ESH10000533 - M.2 PSU Module

Overview

The ESH10000533 is a high-performance power supply module featuring dual-channel power management based on the Linear Technology LTC3889 PMBus controller, designed for M.2 device testing and validation.

Description

The M.2 PSU module provides two independent, precision-controlled DC/DC converter channels with comprehensive PMBus monitoring and control capabilities. Built around the LTC3889 power management IC, this module offers real-time telemetry, fault protection, calibration support, and temperature monitoring for demanding power delivery applications.

Key Features:

• Dual Independent Power Channels (CH1, CH2): Precision voltage and current control

  • Maximum 60W per channel
  • Programmable output voltage via PMBus VOUT_COMMAND
  • Configurable voltage and current limits
  • Margin high/low voltage support
  • Soft-start and shutdown sequencing

• Comprehensive Fault Protection: Multi-level protection with configurable responses

  • Output overvoltage/undervoltage fault and warning limits
  • Output overcurrent protection
  • Input overvoltage/undervoltage monitoring
  • Overtemperature and undertemperature protection
  • TON_MAX fault detection for startup monitoring

• PMBus Monitoring: Real-time telemetry for all critical parameters

  • Output voltage (READ_VOUT)
  • Output current (READ_IOUT)
  • Input voltage (READ_VIN)
  • Input current (READ_IIN)
  • Temperature (READ_TEMPERATURE_1, READ_TEMPERATURE_2)
  • Power output (READ_POUT)
  • Efficiency calculations

• Calibration Support: Per-channel current sense calibration

  • IOUT_CAL_GAIN: Current sense resistor calibration (typical 2mΩ)
  • MFR_IOUT_CAL_GAIN_TC: Temperature coefficient compensation (typical 50 ppm/°C)
  • MFR_IIN_CAL_GAIN: Input current calibration
  • Persistent calibration storage by product ID, revision, and serial number
  • User-accessible CALIBRATION channel for reading/updating calibration data

• Temperature Monitoring: Dual-sensor temperature reporting with ITempReporter interface

  • Warning threshold: 60°C
  • Error threshold: 90°C
  • Automatic temperature invalidation every 10 seconds
  • Reports maximum temperature across all sensors

• Status and Fault Reporting: Comprehensive status registers per PMBus specification

  • STATUS_BYTE, STATUS_WORD: Overall unit status
  • STATUS_VOUT, STATUS_IOUT: Per-channel output status
  • STATUS_INPUT: Input voltage/current status
  • STATUS_TEMPERATURE: Temperature status
  • STATUS_CML: Communication and memory status
  • STATUS_MFR_SPECIFIC: Manufacturer-specific status

Hardware Details

Power Management Controller:

• Chip: Linear Technology LTC3889
• I²C Address: 0x4F (7-bit)
• Channels: 2 independent DC/DC converters (CH1, CH2)
• Communication: PMBus over I²C
• Silicon Revision: 2.0

Power Specifications:

• Maximum Power per Channel: 60W
• Switching Frequency: Configurable via FREQUENCY_SWITCH register
• Voltage Protection Levels (configurable):
  • Overvoltage Fault Limit: +20% of nominal
  • Overvoltage Warning Limit: +10% of nominal
  • Margin High: +5% of nominal
  • Margin Low: -5% of nominal
  • Undervoltage Warning Limit: -10% of nominal
  • Undervoltage Fault Limit: -20% of nominal
  • Power Good On: -10% of nominal
  • Power Good Off: -20% of nominal

Current Sensing:

• Sense Resistor: External (typically 0.1mΩ for input monitoring)
• Calibration: Per-channel gain and temperature coefficient
• Overcurrent Warning Limit: Configurable (default 5A)

Channel Naming Convention

All channels follow the naming pattern: {ModuleIndex}.ESH10000533.{Address}.{ChannelName}

Where:

• {ModuleIndex} is the position of the module in the system (e.g., 0, 1, 2...)
• ESH10000533 is the module type identifier
• {Address} is the PMBus device address (0x4F)
• {ChannelName} is the specific PMBus register/command name

Examples:

• Global register: 0.ESH10000533.0x4F.VIN_ON
• CH1 register: 0.ESH10000533.0x4F.CH1.VOUT_COMMAND
• CH2 register: 0.ESH10000533.0x4F.CH2.READ_IOUT
• Calibration: 0.ESH10000533.CALIBRATION

