Re: How to properly use a 74259 (addressable latch)

From: Jim Thompson (thegreatone_at_example.com)
Date: 01/26/05 

Date: Wed, 26 Jan 2005 09:01:09 -0700

On Wed, 26 Jan 2005 10:57:16 -0500, "Tam/WB2TT"
<t-tammaru@c0mca$t.net> wrote:

>
>"sryth" <sryth@yahoo.com> wrote in message
>news:1106707934.008771.32480@c13g2000cwb.googlegroups.com...
>>I am thinking of connecting a 74259 (8-bit addressable latch) to a
>> USBMOD4 device to ultimately control 8 mosfets. The data sheet for the
>> latch said that you should hold pin G high while changing address lines
>> to avoid mangling your stored values, and I'm trying to come up with an
>> elegant solution.
>>
>> My device sets all 8 data lines "simultaneously"; I need to ensure that
>> the line connected to the enable doesn't drop until the address/data
>> lines are set up.
>>
>> I was thinking of a simple RC circuit sent into an schmitt inverter to
>> delay the dropping of G for ~100ms...would this work reliably? Are
>> there better ways of doing this?
>>
>
>This used to be one of my favorite parts. I always made WR* or DS* as part
>of the Chip Select. You just have to be sure you end up with enough Address
>and Data hold time.
>
>Tam
>

Why is there a sudden rash of using TTL parts? 74HC259 is a far
superior part for glitch-free operation.

                                        ...Jim Thompson 

-- 
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

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