unknown DC-DC chip of SI-9110 differential probe

[teatime]

Hello all,

Right now I have a defective SI-9110 differential probe,
Input 6Vdc,
the problem is no -12V, +12V is normal.
I checked the waveform of Pin15, the PWM of +12v as  attachement.
But Pin 10 no any waveform.
If using external -12v instead, this differential probe works properly.
So the only problem is the DC-DC chip.
But the factory erase all chip mark.

I have draw the schematic of this part,please see the attachement.
The length of this chip is 1cm.
The bottom marked"NBK" and have a "Philippines" mark.

I hope some one can tell me the model of this chip.
Maybe this chip also used on other type differential probe.

Thanks & Best regards

[BennoG]

I don't see any feedback divider, so this chip is specifically designed to generate +12V and -12V.
But I can not find that kind of boost converter controller.

Benno

[coromonadalix]

but feedback pins are 9 and 16 for the ic  ??

if the schematic is ok ?

[BreakingOhmsLaw]

https://www.analog.com/media/en/technical-documentation/data-sheets/max743.pdf

or a clone of that part.

[fzabkar]

https://ae01.alicdn.com/kf/Sf508e8f9f731407b89c61c5a37d4a0d3K/1pcs-lot-100-New-original-MAX743CWE-MAX743EWE-MAX743-SOP16.jpg

https://ae01.alicdn.com/kf/Hf6e06e2bed7e4a59936f710dc9221ce24/100-Original-New-In-Stock-MAX743CWE-MAX743EWE-MAX743-SOP16.jpg

[asis]

Hi,

Here is part of the diagram of the working product.

[teatime]

After compare with the datesheet, MAX743 is the right chip.
Thanks alot for your great help!
 

[teatime]

After remove the chip, then I draw this schematic, it's right.
The chip MAX743 is the chip I needed.