable hot swap timing via TIMER pin UNDERVOLTAGE COMPARATOR Active high ON pin ALERTB output for overcurrent interrupt GND TIMER 2 I C fast mode-compliant interface (400 kHz maximum) Figure 1. 10-lead MSOP 3.15V TO 16.5V APPLICATIONS R N-CHANNEL FET SENSE Power monitoring/power budgeting Central office equipment VCC SENSE CONTROLLER Telecommunications and data communications equipment GATE PCs/servers ADM1178 P = VI GENERAL DESCRIPTION SDA SDA ON SCL SCL The ADM1178 is an integrated hot swap controller and current ALERTB INTERRUPT sense amplifier that offers digital current and voltage monitoring TIMER via an on-chip 12-bit analog-to-digital converter (ADC), GND ADR 2 communicated through an I C interface. Figure 2. Applications Diagram An internal current sense amplifier measures voltage across the sense resistor in the power path via the VCC pin and the SENSE pin. The ADM1178 limits the current through this resistor by control- A 12-bit ADC can measure the current seen in the sense ling the gate voltage (via the GATE pin) of an external N-channel resistor, as well as the supply voltage on the VCC pin. An alert FET in the power path. The voltage across the sense resistor (and output can be set to trigger when the ADC current reading therefore the inrush current) is kept below a preset maximum. exceeds a programmed overcurrent limit threshold. The ADM1178 protects the external FET by limiting the time that 2 An industry-standard I C interface allows a controller to read the maximum current runs through it. This current limit period current and voltage data from the ADC. Measurements can be is set by the value of the capacitor attached to the TIMER pin. 2 initiated by an I C command. Alternatively, the ADC can run Additionally, the device provides protection from overcurrent continuously, and the user can read the latest conversion data events that may occur after the hot swap event is complete. In 2 whenever it is required. Up to four unique I C addresses can be case of a short-circuit event, the current in the sense resistor created, depending on how the ADR pin is connected. exceeds an overcurrent trip threshold, and the FET is switched The ADM1178 is packaged in a 10-lead MSOP. off immediately by pulling down the GATE pin. Rev. D 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. 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All rights reserved. 06048-002 06048-001ADM1178 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Initial Timing Cycle ................................................................... 13 Applications ....................................................................................... 1 Hot Swap Retry Cycle on the ADM1178-1 ............................. 14 General Description ......................................................................... 1 Voltage and Current Readback ..................................................... 15 Functional Block Diagram .............................................................. 1 Serial Bus Interface..................................................................... 15 2 Revision History ............................................................................... 2 Identifying the ADM1178 on the I C Bus ............................... 15 2 Specifications ..................................................................................... 3 General I C Timing .................................................................... 15 Absolute Maximum Ratings ............................................................ 5 Write and Read Operations ........................................................... 17 Thermal Characteristics .............................................................. 5 Quick Command ........................................................................ 17 ESD Caution .................................................................................. 5 Write Command Byte ................................................................ 17 Pin Configuration and Function Descriptions ............................. 6 Write Extended Command Byte .............................................. 18 Typical Performance Characteristics ............................................. 7 Read Voltage and/or Current Data Bytes ................................ 19 Overview of the Hot Swap Function ............................................ 12 Applications Information .............................................................. 21 Undervoltage Lockout ............................................................... 12 Applications Waveforms ............................................................ 21 ON Function ............................................................................... 12 ALERTB Output ......................................................................... 22 TIMER Function ........................................................................ 12 Kelvin Sense Resistor Connection ........................................... 22 GATE and TIMER Functions During a Hot Swap Operation Outline Dimensions ....................................................................... 23 ....................................................................................................... 13 Ordering Guide .......................................................................... 23 Calculating Current Limits and Fault Current Limit Time .. 13 REVISION HISTORY 6/12Rev. C to Rev. D Changes to Table 5 .......................................................................... 16 Changes to Low Level Input Voltage, VIL Parameter, Test Changes to Quick Command Section ......................................... 18 Conditions/Comments Column, Table 1 and High Level Input Changes to Figure 38 ...................................................................... 18 Voltage, V Parameter, Test Conditions/Comments Column, Changes to Table 7 .......................................................................... 18 IH Table 1 ................................................................................................ 3 Changes to Write Extended Command Byte Section ................ 19 Changes to ALERTB Output Section and Kelvin Sense Resistor Changes to Figure 40 ...................................................................... 19 Connection Section ........................................................................ 22 Changes to Table 9 and Table 11 .................................................. 19 Deleted Figure 50 Renumbered Sequentially............................. 23 Changes to Converting ADC Codes to Voltage and Updated Outline Dimensions ....................................................... 23 Current Readings Section .............................................................. 20 5/09Rev. B to Rev. C 4/07Rev. 0 to Rev. A Changes to Figure 1 .......................................................................... 1 Changes to Table 1 ............................................................................. 3 Changes to GATE and TIMER Functions During 2/08Rev. A to Rev. B a Hot Swap Section ......................................................................... 14 Changed V Changes to Calculating Current Limits and VCC to VCC Throughout ................................................. 3 Changes to Input Current for 11 Decode, IADRHIGH, Parameter ... 3 Fault Current Limit Time Section ................................................ 14 Changes to Input Current for 00 Decode, IADRLOW, Parameter ... 3 Changes to Initial Timing Cycle Section ..................................... 15 Added ADC Conversion Time Parameter .................................... 5 Changes to Table 5 .......................................................................... 16 Added Fast Overcurrent Response Time Parameter ................... 5 Changes to Figure 35 and Figure 36 ............................................ 17 Added Endnote 2 and Endnote 3 ................................................... 5 Changes to Figure 40 ...................................................................... 19 Changes to Figure 14 ........................................................................ 9 Changes to Figure 42 and Figure 43 ............................................ 20 Changes to Figure 15 Caption ......................................................... 9 Added Applications Information Heading ................................. 22 Changes to Figure 24 ...................................................................... 11 Changes to TIMER Function Section .......................................... 13 9/06Revision 0: Initial Version 2 Changes to General I C Timing Section, Step 3 ......................... 16 Rev. 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