SLVSGC5B January   2023  – May 2024 TPS62870 , TPS62871 , TPS62872 , TPS62873

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Description (continued)
  6. 5 Device Options
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings_Catalog
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 I2C Interface Timing Characteristics
    7. 7.7 Timing Requirements
    8. 7.8 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Fixed-Frequency DCS Control Topology
      2. 8.3.2  Forced PWM and Power Save Modes
      3. 8.3.3  Precise Enable
      4. 8.3.4  Start-Up
      5. 8.3.5  Switching Frequency Selection
      6. 8.3.6  Output Voltage Setting
        1. 8.3.6.1 Output Voltage Range
        2. 8.3.6.2 Output Voltage Setpoint
        3. 8.3.6.3 Non-Default Output Voltage Setpoint
        4. 8.3.6.4 Dynamic Voltage Scaling
      7. 8.3.7  Compensation (COMP)
      8. 8.3.8  Mode Selection and Clock Synchronization (MODE/SYNC)
      9. 8.3.9  Spread Spectrum Clocking (SSC)
      10. 8.3.10 Output Discharge
      11. 8.3.11 Undervoltage Lockout (UVLO)
      12. 8.3.12 Overvoltage Lockout (OVLO)
      13. 8.3.13 Overcurrent Protection
        1. 8.3.13.1 Cycle-by-Cycle Current Limiting
        2. 8.3.13.2 Hiccup Mode
        3. 8.3.13.3 Current Limit Mode
      14. 8.3.14 Power Good (PG)
        1. 8.3.14.1 Standalone or Primary Device Behavior
        2. 8.3.14.2 Secondary Device Behavior
      15. 8.3.15 Remote Sense
      16. 8.3.16 Thermal Warning and Shutdown
      17. 8.3.17 Stacked Operation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-On Reset
      2. 8.4.2 Undervoltage Lockout
      3. 8.4.3 Standby
      4. 8.4.4 On
    5. 8.5 Programming
      1. 8.5.1 Serial Interface Description
      2. 8.5.2 Standard, Fast, Fast Mode Plus Protocol
      3. 8.5.3 I2C Update Sequence
      4. 8.5.4 I2C Register Reset
  10. 9 Register Map
  11. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Selecting the Inductor
        2. 10.2.2.2 Selecting the Input Capacitors
        3. 10.2.2.3 Selecting the Compensation Resistor
        4. 10.2.2.4 Selecting the Output Capacitors
        5. 10.2.2.5 Selecting the Compensation Capacitor, CC
        6. 10.2.2.6 Selecting the Compensation Capacitor, CC2
      3. 10.2.3 Application Curves
    3. 10.3 Best Design Practices
    4. 10.4 Power Supply Recommendations
    5. 10.5 Layout
      1. 10.5.1 Layout Guidelines
      2. 10.5.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.4 Start-Up

When the voltage on the VIN pin exceeds the positive-going UVLO threshold, the device initializes as follows:

  • The device pulls the EN pin low.
  • The device enables the internal reference voltage.
  • The device reads the state of the VSEL, FSEL, and SYNC_OUT pins.
  • The device loads the default values into the device registers.

When initialization is complete, the device enables I2C communication and releases the EN pin. The external circuitry controlling the EN pin now determines the behavior of the device:

  • If the EN pin is low, the device is disabled. The user can write to and read from the device registers, but the DC/DC converter does not operate.
  • If the EN pin is high, the device is enabled. The user can write to and read from the device registers and, after a short delay, the DC/DC converter starts to ramp up the output.

Figure 8-7 shows the start-up sequence when the EN pin is pulled up to VIN.


TPS62870 TPS62871 TPS62872 TPS62873 Start-Up Timing When EN is Pulled Up to VIN
Figure 8-7 Start-Up Timing When EN is Pulled Up to VIN

Figure 8-8 shows the start-up sequence when an external signal is connected to the EN pin.


TPS62870 TPS62871 TPS62872 TPS62873 Start-Up Timing When an External Signal is Connected to the EN Pin
Figure 8-8 Start-Up Timing When an External Signal is Connected to the EN Pin

The SSTIME[1:0] bits in the CONTROL2 register select the duration of the soft-start ramp:

  • td(RAMP) = 500μs
  • td(RAMP) = 1ms (default)
  • td(RAMP) = 2ms
  • td(RAMP) = 4ms

The device ignores new values until the soft-start sequence is complete if the user programs the following when the device soft-start sequence has already started:

  • A new output voltage setpoint (VOUT[7:0])
  • An output voltage range (VRANGE[1:0])
  • Soft-start time (SSTIME[1:0]) settings

If the user change the value of VSET[7:0] during soft start, the device first ramps to the value that VSET[7:0] had when the soft-start sequence began. Then, when soft start is complete, the device ramps up or down to the new value.

The device can start up into a prebiased output. In this case, only a portion of the internal voltage ramp is seen externally (see Figure 8-9).


TPS62870 TPS62871 TPS62872 TPS62873 Start-Up into a Prebiased Output
Figure 8-9 Start-Up into a Prebiased Output

Note that the device always operates in DCM during the start-up ramp, regardless of other configuration settings or operating conditions.