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MAX34461

PMBus 16-Channel Voltage Monitor and Sequencer

General Description

The MAX34461 is a system monitor that is capable of

managing up to 16 power supplies. The power-supply

manager monitors the power-supply output voltages and

constantly checks for user-programmable overvoltage

and undervoltage thresholds. If a fault is detected,

the device automatically shuts down the system in an

orderly fashion. The device can sequence the supplies

in any order at both power-up and power-down. With

the addition of external current DACs, the device has

the ability to close-loop margin the power-supply output

voltages up or down to a user-programmable level. The

device contains an internal temperature sensor and can

support up to four external remote temperature sensors.

Once configured, the device can operate autonomously

without any host intervention.

Applications

Network Switches/Routers

Base Stations

Servers

Smart Grid Network Systems

Features

S 16 Channels of Power-Supply Management

S Power-Supply Voltage Measurement and

Monitoring

S Fast Minimum/Maximum Threshold Excursion

Detection

S Remote Ground Sensing Improves Measurement

Accuracy

S Automatic Closed-Loop Margining

S Programmable Up and Down Sequencing

S Supports Up to Five Temperature Sensors

(One Internal/Four Remote)

S Fault Detection on All Temperature Sensors

S Reports Peak and Average Levels for a Number of

Parameters

S PMBus™-Compliant Command Interface

S I

C/SMBus-Compatible Serial Bus with Bus

Timeout Function

S On-Board Nonvolatile Black Box Fault Logging

and Default Configuration Setting

S Expandable Channel Operation with Parallel Devices

S Up to 16 GPOs

S No External Clocking Required

S 3.0V to 3.6V Supply Voltage

Differences from MAX34460

S Adds 4 Channels of Monitoring, Sequencing, and

Margining

S Removes Dual Loop Sequencing, Watchdog, and

Alarm Output Functionality

19-6485; Rev 1; 11/13

Ordering Information and Typical Operating Circuit appear

at end of data sheet.

PMBus is a trademark of SMIF, Inc.

For related parts and recommended products to use with this part, refer to: www.maximintegrated.com/MAX34461.related

