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I've been trying to reverse-engineer this circuit but I'm an ME, so my knowledge of electronics is limited to pretty much Arduinos.

I have a simple circuit and I'm trying to identify one of the components.

The component is a small IC, DFN-6 (3x3) package size, and is wired as shown in the drawn schematic. The part number that I can make out I think is 26T6 TIW 957M.

The circuit is on a lithium BMS board and is used for the initial handshake when connecting a tool to the battery.

The circuit is separate from the rest of the BMS as I've isolated the components.

With the circuit isolated, applying a 1 kHz positive square wave produces the signal shown in the below oscilloscope screen capture.

What I've concluded is that it's some sort of fixed/pre-programmed oscillator, but the input is the same as the output...?

(Click on an image for a larger version)

Traced schematic

Figure 1: Traced schematic

Oscilloscope capture

Figure 2: Oscilloscope capture

Top marking on unknown device

Figure 3: Top marking on unknown device

PCB showing unknown device

Figure 4: PCB showing unknown device

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It is probably a 1-wire temperature sensor and unique ID something like this although the package is different:

1-Wire® Temperature Sensor:

Battery charging is critically dependent on measuring the battery temperature enter image description here

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  • \$\begingroup\$ There's a separate circuit and pin for an NTC thermistor that's embedded directly against the lithium cells. This chip is placed far any current path or other components that I think would need temp monitoring. \$\endgroup\$ Commented Mar 14, 2021 at 21:05
  • \$\begingroup\$ @ericthepoolboy It's definitely a 1-wire something. Maybe some kind of ID chip, to say that it's a genuine battery pack for whatever tool it's used with--unfortunately a fairly common practice. \$\endgroup\$
    – Hearth
    Commented Mar 14, 2021 at 22:21

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