SLVUCE1A march   2023  – august 2023 TPS56837

 

  1.   1
  2.   TPS56837EVM 8-A, Regulator Evaluation Module
  3.   Trademarks
  4. 1Introduction
  5. 2Performance Specification Summary
  6. 3Modifications
    1. 3.1 Output Voltage Setpoint
    2. 3.2 Mode Selection
    3. 3.3 Adjustable UVLO
  7. 4Test Setup and Results
    1. 4.1 Input, Output Connections
    2. 4.2 Start-Up Procedure
    3. 4.3 Output Voltage Ripple
    4. 4.4 Start-Up
    5. 4.5 Shutdown
  8. 5Board Layout
    1. 5.1 Layout
  9. 6Schematic, List of Materials, and Reference
    1. 6.1 Schematic
    2. 6.2 List of Materials
    3. 6.3 Reference
  10. 7Revision History

3.1 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. GUID-FFDDB289-3A71-45A4-92BD-BC02F0E3DE5F-low.gif

Table 3-1 lists the R6 and R7 values for some common output voltages.

Table 3-1 Recommended Component Values

Switching Frequency (kHz)

Output Voltage(1) (V)R6(2) (kΩ)R7 (kΩ)L1 (µH)COUT(3) (µF)C10 (4)(pF)
TYP

500

1.057.510168
1.820101.568
3.345.3102.262

150

573.2103.3

35

150

9

140

10

4.7

22

100

12

383

20

5.6

17

30

800

1.05

7.5

10

0.68

68

1.8

20

10

1

68

3.3

45.3

10

1.5

62

150

5

73.2

10

2.2

35

150

9

140

10

3.3

22

100

12

383

20

3.3

17

30

1200

1.05

7.5

10

0.47

68

1.8

20

10

0.68

68

3.3

45.3

10

1

62

150

5

73.2

10

1.5

35

150

9

140

10

2.2

22

100

12

383

20

2.2

17

30

(1) Please use the recommended L1 and COUT combination of the higher and closest output rail for unlisted output rails.
(2) R6 = 0 Ω for VOUT = 0.6 V.
(3) COUT is the sum of effective output capacitance. In this data sheet, 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 verify that the minimum value of effective capacitance is provided. Refer to the information of DC bias and temperature characteristics from manufacturers of ceramic capacitors.
(4) 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.