AP08056
Power Saving Features
Stopping the Clocks of Individual System Components
Application Note
16
V1.0, 2006-12
5
Stopping the Clocks of Individual System
Components (Peripheral Management)
Peripherals which are not required for a particular functionality can be disabled by
programming the assigned register bits in PMCON1 and PMCON2 which would gate off
clock inputs. This would further reduce overall power consumption of the device.
shows the amount of current that can be saved when
each/all of the peripheral module(s) are disabled by a XC866-1FR, XC866-4FR and a
XC886 device at different peripheral clock frequency (f
PCLK
). It can be observed that
when the peripheral clock is reduced, the power consumed by the peripherals will also
reduce, which means that less current can be saved.
Software example to disable all peripherals on a XC886/888 device:
SCU_PAGE = 0x01;
//Open SCU page 1 to access PMCON1
PMCON1 |= 0x7F;
//Disable ADC, CCU, SSC, T2, MDU, CAN and
//CORDIC
SCU_PAGE = 0x03;
//Open SCU page 3 to access PMCON2
PMCON2 |= 0x03;
//Disable T21 and UART1
For XC866, only ADC, CCU, SSC and T2 can be disabled by setting the corresponding
bits in PMCON1.
Table 8
Current consumption by the peripherals of a XC866-1FR device at
different peripheral clock (PCLK) frequencies
Current (mA)
Peripheral Frequency
(MHz)
26.800
6.700
0.838
0.209
0.013
CLKREL
0000
B
0010
B
0101
B
0111
B
1011
B
ADC
0.80
0.20
0.03
0.01
0
1)
1) < 10 µA
CCU
1.45
0.36
0.05
0.02
0
SSC
0.51
0.12
0.02
0.01
0
T2
0.16
0.04
0.01
0
0
All
2.95
0.73
0.10
0.03
0
