im looking for an 8 bit push on, push off latch dip ic

7

777xxx

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do they exist? i need it so that you press a button and it latches electronically, not psychically. and when you press it again it unlatches. i know that latch ic's exist btw
 
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Not really..

You can make a single button, alternate action toggle with a "D Type" bistable, a couple of resistors and a cap.

You can only get two D types (with independent clock inputs, which are required) in each IC, as far as I am aware. eg. 7474, 74HC74 etc.

Other than that, it could be made using a microcontroller, with that doing the switch debounce and toggle in software. eg. a PIC16F18446 would probably be suitable, a 20 pin device.
It should even be possible to arrange eight inputs on one side and eight outputs on the other.
 
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Google "8 bit latch cmos", lots of hits.

When unlatched outputs follow inputs ? Or just present last data
when latch edge occured ?

Here is a latch/hold solution, 1 chip -



Regards, Dana.
 
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Your question is missing a LOT of information. For example, are there 8 switches, one for each bit, or one switcn controlling an 8-bit latch?

Operating voltage?

Source of whatever is being latched?

What is the latch output driving?

ak
 
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Here is a fall thru octal latch, one button push data is latched, next push
data flows thru latch, rinse and repeat.




Lots of chip resources left for other uses.....


Regards, Dana.
 
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AnalogKid said:
Your question is missing a LOT of information. For example, are there 8 switches, one for each bit, or one switcn controlling an 8-bit latch?

Operating voltage?

Source of whatever is being latched?

What is the latch output driving?

ak
Click to expand...
one for each latch. 3.3v. push buttons are the source. its driving led's
 
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Updated per comments in post #6, no code solution, one chip.



Basically button pressed, debounced, and it toggles the T F-F to turn on or off the
LED.


Regards, Dana.
 
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Papabravo said:
In the sense that a 555 configured as a bistable has one pin to set the flip-flop and a different pin to clear the flip-flop.
Click to expand...
There is a very common 555 circuit that acts as a toggle flipflop with a simple SPST switch.

To the OP: So now it sounds like there are eight SPST momentary pushbutton switches, each one controlling a toggle flipflop, and each flipflop output drives one LED. Eight fully independent circuits, no common reset or anything else.

yes / no ?

If that is correct, then yes, eight 555 circuits can do this.

Or eight 2-transistor flipflops.

Or four CD4093 quad NAND gates, with each pair of gates configured as a toggle flipflop.

Or four CD4013 dual flipflops, with each one configured as a toggle flipflop.

Here is the 555 circuit.

ak

 
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yes
 
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The boards that will do all 8 channels in post #10 (you only need 1 board to do the 8 channels) :

CY8CKIT-059



CY8CKIT-043

Shop them, I see the 059 board as low as ~ $16, which is a much more capable target chip.
Note the boards have two PSOC chips on them, one the target, the other for debug/programming.
You snap off programmer when done with design. Note it can be used as another stand alone
design, but indepth debug facility no longer present so one debugs writing to ports. Also
it has very limited I/O, but still quite usable for some designs.

The design in post #10 you write no code, although you do a build and then hit program button
as tool generates setup code for the target PSOC. Normally one does write code but many designs
can be done codeless due to their simplicity, as this design is.

The resources in the target chip, multiples in many cases, that you can also use are :




What LED current do you need ?


Regards, Dana.
 
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ZipZapOuch said:
Use a 74ACT825 or other 8-bit D-type flip-flop
Click to expand...
Nope. He wants 8 independent debounced clock pulses, one from each switch, to 8 independent toggle flipflops.

A personal frustration of mine going back to the 60's is that there is no standard TTL or CMOS quad D flipflop. There are quad S-R flipflops, but no quad D's.

It would fit in one 14-pin package. Each circuit would have a D input, a CLK input, and a -Q output. It is the four independent clocks that would make this part an absolute all-star. A 16 pin package would let you have a master reset plus one more control pin. This could be either an output enable, or, for super-extra-special functionality, an output polarity select. With that, the part could be an inverting latch, a non-inverting latch, or configurable as four toggle ff's. Granted, it would have been much more complex than the typical TTL part back then, but waaaaay better that that stupid 7475.

Something even more useful, but way beyond conventional thinking back then, would be six pre-wired toggle flipflops in one 16-pin package, again with a a master clear and OE. There were hex latches and bus drivers, so . . .

These days you could program a PIC or whatever to do the equivalent functions is firmware, but it would be relatively expensive for a simple logic function.

Grrrrrr

ak
 
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3.3v
 
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