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Maxim Integrated Products, Inc. 1
USER GUIDE 5941
MAX20751 PMBus USER GUIDE
1.0 MAX20751 PMBus INTERFACE OVERVIEW
The MAX20751 master controller includes a serial bus
(PMBus™) that supports advanced regulator monitoring and
control capabilities. The PMBus interface supports a subset
of the PMBus 1.2 and SMBus 2.0 specifications. More infor-
mation about these specifications can be found at
www.pmbus.org and www.smbus.org. The following features
are supported.
• Static PMBus Address Programming with External
Resistors
• Compliant with High-Power SMBus DC Specification
(3.1.3)
• Supported PMBus Protocols
– Write Byte/Word (5.5.4)
– Read Byte/Word (5.5.5)
– Send Byte (5.5.2)
– Block Write
– Block Read
– Block Write Block Read Process Call
– Packet Error Checking Mechanism Support (5.4)
• SMBALERT# Signal via ALERTB Pin
•Clock Stretching
1.1 Monitoring Functions
The following monitoring functions are available via the
MAX20751 PMBus interface.
• Various Fault Status
• Manufacturer’s Device ID
• Manufacturer’s Model
• Manufacturer’s Revision
• Manufacturer’s Serial Number
• Input Voltage
• Output Voltage
•Temperature
• Power Output
• Output Current
• System Fault Log (saves up to 5 system faults in chrono-
logical order, fault log must be cleared before other
faults will be logged)
• PMBus Revision
PMBus is a trademark of SMIF, Inc.
1.2 Control Functions
• Overtemperature Warning and Fault Thresholds
• Undertemperature Warning Threshold
• Input Voltage Overvoltage (OV) Warning and
Fault Thresholds
• Input Voltage Undervoltage (UV) Warning and
Fault Thresholds
• Output Current Warning Threshold
• Output Voltage OV Warning Threshold
• Output Voltage UV Warning and Fault Thresholds
• Output Voltage Command
• Output Voltage Margin Low and High Thresholds
• Power-Good On and Off Threshold
• Operation – On and Off Configuration
• Restore/Store Default and User Settings
• Startup T
ON
and T
OFF
Delay Timing
• Maximum T
ON
Fault
• Switching Frequency
• Orthogonal Current Rebalance Gain
• Output Voltage Slew Rate
• Fault Responses
1.3 Calibration Features
• Output Current Gain and Offset
• Input Voltage-Divider Ratio and Offset
• Output Voltage Offset
