PSD4XX Datasheet, PDF (83/123 Pages) STMicroelectronics – Low Cost Field Programmable Microcontroller Peripherals

PSD4XX Family
Specifications
(cont.)
13.5 Example of ZPSD4XX Typical Power Calculation at V_CC = 5.0 V
Conditions
Composite PLD input frequency (Freq PLD)
MCU ALE frequency (Freq ALE)
= 8 MHz
= 4 MHz
% EPROM Access
% SRAM access
% I/O access
= 80%
= 15%
= 5% (no additional power above base)
Operational Modes
% Normal
= 10%
% Sleep
= 90%
Number of product terms used (from fitter report) = 29 PT
% of total product terms
= 29/118 = 24.6%
Turbo = off
CMiser = on
8-bit bus mode
Calculation (typical numbers used)
I_CC total = Isleep x %sleep + %normal x (I_CC (ac) + I_CC (dc))
= Isleep x %sleep + %normal x (%EPROM x 0.8 mA/MHz x Freq ALE
+ %SRAM x 1.4 mA/MHz x Freq ALE
+ %PLD x 2.5 mA/MHz x Freq PLD + #PT x 400 µA/PT)
= 10 µA x 0.90 + 0.1 x (0.8 x 0.8 mA/MHz x 4 MHz
+ 0.15 x 1.4 mA/MHz x 4 MHz + 0.95 x 2.5 x 8 + 29 x 0.4 mA/PT)
= 0.9 µA + 0.1 x (2.56 + 0.84 + 19 + 11.6 mA)
= 0.9 µA + 0.1 x 34
= 0.9 µA + 3.4 mA
= 3.4 mA
Notes: Standby current consumption is handled similarly to Sleep Mode shown above.
Calculation assumes I_OUT = 0 mA.
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