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Subject: Re: Use SLEEP instruction for longer (?) runtime
From: Bjrn Stenberg (bjorn_at_haxx.se)
Date: 2003-01-25


Andrew Jamieson wrote:
> No power save mode: 110mA
> CPU Sleep: 98mA
> CPU Stop: 95mA
> CPU Standby: 81mA

These numbers are strange. The drop from sleep to standby should be at least 40mA, according to the CPU docs:

Table 20.2 DC Characteristics (cont)

Item Symbol Min Typ Max Unit Test Conditions
---------------------------------------------------------------------------
Current Ordinary Icc -- 60 90 mA f = 12.5 MHz
consumption operation -- 80 110 mA f = 16.6 MHz

              Sleep -- 40 70 mA f = 12.5 MHz
                                   -- 50 60 mA f = 16.6 MHz

              Standby -- 0.01 5 A Ta < 50C
                                   -- -- 20.0 A 50C < Ta
---------------------------------------------------------------------------

Notes: 1. 50 A for the SH7032.
       2. 300 A for the SH7032.

How can standby mode only drop 14 mA?

> So, it seems having a more efficient scheduler to increase the time spent
> sleeping does not seem worthwhile, as the best we can get it only 3mA more
> than what we have at the moment (Simon's implementation).

I agree. Since measurements show this model actually does have a significant effect, I now approve of it.

-- 
Bjrn



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