User-Accessible Channels

The module exposes approximately ~100 PMBus registers as user-accessible channels, organized into three categories:

Global Channels (Applied to entire PSU)

Per-Channel Registers (CH1 and CH2)

Each channel (CH1, CH2) has the following registers:

Control Registers:

Current Configuration:

Voltage Protection:

Temperature Protection:

Timing Configuration:

Status Registers (Read-Only):

Telemetry Registers (Read-Only):

Special Channels

Total User-Accessible Channels: ~100 (38 global + ~59 per channel × 2 channels + special channels)

Channel Configuration

Setting Output Voltage

The primary use case is controlling output voltage via VOUT_COMMAND:

// Set CH1 output to 3.3V
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.VOUT_COMMAND" },
    new[] { "3.3" }
);

// Set CH2 output to 5.0V
SetValues(
    new[] { "0.ESH10000533.0x4F.CH2.VOUT_COMMAND" },
    new[] { "5.0" }
);

Reading Telemetry

Monitor voltage, current, and power output:

// Read CH1 output voltage and current
string[] values = GetValues(new[] {
    "0.ESH10000533.0x4F.CH1.READ_VOUT",
    "0.ESH10000533.0x4F.CH1.READ_IOUT",
    "0.ESH10000533.0x4F.CH1.READ_POUT"
});

double voltage = double.Parse(values[0]);  // Volts
double current = double.Parse(values[1]);  // Amps
double power = double.Parse(values[2]);    // Watts

Enabling/Disabling Channels

Control channel operation via OPERATION register:

// Turn CH1 ON (0x80 = On, immediate)
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.OPERATION" },
    new[] { "0x80" }
);

// Turn CH1 OFF (0x00 = Off, immediate)
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.OPERATION" },
    new[] { "0x00" }
);

Configuring Protection Limits

Set overcurrent protection:

// Set CH1 overcurrent warning to 4.5A
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.IOUT_OC_WARN_LIMIT" },
    new[] { "4.5" }
);

// Set CH1 overvoltage fault to 3.6V (for 3.3V nominal)
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.VOUT_OV_FAULT_LIMIT" },
    new[] { "3.6" }
);

PMBus Register Access

PMBus registers use Linear11 (L11) or Linear16 (L16) data formats. The module handles conversion automatically:

• L16: Used for VOUT registers (voltage)
• L11: Used for most other registers (current, power, temperature)
• Reg: Binary register values (for control/status registers)

Calibration Channel

The CALIBRATION channel provides access to persistent calibration data:

Calibration Table Structure:

// Default calibration values:
CH1.IOUT_CAL_GAIN = 2.000 mΩ           // Current sense resistor
CH2.IOUT_CAL_GAIN = 2.000 mΩ
CH1.MFR_IOUT_CAL_GAIN_TC = 50 ppm/°C   // Temperature coefficient
CH2.MFR_IOUT_CAL_GAIN_TC = 50 ppm/°C
MFR_IIN_CAL_GAIN = 2.000 mΩ            // Input current sense
CH1.IOUT_OC_WARN_LIMIT = 5.000 A       // Overcurrent warning
CH2.IOUT_OC_WARN_LIMIT = 5.000 A

Reading Calibration Data:

string[] values = GetValues(new[] { "0.ESH10000533.CALIBRATION" });
CalibrationTable cal = SerializableHelpers.CreateFromBase64<CalibrationTable>(values[0]);

foreach (var row in cal.CalData)
{
    Console.WriteLine($"{row.Key}: Gain={row.Gain}, Offset={row.Offset}");
}

Updating Calibration Data:

// Modify only gain and offset values in the table
cal["CH1.IOUT_CAL_GAIN"].Gain = 2.05;  // Adjusted for actual resistor value
cal["CH1.MFR_IOUT_CAL_GAIN_TC"].Gain = 48;  // Measured temperature coefficient

// Write back
string base64Cal = SerializableHelpers.AsBase64(cal);
SetValues(
    new[] { "0.ESH10000533.CALIBRATION" },
    new[] { base64Cal }
);

Important: The module automatically applies calibration values to the hardware registers on startup and after calibration updates.

