Table of Contents

Description

This part was taken from a Motronic M1.7.3 engine control unit (ECU), which was commonly used on 1.6L & 1.8L 4-cylinder BMWs of the mid-E36 generation. While this chip was likely used on a number of ECUs, the specific one in this case had Bosch PN 0 261 203 661.

This chip is known, with certainty, to be a TI TLC272C dual opamp, thanks to the clear markings on the die. The package was partially customized by Bosch to obfuscate this. Functionally, one of the opamp circuits is used as a unity gain buffer for an analog output from b30098, which is switched by b57803 before being fed to this chip. The other opamp circuit is unused.

The interesting thing about this chip is that TI sold it as a die, and the datasheet actually provides relatively detailed information about what is what on the die. This chip RE effort could possibly provide a useful basic tutorial for recognizing certain circuit elements, at least on really old devices.

Datasheet: http://www.ti.com/lit/ds/symlink/tlc272a.pdf

Package

Label (top):

B57820 (Bosch internal PN)
[TI Logo] 62T
AXYV

Die

Decap Steps:
(Bic lighter + water quench) x 2 cycles
Selective crushing with pliers and bench vise

Capture Details:
Imaging device: Keyence VHX-2000
Magnification: 500X

Markings:
LT 705D

Imaged using normal / center lighting:

Imaged using edge lighting, for enhanced shadow contrast:

 
felinefriendly/bosch/b57820.txt · Last modified: 2018/07/27 15:36 by e30tuner
 
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