LTM4681 (Rev. 0) - Analog Devices

1 LTM46811 Rev. 0 For more information FeedbackTYPICAL APPLICATIONFEATURESDESCRIPTIONQuad or Single 125A Module Regulator with Digital Power System ManagementThe LTM 4681 is a quad or single 125A step-down Module (power module) DC/DC regulator fea-turing remote configurability and telemetry-monitoring of power management parameters over PMBus. The LTM4681 is comprised of digitally programmable Analog control loops , precision mixed-signal circuitry, EEPROM, power MOSFETs, inductors and supporting LTM4681 s 2-wire serial interface allows outputs to be margined, tuned and ramped up and down at pro-grammable slew rates with sequencing delay times. True input current sense, output currents and voltages, output power, temperatures, uptime and peak values are read-able.

2 Custom configuration of the EEPROM contents is not required. At start-up, output voltages, switching frequency, and channel phase angle assignments can be set by pin-strapping resistors. The LTpowerPlay GUI and DC1613 USB-to-PMBus converter and demo kits are LTM4681 is offered in a 15mm 22mm BGA package available with SnPb or RoHS compliant terminal finish. APPLICATIONS nQuad Digitally Adjustable Analog loops with Digital Interface for Control and Monitoring nWide Input Voltage Range: to 16V nOutput Voltage Range: to n Maximum DC Output Error Over Temperature n 4% Current Readback Accuracy: 0 C to 125 C nIntegrated Input Current Sense Amplifier n400kHz PMBus-Compliant I2C Serial Interface nSupports Telemetry Polling Rates Up to 125Hz nIntegrated 16-Bit ADC nParallel and Current Share Multiple Modules n15mm 22mm BGA PackageReadable Data: nInput and Output Voltages, Currents, and Temperatures nRunning Peak Values, Uptime, Faults and Warnings nOnboard EEPROM Fault Log RecordWritable Data and Configurable Parameters.

3 NOutput Voltage, Voltage Sequencing and Margining nDigital Soft-Start/Stop Ramp, Program Analog Loop nOV/UV/OT, UVLO, Frequency and Phasing nMulti-Rail Processor Power, Configurable Core PowerAll registered trademarks and trademarks are the property of their respective owners. Protected by Patents including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 7420359, 8163643. Licensed under Patent 7000125 and other related patents Module Regulator with Digital Interface for Control and MonitoringChannel Efficiency vs Load CurrentPOWER GOOD MONITORSFAULT INTERRUPTSON/OFF TO TO 16 VCBULK22 F 622 F AT AT AT AT TA01aPGOOD0,1,2,3WP_23WP_01 SYNC_01 SYNC_23 SHARE_CLK_01 SHARE_CLK_23 ALERT_01 ALERT_23 SDA_01 SDA_23 SCL_01 GNDSGND_23 SGND_01 SCL_23 FAULT0,1,2,3 RUN0,1,2.

4 3 RUNPVIN_VBIASSVIN_23 VIN23IN_23 IN_23+SVIN_01 VIN01IN_01 IN_01+VOSNS3 VOSNS3+VOUT3 VOSNS2 VOSNS2+VOUT2 VOSNS1 VOSNS1+VOUT1 VOSNS0 VOSNS0+VOUT0 LTM4681I2C/SMBus I/F WITH PMBus COMMANDSET TO/FROM IPMI OR OTHERBOARD MANAGEMENT CONTROLLERSYNCHRONIZATION TIMEBASE REGISTER WRITEPROTECTIONFOR COMPLETE CIRCUITSEE FIGURE 48(FROM TO VIN, SVIN,AND INTVCC TOGETHER)++++RSENSE1 RSENSE2 OUTPUT CURRENT (A)0 EFFICIENCY (%)958694929088939189878525154681 TA01b35201030512 VIN, , 250kHz12 VIN, , 250kHz12 VIN, , 350kHz12 VIN, , 425kHzConfigurable Output 0 For more information OF CONTENTSF eatures ..1 Applications ..1 Typical Application .. 1 Table of Contents ..2 Absolute Maximum Ratings ..4 Order Information ..4 Pin Configuration ..4 Electrical Characteristics.

5 5 Typical Performance Characteristics ..12 Pin Functions ..16 Simplified Block Diagram ..24 Decoupling Requirements ..24 Functional Diagram ..25 Test Circuits ..26 Test Circuits .. 28 Power Module Introduction ..28 Power Module Overview, Major Features ..28 EEPROM with ECC ..29 Power-Up and Initialization ..30 Soft-Start ..31 Time-Based Sequencing ..31 Voltage-Based Sequencing ..32 Shutdown ..32 Light-Load Current Operation ..32 Switching Frequency and Phase ..33 PWM Loop Compensation ..33 Output Voltage Sensing ..33 INTVCC/VBIAS Power ..33 Output Current Sensing and Sub Milliohm DCR Current Sensing ..34 Input Current Sensing ..34 PolyPhase Load Sharing ..34 Internal Temperature Sense ..35 RCONFIG (Resistor Configuration) Pins ..35 Table 1.

