SNVS700G December   2010  – October 2016 LM25066A


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements: SMBus Communications
    7. 7.7 Switching Characteristics
    8. 7.8 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Current Limit
      2. 8.3.2 Circuit Breaker
      3. 8.3.3 Power Limit
      4. 8.3.4 Undervoltage Lockout (UVLO)
      5. 8.3.5 Overvoltage Lockout (OVLO)
      6. 8.3.6 Power Good
      7. 8.3.7 VDD Sub-Regulator
      8. 8.3.8 Remote Temperature Sensing
      9. 8.3.9 Damaged MOSFET Detection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power Up Sequence
      2. 8.4.2 Gate Control
      3. 8.4.3 Fault Timer and Restart
      4. 8.4.4 Shutdown Control
      5. 8.4.5 Enabling/Disabling and Resetting
    5. 8.5 Register Maps
      1. 8.5.1 PMBus Command Support
        1. Standard PMBus™ Commands
          1.  OPERATION (01h)
          2.  CLEAR_FAULTS (03h)
          3.  CAPABILITY (19h)
          4.  VOUT_UV_WARN_LIMIT (43h)
          5.  OT_FAULT_LIMIT (4Fh)
          6.  OT_WARN_LIMIT (51h)
          7.  VIN_OV_WARN_LIMIT (57h)
          8.  VIN_UV_WARN_LIMIT (58h)
          9.  STATUS_BYTE (78h)
          10. STATUS_WORD (79h)
          11. STATUS_VOUT (7Ah)
          12. STATUS_INPUT (7Ch)
          13. STATUS_TEMPERATURE (7Dh)
          14. STATUS_CML (7Eh)
          15. STATUS_MFR_SPECIFIC (80h)
          16. READ_VIN (88h)
          17. READ_VOUT (8Bh)
          18. READ_TEMPERATURE_1 (8Dh)
          19. MFR_ID (99h)
          20. MFR_MODEL (9Ah)
          21. MFR_REVISION (9Bh)
        2. Manufacturer Specific PMBus™ Commands
          1.  MFR_SPECIFIC_00: READ_VAUX (D0h)
          2.  MFR_SPECIFIC_01: MFR_READ_IIN (D1h)
          3.  MFR_SPECIFIC_02: MFR_READ_PIN (D2h)
          4.  MFR_SPECIFIC_03: MFR_IN_OC_WARN_LIMIT (D3h)
          5.  MFR_SPECIFIC_04: MFR_PIN_OP_WARN_LIMIT (D4h)
          6.  MFR_SPECIFIC_05: READ_PIN_PEAK (D5h)
          7.  MFR_SPECIFIC_06: CLEAR_PIN_PEAK (D6h)
          8.  MFR_SPECIFIC_07: GATE_MASK (D7h)
          9.  MFR_SPECIFIC_08: ALERT_MASK (D8h)
          10. MFR_SPECIFIC_09: DEVICE_SETUP (D9h)
          11. MFR_SPECIFIC_10: BLOCK_READ (DAh)
          12. MFR_SPECIFIC_11: SAMPLES_FOR_AVG (DBh)
          13. MFR_SPECIFIC_12: READ_AVG_VIN (DCh)
          14. MFR_SPECIFIC_13: READ_AVG_VOUT (DDh)
          15. MFR_SPECIFIC_14: READ_AVG_IIN (DEh)
          16. MFR_SPECIFIC_15: READ_AVG_PIN (DFh)
          17. MFR_SPECIFIC_16: BLACK_BOX_READ (E0h)
          19. MFR_SPECIFIC_18: AVG_BLOCK_READ (E2h)
        3. Reading and Writing Telemetry Data and Warning Thresholds
        4. Determining Telemetry Coefficients Empirically With Linear Fit
        5. Writing Telemetry Data
        6. PMBus™ Address Lines (ADR0, ADR1, ADR2)
        7. SMBA Response
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 12-V, 45-A PMBus Hotswap Design
        1. Design Requirements
        2. Detailed Design Procedure
          1.  Select RSNS and CL Setting
          2.  Selecting the Hotswap FETs
          3.  Select Power Limit
          4.  Set Fault Timer
          5.  Check MOSFET SOA
          6.  Switching to dV/dt based Start-up
          7.  Choosing the VOUT Slew Rate
          8.  Select Power Limit and Fault Timer
          9.  Set Undervoltage and Overvoltage Threshold
            1. Option A
            2. Option B
            3. Option C
            4. Option D
          10. Power Good Pin
          11. Input and Output Protection
          12. Final Schematic and Component Values
      2. 9.2.2 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Pin Configuration and Functions

NHZ Package
24-Pin WQFN
Top View
LM25066A 30146002.gif
Solder the exposed pad to ground.

