SLVSFU1C April   2023  – October 2024 TPS62874-Q1 , TPS62875-Q1 , TPS62876-Q1 , TPS62877-Q1

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Options
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings - Q100
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Interface Timing Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
  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  Transient Non-Synchronous Mode (optional)
      4. 8.3.4  Precise Enable
      5. 8.3.5  Start-Up
      6. 8.3.6  Switching Frequency Selection
      7. 8.3.7  Output Voltage Setting
        1. 8.3.7.1 Output Voltage Range
        2. 8.3.7.2 Output Voltage Setpoint
        3. 8.3.7.3 Non-Default Output Voltage Setpoint
        4. 8.3.7.4 Dynamic Voltage Scaling
        5. 8.3.7.5 Droop Compensation
      8. 8.3.8  Compensation (COMP)
      9. 8.3.9  Mode Selection / Clock Synchronization (MODE/SYNC)
      10. 8.3.10 Spread Spectrum Clocking (SSC)
      11. 8.3.11 Output Discharge
      12. 8.3.12 Undervoltage Lockout (UVLO)
      13. 8.3.13 Overvoltage Lockout (OVLO)
      14. 8.3.14 Overcurrent Protection
        1. 8.3.14.1 Cycle-by-Cycle Current Limiting
        2. 8.3.14.2 Hiccup Mode
        3. 8.3.14.3 Current-Limit Mode
      15. 8.3.15 Power Good (PG)
        1. 8.3.15.1 Standalone, Primary Device Behavior
        2. 8.3.15.2 Secondary Device Behavior
      16. 8.3.16 Remote Sense
      17. 8.3.17 Thermal Warning and Shutdown
      18. 8.3.18 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 HS-Mode Protocol
      4. 8.5.4 I2C Update Sequence
      5. 8.5.5 I2C Register Reset
      6. 8.5.6 Dynamic Voltage Scaling (DVS)
  10. 9 Device Registers
  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 Inductor Selection
        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 Typical Application Using Two TPS62876-Q1 in a Stacked Configuration
      1. 10.3.1 Design Requirements For Two Stacked Devices
      2. 10.3.2 Detailed Design Procedure
        1. 10.3.2.1 Selecting the Compensation Resistor
        2. 10.3.2.2 Selecting the Output Capacitors
        3. 10.3.2.3 Selecting the Compensation Capacitor CC
      3. 10.3.3 Application Curves for Two Stacked Devices
    4. 10.4 Typical Application Using Three TPS62876-Q1 in a Stacked Configuration
      1. 10.4.1 Design Requirements For Three Stacked Devices
      2. 10.4.2 Detailed Design Procedure
        1. 10.4.2.1 Selecting the Compensation Resistor
        2. 10.4.2.2 Selecting the Output Capacitors
        3. 10.4.2.3 Selecting the Compensation Capacitor CC
      3. 10.4.3 Application Curves for Three Stacked Devices
    5. 10.5 Best Design Practices
    6. 10.6 Power Supply Recommendations
    7. 10.7 Layout
      1. 10.7.1 Layout Guidelines
      2. 10.7.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    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

8.3.2 Forced-PWM and Power-Save Modes

The device can control the inductor current in three different ways to regulate the output:

  • Pulse-width modulation with continuous inductor current (PWM-CCM)
  • Pulse-width modulation with discontinuous inductor current (PWM-DCM)
  • Pulse-frequency modulation with discontinuous inductor current and pulse skipping (PFM-CCM)

During PWM-CCM operation, the device switches at a constant frequency and the inductor current is continuous (see Figure 8-2). PWM operation achieves the lowest output voltage ripple and the best transient performance.


TPS62874-Q1 TPS62875-Q1 TPS62876-Q1 TPS62877-Q1 Continuous Conduction Mode (CCM) Current Waveform

Figure 8-2 Continuous Conduction Mode (CCM) Current Waveform

During PWM-DCM operation the device switches at a constant frequency and the inductor current is discontinuous (see Figure 8-3). In this mode the device controls the peak inductor current to maintain the selected switching frequency while still being able to regulate the output.


TPS62874-Q1 TPS62875-Q1 TPS62876-Q1 TPS62877-Q1 Discontinuous Conduction Mode (DCM) Waveform

Figure 8-3 Discontinuous Conduction Mode (DCM) Waveform

During PFM-DCM operation the device keeps the peak inductor current constant (at a level corresponding to the minimum on-time of the converter) and skips pulses to regulate the output (see Figure 8-4). The switching pulses that occur during PFM-DCM operation are synchronized to the internal clock.

.
TPS62874-Q1 TPS62875-Q1 TPS62876-Q1 TPS62877-Q1 Discontinuous Conduction Mode (PFM-DCM) Current Waveform Figure 8-4 Discontinuous Conduction Mode (PFM-DCM) Current Waveform

Use Equation 1 to calculate the output current threshold at which the device enters PFM-DCM:

Equation 1. I O U T ( P F M ) = V I N – V O U T 2 L t O N 2 V I N V O U T f s w

The following figure shows how this threshold typically varies with VIN and VOUT for a switching frequency of 2.25MHz

TPS62874-Q1 TPS62875-Q1 TPS62876-Q1 TPS62877-Q1 Output Current PFM-DCM Entry Threshold for fSW = 2.25MHz Figure 8-5 Output Current PFM-DCM Entry Threshold for fSW = 2.25MHz

Configure the device to use either Forced-PWM (FPWM) mode or Power-Save Mode (PSM):

  • In forced-PWM mode. the device uses PWM-CCM at all times.
  • In power-save mode, the device uses PWM-CCM at medium and high loads, PWM-DCM at low loads, and PFM-DCM at very low loads. Transition between the different operating modes is seamless.

Table 8-1 shows the function table of the MODE/SYNC pin and the FPWMEN bit in the CONTROL1 register, which control the operating mode of the device.

Table 8-1 FPWM Mode and Power-Save Mode Selection
MODE/SYNC Pin FPWMEN Bit Operating Mode Remark
Low 0 PSM Do not use in a stacked configuration
1 FPWM
High X FPWM
Sync Clock X FPWM