EVALUATION KIT AVAILABLE

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

Summary of content (59 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer General Description The MAX34461 is a system monitor that is capable of managing up to 16 power supplies. The power-supply manager monitors the power-supply output voltages and constantly checks for user-programmable overvoltage and undervoltage thresholds. If a fault is detected, the device automatically shuts down the system in an orderly fashion.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer TABLE OF CONTENTS General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer TABLE OF CONTENTS (continued) Interpreting Received DIRECT Format Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Sending a DIRECT Format Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Fault Management and Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer TABLE OF CONTENTS (continued) TON_MAX_FAULT_LIMIT (62h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 STATUS_WORD (79h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 STATUS_VOUT (7Ah) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer TABLE OF CONTENTS (continued) MFR_TEMP_SENSOR_CONFIG (F0h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 VDD, VDDA, and REG18 Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer LIST OF TABLES Table 1. PMBus Command Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Table 2. PMBus/SMBus Serial-Port Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Table 3. PMBus Command Code Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer ABSOLUTE MAXIMUM RATINGS VDD and VDDA to VSS...........................................-0.3V to +4.0V SDA, SCL, MSDA, and MSCL to VSS....................-0.3V to +4.0V RSG0 and RSG1 to VSS........................................-0.3V to +0.3V RSn to VSS................................................ -0.3V to (VDD + 0.3V)* RSn to VSS with 100ω of series resistance...........-0.3V to +2.0V All Other Pins Relative to VSS.................. -0.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer ELECTRICAL CHARACTERISTICS (continued) (VDD and VDDA = 3.0V to 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD/VDDA = 3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Output Logic-Low SCL, SDA, MSCL, MSDA VOL2 IOL = 4mA (Note 1) 0.4 V SCL, SDA, MSCL, MSDA Leakage ILI2C VDD = 0V or unconnected Q5 FA CONTROL Threshold 2.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer I2C/SMBus INTERFACE ELECTRICAL SPECIFICATIONS (VDD and VDDA = 3.0V to 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD/VDDA = 3.3V, TA = +25NC.) PARAMETER SYMBOL SCL Clock Frequency CONDITIONS MIN 10 fSCL MSCL Clock Frequency TYP fMSCL MAX UNITS 400 kHz 100 kHz Bus Free Time Between STOP and START Conditions tBUF 1.3 Fs Hold Time (Repeated) START Condition tHD:STA 0.6 Fs Low Period of SCL tLOW 1.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Typical Operating Characteristics (VDD = 3.3V and TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 13.0 12.0 TA = +85°C 13.0 IDD (mA) 12.5 13.5 MAX34461 toc02 13.5 IDD (mA) 14.0 MAX34461 toc01 14.0 12.5 12.0 11.5 11.5 11.0 11.0 10.5 10.5 TA = +25°C TA = -40°C 10.0 10.0 -20 -40 0 20 40 60 80 3.0 100 3.1 3.2 3.3 3.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Typical Operating Characteristics (continued) (VDD = 3.3V and TA = +25°C, unless otherwise noted.) VOUT STEPS DURING MARGINING RST PIN DURING POWER-UP MAX34461 toc08 MAX34461 toc07 VOUT 50mV/div 1V/div VDD 1V/div RST 200µs/div 20ms/div IDD vs. TIME DURING A NONVOLATILE LOG WRITE IDD vs.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer PSEN13 ALERT A1/ PG PSEN14 PSEN15 RSG0 RSG1 PSEN0 PSEN1 PSEN3 PSEN2 TOP VIEW PSEN4 Pin Configuration 36 35 34 33 32 31 30 29 28 27 26 25 PSEN5 37 24 PSEN12 PSEN6 38 23 PSEN11 PSEN7 39 22 PSEN10 RS13 40 21 PSEN9 RS12 41 20 PSEN8 RS11 42 19 MSDA MAX34461 RS10 43 18 MSCL RS9 44 17 RS14 RS8 45 16 REG18 RS7 46 RS6 47 15 VDD EP/ VSS + 14 SCL RS5 48 RS0 9 10 11 12 RS15 RS1 8 RST RS2 7 CONTROL RS3 6 N.C.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Pin Description (continued) PIN* NAME TYPE** 10 CONTROL AI 11 RST DIO FUNCTION Power-Supply Master On/Off Control. Active low or active high based on the ON_OFF_ CONFIG command. Active-Low Reset Input/Output. Contains an internal pullup. ADC Voltage-Sense Input 15. Connect to VSS if unused.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Pin Description (continued) PIN* NAME TYPE** FUNCTION 41 RS12 AI ADC Voltage-Sense Input 12. Connect to VSS if unused. 42 RS11 AI 43 RS10 AI ADC Voltage-Sense Input 11. Connect to VSS if unused. ADC Voltage-Sense Input 10. Connect to VSS if unused. 