Internal Channels (Not User-Accessible)

The following PMBus registers are marked as HIDDEN and not exposed to users:

• CLEAR_FAULTS (0x03): Use CLEAR_ERRORS special channel instead
• WRITE_PROTECT (0x10): Internal write protection control
• STORE_USER_ALL (0x15): EEPROM storage
• RESTORE_USER_ALL (0x16): EEPROM restore
• SMBALERT_MASK (0x1B): Alert masking
• Various manufacturer-specific internal registers

These channels are used internally by the module for configuration and fault management.

Programming Interface

Basic Power Output Control:

// Set CH1 to 1.8V, CH2 to 3.3V
SetValues(
    new[] {
        "0.ESH10000533.0x4F.CH1.VOUT_COMMAND",
        "0.ESH10000533.0x4F.CH2.VOUT_COMMAND"
    },
    new[] { "1.8", "3.3" }
);

// Enable both channels
SetValues(
    new[] {
        "0.ESH10000533.0x4F.CH1.OPERATION",
        "0.ESH10000533.0x4F.CH2.OPERATION"
    },
    new[] { "0x80", "0x80" }  // On, immediate
);

Comprehensive Monitoring:

// Read all telemetry for CH1
string[] ch1Telemetry = GetValues(new[] {
    "0.ESH10000533.0x4F.CH1.READ_VOUT",
    "0.ESH10000533.0x4F.CH1.READ_IOUT",
    "0.ESH10000533.0x4F.CH1.READ_POUT",
    "0.ESH10000533.0x4F.READ_TEMPERATURE_1",
    "0.ESH10000533.0x4F.READ_VIN",
    "0.ESH10000533.0x4F.READ_IIN"
});

double vout = double.Parse(ch1Telemetry[0]);
double iout = double.Parse(ch1Telemetry[1]);
double pout = double.Parse(ch1Telemetry[2]);
double temp = double.Parse(ch1Telemetry[3]);
double vin = double.Parse(ch1Telemetry[4]);
double iin = double.Parse(ch1Telemetry[5]);

Console.WriteLine($"CH1: {vout}V @ {iout}A = {pout}W, Temp: {temp}°C");
Console.WriteLine($"Input: {vin}V @ {iin}A");

Fault Status Checking:

// Check for faults
string[] status = GetValues(new[] {
    "0.ESH10000533.0x4F.CH1.STATUS_WORD",
    "0.ESH10000533.0x4F.CH1.STATUS_VOUT",
    "0.ESH10000533.0x4F.CH1.STATUS_IOUT"
});

// Parse status registers (implementation depends on PMBus handler)
ushort statusWord = ushort.Parse(status[0]);
byte statusVout = byte.Parse(status[1]);
byte statusIout = byte.Parse(status[2]);

if ((statusWord & 0x0010) != 0)  // VOUT fault bit
    Console.WriteLine("Output voltage fault detected!");
if ((statusWord & 0x0080) != 0)  // IOUT/POUT fault bit
    Console.WriteLine("Output current fault detected!");

Clearing Faults:

// Clear all fault conditions
SetValues(
    new[] { "0.ESH10000533.0x4F.CLEAR_ERRORS" },
    new[] { Guid.NewGuid().ToString() }  // Trigger channel
);

Margin Testing:

// Configure margin high/low for CH1 (3.3V nominal)
SetValues(
    new[] {
        "0.ESH10000533.0x4F.CH1.VOUT_COMMAND",
        "0.ESH10000533.0x4F.CH1.VOUT_MARGIN_HIGH",
        "0.ESH10000533.0x4F.CH1.VOUT_MARGIN_LOW"
    },
    new[] { "3.3", "3.465", "3.135" }  // ±5%
);

// Switch to margin high
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.OPERATION" },
    new[] { "0x98" }  // On, margin high
);

// Switch to margin low
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.OPERATION" },
    new[] { "0xA8" }  // On, margin low
);

// Return to normal
SetValues(
    new[] { "0.ESH10000533.0x4F.CH1.OPERATION" },
    new[] { "0x80" }  // On, immediate
);

Error Handling

The module provides comprehensive error detection and reporting:

Voltage Faults:

• Overvoltage fault (VOUT > VOUT_OV_FAULT_LIMIT)
• Overvoltage warning (VOUT > VOUT_OV_WARN_LIMIT)
• Undervoltage warning (VOUT < VOUT_UV_WARN_LIMIT)
• Undervoltage fault (VOUT < VOUT_UV_FAULT_LIMIT)

