LM34936: Schematic review

Yuta Nishie

Part Number: LM34936
Other Parts Discussed in Thread: CSD19502Q5B, CSD17303Q5, CSD18513Q5A

Hi,

We are considering the circuit configuration shown in the attached image.
Could you please check if there are any problems with the constants of the peripheral components, FETs and inductors?

Q1：CSD19502Q5B, Q2：CSD19502Q5B, Q3：CSD17303Q5, Q4：CSD17303Q5, L：SRP1580CA－２R0M

capacitor constants：ex.)153p -> 15x10^3pF -> 15nF
resistance constants：ex.) 93.1KF -> 93.1kOhm(1%)

LM34936RHFR

Vin=4.5V to 24V, Vout=12V, Iout=10A(max)

Best Regards,

Nishie

over 2 years ago

0 Feng Ji over 2 years ago

TI__Mastermind 22365 points

Hi Nishie,

Please use LM5176 Design Calculator (Rev. A) for a first check as these 2 devices are using the same regulation scheme.

Best regards,

Feng Ji

0 Yuta Nishie over 2 years ago in reply to Feng Ji

Genius 4925 points

Hi Feng-san,

I will check with the documents you gave me.
I just want you to comment on whether there is any problem in selecting FET.

Should I check with the FET team instead of you?

Best Regards,

Nishie

0 Feng Ji over 2 years ago in reply to Yuta Nishie

TI__Mastermind 22365 points

Hi Nishie,

I would think Q3：CSD17303Q5, Q4：CSD17303Q5 are good choice.

Please reconsider Q1：CSD19502Q5B, Q2：CSD19502Q5B because:

1. Min Vin=5V means the gate driver voltage may be 4.5V, CSD19502Q5B will show much higher Rds(on).

2. Considering 24V max input voltage, 80V rating is a bit over designed. I think 40V or 60V will be good.

Best regards,

Feng Ji

+1 Yuta Nishie over 2 years ago in reply to Feng Ji

Genius 4925 points

Hi Feng-san,

Thank you for your support!

I will pass along information to my customer.

Best Regards,

Nishie

0 Yuta Nishie over 2 years ago in reply to Yuta Nishie

Genius 4925 points

Hi Feng-san,

I received an additional question from a customer, so let me discuss it with you.

Since you said about Q1 and Q2 ”Considering 24V max input voltage, 80V rating is a bit over designed. I think 40V or 60V will be good.”.

Is there any problem if the Q1 to Q4 FETs are CSD18513Q5A?

Best Regards,

Nishie

+1 Feng Ji over 2 years ago in reply to Yuta Nishie

TI__Mastermind 22365 points

Hi Nishie,

We can use CSD18513Q5A as a starting point.

Best Regards,

Feng Ji

0 Yuta Nishie over 2 years ago in reply to Feng Ji

Genius 4925 points

Hi Ferg-san,

Thank you for your support!

Best Regards,

Nishie

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LM34936: Schematic review