LM3410-Q1: issues

Ivy Jin

Part Number: LM3410-Q1
Other Parts Discussed in Thread: LM3410

Hi team，

My customer use LM3410XQMF/NOPB in their project.

But in the test, they met two issues:

1. When Vin=5V, FB Pin is 0.6V and not 0.19V with a backup battery (3.9V charge) connected. The current limit of 50mA was not reached for an unknown reason.

2. When Vin=5V, disconnect the backup battery. The LM3410 consumes approximately 1A of high current and is overheating.

The result we expect is a stable charge current of 50 mA when a backup battery is connected at Vin=5V. When the backup battery is disconnected, the device is automatically protected from high current.

Could you please help give some comments or suggestions on these questions ?

Thank you in advance!

Regards,

Ivy

over 3 years ago

0 Irwin Nederbragt over 3 years ago

TI__Mastermind 28655 points

Hello Ivy,

What is the output load, how many LEDs and what is the LED forward voltage?

What is D3011 for?

Best Regards,

0 Ivy Jin over 3 years ago in reply to Irwin Nederbragt

TI__Intellectual 2925 points

HI Irwin,

Sorry for the unclear description.

1. The customer uses the LM3410XQMF/NOPB to supply 50 mA of charging current to 3 NiMH backup batteries.

So the output load is 3 NiMH backup batteries(total 3.9V), not for LEDs.

2. The D3011 function is to draw a high current from the ground to form a loop when the backup battery is enabled to power the T-BOX.

3. For CN3000,

Pin 1 : Backup battery positive

Pin 2 :Backup battery internal thermistor

Pin 3: Backup battery negative.

If you have any questions, please let me know.

Thank you.

Ivy

+1 Irwin Nederbragt over 3 years ago in reply to Ivy Jin

TI__Mastermind 28655 points

Hello Ivy,

The output voltage needs to be higher than the input voltage for a boost converter. Can you look at Vin at the IC, the switch node and Vout?

If the input voltage is 5V and the output voltage is 3.9V it will draw excess current because this is a boost converter. The input goes to the output through the boost diode and inductor.

If you are disconnecting the battery and the output is open it will damage the LM3410 since it does not have the OVP circuit on your schematic, see section 8.1.1.7 on page 14 of the datasheet.

Best Regards,

0 Ivy Jin over 3 years ago in reply to Irwin Nederbragt

TI__Intellectual 2925 points

Hi Irwin，

Thanks for your comments, It's really helpful.

Seems like we have found the reason of the issue.

Many thanks！

Regards，

Ivy

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LM3410-Q1: issues