SLVSC70B January   2015  – January 2022 TPS65251-1 , TPS65251-2 , TPS65251-3

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics for Buck 1
    7. 6.7 Typical Characteristics for Buck 2
    8. 6.8 Typical Characteristics for Buck 3
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjustable Switching Frequency
      2. 7.3.2  Synchronization
      3. 7.3.3  Out-of-Phase Operation
      4. 7.3.4  Delayed Start-Up
      5. 7.3.5  Soft-Start Time
      6. 7.3.6  Adjusting the Output Voltage
      7. 7.3.7  Input Capacitor
      8. 7.3.8  Bootstrap Capacitor
      9. 7.3.9  Error Amplifier
      10. 7.3.10 Slope Compensation
      11. 7.3.11 Power Good
      12. 7.3.12 3.3-V and 6.5-V LDO Regulators
      13. 7.3.13 Current Limit Protection
      14. 7.3.14 Overvoltage Transient Protection (OVP)
      15. 7.3.15 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Low-Power/Pulse Skipping Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Loop Compensation Circuit
        2. 8.2.2.2  Selecting the Switching Frequency
        3. 8.2.2.3  Output Inductor Selection
        4. 8.2.2.4  Output Capacitor
        5. 8.2.2.5  Input Capacitor
        6. 8.2.2.6  Soft-Start Capacitor
        7. 8.2.2.7  Bootstrap Capacitor Selection
        8. 8.2.2.8  Adjustable Current Limiting Resistor Selection
        9. 8.2.2.9  Output Voltage and Feedback Resistors Selection
        10. 8.2.2.10 Compensation
        11. 8.2.2.11 3.3-V and 6.5-V LDO Regulators
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

5 Pin Configuration and Functions

GUID-46962227-8D65-4AB2-BC37-1C838CB1DC03-low.gif
Table 5-1 Pin Functions
PIN I/O DESCRIPTION
NAME NO.
RLIM3 1 I Current limit setting for Buck 3. Fit a resistor from this pin to ground to set the peak current limit on the output inductor.
SS3 2 I Soft-start pin for Buck 3. Fit a small ceramic capacitor to this pin to set the converter soft-start time.
COMP3 3 O Compensation for Buck 3. Fit a series RC circuit to this pin to complete the compensation circuit of this converter.
FB3 4 I Feedback input for Buck 3. Connect a divider set to 0.8 V from the output of the converter to ground.
SYNC 5 I Synchronous clock input. If there is a sync clock in the system, connect to the pin. When not used, connect to GND.
ROSC 6 I Oscillator set. This resistor sets the frequency of the internal autonomous clock. If external synchronization is used, the resistor should be fitted and set to about 70% of external clock frequency.
FB1 7 I Feedback pin for Buck 1. Connect a divider set to 0.8 V from the output of the converter to ground.
COMP1 8 O Compensation pin for Buck 1. Fit a series RC circuit to this pin to complete the compensation circuit of this converter.
SS1 9 I Soft-start pin for Buck 1. Fit a small ceramic capacitor to this pin to set the converter soft-start time.
RLIM1 10 I Current limit setting pin for Buck 1. Fit a resistor from this pin to ground to set the peak current limit on the output inductor.
EN1 11 I Enable pin for Buck 1. A low-level signal on this pin disables it. If pin is left open, a weak internal pull-up to V3V allows for automatic enable. For a delayed start-up, add a small ceramic capacitor from this pin to ground.
BST1 12 I Bootstrap capacitor for Buck 1. Fit a 47-nF ceramic capacitor from this pin to the switching node.
VIN1 13 I Input supply for Buck 1. Fit a 10-µF ceramic capacitor close to this pin.
LX1 14 O Switching node for Buck 1
15
LX2 16 O Switching node for Buck 2
17
VIN2 18 I Input supply for Buck 2. Fit a 10-µF ceramic capacitor close to this pin.
BST2 19 I Bootstrap capacitor for Buck 2. Fit a 47-nF ceramic capacitor from this pin to the switching node.
EN2 20 I Enable pin for Buck 2. A low-level signal on this pin disables it. If pin is left open, a weak internal pull-up to V3V allows for automatic enable. For a delayed start-up, add a small ceramic capacitor from this pin to ground.
RLIM2 21 I Current limit setting for Buck 2. Fit a resistor from this pin to ground to set the peak current limit on the output inductor.
SS2 22 I Soft-start pin for Buck 2. Fit a small ceramic capacitor to this pin to set the converter soft-start time.
COMP2 23 O Compensation pin for Buck 2. Fit a series RC circuit to this pin to complete the compensation circuit of this converter
FB2 24 I Feedback input for Buck 2. Connect a divider set to 0.8 V from the output of the converter to ground.
LOW_P 25 I Low-power operation mode (active-high) input for TPS65251
GND 26 Ground pin
PGOOD 27 O Power good. Open-drain output asserted after all converters are sequenced and within regulation. Polarity is factory selectable (active-high default).
V7V 28 O Internal supply. Connect a 10-μF ceramic capacitor from this pin to ground.
V3V 29 O Internal supply. Connect a 3.3- to 10-μF ceramic capacitor from this pin to ground.
AGND 30 Analog ground. Connect all GND pins and the power pad together.
GND 31 Ground pin
VIN 32 I Input supply
33
34
GND 35 Ground pin
LX3 36 O Switching node for Buck 3
37
VIN3 38 Input supply for Buck 3. Fit a 10-µF ceramic capacitor close to this pin.
BST3 39 I Bootstrap capacitor for Buck 3. Fit a 47-nF ceramic capacitor from this pin to the switching node.
EN3 40 I Enable pin for Buck 3. A low-level signal on this pin disables it. If pin is left open, a weak internal pull-up to V3V allows for automatic enable. For a delayed start-up, add a small ceramic capacitor from this pin to ground.
PAD — — Power pad. Connect to ground.