LTC2974 - 4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement

Features

  • Order Custom Programmed Parts
  • Sequence, Trim, Margin and Supervise Four Power Supplies
  • Manage Faults, Monitor Telemetry and Create Fault Logs
  • PMBus Compliant Command Set
  • Supported by LTpowerPlayTM GUI
  • Margin or Trim Supplies to 0.25% Accuracy
  • Fast OV/UV Supervisors Per Channel
  • Fast Output Current Supervisors Per Channel
  • Coordinate Sequencing and Fault Management Across Multiple Chips
  • Automatic Fault Logging to Internal EEPROM
  • Operate Autonomously without Additional Software
  • External Temperature and Input Voltage Supervisors
  • Accurate Monitoring of Four Output Voltages, Four Output Currents, Four External Temperatures, Input Voltage and Internal Die Temperature
  • I2C/SMBus Serial Interface
  • Can Be Powered from 3.3V, or 4.5V to 15V
  • Available in 64-Lead 9mm × 9mm QFN Package
  • LTpowerPlay Configuration and Development Tool
Designed for Automotive and Transportation Applications
AEC-Q100 data available for specific packages


Typical Application

LTC2974 Typical Application
LTC2974 Typical Application

Description

The LTC®2974 is a 4-channel Power System Manager used to sequence, trim (servo), margin, supervise, manage faults, provide telemetry and create fault logs. PMBus commands support power supply sequencing, precision point-of-load voltage adjustment and margining. DACs use a proprietary soft-connect algorithm to minimize supply disturbances. Supervisory functions include over and under current, voltage and temperature threshold limits for four power supply output channels as well as over and under voltage threshold limits for a single power supply input channel. Programmable fault responses can disable the power supplies with optional retry after a fault is detected. Faults that disable a power supply can automatically trigger black box EEPROM storage of fault status and associated telemetry. An internal 16-bit ADC monitors four output voltages, four output currents, four external temperatures, one input voltage and die temperature. Output power is also calculated. A programmable watchdog timer monitors microprocessor activity for a stalled condition and resets the microprocessor if necessary. A single wire bus synchronizes power supplies across multiple LTC power system management devices. Configuration EEPROM supports autonomous operation without additional software.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC2974CUP#PBF 9x9 QFN-64 UP C 05-08-1705 Yes
LTC2974CUP#TRPBF 9x9 QFN-64 UP C 05-08-1705 Yes
LTC2974IUP#PBF 9x9 QFN-64 UP I 05-08-1705 Yes
LTC2974IUP#TRPBF 9x9 QFN-64 UP I 05-08-1705 Yes


LTC2974 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC2974CUP#PBF 9x9 QFN-64 C $12.64 $8.85 Yes
LTC2974CUP#TRPBF 9x9 QFN-64 C $8.91 Yes
LTC2974IUP#PBF 9x9 QFN-64 I $14.54 $10.18 Yes
LTC2974IUP#TRPBF 9x9 QFN-64 I $10.24 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1508B-B LTC2974, LTC2975 Socketed Programming Board [requires DC1613] $95.00
DC1962C Power System Management Demo Board (PowerStick): 14-Supply Management with LTC2977, LTC2974 & LTC3880 [Requires DC1613] $95.00
DC1962C-KIT Starter Kit for Power System Management [Includes DC1962C, DC1613A] $125.00
DC1978A LTC2974 Demoboard Kit (includes DC1809 + DC1810), requires DC1613 $200.00
Buy Now

Companion Boards

Part Number Description Price Documentation
DC1613A USB-to-PMBus Controller for Use with LTpowerPlay $50.00
DC2026C Linduino One Isolated USB Demo Board: An Arduino- and QuikEval-Compatible Code Development Platform $75.00
DC2294A DC2294A - PSM Linduino One Shield [requires DC2026, CA2978] $50.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Appications

AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC2974IUP#PBF 9x9 QFN-64 I $14.54 $10.18 Yes
LTC2974IUP#TRPBF 9x9 QFN-64 I $10.24 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

  • Computers and Network Servers
  • Industrial Test and Measurement
  • High Reliability Systems
  • Medical Imaging
  • Video

Product Notifications

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Need help? Email mylinear@linear.com with questions and comments.

Design Tools

Linduino

Linduino is an Arduino compatible platform for developing and distributing firmware libraries and code for SPI and I²C-compatible integrated circuits. The Linduino One board interfaces to more than 300 QuikEval demonstration cards, supporting a variety of product types including analog-to-digital converters (ADCs)digital-to-analog converters (DACs)power monitors, and more. Firmware libraries for individual devices are written in C and designed to be portable to a wide variety of processors and microcontrollers. Each library has a demonstration program that can be uploaded to the Linduino One platform to allow the circuit and software to be quickly and easily verified.

