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Original question:

TPS65982: Peak current setting for each PDOs

TPS65982: EVM module OCP function do not meet the datasheet

Picher
Prodigy 130 points
Part Number: TPS65982

Hi, team

I used the TPS65982 EVM module to validate the OCP functions of TPS65982. I measured the OCP threshold 

under various Maximum Current and Peak Current setting. And below is the test results.

I have some questions about the test result.

1. Is my test results correct?

2. If the test result is correct, so can we get the followings :

  • When TPS65982 GUI tool sets TPS65983 or TPS65982 peak current as 100%, actual peak current set is 100%.
  • When TPS65982 GUI tool sets TPS65983 or TPS65982 peak current as 130%, actual peak current set is 150%.
  • When TPS65982 GUI tool sets TPS65983 or TPS65982 peak current as 150% or 200%, actual peak current set is 200%.

TI TPS65982 EVM Measured OCP thresholds under various Maximum Current and Peak Current settings.

Maximum current

Setting

(A)

Peak current setting

Source 5V from Internal

Switch

OCP (A)

Source 5V from external

Switch

OCP(A)

Source 9V from external

Switch

OCP(A)

Source 12V from external

Switch

OCP(A)

Source 15V from external

Switch

OCP(A)

Source 20V from external

Switch

OCP(A)

0.5

100%

1.09

1.92

1.93

1.94

1,96

1.98

130%

1.09

1.92

1.93

1.94

1,96

1.98

150%

1.23

1.92

1.93

1.94

1,96

1.98

200%

1.23

1.92

1.93

1.94

1,96

1.98

1

100%

1.23

1.92

1.93

1.94

1,96

1.98

130%

1.75

1.92

1.93

1.94

1,96

1.98

150%

2.28

2.49

2.49

2.51

2.54

2.57

200%

2.28

2.49

2.49

2.51

2.54

2.57

1.5

100%

1.75

1.92

1.93

1.94

1,96

1.98

130%

2.52

2.49

2.49

2.51

2.54

2.57

150%

3.34

3.61

3.62

3.65

3.69

3.74

200%

3.34

3.61

3.62

3.65

3.69

3.74

2

100%

2.28

2.49

2.5

2.52

2.54

2.57

130%

3.34

3.61

3.62

3.65

3.69

3.74

150%

3.34

4.73

4.74

4.79

4.84

4.91

200%

3.34

4.73

4.74

4.79

4.84

4.91

2.5

100%

2.78

3.04

3.05

3.08

3.1

3.14

130%

3.34

4.16

4.17

4.21

4.25

4.31

150%

3.34

5.85

5.87

5.92

5.99

6.07

200%

3.34

5.85

5.87

5.92

5.99

6.07

3

100%

3.34

3.61

3.62

3.65

3.69

3.72

130%

3.34

5.28

5.3

5.35

5.4

5.48

150%

3.34

6.95

6.98

7.04

7.11

7.22

200%

3.34

6.95

6.98

7.04

7.11

7.22

4

100%

3.34

3.61

3.62

3.65

3.69

3.72

130%

3.34

5.28

5.3

5.35

5.4

5.48

150%

3.34

6.95

6.98

7.04

7.11

7.22

200%

3.34

6.95

6.98

7.04

7.11

7.22

5

100%

3.34

3.61

3.62

3.65

3.69

3.72

130%

3.34

5.28

5.3

5.35

5.4

5.48

150%

3.34

6.95

6.98

7.04

7.11

7.22

200%

3.34

6.95

6.98

7.04

7.11

7.22

3.  Figure below shows the 0x32 register of TPS65982, 15V PDO Peak current always keep at 100% and can’t change by the firmware configure tool.

  Is there any bugs about this?

  • 0
    TI__Mastermind 36756 points

    Hi Picher,

    Your results look correct. I don't see any issues with them. Please note that the PP_Ext current limit is done through the SENSE_P/N pins and is subject to the internal ADC accuracy. It is expected to see some tolerance on the current limit.

    Thanks,
    Eric

  • 0 in reply to Eric Beljaars
    Prodigy 130 points

    Hi, Eric

    1. As you see, when Maximum Current = 3A, Peak Current = 130, 3A*130%=3.9A, but the PP_EXT OCP threshold is about 5.3A, this is still caused by tolerance? If so it's a very bad  tolerance.

    2. When Peak Current = 150%, OCP threshold is same with Peak Current = 200%. 

    From above two points I think we can get the conclusions below, but want to confirm with TI team.

    • When TPS65982 configure tool sets TPS65982 peak current as 100%, actual peak current set is 100%.
    • When TPS65982 configure tool sets TPS65982 peak current as 130%, actual peak current set is 150%.
    • When TPS65982 configure tool sets TPS65982 peak current as 150% or 200%, actual peak current set is 200%.

    3. Why the register 0x32 shows that  15V PDO Peak Current always keep at 100%? Is there any answer?

  • 0 in reply to Picher
    TI__Mastermind 36756 points

    Hi Picher,

    Your summary looks correct. Please ensure you are setting the correct IOC setting for the 15V PDO as well.

    Thanks,
    Eric

  • 0 in reply to Eric Beljaars
    Prodigy 130 points

    Hi, Eric

    Thanks for your help.

    I'm sure I have set the correct IOC setting for 15V PDO same with other PDOs. And the other PDOs is set as expected, except 15V PDO is alway keep at 100% IOC.

    And if firmware sets 5V PDO to feed PP_VBUS via internal switch (PP_5V0 to PP_VBUS path) as default: 15V PDO OCP happens at nominal 5.4A (2.5x200%) as expected (firmware tools settings: Maximum Current = 2.5A and Peak Current = 150% or 200%).

    But if firmware sets 5V PDO to feed PP_VBUS via external switch (PP_EXT to PP_VBUS path) as default: 15V PDO OCP happens at nominal 2.5A (2.5Ax100%) (not 5.4A) (firmware tools settings: Maximum Current = 2.5A and Peak Current = 150% or 200%).

    So, is the 5V PDO must to set to feed PP_VBUS via internal switch (PP_5V0 to PP_VBUS path) as default ?

    Thanks,

    Picher

  • 0 in reply to Picher
    TI__Mastermind 36756 points

    Hi Picher,

    It is recommended to use the internal 5V path to source 5V to VBUS. This internal power path was designed and optimized for the 5V source use case. The best performance and protection will be realized when using the internal 5V path.

    Thanks,
    Eric