15 Aug
2010
15 Aug
'10
7:02 p.m.
On 15 Aug 2010 at 10:12, Glen Slick wrote:
One other thing that might help the situation is that
the 2147 enters
an automatic power-down mode when the CE# input is at a high level.
For example the datasheet for the CY2147-35 says the max operating
current is 125ma while the max standby current is 25ma.
Do MM5257 parts enter a standby mode when not selected? I don't have
a datasheet handy. Which would draw more current total, two banks of
MM5257 parts, or two banks of CY2147 parts where at least one of the
two banks should be in standby mode?
If the 5257 parts are like the TMS4044 parts, standy is entered by
reducing Vcc to 2.4V. Otherwise, maximum operating power dissipation
is given as 303 mW. I somehow doubt that the memory board in
question has the smarts to drop Vcc.
There also exist CMOS versions of the same chip--the Motorola
MCM146504, the Harris HM6504 or the Intersil IM6504 is one such, with
a standby power of 10mW. These are the same speed (450nsec) as the
TMS4044s. So more grist for your mill...
--Chuck