Click here for more information on Linduino

LTpowerPlay

LTpowerPlay is a powerful development environment supporting Linear Technology's Digital Power System Management (PSM) products, providing unprecedented diagnostic and debug features.

Click here to download LTpowerPlay

LTpowerPlay is the FREE Graphical User Interface (GUI) software provided by Linear Technology for use with our family of digital power products. LTpowerPlay provides unprecedented diagnostic and debug features. It becomes a valuable diagnostic tool during board bring-up to program or tweak the power management scheme in a system or to diagnose power issues when bringing up rails.

  • Download LTpowerPlay software
  • When LTpowerPlay launches the first time, it will prompt you to request a license, click 'Request a License Key...', enter the required information, then click 'Send License Request'
  • Once you have entered the registration information, you will receive an email with your license file and instructions for installing it
  • For further information, please visit www.linear.com/ltpowerplay
  • Access technical support documents for LTC Digital Power Products by visiting www.ltpowerplay.com/help

Code

Linduino is Linear Technology's Arduino compatible system for developing and distributing firmware libraries and example code for Linear Technology’s integrated circuits. The code below can be downloaded or copied and pasted into your project. Please visit the Linduino Home Page for demo board, manual and setup information.

This part is Code Supported: There is example code available for this part. The code below may rely on other drivers available in the full library.

Download LTC2974 - DC1978 Linduino.INO File

/*!
Linear Technology DC1978A Demonstration System (2-Board Set)
DC1809 - LTC2974 Board (manager)
DC1810 - LTM4620 Board (4 rails)

@verbatim

NOTES
  Setup:
   Set the terminal baud rate to 115200 and select the newline terminator.

@endverbatim

http://www.linear.com/product/LTC2974

http://www.linear.com/demo/DC1978

REVISION HISTORY
$Revision: 4080 $
$Date: 2015-09-24 16:36:34 -0600 (Thu, 24 Sep 2015) $

Copyright (c) 2016, Linear Technology Corp.(LTC)
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation are those
of the authors and should not be interpreted as representing official policies,
either expressed or implied, of Linear Technology Corp.

The Linear Technology Linduino is not affiliated with the official Arduino team.
However, the Linduino is only possible because of the Arduino team's commitment
to the open-source community.  Please, visit http://www.arduino.cc and
http://store.arduino.cc , and consider a purchase that will help fund their
ongoing work.
*/

/*! @file
    @ingroup LTC2974
*/

#include 
#include 
#include "Linduino.h"
#include "UserInterface.h"
#include "LT_I2CBus.h"
#include "LT_SMBusNoPec.h"
#include "LT_SMBusPec.h"
#include "LT_PMBusMath.h"
#include "LT_PMBus.h"

#define LTC2974_I2C_ADDRESS 0x5C

// Global variables
static uint8_t ltc2974_i2c_address;
static LT_PMBusMath *math = new LT_PMBusMath();
static LT_SMBus *smbus = new LT_SMBusPec();
static LT_PMBus *pmbus = new LT_PMBus(smbus);

//! Initialize Linduino
//! @return void
void setup()
{
  Serial.begin(115200);         //! Initialize the serial port to the PC
  print_title();
  ltc2974_i2c_address = LTC2974_I2C_ADDRESS;
  print_prompt();
}

//! Repeats Linduino loop
//! @return void
void loop()
{
  uint8_t user_command;
  uint8_t res;
  uint8_t model[7];
  uint8_t revision[10];
  uint8_t *addresses = NULL;

  if (Serial.available())                          //! Checks for user input
  {
    user_command = read_int();                     //! Reads the user command
    if (user_command != 'm')
      Serial.println(user_command);

    switch (user_command)                          //! Prints the appropriate submenu
    {
      case 1:
        menu_1_basic_commands();                 // Print single-ended voltage menu
        break;
      case 2:
        menu_2_vid_commands();                   // Print VID menu
        break;
      case 3:
        menu_3_vid_commands();                   // Print VID menu
        break;
      case 4:
        pmbus->enablePec(ltc2974_i2c_address);
        delete smbus;
        delete pmbus;
        smbus = new LT_SMBusPec();
        pmbus = new LT_PMBus(smbus);
        break;
      case 5:
        pmbus->disablePec(ltc2974_i2c_address);
        delete smbus;
        delete pmbus;
        smbus = new LT_SMBusNoPec();
        pmbus = new LT_PMBus(smbus);
        break;
      case 6:
        addresses = smbus->probe(0);
        while (*addresses != 0)
        {
          Serial.print(F("ADDR 0x"));
          Serial.println(*addresses++, HEX);
        }
        break;
      case 7 :
        pmbus->startGroupProtocol();
        pmbus->restoreFromNvm(ltc2974_i2c_address);
        pmbus->executeGroupProtocol();
        break;
      default:
        Serial.println(F("Incorrect Option"));
        break;
    }
    print_prompt();
  }

