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Replacement for Fluke 700013 IC (quad SPST analog switch)
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Noopy:


The second dead 700013 was a U302.






Big areas of the die are destroyed but here most of the destruction is located in the control part of the 700013.




Besides some other destruction in the control circuit of the switches A and B the two 5V supply lines are interrupted.




In the control circuit of the switches C and D there is global damage too.








There are interesting dendrites!


https://www.richis-lab.de/aswitch03.htm

 :-/O
Kleinstein:
The prime suspects for the damage is a latch up. So substrate currents current triggering a parasitic SCR to short the supply. AFAIK the CMOS switches are in principle susceptible to this kind of failure. Newer chips improved on this, making it harder to trigger.

The "dendrites" look indeed strange. This too could be a process leading to failure. It could be still something (like a fungus) growing an top of the chip, with little effect on the function.
Noopy:
My first assumption was latch-up too but as a result of a latch-up I would have expected a major damage at one point and the rest looking "good" not this all over the die mess.
Noopy:


I wasn´t sure about posting the ADG441 here too. But since the topic is about analog switch replacement I think it makes sense.
After looking into the ADG444 (https://www.richis-lab.de/aswitch02.htm) I was interested in the ADG441 with it´s integrated logic supply.




The ADG444 appeared to having the logic supply integrated too but doesn´t use it. "Unfortunately" I wasn´t able to confirm that the ADG444 and the ADG441 are the same because here we have a new design!
The ADG441 die is a little smaller than the ADG444 die, 2,1mm x 1,3mm.




ADG444 was a 1993 design. ADG441 is a 2004 design.




And now I think I can tell you more about these numbers.
BV is probably Beaverton. Analog does some development there.
A94 seems to be this analog switch project. In the ADG444 the name was followed by a 2, perhaps a variant.
The last letter is a C. In the ADG444 it was a B. That is probably the revision.




The analog switches are in the four corners (red). Above and under these switches there are the control circuits (blue). In the middle of the die there seems to be the voltage regulator for the logic supply (white). At the lower edge there are two big structures probably for overvoltage protection (yellow).








Between the potentials to be connected there is a p-MOS transistor pair (blue) and an n-MOS transistor pair (red). The larger transistor is probably the p-MOSFET since these usually have slightly worse characteristics. The bond pads are connected to electrodes that are alternately passed over the transistors where they contact the drain and source of both transistor pairs.
At the bondpads of the analog switches there are obviously protection structures (white). The area in the lower left corner (green) seems to be necessary for controlling the transistors. At the bottom there is a relatively large transistor. Probably this one connects the bulk potential of the n-MOS transistor with the negative supply like in the ADG444. This reduces the leakage current when the device is switched off.


https://www.richis-lab.de/aswitch04.htm

 :-/O
Noopy:


Nobody complained about me posting analog switches here so I will go on with it.  ;D
RCA CD74HCT4067, a 16 channel analog switch for 0-5V. It´s bidirectional therefore a multiplexer/demultiplexer.




The die is 2,7mm x 2,3mm.




I found no RCA datasheet but you can see the internals in a Texas Instruments Datasheet.
Interesting point: The inverter/AND combination slows down the switch on while the switch off is faster. That´s important so you have never two active switches in parallel.




You can find every part of the schematic on the die. On the right side there are the input circuits for the channel selection and enable (red/yellow). In the middle of the die a circuit generates 16 signals for the channel selection (blue). Around this circuit you can see 16 driver circuits for the analog switches (purple). At the edges of the die there are the 16 analog switches (green).
The Vcc supply is connected to the outer frame and quite massive to the analog switches. The analog bus is quite wide too.




I3706B or 13706B, probably an internal naming.




Input protection: A current limit resistor (green) and two clamping diodes (red/blue).




Enable input circuit, you can see the push-pull output stage in the lower area.




The input circuits for the channel selection are placed in parallel each putting out a differential signal.




Making 16 signals out of the 4Bit channel selection.




The analog switch driver is a little confusing...






The analog switch is interesting. We have a NMOS and a PMOS (blue/red). The PMOS is quite large.
Each transistor has two frame structures. The outer frame is permanently connected to Vcc and isolates the switch (cyan). Around the PMOS the inner frame is permanently connected to Vcc too. That´s probably the bulk potential. Around the NMOS the bulk potential is switchable (green).
As will be shown in a moment in the off state the driver circuit connects the bulk of the NMOS to GND. That guarantees a high isolation resistance. The two analog switch transistors each have a small section that connects the bulk potential of the NMOS to the input potential when switched on (green). The higher potential provides a lower resistance. This explains the much smaller area of the NMOS transistor. In the case of an analog switch matching PMOS and NMOS is particularly important so the resistance doesn´t vary too much over the input voltage range.




Back to the driver circuit we can find the driver for the PMOS (red) and the much smaller driver of the NMOS (blue).
There are two transistors in series connecting the NMOS bulk with GND (green). One transistor is controlled by the input signal, one is controlled by the PMOS gate signal. That´s probably for switching time optimization.


https://www.richis-lab.de/aswitch05.htm

 :-/O
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