C8051F960-B-GM Datasheet, PDF (315/492 Pages) Silicon Laboratories – Ultra Low Power 128K, LCD MCU Family

C8051F96x
25.3. Programmable Pull-Up Resistors
The Pulse Counter features low-power pull-up resistors with a programmable resistance and duty-cycle.
The average pull-up current will depend on the selected resistor, sample rate, and pull-up duty-cycle multi-
plier. Example code is available that will calculate the values for the Pull-Up configuration SFR (PC0PCF).
Table 25.1through Table 25.3 are used with Equation 25.1 to calculate the average pull-up resistor current.
Table 25.4through Table 25.7 give the average current for all combinations.
Ipull-up = IR  DSR  DPU
Equation 25.1. Average Pull-Up Current
Where:
I_R = Pull-up Resistor current selected by PC0PCF[4:2].
D_SR = Sample Rate Duty Cycle Multiplier selected by PC0MD[5:4].
D_PU = Pull-Up Duty Cycle Multiplier selected by PC0PCF[4:2].
Table 25.1. Pull-Up Resistor Current
PC0PCF[4:2]
000
001
010
011
100
101
110
111
I_R
0
1 A
4 A
16 A
64 A
256 A
1 mA
4 mA
Table 25.2. Sample Rate Duty-Cycle Multiplier
PC0MD[5:4]
D_SR
000
1
001
1/2
010
1/4
011
1/8
Table 25.3. Pull-Up Duty-Cycle Multiplier
PC0PCF[4:2]
D_PU
000
1/4
001
3/8
010
1/2
011
3/4
Rev. 1.0
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