TIDA-020047: LM62460-Q1 Not working

Amine LTAIEF

Part Number: TIDA-020047
Other Parts Discussed in Thread: LM62460-Q1

Hello ,

I'm trying to understand why the LM62460-Q1 preregulator isn't functioning properly. When I measured the voltage at R217, which is connected to the PRE_REG_PG pin, I found it to be 0V. Could this indicate a fault with the preregulator? Should I consider replacing it to resolve the issue?

PS: I'm working on TIDA020047 board.

Regards

Amine.

5 months ago

0 Brian Shaffer 5 months ago

TI__Intellectual 1130 points

Hi Amine,

Please check:

1. What is the voltage on the ENABLE pin? What resistors do you have populated in the ENABLE "mux"? (R205, R206, R207, and R208)

2. What is the voltage on VIN?

3. Is there any activity on the SW pin?

Best Regards,

Brian

0 Amine LTAIEF 5 months ago in reply to Brian Shaffer

Intellectual 505 points

Hi Brian,

Here below my comments.

1. in the enable pin I have 24O mV. All the resistors 205,206 , R207 and R208 are populated.

2. VIN is 12 Volts

3.0 Volt in SW pin

Regards

Amine

0 Brian Shaffer 5 months ago in reply to Amine LTAIEF

TI__Intellectual 1130 points

Hi Amine,

If you have a solid 3V on the SW pin, That would lead me to think you have a large load dragging down the supply. The FETs are on, but the output is not coming up high enough for them to switch off. (regulate)

You should have a "high" on ENABLE. So, you need to decide which signal you want driving this pin and depopulate either R206 or R207. Are you wanting to use the Inhibit from CAN or Ethernet? Remove the one you are not using.

Best Regards,

Brian

0 Amine LTAIEF 5 months ago in reply to Brian Shaffer

Intellectual 505 points

Hi Brian,

we don't use the ethernet,we are using only CAN FD1 and we didn't provide anything in "PRE_REG_EN". so in this case do I need to remove R206 and R207 and provide signal on J9 connector for PRE_REG_EN pin ?

Regards

Amine

+1 Brian Shaffer 5 months ago in reply to Amine LTAIEF

TI__Intellectual 1130 points

Hi Amine,

You need a "high" on ENABLE. So, you need to decide which signal you want driving this pin. If you will not be driving it with either INH, then remove resistors from the mux and add a resistor to pull ENABLE up. It's up to you how you do it, but you need to ensure that the buck is enabled.

Regards,

Brian

0 Amine LTAIEF 5 months ago in reply to Brian Shaffer

Intellectual 505 points

Thank you so much for your help

Regards

Amine

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TIDA-020047: LM62460-Q1 Not working