6 VOUTn _CFG Pin Strapping Look-Up Table for the LTM4681 s Output Voltage, Coarse Setting (Not Applicable if MFR_CONFIG_ALL[6] = 1b) Top Resistor = 2. VTRIMn_CFG Pin Strapping Look-Up Table for the LTM4681 s Output Voltage, Fine Adjustment Setting (Not Applicable if MFR_CONFIG_ALL[6] = 1b) Top Resistor = 3. FSWPH_nn_CFG Pin Strapping Look-Up Table to Set the LTM4681 s Switching Frequency and Channel Phase-Interleaving Angle (Not Applicable if MFR_CONFIG_ALL[6] = 1b), nn = 0,1 or 2,3 Channels, set top resistor to ..37 Table 4. ASEL_nn Pin Strapping Look-Up Table to Set the LTM4681 s Slave Address (Applicable Regardless of MFR_CONFIG_ALL[6] Set ting) ..38 Table 5. LTM4681 MFR_ADDRESS Command Examples Expressed in 7- and 8-Bit Addressing 38 Fault Detection and Handling.

7 38 Status Registers and ALERT Masking ..39 Figure 5. LTM4681 Status Register Summary per Controller ..40 Mapping Faults to FAULTn Pins ..41 Power Good Pins ..41 CRC Protection ..41 Serial Interface ..41 Communication Protection ..41 Device Addressing ..41 Responses to VOUT and IIN/IOUT Faults ..42 Output Overvoltage Fault Response ..42 Output Undervoltage Response ..43 Peak Output Overcurrent Fault Response ..43 Responses to Timing Faults ..43 Responses to VIN OV Faults ..43 Responses to OT/UT Faults ..43 Internal Overtemperature Fault and Undertemperature Fault Response ..44 Responses to Input Overcurrent and Output Undercurrent Faults ..44 Responses to External Faults ..44 Fault Logging ..44 Bus Timeout Protection ..44 Similarity Between PMBus, SMBus and I2C 2-Wire Interface.

8 45 PMBus Serial Digital Interface ..45 Table 6. Abbreviations of Supported Data Formats .. 46 Figure 6. PMBus Timing Diagram ..46 Figure 7 to Figure 24 PMBus Protocols ..47 PMBus Command Summary ..50 PMBus Commands ..50 LTM46813 Rev. 0 For more information OF CONTENTST able 7. PMBus Commands Summary (Note: The Data Format Abbreviations Are Detailed in Table 8) ..50 Table 8. Data Format Abbreviations ..55 Applications Information ..56 VIN to VOUT Step-Down Ratios ..56 Input Capacitors ..56 Output Capacitors ..56 Light Load Current Operation ..56 Switching Frequency and Phase ..57 Output Current Limit Programming ..58 Minimum On-Time Delay Time, Soft-Start and Output Voltage Ramping ..59 Digital Servo Mode ..59 Soft Off (Sequenced Off).

9 60 Undervoltage Lockout ..61 Fault Detection and Handling ..61 Open-Drain Pins ..61 Phase-Locked Loop and Frequency Synchronization .. 62 Input Current Sense Amplifier ..63 Programmable Loop Compensation ..63 Checking Transient Response ..64 PolyPhase Configuration ..65 Connecting The USB to I2C/SMBus/PMBus Controller to the LTM4681 In System ..65 LTpowerPlay: An Interactive GUI for Digital Power . 66 PMBus Communication and Command Processing 66 Thermal Considerations and Output Current Derating . 68 Table 10 through Table 12: Output Current Derating ..71 Table 13. Single Channel Output Voltage vs Capacitor Selection, 10A to 20A Load Step with 10A/ s Slew Rate ..72 Table 14. Single Channel Output Voltage vs Capacitor Selection, All Ceramic Configuration, 10A to 20A Load Step with 10A/ s Slew Rate.

10 73 Table 15. Dual Connected Channels Output Voltage vs Capacitor Selection, Bulk and Ceramic Cap Configuration, 10A to 30A Load Step with 20A/ s Slew Rate ..74 Table 16. Quad Connected Channels Output Voltage vs Capacitor Selection, Bulk and Ceramic Cap Configuration, 10A to 40A Load Step with 15A/ s Slew Rate ..74 Derating Curves ..75 EMI Performance ..77 Safety Considerations ..77 Layout Checklist/Example ..77 Typical Applications ..79 PMBus Command Details ..84 Addressing and Write Protect ..84 General Configuration Commands ..86On/Off/Margin ..87 PWM Configuration ..89 Voltage ..92 Input Voltage and Limits ..92 Output Voltage and Limits ..93 Output Current and Limits ..96 Input Current and Limits ..98 Temper atur e ..99 Power Stage DCR Temperature Stage Temperature Limits.