}

// Function Definitions

//! Prints the title block when program first starts.
//! @return void
void print_title()
{
  Serial.print(F("\n*****************************************************************\n"));
  Serial.print(F("* DC1978A Hello World Demonstration Program                     *\n"));
  Serial.print(F("*                                                               *\n"));
  Serial.print(F("* This program demonstrates how to send and receive data from   *\n"));
  Serial.print(F("* the LTC2974 on the demo board.                                *\n"));
  Serial.print(F("*                                                               *\n"));
  Serial.print(F("* Set the baud rate to 115200 and select the newline terminator.*\n"));
  Serial.print(F("*                                                               *\n"));
  Serial.print(F("*****************************************************************\n"));
}

//! Prints main menu.
//! @return void
void print_prompt()
{
  Serial.print(F("\n  1-Basic Commands\n"));
  Serial.print(F("  2-VID Commands (L16)\n"));
  Serial.print(F("  3-VID Commands (float) \n"));
  Serial.print(F("  4-PEC On\n"));
  Serial.print(F("  5-PEC Off\n"));
  Serial.print(F("  6-Bus Probe\n"));
  Serial.print(F("  7-Reset\n"));
  Serial.print(F("\nEnter a command:"));
}

//! Prints a warning if the demo board is not detected.
//! @return void
void print_warning_prompt()
{
  Serial.println(F("\nWarning: Demo board not detected. Linduino will attempt to proceed."));
}

//! Prints all voltages
//! @return void
void print_all_voltages()
{
  float   voltage;
  uint8_t page;

  for (page = 0; page < 4; page++)
  {
    pmbus->setPage(ltc2974_i2c_address, page);
    voltage = pmbus->readVout(ltc2974_i2c_address, false);
    Serial.print(F("LTC2974 VOUT "));
    Serial.println(voltage, DEC);
  }
}

//! Prints all currents
//! @return void
void print_all_currents()
{
  float   current;
  uint8_t page;

  for (page = 0; page < 4; page++)
  {
    pmbus->setPage(ltc2974_i2c_address, page);
    current = pmbus->readIout(ltc2974_i2c_address, false);
    Serial.print(F("LTC2974 IOUT "));
    Serial.println(current, DEC);
  }
}

//! Prints all status bytes and words
//! @return void
void print_all_status()
{
  uint8_t b;
  uint16_t w;
  uint8_t page;

  for (page = 0; page < 4; page++)
  {
    Serial.print(F("PAGE "));
    Serial.println(page, DEC);
    pmbus->setPage(ltc2974_i2c_address, page);
    b = pmbus->readStatusByte(ltc2974_i2c_address);
    Serial.print(F("LTC2974 STATUS BYTE 0x"));
    Serial.println(b, HEX);
    w = pmbus->readStatusWord(ltc2974_i2c_address);
    Serial.print(F("LTC2974 STATUS WORD 0x"));
    Serial.println(w, HEX);
  }
}

// Sequence off then on
//! @return void
void sequence_off_on()
{
  pmbus->sequenceOffGlobal();
  delay (2000);
  pmbus->sequenceOnGlobal();
}

//! Margin high
//! @return void
void margin_high()
{
  pmbus->marginHighGlobal();
}

//! Margin low
//! @return void
void margin_low()
{
  pmbus->marginLowGlobal();
}

//! Go to nominal
//! @return void
void margin_off()
{
  pmbus->sequenceOnGlobal();
}

void increment_page()
{
  uint8_t reg_page;
  reg_page = smbus->readByte (ltc2974_i2c_address, 0x00);      // Read current page number
  reg_page = (reg_page < 0x02) ? reg_page + 0x01 : 0x00 ;
  smbus->writeByte (ltc2974_i2c_address, 0x00, reg_page);      // Write current page number
  reg_page = smbus->readByte (ltc2974_i2c_address, 0x00);      // Read current page number
  Serial.print(F("LTC2974 PAGE SET TO : "));
  Serial.println(reg_page, HEX);

