Hot Swap Controller and Digital Power Monitor with Soft Start Pin Data Sheet ADM1177 FEATURES FUNCTIONAL BLOCK DIAGRAM Allows safe board insertion and removal from ADM1177 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 Soft start pin for reference adjustment and programming of GND SS TIMER initial current ramp rate Figure 1. Active high ON pin 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 VCC SENSE CONTROLLER Central office equipment GATE Telecommunications and data communications equipment ADM1177 P = VI PCs/servers SDA SDA ON SCL SCL GENERAL DESCRIPTION SS The ADM1177 is an integrated hot swap controller that offers TIMER GND ADR digital current and voltage monitoring via an on-chip, 12-bit analog-to-digital converter (ADC), communicated through an 2 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 A soft start pin (SS) is also included. This gives the user control SENSE pin. over the reference on the current sense amplifier. An internal The ADM1177 limits the current through this resistor by current source charges a capacitor on this pin at startup, allowing controlling the gate voltage (via the GATE pin) of an external the user to set the profile of the initial current ramp. A voltage N-channel FET in the power path. The voltage across the sense can also be driven on this pin to alter the reference. resistor (and, therefore, the inrush current) is kept below a A 12-bit ADC can measure the current seen in the sense resistor, preset maximum. as well as the supply voltage on the VCC pin. An industry-standard 2 The ADM1177 protects the external FET by limiting the time I C interface allows a controller to read current and voltage data 2 that the maximum current runs through it. This current limit from the ADC. Measurements can be initiated by an I C command. period is set by the value of the capacitor attached to the TIMER Alternatively, the ADC can run continuously, and the user can pin. Additionally, the device provides protection from overcurrent read the latest conversion data whenever it is required. Up to 2 events that may occur once the hot swap event is complete. In four unique I C addresses can be created, depending on how the the case of a short-circuit event, the current in the sense resistor ADR pin is connected. exceeds an overcurrent trip threshold, and the FET is switched off The ADM1177 is packaged in a 10-lead MSOP. immediately by pulling down the GATE pin. Rev. C Document Feedback 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 20062012 Analog Devices, Inc. All rights reserved. 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. Technical Support www.analog.com 06047-002 06047-001ADM1177 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Initial Timing Cycle ................................................................... 13 Applications ....................................................................................... 1 Hot Swap Retry Cycle on the ADM1177-1 ............................. 14 General Description ......................................................................... 1 Soft Start (SS Pin) ....................................................................... 14 Functional Block Diagram .............................................................. 1 Voltage and Current Readback ..................................................... 15 Revision History ............................................................................... 2 Serial Bus Interface..................................................................... 15 2 Specifications ..................................................................................... 3 Identifying the ADM1177 on the I C Bus ............................... 15 2 Absolute Maximum Ratings ............................................................ 5 General I C Timing .................................................................... 15 Thermal Characteristics .............................................................. 5 Write and Read Operations ........................................................... 17 ESD Caution .................................................................................. 5 Quick Command ........................................................................ 17 Pin Configuration and Function Descriptions ............................. 6 Write Command Byte ................................................................ 17 Typical Performance Characteristics ............................................. 7 Write Extended Command Byte .............................................. 18 Overview of the Hot Swap Function ............................................ 12 Read Voltage and/or Current Data Bytes ................................ 19 Undervoltage Lockout ............................................................... 12 Applications Information .............................................................. 21 ON Function ............................................................................... 12 Applications Waveforms ............................................................ 21 TIMER Function ........................................................................ 12 Kelvin Sense Resistor Connection ........................................... 22 GATE and TIMER Functions During a Hot Swap Outline Dimensions ....................................................................... 23 Operation ..................................................................................... 13 Ordering Guide .......................................................................... 23 Calculating Current Limits and Fault Current Limit Time .. 13 REVISION HISTORY 10/12Rev. B to Rev. C Changes to Table 7 .......................................................................... 17 Changes to Table 1 ............................................................................ 4 Changes to Write Extended Command Byte Section ................ 18 Changes to Kelvin Sense Resistor Connection Section ............. 22 Changes to Figure 39 ...................................................................... 18 Deleted Figure 49, Renumbered Sequentially............................. 22 Changes to Table 9 and Table 11 .................................................. 18 Updated Outline Dimensions ....................................................... 23 Changes to Converting ADC Codes to Voltage and Changes to Ordering Guide .......................................................... 23 Current Readings Section .............................................................. 19 2/08Rev. A to Rev. B 4/07Rev. 0 to Rev. A Changed VVCC to VCC Throughout ................................................. 3 Changes to GATE and TIMER Functions During Changes to Input Current for 00 Decode, IADRLOW Parameter ......... 3 a Hot Swap Section ......................................................................... 14 Changes to Input Current for 11 Decode, IADRHIGH Parameter ........ 3 Changes to Calculating Current Limits and Fault Current Added ADC Conversion Time Parameter .................................... 4 Limit Time Section ......................................................................... 14 Added Fast Overcurrent Response Time Parameter ................... 4 Changes to Initial Timing Cycle Section ..................................... 14 Added Endnote 2 and Endnote 3 ................................................... 4 Changes to Soft Start (SS Pin) Section ........................................ 15 Changes to Figure 14 ........................................................................ 8 Changes to Table 5 .......................................................................... 16 Changes to Figure 15 Caption ......................................................... 8 Changes to Figure 34 and Figure 35 ............................................ 17 Changes to Figure 24 ...................................................................... 10 Changes to Figure 39 ...................................................................... 19 Changes to TIMER Function Section .......................................... 12 Changes to Figure 41 and Figure 42 ............................................ 20 Changes to Table 5 .......................................................................... 15 Added Applications Information Heading ................................. 22 2 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. C Page 2 of 24