Help ID SMD part

Sep 21, 2015 5 Replies

Does anyone know what this part labelled ABG could be?



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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:



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


RoRo

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

Robert Roland schrieb:

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

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

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

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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