Current Faults:

• Overcurrent fault (IOUT > IOUT_OC_FAULT_LIMIT)
• Overcurrent warning (IOUT > IOUT_OC_WARN_LIMIT)

Temperature Faults:

• Overtemperature fault (Temp > OT_FAULT_LIMIT)
• Overtemperature warning (Temp > OT_WARN_LIMIT)
• Undertemperature fault (Temp < UT_FAULT_LIMIT)
• Module-level warnings at 60°C, errors at 90°C

Input Faults:

• Input overvoltage fault (VIN > VIN_OV_FAULT_LIMIT)
• Input undervoltage warning (VIN < VIN_UV_WARN_LIMIT)
• Input overcurrent warning (IIN > IIN_OC_WARN_LIMIT)

Startup Faults:

• TON_MAX fault: Output failed to reach regulation within TON_MAX_FAULT_LIMIT

Fault Responses: Each fault type has a configurable response register that determines the action:

• Ignore (continue operating)
• Shutdown (disable output)
• Shutdown and retry
• Shutdown and latch off (requires CLEAR_ERRORS to recover)

Best Practices

1. Always check input voltage before enabling outputs: Verify VIN is within VIN_ON and VIN_OFF thresholds
2. Set appropriate protection limits: Configure VOUT_OV_FAULT_LIMIT and IOUT_OC_WARN_LIMIT for your application
3. Monitor STATUS registers: Regularly poll STATUS_WORD and STATUS_VOUT/IOUT for fault detection
4. Use calibration for accuracy: Load and verify calibration data for precise current measurements
5. Clear faults after configuration changes: Use CLEAR_ERRORS after modifying limits to reset fault latches
6. Apply configuration to RAM: After loading project config, trigger SET_TO_RAM to activate settings
7. Monitor temperature: The module reports max temperature across both sensors; ensure adequate cooling
8. Use margin testing for validation: Utilize VOUT_MARGIN_HIGH/LOW for power supply acceptance testing
9. Implement proper sequencing: Use TON_DELAY and TOFF_DELAY for multi-rail power sequencing
10. Handle PMBus exceptions: PMBus operations can fail; implement retry logic with timeouts

Module Initialization Sequence

On Reset(), the module performs the following initialization:

1. Call base.Reset() to clear channels and initialize PMBus handler
2. Load project configuration file: psu_r0.2.proj
   • Contains LTC3889 chip configuration
   • Defines register default values
   • Configures CH1 and CH2 pages
3. Write project configuration to ProjectConfig channel (Base64 encoded)
4. Trigger SET_TO_RAM to apply configuration to device RAM
5. Clear any existing fault conditions via CLEAR_ERRORS
6. Load calibration table from persistent storage
   • Create default calibration if none exists
   • Default values: 2mΩ sense resistors, 50ppm/°C TC, 5A OC warning
7. Apply calibration values to hardware registers
8. Create CALIBRATION channel for user access to calibration data

Post-Reset State:

• All PMBus registers accessible as channels
• Device configured per project file defaults
• Calibration factors loaded and applied
• Outputs disabled (require OPERATION command to enable)
• Faults cleared and ready for operation

Temperature Monitoring

The module implements the ITempReporter interface for system-level temperature monitoring:

Temperature Reporting:

• Device Name: PSU1, PSU2, etc. (based on module instance)
• Warning Threshold: 60°C
• Error Threshold: 90°C
• Update Interval: 10 seconds (via Invalidate() method)

Temperature Sources:

• READ_TEMPERATURE_1: Primary temperature sensor
• READ_TEMPERATURE_2: Secondary temperature sensor
• Reports the maximum of all temperature sensors

Integration: Temperature data is automatically reported to the system thermal management subsystem for monitoring and protection.

Revision History

• ESH10000533: Current production version
  • Based on Linear Technology LTC3889 PMBus controller
  • Dual independent channels (CH1, CH2)
  • Maximum 60W per channel
  • I²C address: 0x4F
  • Silicon revision: 2.0
  • Project file: psu_r0.2.proj
  • Calibration support for current sensing
  • Temperature monitoring and reporting
  • Comprehensive PMBus register access (~100 channels)