LMR61428 design for 5V to 12V / 100mA

hemant undale

Prodigy 30 points

Other Parts Discussed in Thread: LMR61428

i am using LMR61428 ic for 5V to 12V / 100mA conversion.

Below symbols are as per datasheet of IC.

According to datasheet i have designed Rf1, Rf2.

My question are

1) How to design R1, Rfq, C3 values??

2) Is there thermal protection required in this case as my Pdmax=500mWatt.

3) on page 10 line 5 it is written that The max acceptable voltage at BOOT pin (pin7) is 10V. What this means?? How can i choose value of R1 in my case???

Thanks

over 10 years ago

0 Anston Lobo over 10 years ago

TI__Genius 16025 points

Hi Hemant,

We've received your query and will get back to you shortly.

Thanks,

Anston

0 Anston Lobo over 10 years ago in reply to Anston Lobo

TI__Genius 16025 points

Hi Hemant,

For your application you should tie the BOOT, VDD and EN pins to +5Vin. Since your Vout is 12V. These pins should not be driven above 10V as they control the FET drive and control circuitry. To supply anything greater than 10V will damage this circuitry.

With regards to Thermal, you should expect a total Pd of about 150mW and IC Power dissipation of 20mW. You should have no issues with thermal for your application.

Attached is the circuit you are looking for : 3835.E2E - Hemant Undale - LMR61428 Boost design.pdf

We used webench which is a free TI tool to help create these schematics.

Thanks,

Anston

0 hemant undale over 10 years ago in reply to Anston Lobo

Prodigy 30 points

Thanks Anston, really mean a lot!!

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LMR61428 design for 5V to 12V / 100mA