In article <do6dnR8ku-e_faDanZ2dnUVZ_jydnZ2d@giganews.com>, 
akagan@emphatec.com says...
> 
> >>   What is a good way to control the power to a memory module.  One of
> >> the memory modules (4MB FIFO) that I intend to use consumes 14mA in
> >> standby mode, which is one order of magnitude of what I want.  Is
> >> there a way to turn off power to components and use something in the
> >> order of uA instead of mA when not in use?
> 
> >
> It is possible to control by using a transistor in the ground line or in
> the supply line. 
> 
> But there are more considerations. What you have to be careful of is what
> the other inputs to the memory are doing. I know from experience (many
> years ago, so technology may have changed a bit) that if you switch the
> supply side, each input acts as if it is shorted to the ground pin (or are
> connected via an internal diode), so it will load every signal that is on
> the device. You need to be able to set these signals to a logic low (in
> this case, perhaps a logic high if you are switching the ground) and keep
> them there while the memory is powered down. If you need the control
> signals for other devices while the memory is powered down, you will need
> a way to separate the control signal. 30 years ago, I used the CMOS
> CD4050, powered from the same supply as the memory. Its inputs are
> floating gates and will tolerate signals beyond the supply rails. Today I
> suppose you could use a voltage level translator.
> 
> Actually continuing with the idea, you also need to investigate what the
> outputs of the memory are going to do in power down- they could also end
> up  loading any signal they are connected to. If memory serves i was using
> an open collector data bus on the memory. 
> 
In one case where I wanted to disconnect and power down  a component, I 
simply interposed tristate buffers between the device and the MPU
bus.  You have to do this on both the inputs and outputs of the device.

There are also bidirectional bus switch packages that might be easier
to implement.

Mark Borgerson

>>   What is a good way to control the power to a memory module.  One of
>> the memory modules (4MB FIFO) that I intend to use consumes 14mA in
>> standby mode, which is one order of magnitude of what I want.  Is
>> there a way to turn off power to components and use something in the
>> order of uA instead of mA when not in use?

>
It is possible to control by using a transistor in the ground line or in
the supply line. 

But there are more considerations. What you have to be careful of is what
the other inputs to the memory are doing. I know from experience (many
years ago, so technology may have changed a bit) that if you switch the
supply side, each input acts as if it is shorted to the ground pin (or are
connected via an internal diode), so it will load every signal that is on
the device. You need to be able to set these signals to a logic low (in
this case, perhaps a logic high if you are switching the ground) and keep
them there while the memory is powered down. If you need the control
signals for other devices while the memory is powered down, you will need
a way to separate the control signal. 30 years ago, I used the CMOS
CD4050, powered from the same supply as the memory. Its inputs are
floating gates and will tolerate signals beyond the supply rails. Today I
suppose you could use a voltage level translator.

Actually continuing with the idea, you also need to investigate what the
outputs of the memory are going to do in power down- they could also end
up  loading any signal they are connected to. If memory serves i was using
an open collector data bus on the memory. 

-Aubrey

On Sep 19, 9:08 pm, amerdsp <amer...@hotmail.com> wrote:
> Greetings,
>   What is a good way to control the power to a memory module.  One of
> the memory modules (4MB FIFO) that I intend to use consumes 14mA in
> standby mode, which is one order of magnitude of what I want.  Is
> there a way to turn off power to components and use something in the
> order of uA instead of mA when not in use?
>

Were you able to do that ? Can you tell me the method / link for
this ?

Karthik Balaguru

"amerdsp" <amerdsp@hotmail.com> wrote in message 
news:1190218099.995351.172160@y42g2000hsy.googlegroups.com...
> Greetings,
>  What is a good way to control the power to a memory module.  One of
> the memory modules (4MB FIFO) that I intend to use consumes 14mA in
> standby mode, which is one order of magnitude of what I want.  Is
> there a way to turn off power to components and use something in the
> order of uA instead of mA when not in use?
>
> Thanks,
>
> A
>
If there is no STBY pin ( I assume there isn't) a mosfet in the ground line 
will do it.... 

Greetings,
  What is a good way to control the power to a memory module.  One of
the memory modules (4MB FIFO) that I intend to use consumes 14mA in
standby mode, which is one order of magnitude of what I want.  Is
there a way to turn off power to components and use something in the
order of uA instead of mA when not in use?

Thanks,

A