44 RS9 AI ADC Voltage-Sense Input 9. Connect to VSS if unused. 45 RS8 AI 46 RS7 AI ADC Voltage-Sense Input 8. Connect to VSS if unused. ADC Voltage-Sense Input 7.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Block Diagram MSDA MSCL SDA SCL SMBus MASTER SMBus SLAVE MAX34461 ALERT FAULT PULLUP A0/MONOFF A1/PG PULLUP RST VDD REG18 PMBus CONTROL AND MONITORING ENGINE POWER-SUPPLY OUTPUT ENABLES PSEN0– PSEN15 16 POWER CONTROL CONTROL 1.8V VREG AUTO SEQUENCER EP/VSS VDDA 8 DIGITAL COMPARATORS ADC RESULTS SRAM VREF 2.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer output and then measures the resultant output voltage. The power-supply manager can also sequence the supplies in any order at both power-up and power-down. temperature sensors. Communications with the DS75LV temperature sensors is conducted through a dedicated I2C/SMBus interface.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 1. PMBus Command Codes (continued) CODE COMMAND NAME TYPE PAGE 0–15 PAGE 17–21 PAGE 255 (NOTE 1) 99h MFR_ID 9Ah 9Bh NO.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Address Select On device power-up, the device samples the A0 and A1 pins to determine the PMBus/SMBus serial-port address. The combination of the components shown below determines the serial-port address (see also Table 2). MAX34461 R1 SMBus/PMBus Operation The device implements the PMBus command structure using the SMBus format.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer SMBus/PMBus Communication Examples READ WORD FORMAT 1 7 S SLAVE ADDRESS 1 W 1 8 A COMMAND CODE 1 1 7 A Sr SLAVE ADDRESS 1 8 A COMMAND CODE A 1 1 8 1 8 1 1 R A DATA BYTE LOW A DATA BYTE HIGH NA P 1 1 7 1 1 8 1 1 SLAVE ADDRESS Sr R A DATA BYTE NA P READ BYTE FORMAT 1 7 S SLAVE ADDRESS 1 W WRITE WORD FORMAT 1 7 1 1 8 1 8 1 8 1 1 S SLAVE ADDRESS W A COMMAND CODE A DATA BYTE LOW A DATA
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Group Command The device supports the group command. With the group command, a host can write different data to multiple devices on the same serial bus with one long continuous data stream. All the devices addressed during this transaction wait for the host to issue a STOP before beginning to respond to the command.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Alert Response Address (ARA) Byte Format 1 7 1 1 8 1 1 S ARA 0001100 R A DEVICE SLAVE ADDRESS WITH LSB = 0 NA P Host Sends or Reads Too Few Bits If, for any reason, the host does not complete writing a full byte or reading a full byte from the device before a START or STOP is received, the device does the following: Host Sends Improperly Set Read Bit in the Slave Address Byte 1) Ignores the command.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Host Reads from a Write-Only Command When a read request is issued to a write-only command (CLEAR_FAULTS, STORE_DEFAULT_ALL, RESTORE_ DEFAULT_ALL, OPERATION with PAGE = 255), the device does the following: 1) ACKs the address byte. 2) Ignores the command. 3) Sends all ones (FFh), as long as the host keeps acknowledging. 4) Sets the CML bit in STATUS_WORD. 5) Sets the DATA_FAULT bit in STATUS_CML.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 3.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Power supplies and power converters generally have no way of knowing how their outputs are connected to ground. Within the power supply, all output voltages are most commonly treated as positive. Accordingly, all output voltages and output voltage-related parameters of PMBus devices are commanded and reported as positive values. It is up to the system to know that a particular output is negative if that is of interest to the system.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer PMBus-Defined Time-Based Sequencing Figure 1 details a simple sequencing scheme using four power supplies. When either the CONTROL pin goes active or the OPERATION command is received (as defined by the ON_OFF_CONFIG command), each enabled PSENn output goes active (can be active high or low, as defined in MFR_PSEN_CONFIG) after the associated delay time programmed in TON_DELAY. The power supplies can be sequenced on in any order.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Timeslot-Defined Event-Based Sequencing As an example of timeslot sequencing, Figure 2 details a simple sequencing scheme using four power supplies.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer timeslot 2 begins. The power supplies can be sequenced on in any order. Since multiple power supplies can be assigned to a single timeslot, not all timeslots may be needed. However, timeslot assignment must be sequential. GLOBAL channels must start in timeslot 0, whereas local channels can be assigned to any timeslot. After all enabled supplies are turned on and above their respective power-good-on levels, the PG output transitions high.