Pin Functions

1 ADR2 SMBUS address line 2 3 - state address line. Should be connected to GND, VDD, or left floating.
2 ADR1 SMBUS address line 1 3 - state address line. Should be connected to GND, VDD, or left floating.
3 ADR0 SMBUS address line 0 3 - state address line. Should be connected to GND, VDD, or left floating.
4 VDD Internal sub-regulator output Internally sub-regulated 4.5-V bias supply. Connect a 1-µF capacitor on this pin to ground for bypassing.
5 CL Current limit range Connect this pin to GND to set the nominal overcurrent threshold at 25 mV. Connecting CL to VDD sets the overcurrent threshold to be 46 mV.
6 CB Circuit breaker range This pin sets the circuit breaker protection point in relation to the overcurrent trip point. When connected to GND, this pin sets the circuit breaker point to be 1.8 times the overcurrent threshold. Connecting this pin to VDD sets the circuit breaker trip point to be 3.6 times the overcurrent threshold.
7 FB Power Good feedback An external resistor divider from OUT sets the output voltage at which the PGD pin switches. The threshold at the pin is 1.167 V. An internal 24-µA current source provides hysteresis.
8 RETRY Fault retry input This pin configures the power up fault retry behavior. When this pin is grounded, the device continually tries to engage power during a fault. If the pin is connected to VDD, the device will latch off during a fault.
9 TIMER Timing capacitor An external capacitor connected to this pin sets the insertion time delay, fault timeout period and restart timing.
10 PWR Power limit set An external resistor connected to this pin, in conjunction with the current sense resistor (RS), sets the maximum power dissipation allowed in the external series pass MOSFET.
11 PGD Power Good indicator An open drain output. This output is high when the voltage at the FB pin is above 1.167 V and the input supply is within its undervoltage and overvoltage thresholds. Connect through a pullup resistor to the output rail (external MOSFET source) or any other voltage to be monitored.
12 OUT Output feedback Connect to the output rail (external MOSFET source). Internally used to determine the MOSFET VDS voltage for power limiting, and to monitor the output voltage.
13 GATE Gate drive output Connect to the external MOSFET's gate.
14 SENSE Current sense input The voltage across the current sense resistor (RS) is measured from VIN to this pin. If the voltage across RS reaches overcurrent threshold, the load current is limited and the fault timer activates.
15 VIN Positive supply input A small ceramic bypass capacitor close to this pin is recommended to suppress transients which occur when the load current is switched off.
16 UVLO/EN Under-voltage lockout An external resistor divider from the system input voltage sets the undervoltage turnon threshold. An internal 23-µA current source provides hysteresis. The enable threshold at the pin is 1.16 V. This pin can also be used for remote shutdown control.
17 OVLO Over-voltage lockout An external resistor divider from the system input voltage sets the overvoltage turnoff threshold. An internal 23-µA current source provides hysteresis. The disable threshold at the pin is 1.16 V.
18 GND Circuit ground
19 SDA SMBus data pin Data pin for SMBus.
20 SCL SMBus clock Clock pin for SMBus.
21 SMBA SMBus alert line Alert pin for SMBus, active low.
22 VREF Internal Reference Internally generated precision 2.73-V reference used for analog to digital conversion. Connect a 1-µF capacitor on this pin to ground for bypassing.
23 DIODE External diode Connect this to a diode-configured NPN transistor for temperature monitoring.
24 VAUX Auxiliary voltage input Auxiliary pin allows voltage telemetry from an external source. Full scale input of 1.16 V.
Pad Exposed Pad Exposed pad of WQFN package No internal electrical connections. Solder to the ground plane to reduce thermal resistance.