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Help ID SMD part

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  Help ID SMD part Robert Roland <fake@ddress.no> - 2015-09-21 21:37 +0200
    Re: Help ID SMD part legg <legg@nospam.magma.ca> - 2015-09-21 22:46 -0400
      Re: Help ID SMD part Robert Roland <fake@ddress.no> - 2015-09-25 23:08 +0200
        Re: Help ID SMD part legg <legg@nospam.magma.ca> - 2015-09-29 14:55 -0400
    Re: Help ID SMD part Tilmann Reh <usenet2007nospam@autometer.de> - 2015-09-22 08:21 +0200
    Re: Help ID SMD part legg <legg@nospam.magma.ca> - 2015-09-22 16:50 -0400

#5761 — Help ID SMD part

Does anyone know what this part labelled ABG could be?

http://s24.postimg.org/95ajdziid/Still001.gif

It seems to interface a micro to an open drain serial bus.

The pin connections:

1: CPU UART TX
2: GND
3: CPU UART RX
4: Open drain serial bus
5: VDD
6: CPU I/O pin

I'm guessing it's a dual transistor of some sort, but I have not been
able to find any reference to it. This is the closest I've come:

http://www.alibaba.com/product-detail/-Transistor-Surface-mount-Marking-code_1751116980.html

...but there is no data sheet or pinout.
-- 
RoRo

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#5762

On Mon, 21 Sep 2015 21:37:45 +0200, Robert Roland <fake@ddress.no>
wrote:

>Does anyone know what this part labelled ABG could be?
>
>http://s24.postimg.org/95ajdziid/Still001.gif
>
>It seems to interface a micro to an open drain serial bus.
>
>The pin connections:
>
>1: CPU UART TX
>2: GND
>3: CPU UART RX
>4: Open drain serial bus
>5: VDD
>6: CPU I/O pin
>
>I'm guessing it's a dual transistor of some sort, but I have not been
>able to find any reference to it. This is the closest I've come:
>
>http://www.alibaba.com/product-detail/-Transistor-Surface-mount-Marking-code_1751116980.html
>
>...but there is no data sheet or pinout.

The part they are advertizing on alibaba is MAX6411BS41-T, in a
4-terminal solder bump package (no leads) measuring 2x2mm. Not a six
pin part. I have no info on 6 pin parts with that marking.

The part you're looking for serves the function of a SPDT data switch.

Something like NC7SB3157 / FSA3157

RL

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#5766

On Mon, 21 Sep 2015 22:46:36 -0400, legg <legg@nospam.magma.ca> wrote:

>The part you're looking for serves the function of a SPDT data switch.

That seems to fit perfectly.

I have now hooked up a logic analyzer to see what's going on.

When the control pin is high, the bus data is visible on the CPU's Tx
pin and the Rx pin is quiet. When the control pin goes low, it's the
other way around.

When the CPU is ready to transmit on the bus, it switches to Rx mode
and listens for its address. When it detects its address, it switches
to Tx mode (disconnecting the Rx pin) before it starts transmitting.
That way, it avoids receiving its own data.

I don't actually need to ID the exact chip. As long as I know what it
does, I'm happy. I want to write new firmware for the microcontroller.

Thank you for the help.
-- 
RoRo

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#5781

On Fri, 25 Sep 2015 23:08:21 +0200, Robert Roland <fake@ddress.no>
wrote:

>On Mon, 21 Sep 2015 22:46:36 -0400, legg <legg@nospam.magma.ca> wrote:
>
>>The part you're looking for serves the function of a SPDT data switch.
>
>That seems to fit perfectly.
>
>I have now hooked up a logic analyzer to see what's going on.
>
>When the control pin is high, the bus data is visible on the CPU's Tx
>pin and the Rx pin is quiet. When the control pin goes low, it's the
>other way around.
>
>When the CPU is ready to transmit on the bus, it switches to Rx mode
>and listens for its address. When it detects its address, it switches
>to Tx mode (disconnecting the Rx pin) before it starts transmitting.
>That way, it avoids receiving its own data.
>
>I don't actually need to ID the exact chip. As long as I know what it
>does, I'm happy. I want to write new firmware for the microcontroller.
>
>Thank you for the help.

Don't get hung up by the 'data' part of the switch description - they
are mostly analog anyways, simply ensuring break before make with
graduating Ron and crosstalk for different application frequencies.

RL

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#5763

Robert Roland schrieb:

> Does anyone know what this part labelled ABG could be?
> http://s24.postimg.org/95ajdziid/Still001.gif
> It seems to interface a micro to an open drain serial bus.
> 
> The pin connections:
> 1: CPU UART TX
> 2: GND
> 3: CPU UART RX
> 4: Open drain serial bus
> 5: VDD
> 6: CPU I/O pin
> 
> I'm guessing it's a dual transistor of some sort, but I have not been
> able to find any reference to it. ...

I'd rather suspect it is a TVS array, something similar to Littlefuse
SRV05-4. However, I also don't know manufacturer or type for this marking.

Tilmann

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#5764

On Mon, 21 Sep 2015 21:37:45 +0200, Robert Roland <fake@ddress.no>
wrote:

>Does anyone know what this part labelled ABG could be?
>
>http://s24.postimg.org/95ajdziid/Still001.gif
>
>It seems to interface a micro to an open drain serial bus.
>
>The pin connections:
>
>1: CPU UART TX
>2: GND
>3: CPU UART RX
>4: Open drain serial bus
>5: VDD
>6: CPU I/O pin
>
>I'm guessing it's a dual transistor of some sort, but I have not been
>able to find any reference to it. This is the closest I've come:
>
>http://www.alibaba.com/product-detail/-Transistor-Surface-mount-Marking-code_1751116980.html
>
>...but there is no data sheet or pinout.

The only SPDT analog switch in the Digi-Key website inventory, with
SOT23-6 type body size (reduces to about 200 line items) and a marking
code that could produce 'ABG'  is AOZ6135HI. 

Its marking code is 'Axy', where x is a datecode and y is a lot
designator. 

The body size is SC70-6 which is smaller than SOT23-6;
2mm breadth vs 3mm breadth
.65mm pin pitch vs .95mm.
footprint tip to tip 2.1mm  vs 2.8mm.

RL

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