Hot Swap Controller and Digital Power Monitor with Convert Pin Data Sheet ADM1175 FEATURES FUNCTIONAL BLOCK DIAGRAM Allows safe board insertion and removal from ADM1175-1 CONV a live 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 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 UV COMPARATOR Active high and active low ON/ONB pin options GND TIMER Convert start pin (CONV) Figure 1. 2 I C fast mode-compliant interface (400 kHz maximum) 10-lead MSOP 3.15V TO 16.5V R N-CHANNEL FET SENSE APPLICATIONS Power monitoring/power budgeting Central office equipment VCC SENSE CONTROLLER Telecommunications and data communications equipment GATE PCs/servers ADM1175-1 P = VI SDA SDA ON GENERAL DESCRIPTION SCL SCL CONV The ADM1175 is an integrated hot swap controller and current CONV sense amplifier that offers digital current and voltage monitoring TIMER ADR GND via an on-chip, 12-bit analog-to-digital converter (ADC), 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. 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 The ADM1175 limits the current through this resistor by 2 I C interface allows a controller to read current and voltage data controlling the gate voltage (via the GATE pin) of an external 2 from the ADC. Measurements can be initiated by an I C command N-channel FET in the power path. The voltage across the sense or via the convert (CONV) pin. The CONV pin is especially resistor (and, therefore, the inrush current) is kept below a preset maximum. useful for synchronizing reads on multiple ADM1175 devices. Alternatively, the ADC can run continuously, and the user can The ADM1175 protects the external FET by limiting the time read the latest conversion data whenever it is required. Up to four that the maximum current runs through it. This current limit 2 unique I C addresses can be created, depending on how the ADR period is set by the value of the capacitor attached to the TIMER pin is connected. pin. Additionally, the device provides protection from overcurrent The ADM1175 is packaged in a 10-lead MSOP. 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. 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. 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All rights reserved. 05647-002 05647-001ADM1175 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Initial Timing Cycle ................................................................... 13 Applications ....................................................................................... 1 Hot Swap Retry Cycle on the ADM1175-1 and the ADM1175-3 ................................................................................ 14 General Description ......................................................................... 1 Voltage and Current Readback ..................................................... 15 Functional Block Diagram .............................................................. 1 Serial Bus Interface ..................................................................... 15 Revision History ............................................................................... 2 2 Identifying the ADM1175 on the I C Bus ............................... 15 Specif icat ions ..................................................................................... 3 2 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/ONB Function ..................................................................... 12 Kelvin Sense Resistor Connection ........................................... 21 TIMER Function ........................................................................ 12 Outline Dimensions ....................................................................... 22 GATE and TIMER Functions During a Hot Swap O p erat ion ..................................................................................... 13 Ordering Guide .......................................................................... 22 Calculating Current Limits and Fault Current Limit Time .. 13 REVISION HISTORY 5/12Rev. B to Rev. C Changes to Table 7 .......................................................................... 17 Changes to Write Extended Command Byte Section ................ 18 Added VBUS = 3.0 V to 5.5 V Condition to VIL and VIH, Table 1 ..... 4 Changes to Figure 37 ...................................................................... 18 Changes to Kelvin Sense Resistor Connection Section ............. 22 Changes to Table 9 and Table 11 .................................................. 18 Deleted Figure 46 ............................................................................ 23 Changes to Converting ADC Codes to Voltage and Updated Outline Dimensions ....................................................... 23 Current Readings Section .............................................................. 19 2/08Rev. A to Rev. B 4/07Rev. 0 to Rev. A Changed V to V Throughout ................................................. 3 VCC CC Changes to Table 4 ............................................................................. 7 Changes to Input Current for 00 Decode, I Parameter ......... 3 ADRLOW Changes to GATE and TIMER Functions During Changes to Input Current for 11 Decode, IADRHIGH Parameter ........ 3 a Hot Swap Section ......................................................................... 14 Added ADC Conversion Time Parameter .................................... 4 Changes to Calculating Current Limits and Added Fast Overcurrent Response Time Parameter ................... 4 Fault Current Limit Time Section ................................................ 14 Added Endnote 2 and Endnote 3 ................................................... 4 Changes to Initial Timing Cycle Section ..................................... 14 Changes to Figure 14 ........................................................................ 8 Changes to Table 5 .......................................................................... 16 Changes to Figure 15 Caption ......................................................... 8 Changes to Figure 32 and Figure 33............................................. 17 Changes to Figure 24 ...................................................................... 10 Changes to Figure 37 ...................................................................... 19 Changes to TIMER Function Section .......................................... 12 Changes to Figure 39 and Figure 40............................................. 20 Changes to Table 5 .......................................................................... 15 2 Added Applications Information Heading ................................. 22 Changes to General I C Timing Section ...................................... 15 Changes to Quick Command Section ......................................... 17 9/06Revision 0: Initial Version Changes to Figure 35 ...................................................................... 17 Rev. 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