Help identifying a 6-pin SMD IC in a power supply.

[GonzoTheGreat]

Guys,

Could you help me identify the 6-pin SMD integrated circuit, that functions in the schematic attached below (marked in blue)?
The SOT23-6 package has the markings C1EH (or CIEH) and 9013, but I cannot find these markings in any datasheets I looked at.

Thanks in advance,
Gonzo

[jdraughn]

Looks pretty close http://www.richtek.com/m/Products/AC_DC/Flyback%C2%A0Controller/R7711A

[GonzoTheGreat]

Thank you for trying to help me, unfortunately the R7711A chip has the V_DD on Pin3 and the Gate driver on Pin1, while this mystery chip has the V_DD on Pin1 and the Gate driver on Pin3.

Also, the SOT23-6 markings are different.  See the attached datasheet...

[GonzoTheGreat]

Some additional info. 
The switching frequency of this mystery IC is 24kHz.

[BrianHG]

You have Pin1 mislabeled in your schematic.  Rotate the R7711A by 180 degrees in the data sheet and see how the pins line up.
However, I still can be wrong...  Because now, pin 6 and 4 are actually backwards.
Did you draw this schematic?

[xavier60]

If that diagram is drawn correctly, the control IC is expecting a negative voltage on its CS pin with respect to its ground pin, witch is unusual.

[GonzoTheGreat]

You have Pin1 mislabeled in your schematic.  Rotate the R7711A by 180 degrees in the data sheet and see how the pins line up.
However, I still can be wrong...  Because now, pin 6 and 4 are actually backwards.
Did you draw this schematic?

Yes, I drew this schematic by reverse engineering the PCB. I arranged IC pins that way on this drawing, so there are minimum wire intersections.
Below is the same schematic with these IC pins arranged in a different way. I triple checked that it is correct.

[GonzoTheGreat]

If that diagram is drawn correctly, the control IC is expecting a negative voltage on its CS pin with respect to its ground pin, witch is unusual.

If you mean Pin1, I don't know what you mean. 
IMO both the 22uF cap and the diode feeding it through the 10Ohm resistor, are arranged to feed Pin1 with a positive voltage.

[xavier60]

I should have said Current Sense pin 6.

[GonzoTheGreat]

I should have said Current Sense pin 6.

Indeed the voltage is negative on Pin6 while the MOSFET is conducting,

[xavier60]

I should have said Current Sense pin 6.

Indeed the voltage is negative on Pin6 while the MOSFET is conducting,

Usually that kind of power supply circuit uses an IC that is also intended for conventional flyback designs which use an isolating transformer.
Are you certain that the circuit is drawn correctly?

[GonzoTheGreat]

Are you certain that the circuit is drawn correctly?

Yes, I verified it again.
I even took apart the inductor.  It consists of 2 windings (25 turns and 103 turns) connected in series.

[ebclr]

https://www.richtek.com/assets/product_file/RT9013/DS9013-10.pdf

[xavier60]

https://www.richtek.com/assets/product_file/RT9013/DS9013-10.pdf

Is that the correct link?

[ebclr]

Just opened now https://www.richtek.com/assets/product_file/RT9013/DS9013-10.pdf

[Circlotron]

The way it is drawn is difficult to follow but it looks like some kind of non-isolated buck regulator with the ground reference point of the control ic flapping up and down with the inductor input voltage.

[GonzoTheGreat]

Going out on a limb:  Perhaps the power MOSFET and this Mystery IC came in some kind of a kit from the same manufacturer.
So if we could identify who made this MOSFET, maybe that will also point to the manufacturer of this IC.

The logo on the MOSFET does not resemble Signetics nor Siliconix.  Any ideas who made it ? 
See the photo attached below.

[GonzoTheGreat]

The way it is drawn is difficult to follow but it looks like some kind of non-isolated buck regulator with the ground reference point of the control ic flapping up and down with the inductor input voltage.

Indeed it is a non-isolated constant current regulator (320mA, 50-80VDC out).  I admit, it was my assumption that Pin2 is the GND.
What would be a better way of drawing the schematic?

P.S.
Indeed, the scope shows the Pin2 flapping at 24kHz.

[iainwhite]

Re: the MOSFET

I did a google search for D5N50 and came up with a SiHD5N50D Mosfet from Vishay Siliconix   - do you think that is it? Could it be an earlier logo for Siliconix ??



Update:
I put the phrase "Siliconix C1EH"  into google and it pointed me to a Texas Instruments step down TPS64203 regulator

Maybe i'm running off in the wrong direction here  ??

[GonzoTheGreat]

I did a google search for D5N50 and came up with a SiHD5N50D Mosfet from Vishay Siliconix   - do you think that is it?

I don't think so because if you zoom-in the photo of the blown MOSFET, its number appears to be ?SD5N50 since there is a fragment of the letter "S" in front of the "D".
 

Could it be an earlier logo for Siliconix ??

The entire device is maximum 2 years old  ...and I don't think that DPAK cases existed 15 years ago.

I put the phrase "Siliconix C1EH"  into google and it pointed me to a Texas Instruments step down TPS64203 regulator

That was a good try but the pinout is different and I cannot find the string "C1EH" anywhere in the TPS64203 datasheet.

Thanks for trying 

[iainwhite]

Thanks for trying 

Looks like I let my creative thinking run away too much!

[GonzoTheGreat]

Just opened now https://www.richtek.com/assets/product_file/RT9013/DS9013-10.pdf

Isn't this a linear regulator ?

[Anatoly]

Hi, your chip looks very similar to chinese SF6761S http://www.sifirsttech.com/admin/datasheet/SF6761S_DS_final_v1.0.pdf
However, if your diagram is drawn right: 1). You must solder this chip upside down 2) This chip has positive current sense voltage. Must say, I've never seen modern pwm chips with negative CS, so it looks really very strange to me... Maybe you can post photos of your PCB so we can see this wonder?...

[vuko]

I was looking for chip with similar markings and found this:
http://www.icpower.com.cn/UploadFile/Soft/SD6900%20datasheet_1.4.pdf

[GonzoTheGreat]

I was looking for chip with similar markings and found this:
http://www.icpower.com.cn/UploadFile/Soft/SD6900%20datasheet_1.4.pdf

This one seems to be a match !
What were your markings ?

[vuko]

Markings are: "e2eh 9l21". I have ended replacing it with SQ6211. It has similar pinout but with dimming input.