Eurotech Appliances VIPER / VIPER-LITE PXA255 - Manual (Page 79)

VIPER Technical Manual Power and power management
© 2007 Eurotech Ltd Issue E 79
Power estimate examples
Example 1: VIPER [Linux] asleep (microprocessor in sleep mode and every power saving option enabled)
In this case, the power consumed by the respective categories is:
• VIPER current (Linux default) = 334mA ±3mA.
• Power saving = 285mA (all power saving options enabled).
• External peripheral current = 0mA.
Therefore, the estimated VIPER current is:
334mA ±3mA - 285mA + 0mA
= 49mA ±3mA (245mW ±15mW).
Example 2: VIPER [Linux] at 200MHz in performance mode + LCD with backlight on
In this case, the power consumed by the respective categories is:
• VIPER current while idle = 334mA ±3mA - 7mA = 327mA ±3mA.
VIPER current while active = 334mA + 47mA ±20mA = 381mA ±20mA.
• Power saving = 0mA.
• External peripheral current = 650mA (LCD).
Therefore, the estimated VIPER current while idle (min) is:
327mA ±3mA + 650mA
= 977mA, ±3mA (4885mW, ±15mW).
and the estimated VIPER current while active (max) is:
381mA ±20mA + 650mA
= 1031mA, ±20mA (5155mW, ±100mW).