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer System Watchdog Timer The device uses an internal watchdog timer that is internally reset every 5ms. In the event the device is locked up and this watchdog reset does not occur after 210ms, the device automatically resets. After the reset occurs, the device reloads all configuration values that were stored to flash and begins normal operation. After the reset, the device also does the following: 1) Sets the MFR bit in STATUS_WORD.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 6. PAGE Commands PAGE ASSOCIATED CONTROL 0 Power supply monitored by RS0 and controlled by PSEN0 and optionally margined by OUT0 of the external DS4424 at I2C address 20h. 1 Power supply monitored by RS1 and controlled by PSEN1 and optionally margined by OUT1 of the external DS4424 at I2C address 20h. 2 Power supply monitored by RS2 and controlled by PSEN2 and optionally margined by OUT2 of the external DS4424 at I2C address 20h.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer OPERATION (01h) The OPERATION command is used to turn the power supply on and off in conjunction with the CONTROL input pin. The OPERATION command is also used to cause the power supply to set the output voltage to the upper or lower margin voltages. The power supply stays in the commanded operating mode until a subsequent OPERATION command or a change in the state of the CONTROL pin (if enabled) instructs the power supply to change to another state.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer ON_OFF_CONFIG (02h) The ON_OFF_CONFIG command configures the combination of CONTROL input and PMBus OPERATION commands needed to turn the power supply on and off. This indicates how the power supply is commanded when power is applied. Table 9 describes the ON_OFF_ CONFIG message content. The host should not modify ON_OFF_CONFIG while the power supplies are active.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STORE_DEFAULT_ALL (11h) The STORE_DEFAULT_ALL command instructs the device to transfer the complete device configuration information to the internal flash memory array. Not all information is stored; only configuration data is stored, not any status or operational data. If an error occurs during the transfer, ALERT asserts if enabled and the CML bit in and STATUS_WORD is set to 1. No bits are set in STATUS_CML. This command is write-only.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer command. The 2 data bytes are in DIRECT format. If the device cannot successfully close-loop margin the power supply, the device keeps attempting to margin the supply and does the following: 2) Sets the MARGIN_FAULT bit in STATUS_MFR_ SPECIFIC (PAGE 0–15). 3) Notifies the host through ALERT assertion (if enabled in MFR_MODE). 1) Sets the MARGIN bit in STATUS_WORD. 2) Sets the MARGIN_FAULT bit in STATUS_MFR_ SPECIFIC (PAGE 0–15).
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 13. Parametric Monitoring States PARAMETER REQUIRED CONDITIONS FOR ACTIVE MONITORING ACTION DURING A FAULT • Power supply enabled (TON_MAX_FAULT_LIMIT ≠ 8000h to FFFFh) Stop monitoring while PSENn is inactive and resume monitoring before channel is restarted.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer to violation of the VOUT_UV_FAULT_LIMIT, the device does the following: 1) Sets the VOUT bit in STATUS_WORD. 2) Sets the VOUT_UV_FAULT bit in STATUS_VOUT. 3) Responds as specified in MFR_FAULT_RESPONSE. 4) Notifies the host using ALERT assertion (if enabled in MFR_MODE). OT_FAULT_LIMIT (4Fh) The OT_FAULT_LIMIT command sets the temperature, in degrees Celsius, of the selected temperature sensor at which an overtemperature fault is detected.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 14. TON_MAX_FAULT_LIMIT Device Response DEVICE RESPONSE (FOR EACH ASSOCIATED PAGE) (NOTE 1) SEQUENCING CONFIGURATION (NOTE 2) TON_MAX_ FAULT_LIMIT VALUE Standard SEQUENCING RESPONSE VOLTAGE FAULT MONITORING (NOTE 3) USE PSENn AS GPO (NOTE 4) 0001h to 7FFFh Device asserts PSENn and monitors RSn to cross the undervoltage-fault limit in the time set by TON_MAX_FAULT_LIMIT.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STANDARD SEQUENCING TON_MAX_FAULT_LIMIT = 0001h TO 7FFFh MAX34461 SEQUENCER GPO PAGE n PSENn POWER SUPPLY ENABLE OV/UV MONITOR READ_VOUT / PG BLIND SEQUENCING TON_MAX_FAULT_LIMIT = 0000h RSn MAX34461 SEQUENCER GPO PAGE n PSENn READ_VOUT /PG RSn MAX34461 SEQUENCER POWER SUPPLY ENABLE VOUT OV/UV MONITOR MONITORING ONLY TON_MAX_FAULT_LIMIT = 0000h VOUT GPO VOLTAGE SOURCE PAGE n PSENn DIGITAL OUTPUT OV/UV MONITOR READ_VOUT/PG CHANNE
