psd311-b-90ui STMicroelectronics, psd311-b-90ui Datasheet - Page 37

• Manufacturer Part Number: psd311-b-90ui
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

34
PSD3XX Family
17.
Calculating
Power
Once you have read the “Power Management” section, you should be able to calculate
power. The following is a sample power calculation:
NOTES: 1. Calculation is based on the assumption that I
Conditions
Part Used
MCU ALE Clock Frequency
Composite ZPLD Input Frequency
% EPROM Access
% SRAM Access
% I/O access
%Time CSI is high (standby mode)
%Time CSI is low (normal operation mode)
# Product terms used (see previous section) = 13 (13/40 = 33%)
Turbo bit
CMiser bit
MCU Bus Configuration
Calculation (Based on Typical AC and DC Currents)
I
CC
total = Istandby x % time CSI is high +
2. I
3. 13 product terms: 8 for EPROM, 3 for Chip Selects, 1 for SRAM, 1 for CSIOPORT.
4. The 5% I/O access in the conditions section is when the MCU accesses CSIOPORT space.
5. Standby Mode can also be achieved without using the CSI pin. The ZPSD device will automatically
go into Standby while no inputs are changing on any pin, and Turbo Mode is disabled.
CC
= Istandby x % time CSI is high +
= 10 µA x 0.9 + (0.8 x 0.8 mA/MHz x 2 MHz + 0.15 x 1.4 mA/MHz x 2 MHz
= 9.0 µA + (1.28 mA + 0.42 mA + 5.0 mA) x 0.1
= 679 µA, based on the system operating in standby 90% of the time
(DC) is zero for all ZPSD devices operating in non-turbo mode.
+ 5.0 mA) x 0.1
[% EPROM Access x 0.8 mA/MHz x Freq. of ALE
+ % SRAM x 1.4 mA/MHz x Freq of ALE
+ ZPLD AC current (Figure 14: 13 PTs, 8 MHz, Non-Turbo)
x % time CSI is low
[
OUT
I
CC
= ZPSD3XX (V
= 2.0 MHz
= 8.0 MHz (see example in above section)
= 80%
= 15%
= 5%
= 90%
= 10%
= OFF (Turbo Mode disabled)
= ON
= 8-bit multiplexed bus mode
= 0 mA (no I/O pin loading)
(AC) + I
CC
(DC)
CC
]
= 5.0 V)
x % time CSI is low.
]