SLVUBX0A July   2021  – January 2022 TPSM8A28 , TPSM8A29

 

  1.   Trademarks
  2. 1Introduction
  3. 2Description
  4. 3Getting Started With the TPSM8A29EVM
    1. 3.1 J1 - Input Voltage Supply Connector
    2. 3.2 J4 and J7 - Positive and Negative Output Connectors
    3. 3.3 J2 - Enable Header
    4. 3.4 J5 - Switching Frequency and Operating Mode
    5. 3.5 J6 - Output Voltage Selection Header
  5. 4Test Point Description
    1. 4.1 TP12 - SS/REF_IN
    2. 4.2 TP14 - VCC
  6. 5Test Setup and Results
    1. 5.1 Startup Procedure
    2. 5.2 Efficiency
    3. 5.3 Load Regulation
    4. 5.4 Line Regulation
    5. 5.5 Output Voltage Ripple
    6. 5.6 Startup and Shutdown
    7. 5.7 Load Transient
    8. 5.8 Bode Plot
  7. 6TPSM8A29EVM Schematic
  8. 7TPSM8A29EVM PCB Layers
  9. 8TPSM8A29EVM Bill of Materials
  10. 9Revision History

J5 - Switching Frequency and Operating Mode

A jumper on the J5 header configures both the switching frequency and operating mode of the TPSM8A29 with a single resistor as described in Table 3-3. The dual functionality of the TPSM8A29 MODE pin reduces BOM count and solution size.

Three switching frequencies (600 kHz, 800 kHz, 1 MHz) allow the user to optimize the tradeoff between efficiency and layout area. Because the TPSM8A29 has a fixed integrated inductor, the designer only needs to choose an appropriate output capacitance to meet their output voltage ripple and transient response requirements.

The TPSM8A29 can operate in either FCCM or auto-skip DCM mode. When operating in FCCM, the switching frequency is fixed for all output load current conditions. Operating in this mode yields the best output voltage ripple and load regulation at low load currents at the expense of reduced light-load efficiency. When operating in auto-skip DCM, the switching frequency is reduced to maintain high efficiency, even for light load conditions. The disadvantage to operating in DCM is that the light-load output ripple may be greater than in FCCM, the load regulation may be slightly reduced, and the non-fixed switching frequency at light loads may not be desirable for some applications requiring low system noise.

Table 3-3 Switching Frequency and Operating Mode Header
J5 Jumper ConnectionMODE Pin Connection DescriptionSwitching Frequency (kHz)Operating Mode
Pins 1 and 2Shorted to VCC600Auto-skip DCM
Pins 3 and 4AGND through 243 kΩ800
Pins 5 and 6AGND through 121 kΩ1000
Pins 7 and 8AGND through 60.4 kΩ1000FCCM
Pins 9 and 10AGND through 30.1 kΩ800
Pins 11 and 12Shorted to AGND600