Identifying a Mystery IC

[markjmatthews]

I'm repairing an Axis M1054 IP Camera (http://www.axis.com/us/en/products/axis-m1054) that has a fried buck converter IC (I could see it shorting out and overheating with a thermal camera). However, I haven't been able to determine what the IC actually is!

What I know:

• Has the following markings:
      "194B"
      "1034"
      "Z424"
• Is a DFN10 (3.05mm x 3.05mm)
• Appears to convert 5.0V into a "CPU Voltage". 3.3V or 2.5V I'm guessing
• Has the pad layout in the attached photo (chip was de-soldered)

Anyone know how to determine what this IC is? I've already consulted the following top-mark lookups with no luck:
http://www.ti.com/general/docs/partmarking/partmarkinghome.jsp
http://www.maximintegrated.com/en/design/packaging/topmark/
https://www.fairchildsemi.com/get-help/top-mark-search/
http://cds.linear.com/docs/en/packaging/Linear_Technology_Top_Markings.pdf

Any help, direction, pointers or rumours anyone can provide are greatly appreciated. Thanks!

[edpalmer42]

Maybe this one?

SC194B
Year 2010 Week 34
Lot # Z424

http://www.datasheet.hk/download.php?id=1732071&pdfid=0CFADB37FBEF468031169F3D1B41394F&file=0367\sc194b_3286432.pdf

[markjmatthews]

BINGO!!!!

That's a perfect match!! Muchos thanks edpalmer42!!!

I've never heard of Semtech before. Was there any magic search website you used, or you just thought it might have been a Semtech IC?

Regardless... many thanks. I was ready to give up.

[edpalmer42]

I just searched google for <194b "buck converter"> and spent 5 minutes filtering out fluff.  As you can see, the link is to one of those datasheet sites rather than Semtech.

[markjmatthews]

Well, I'm impressed regardless. I probably just didn't filter through the Google results long enough.

 
Thanks!

[sacherjj]

Mine was on the first page with that search:

http://www.semtech.com/images/datasheet/sc194b.pdf

But I've hit semtech before, so Google is probably filtering for me.

[markjmatthews]

SUCCESS!! Sort of...

Just wanted to report back that I was easily able to order a couple of SC194B's from DigiKey, and soldering in a new one brought the unit back to life!! Sort of...

It turned on and all the status LED's lit up (all amber), but it didn't do much after that. I once had the status LED's flash RED, which apparently means "firmware upgrade failure" (and apparently is recoverable), but I could not reproduce this. I also noted that the CPU seemed to be rather hot.

Further investigation showed an SC198A burning up at 100C (again, the thermal camera comes in very useful). The "A" output was 1.24V, well within range. But the "B" output was 3.67V, not within the maximum output voltage of 3.3V. Given the control voltages of:

CTLB0 = 0.0V
CTLB1 = 0.0V
CTLB2 = 0.0V

The "B" output should actually be (per the data sheet) 1.8V.

My guess is that someone over-voltaged the input to this camera and fried both the SC194B and SC198A, which are fed directly from this input. I'm hoping that it's still worth repairing, as it's now possible that the over-voltage from the 198A which feeds directly into the core, has permanently damaged it.

In other bad news, nobody stocks the SC198A. So I might be out of luck on this repair now.

[amyk]

Almost 3.7V into a device designed for 1.8V-only is going to kill it; absolute max for those parts is usually in 2-2.5V range. If the CPU is "rather hot", that probably happened already.

[PhilPet]

How did you dismantle the M1054 ?   (access PCB/remove case etc.)  cheers...