SLVUCT2 December   2023 TPS56837H

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 Modifications
      1. 2.1.1 Output Voltage Setpoint
      2. 2.1.2 Mode Selection
      3. 2.1.3 Adjustable UVLO
  8. 3Implementation Results
    1. 3.1 Test Setup and Results
      1. 3.1.1 Input, Output Connections
      2. 3.1.2 Start-Up Procedure
      3. 3.1.3 Output Voltage Ripple
      4. 3.1.4 Start-Up
      5. 3.1.5 Shutdown
  9. 4Hardware Design Files
    1. 4.1 Schematic
    2. 4.2 PCB Layout
    3. 4.3 Bill of Materials
  10. 5Additional Information
    1.     Trademarks
  11. 6Reference

2.1.1 Output Voltage Setpoint

To change the output voltage of the EVMs, change the value of resistor R6 (RFB_TOP) and resistor R7 (RFB_BOT). Changing the value of R6 and R7 can change the output voltage above 0.6 V. The value of R6 and R7 for a specific output voltage can be calculated using Equation 1.

Equation 1. VOUT=0.6 x (1+R6R7)

Table 2-1 lists the R6 and R7 values for some common output voltages.

Table 2-1 Recommended Component Values

Switching Frequency (kHz)

Output Voltage (V)R6 (kΩ)R7 (kΩ)L1 (µH)COUT(1) (µF)C10 (2)(pF)
TYP

500

530

4.09

4.7

22 uF × 4

150
930

2.14

4.722 uF × 4150
15

30

1.25

4.722 uF × 4

150

20

30

0.93

4.7

22 uF × 4

150

(1) COUT in this data sheet is using TDK C3216X5R1V226M160AC 35VDC capacitor. Recommend to use the same effective output capacitance. The effective capacitance is defined as the actual capacitance under DC bias and temperature, not the rated or nameplate values. All high value ceramic capacitors have a large voltage coefficient in addition to normal tolerances and temperature effects. A careful study of bias and temperature variation of any capacitor bank must be made to make sure that the minimum value of effective capacitance is provided. Refer to the information of DC bias and temperature characteristics from manufacturers of ceramic capacitors. Higher than Cout_max capacitance is allowed by careful tuning the feedforward compensation.
(2) R8 and C10 can be used to improve the load transient response or improve the loop-phase margin. The Optimizing Transient Response of Internally Compensated DCDC Converters with Feed-forward Capacitor application report is helpful when experimenting with a feed-forward capacitor.