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Replacement for Fluke 700013 IC (quad SPST analog switch)

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Kleinstein:
The latch function is a kind of memory function. A 74HC75 could probably do the job. For U403/402, they seem to no use the extra logic AND function. So one could for these positions get away without that extra functions.

A hef4066 would make like more difficult with the logic levels. The 74HC4316 (suggested by EDavid)  and similar would make things easier. For higher supply it might take DG201B or similar.

softfoot:
Hi, I'm yet another Fluke user looking for a solution ...

Did you make any progress on a replacement for the 700013 ??

If you did I'd love to see what you did.

BTW is the 700013 normally open (ie if an input is LOW is the switch OPEN) ??? 
If that is the case then the DG212B (normally open) would be best because the DH211B is normally closed.

Best regards,
Dave

Kjo:
The 700013 and it’s variants are very special devices. First, they are evidently unobtanium.
The latching function reduces the number of signals required from the ADC chip and in-guard uprocessor. Some 700013 switches are used in rather static applications, such as the precision current source. Others are VERY dynamic, such as the DC scaling circuit.
It would be informative in we knew prop delay for digital to analog. It would also be good to know the on and off capacitance presented by analog switch nodes.
The bus between the DC scaling and Sample-hold amp is a very sensitive node. It has like 5 switch nodes in common.
Anyone with a 700013 to spare for testing I would be appreciative.
PM me if so.
I have actually build several prototype 700013 with no success.

g0rsq:
Hi

I am now at the same position as others here, and looking for a solution to the 700013 issue.

I have just made a replacement LCD using a GLCD, only to find one faulty 700013  :-[

Is anyone willing to share their work so far, before I sart looking into building a 700013, as I dont want to go down a blind alley if someone else has already been there!

In the next few days I will be testing the bad 700013 in case it is just one switch that has died (301C).

Then I will put a logic alayser on my good 8840A and work out the timing issues through the chip. I dont want to remove any good 700013's to test though.

Peter

richipedia:
Oh well... 1 year and 9 months since I started my yet unfinished project. Still, glad to see that there are people interested in seeing how far I've come.

The 8842A's manual clearly shows the internal functional blocks of the 700013 IC's:


The logic part consists of 4 2-input AND gates, each having one input connected to a latch and the other input connected to the 8842's electronics either directly or through an inverter.
Mimicking that part using standard logic gates should be easy.

The 700013 is supplied using 3 different voltages:

* Pin 6: This is connected to +5V for all 5 700013 ICs. Seems to be digital supply VDD.
* Pin 10: GND
* Pin 20: +7.5 V for U301, U302, U303 (DC scaling, sampling etc); +15 V for U402 and U403 (precision current source). Seems to be the positive supply voltage V+ for the analog switch.
* Pin 11: -5V for U301, U302; -8.2 V for U303, GND for U402 and U403. Negative supply voltage V- for the analog part, obviously.
For the analog switch, I figured I could use a DG411. Supply voltage is +5V ... +20V for V+ and -5V ... -20V for V-. (Probably made a mistake here, because U402 and U403 use V- = GND, but more on that later.) I do not remember more on why I chose this one, nor do I have a note.
I ruled out the 4066 analog switch. If I remember correctly, the supply voltage requirements did not match at all.

Be aware that the DG411 is active-low (enabled using a low input signal), contradictory to how the 700013's internals are presented in the manual.

For the digital part, I figured I use mostly 74AC logic devices.
With the DG411 having active-low inputs, the AND is replaced with a NAND 74HC00.
For the latch, I chose a 74AC175D. To ensure all analog switches are turned off when the unit is powered on, a little reset circuit is provided.
For the inverter, TI offers the 74LVC2G14 in a handy SOT23-6 package, which is 5V tolerant, so I chose this one.

And there's the schematic:
 Fluke-700013-Replacement_Iteration02-Schematic.pdf (33.77 kB - downloaded 320 times.)

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