LM5164: Suitable for 24V In -17V 0.5A Out Design?

Graham North29

Part Number: LM5164
Other Parts Discussed in Thread: , LM5575

I'm looking for a part to design a 24V In, -17V 0.5A Output supply and put the requirements into Webench.

One option it gave me was LM5164-Q1, but that's not available to buy for me right now. I looked at the datasheets and I can't see why the LM5164 part can not be used?

Is it possible to use the LM5164 in this configuration?

What's the differences between the non Q1 and Q1 parts?

Thanks,

over 5 years ago

0 Graham North29 over 5 years ago

Intellectual 385 points

If it makes any difference, I'd prefer to run the part at a high switching frequency also. 0.7 to 1 MHz range probably.

Thanks,

0 Orlando Murray over 5 years ago in reply to Graham North29

TI__Mastermind 22301 points

You can substitute the LM5164 for the LM5164-Q1 WEBENCH inverting buck boost design.

The integrated circuit is the same, some slight difference in Q1 assembly and test to meet AEC automotive qualification.

700kHz Fsw will see higher switching losses and lower efficiency compared to lower switching frequencies but should be ok.

I would avoid going higher than that though.

-Orlando

0 Graham North29 over 5 years ago in reply to Orlando Murray

Intellectual 385 points

Hi Orlando,

Thank you for confirming the LM5164 can be used.

Could you explain to me what the maximum output current capability will be in this configuration please?

VIn 23-25V

Vout -17V

Also, would you design the ability to fit a snubber network using this part, as discussed in my LM5575 question?

Many thanks,

0 Orlando Murray over 5 years ago in reply to Graham North29

TI__Mastermind 22301 points

Check out https://www.ti.com/lit/an/snva856a/snva856a.pdf

As mentioned in the other thread, the inverting buck boost average inductor current is IL = IOUT * [1+( |VOUT| / VIN )]

This does not include the efficiency term, see eq 4 in that appnote.

For LM5164 1A converter us IL = 1A, VOUT = -17V and VIN = 23V, I get 575mA.

When I include an estimated 80% efficiency I get 520mA.

As Arief mentioned in the other thread an RC snubber from SW to -VOUT can be used yes.

I would include footprints for it and populate if it is needed.

Hope this helps,

-Orlando

Power management

Power management forum

LM5164: Suitable for 24V In -17V 0.5A Out Design?