Hi,

The CD4053B has only 3 identical bilateral analog spdt switches on it. Does anyone know of any chip that has more so I don't have to buy too many of these?

Thanks.

 

hi keii.
Check this link for options.
E
https://uk.farnell.com/c/semiconduc...iplexers/analogue-multiplexers-demultiplexers

 

hi keii.
Check this link for options.
E
https://uk.farnell.com/c/semiconduc...iplexers/analogue-multiplexers-demultiplexers

Thanks, Eric , I started checking the list.

 

The CD4053B has only 3 identical bilateral analog spdt switches on it. Does anyone know of any chip that has more so I don't have to buy too many of these?

What exactly are you switching?

 

What exactly are you switching?

Hi, Sorry for the late reply I am switching a battery backed up ram circuit's address and data bus and CE OE and WE pins between an external programmer and a microprocessor circuit.

Thx.

 

battery backed up ram circuit's address and data bus and CE OE and WE pins

Instead of switches, how about 3 state buffers?
74HC245 octal bus tranceiver; 3 state (for data bus, bi-directioinal)
74HC244 octal buffer/line drivers; 3 state (addresses)
and use your cd4053 (or equiv) for CE OE and WE which might need more care
during switching accesses between ports.

PS: You might have to keep all buffers powered and 3 state the unused ones outputs.

PS2: I seem to remember some similar octal bus chips with better pinouts, ie: the
inputs were all on one side unlike the 74HC244. Look for them, likely higher chip numbers, they came later.
(like 74HC540 but is inverting, or just use 74HC245 for them all?)

 

Address and Data and Control switching shouldn't require analog switches. Digital gates and/or muxes should work.

 

yup.... analog switches are meant for analog signals. digital signals have much faster rise and fall time and levels that are close to supply. what would CE OE and WE interpret something that is not in expected range?

 

analog switches are meant for analog signals.

They can be used for both since they are simply two transmission-gate MOSFETs in parallel when ON that can carry both types of signals.
The usually minor effect they have on the signal would be due to their small parasitic capacitances and low series resistance.

 

Hi, Sorry for the late reply I am switching a battery backed up ram circuit's address and data bus and CE OE and WE pins between an external programmer and a microprocessor circuit.

I don't know your circuit, but likely if you hold the micro in reset mode all the buss pins will go tristate. That way your external programmer can drive directly. You must try it and see, or read the data sheet.

 

I don't know your circuit, but likely if you hold the micro in reset mode all the buss pins will go tristate. That way your external programmer can drive directly. You must try it and see, or read the data sheet.

I will try something similar. its the 8085 mpu. Doing a HOLD will put the bus pins in tri-state.

 

yup.... analog switches are meant for analog signals. digital signals have much faster rise and fall time and levels that are close to supply. what would CE OE and WE interpret something that is not in expected range?

thanks, all, appreciated.