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STATUS_VOUT (PAGES 0–15) EVENT LATCH EVENT LATCH VOUT_OV_WARN EVENT LATCH VOUT_UV_FAULT EVENT LATCH VOUT_UV_WARN EVENT LATCH TON_MAX_FAULT VOUT_OV_FAULT NOTE 1: IF AN EVENT IS STILL PRESENT WHEN THE CLEAR_FAULTS COMMAND IS ISSUED, THE BIT IS IMMEDIATELY ASSERTED ONCE AGAIN. NOTE 2: WHEN THE ALERT LATCH IS CLEARED, IF ANY EVENTS ARE STILL PRESENT, THEY WILL NOT RE-ASSERT THE ALERT OUTPUT.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STATUS_WORD (79h) The STATUS_WORD command returns 2 bytes of information with a summary of the reason for a fault. The STATUS_WORD message content is described in Table 15. See Figure 5 for status register organization. STATUS_VOUT (7Ah) The STATUS_VOUT command returns 1 byte of information with contents, as described in Table 16. All the bits in STATUS_VOUT are latched.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STATUS_TEMPERATURE (7Dh) The STATUS_TEMPERATURE command returns 1 byte of information with contents, as described in Table 17. All the bits in STATUS_VOUT are latched. When cleared, the bits are set again if the condition persists. STATUS_CML (7Eh) The STATUS_CML command returns 1 byte of information with contents, as described in Table 18. The COMM_FAULT and DATA_FAULT bits are latched.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer STATUS_MFR_SPECIFIC (80h) The STATUS_MFR_SPECIFIC message content varies based on the selected page, and is described in Table 19 and Table 20. READ_VOUT (8Bh) The READ_VOUT command returns the actual measured (not commanded) output voltage. READ_VOUT is measured and updated every 5ms. The 2 data bytes are in DIRECT format. Table 19.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer READ_TEMPERATURE_1 (8Dh) The READ_TEMPERATURE_1 command returns the temperature returned from the temperature sensor. READ_ TEMPERATURE_1 returns 7FFFh if the sensor is faulty and 0000h if the sensor is disabled. READ_TEMPERATURE_1 is measured and updated once per second. The 2 data bytes are in DIRECT format. PMBUS_REVISION (98h) The PMBUS_REVISION command returns the revision of the PMBus specification to which the device is compliant.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_MODE (D1h) The MFR_MODE command is used to configure the device to support manufacturer-specific commands. The MFR_MODE command should not be changed while power supplies are operating. The MFR_MODE command is described in Table 21. Table 21.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_PSEN_CONFIG (D2h) The MFR_PSEN_CONFIG command is used to configure the individual PSENn outputs. This command should not be changed while the power supplies are operating. The MFR_PSEN_CONFIG command is described in Table 22 and Table 23. Table 22.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_SEQ_TIMESLOT (D3h) The MFR_SEQ_TIMESLOT command is used in the timeslot-defined sequencing mode (SEQ bit in MFR_MODE is set) to determine which timeslot the PSENn output is associated with. In the timeslot-defined sequencing mode, multiple PSENn outputs can be assigned to the same timeslot. Not all timeslots must be used, but the ordering must be sequential. GLOBAL channels must start with timeslot 0.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_NV_LOG_CONFIG (D8h) The MFR_NV_LOG_CONFIG command is used to configure the operation of the nonvolatile fault logging in the device. The MFR_NV_LOG_CONFIG command is described in Table 25. Table 25. MFR_NV_LOG_CONFIG BIT NAME MEANING FORCE_NV_FAULT_LOG Setting this bit to a 1 forces the device to log data into the nonvolatile fault log. Once set, the device clears this bit when the action is completed.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_FAULT_RESPONSE (D9h) The MFR_FAULT_RESPONSE command specifies the response to each fault or warning condition supported by the device. In response to a fault/warning, the device always reports the fault/warning in the appropriate status register and asserts the ALERT output (if enabled in MFR_MODE). A CML fault cannot cause any device action other than setting the status bit and asserting the ALERT output.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MONITORING 16 CHANNELS FAULT OVERVOLTAGE STATUS REGISTERS WARNING NV_FAULT_LOG FAULT UNDERVOLTAGE WARNING MFR_FAULT_RESPONSE SHUTDOWN SEQUENCING SEQUENCING ERROR FAULT TEMPERATURE SENSORS INTERNAL DS75LV DS75LV FAULT OR WARNING DS75LV DS75LV ON_OFF_CONFIG BIT 0 SHUTDOWN IMMEDIATELY OR SEQUENCE OFF FAULT_IGNORE BIT IN MFR_MODE GLOBAL BIT PSEN0 GLOBAL BIT PSEN1 GLOBAL BIT PSEN2 GLOBAL BIT PSEN3 GLOBAL BIT PSEN4 GLOBAL BIT PSEN5 GL
