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Original question:

CCS/LM5116: LM5116 output voltage only have 3.4V

LM5116: LM5116 have damage risk , Vin=71 to 100v and output=12V/ Input=2A

Lawrence He
Genius 3280 points
Part Number: LM5116

Dear,


our client use LM5116, power spec and schematic as below, and we find IC have damage risk.

sysem power spec:
• Input Range: 72V to 100V
• Output Voltage: 12V
• Output Current: 2A

schematic:

damage picture:

measurment pin to GND.

LM5116 Fail IC

　

Pass

Fail

PIN

to GND Ω

1

3.35M

x

2

3.93M

4M

3

4.16M

11

4

3.82M

3.86M

5

3M

3M

6

GND

GND

7

3.8M

3.8M

8

4M

4M

9

3.27M

3.3M

10

3.8M

3.9M

11

4.06M

4.12M

12

4.4M

4.47M

13

2.2

4.31

14

GND

GND

15

3.7M

4.53

16

27K

29

17

84K

62K

18

3.27M

12K

19

10M

15

20

4.7M

10

measurement waveform:

Also we use AN-1596 LM5116 Evaluation Board to change output voltage 15v, but we find IC Temp Tc was pretty high.

If any suggestion, Please advise me.

Thanks,

Best regards,

Lawrence.

  • 0
    TI__Expert 6245 points
    Hello Lawrence,

    I am forwarding your question to this part’s expert, Tim.

    Regards, Robert
  • 0
    TI__Guru 73652 points
    Hi Lawrence,

    Here are some comments:

    Do not exceed VCCX max operating voltage of 15V. If VOUT is 15V, use a series diode or low voltage zener to reduce the voltage.
    Input capacitors should be much closer to the FETs (this is to reduce power loop parasitic inductance and thus SW voltage overshoot).
    Use a 100nF boot cap (1/10th the value of the VCC cap).
    Use a 1uF decoupling cap from VCCX to GND.
    The boot diode seems large (a smaller footprint is adequate).
    No need for paralleled MOSFETs in a 2A application.


    Regards,
    Tim