}

//! Display menu 1
//! @return void
void menu_1_basic_commands()
{
  uint8_t user_command;

  do
  {
    //! Displays the Read/Write menu
    Serial.print(F("  1-Read All Voltages\n"));
    Serial.print(F("  2-Read All Currents\n"));
    Serial.print(F("  3-Read All Status\n"));
    Serial.print(F("  4-Sequence Off/On\n"));
    Serial.print(F("  5-Margin High\n"));
    Serial.print(F("  6-Margin Low\n"));
    Serial.print(F("  7-Margin Off\n"));
    Serial.print(F("  8-Increment Page Number\n"));
    Serial.print(F("  m-Main Menu\n"));
    Serial.print(F("\nEnter a command: "));

    user_command = read_int();                              //! Reads the user command
    if (user_command == 'm')                                // Print m if it is entered
    {
      Serial.print(F("m\n"));
    }
    else
      Serial.println(user_command);                         // Print user command

    switch (user_command)
    {
      case 1:
        print_all_voltages();
        break;
      case 2:
        print_all_currents();
        break;
      case 3:
        print_all_status();
        break;
      case 4:
        sequence_off_on();
        break;
      case 5:
        margin_high();
        break;
      case 6:
        margin_low();
        break;
      case 7:
        margin_off();
        break;
      case 8:
        increment_page();
        break;
      default:
        if (user_command != 'm')
          Serial.println(F("Invalid Selection"));
        break;
    }
  }
  while (user_command != 'm');
}

//! Display menu 2
//! @return void
void menu_2_vid_commands()
{
  uint8_t user_command;
  uint16_t vcode;
  float voltage;

  voltage = pmbus->readVout(ltc2974_i2c_address, false);
  vcode = math->float_to_lin16 (voltage, 0x13);

  do
  {
    //! Displays the Read/Write menu
    Serial.print(F("  1-VID UP 40 LSB\n"));
    Serial.print(F("  2-VID DN 40 LSB\n"));
    Serial.print(F("  m-Main Menu\n"));
    Serial.print(F("\nEnter a command: "));

    user_command = read_int();                              //! Reads the user command
    if (user_command == 'm')                                // Print m if it is entered
    {
      Serial.print(F("m\n"));
    }
    else
      Serial.println(user_command);                         // Print user command

    switch (user_command)
    {
      case 1:
        vcode += 40;
        smbus->writeWord (ltc2974_i2c_address, 0x21, vcode);
        Serial.print(F("LTC2974 VOUT Code "));
        Serial.println(vcode, HEX);
        delay (1000);
        voltage = pmbus->readVout(ltc2974_i2c_address, false);
        Serial.print(F("LTC2974 VOUT Telemetry "));
        Serial.println(voltage, DEC);
        break;
      case 2:
        vcode -= 40;
        smbus->writeWord (ltc2974_i2c_address, 0x21, vcode);
        Serial.print(F("LTC2974 VOUT Code "));
        Serial.println(vcode, HEX);
        delay (1000);
        voltage = pmbus->readVout(ltc2974_i2c_address, false);
        Serial.print(F("LTC2974 VOUT Telemetry "));
        Serial.println(voltage, DEC);
        Serial.print(F("\n"));
        break;
      default:
        if (user_command != 'm')
          Serial.println(F("Invalid Selection"));
        break;
    }
  }
  while (user_command != 'm');
}

//! Display menu 3
void menu_3_vid_commands()
{
  uint8_t user_command;
  float vid_value;
  float voltage;

  vid_value = pmbus->readVout(ltc2974_i2c_address, false);

  do
  {
    //! Displays the Read/Write menu
    Serial.print(F("  1-VID UP 4mV\n"));
    Serial.print(F("  2-VID DN 4mV\n"));
    Serial.print(F("  m-Main Menu\n"));
    Serial.print(F("\nEnter a command: "));

    user_command = read_int();                              //! Reads the user command
    if (user_command == 'm')                                // Print m if it is entered
    {
      Serial.print(F("m\n"));
    }
    else
      Serial.println(user_command);                         // Print user command

    switch (user_command)
    {
      case 1:
        vid_value += 0.004;
        pmbus->setVout (ltc2974_i2c_address, vid_value);
        Serial.print(F("LTC2974 VOUT "));
        Serial.println(vid_value, DEC);
        delay (1000);
        voltage = pmbus->readVout(ltc2974_i2c_address, false);
        Serial.print(F("LTC2974 VOUT Telemetry "));
        Serial.println(voltage, DEC);
        break;
      case 2:
        vid_value -= 0.004;
        pmbus->setVout (ltc2974_i2c_address, vid_value);
        Serial.print(F("LTC2974 VOUT "));
        Serial.println(vid_value, DEC);
        delay (1000);
        voltage = pmbus->readVout(ltc2974_i2c_address, false);
        Serial.print(F("LTC2974 VOUT Telemetry "));
        Serial.println(voltage, DEC);
        Serial.print(F("\n"));
        break;
      default:
        if (user_command != 'm')
          Serial.println(F("Invalid Selection"));
        break;
    }
  }
  while (user_command != 'm');
}

Technical Support