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 27. MFR_FAULT_RESPONSE Codes for GLOBAL Channels RESPONSE[1:0] 11 10 (retry) 01 (latchoff) 00 FAULT RESPONSE • Set the corresponding fault bit in the appropriate status register. • Log fault into MFR_NV_FAULT_LOG if NV_LOG = 1. • Continue operation. • Shut down the power supply by deasserting the PSENn output.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Power-Supply Retry with Undervoltage Faults If the power supply is configured to retry when an undervoltage fault occurs, the power supply is turned off for the fault retry time and then the power supply is turned back on by asserting the PSENn output. If the undervoltage fault still exists, the TON_MAX_FAULT_LIMIT is exceeded and the device takes fault action as configured.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer There is a FAULT_LOG_COUNT (16-bit counter) at the beginning of each fault log that indicates which fault log is the latest. This counter rolls over should more than 65,535 faults be logged. This counter is not cleared when the CLEAR_NV_FAULT_LOG bit in MFR_NV_LOG_ CONFIG is toggled. The 255 bytes returned by the MFR_ NV_FAULT_LOG command are described in Table 29.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 29.
PAGE 53
MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer MFR_MARGIN_CONFIG (DFh) The MFR_MARGIN_CONFIG command configures the external DS4424 current DAC (if present) to margin the associated power supplies. The MFR_MARGIN_CONFIG command is described in Table 30. For the power supplies connected to PSENn (PAGES 0–15), power-supply margining is implemented using the external DS4424 DAC outputs, according to Table 31. The device’s closed loop controls the DAC output current setting to margin the power supply.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Margining Faults The device detects two possible margining faults. First, if the initial DAC step causes VOUT to exceed the target value (either high or low depending on whether the device has been instructed to margin high or low, respectively), this creates a fault. Second, if the target value cannot be reached when the DAC reaches full scale, this also creates a fault.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Table 33. MFR_TEMP_SENSOR_CONFIG BIT NAME 15 ENABLE 14:0 0 MEANING 0 = Temperature sensor disabled. 1 = Temperature sensor enabled. These bits always return a 0. Keep-Alive Circuit In systems where the power to the device may be not always be present, a keep-alive circuit consisting of a Schottky diode and a bulk capacitor can be added to allow the device time to orderly shut down the power supplies it is controlling before power is lost.
PAGE 56
MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer as a GPO. Also, for these channels, POWER_GOOD_ON should be set to 0000h to force power-good assertion since this channel is not measuring voltage (Figure 9). The current-sense amplifier must have a source impedance of less than the value as constrained by the selection of the ADC_TIME bits in MFR_MODE and the output from the amplifier must not exceed the maximum input-voltage limits of the device.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Typical Operating Circuit OPTIONAL MARGINING SUPPORT FOR CHANNELS 0–15 (UP TO 4) DS4424 I2C 4-CHANNEL CURRENT DAC (I2C ADDRESSES 20h, 60h, A0h, E0h) POWER SUPPLY OPTIONAL DS75LV I2C TEMP SENSOR (I2C ADDRESSES 90/92/94/96h) OPTIONAL REMOTE TEMP SENSORS (UP TO 4) PSEN0–PSEN3/ PSEN12–PSEN15 MSDA IN OUT LOAD EN MSCL VDDA ONLY REQUIRED IF THE MONITORED VOLTAGE IS > 1.8V RS0–RS3/ RS12–RS15 3.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Package Information Ordering Information PART TEMP RANGE PIN-PACKAGE MAX34461ETM+ -40NC to +85NC 48 TQFN-EP* MAX34461ETM+T -40NC to +85NC 48 TQFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. T = Tape and reel. Maxim Integrated For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.
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MAX34461 PMBus 16-Channel Voltage Monitor and Sequencer Revision History REVISION NUMBER REVISION DATE 0 9/12 Initial release 1 11/13 Updated the Absolute Maximum Ratings section; added VDD rise time and trace impedance to the Recommended Operating Conditions table; corrected errors in the 24h and 26h 7-bit slave address of Table 2; added the Protecting Input Pins section DESCRIPTION PAGES CHANGED — 7, 18, 55 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuit