Maxim MAX1636 Low Voltage Step-down controller

 Package

MAX1636 Package

MAX1636 is a synchronous buck switch mode power supply controller for laptop CPU’s. Taken from a Apple Clamshell iBook from 2000. Packaged in a 20 pin DIP with 2000 week 35 date code.

 

 

Die Photo

Die size is 3.5 mm x 2.2 mm (7.7mm2)                               MAX1636 Die Photoclick on image for larger version

Die Marks

 

As well as a fairly large area for the die markings (And mask layer numbering.)  Die code PW80Y that bears no relation to MAX1636.

 

 

 

 

In addition the die has a rather unusual marking. On the wide die seal (Conventionally tied to ground electrically)  in one section the M1-M2 vias have been used to write CAEEFODS with a mirror image.  Probably only 1 or 2 people have any idea what this was for 😉CAEEFODS die marks

Process

Fabricated with a double (Aluminum) metal Bipolar process.  The minimum feature size or critical dimension (CD) is ~1.5μm.  This image shows some conventional NPN Bipolar transistorsNPN Bipolar

And elsewhere on the die are more unusual layout transistors  with I guess greater current capability (Which scales with the emitter area).  

Also on the die are lots of diffusion resistorsDiffusion Resistors with NPNs

and the odd capacitorCapacitors

Datasheet and Pin Out

There is a datasheet for the part.  Switch Mode controllers are fairly complex circuits as can be seen from the block diagram in the datasheet.MAX1636 Block DiagramI’m not able to recognize any of the blocks but here is the pin out of the dieMAX1636 pin out

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2 Responses to Maxim MAX1636 Low Voltage Step-down controller

  1. Jeremy says:

    Not much to say other than thanks for continuing to post neat die photos!

    Do you know much about the protection diodes or other such interfacing features (obviously driver transistors are larger, maybe other visually apparent features?)

    • Gary says:

      I don’t really know much about the ESD protection diodes. I know they evolved from simple reverse-connected diodes to quite sophisticated voltage clamp circuits. It looks like every company seems to do them differently. I have decapped enough parts now to see a variety of layouts, perhaps I should take a closer look at some of them.

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