Для 48:
Low Power Consumption
– Active Mode:
1 MHz, 1.8V: 240μA
32 kHz, 1.8V: 15μA (including Oscillator)
– Power-down Mode:
0.1μA at 1.8V

Для 48Р:
Low Power Consumption at 1 MHz, 1.8V, 25⋅C for ATmega48PA/88PA:
– Active Mode: 0.2 mA
– Power-down Mode: 0.1 μA
– Power-save Mode: 0.75 μA (Including 32 kHz RTC)

Ну и где чудо?..