STM8T141 STMicroelectronics, STM8T141 Datasheet - Page 25

• Manufacturer Part Number: STM8T141
• Description: Single-channel capacitive sensor for touch or proximity detection with shielded sensing electrode
• Manufacturer: STMicroelectronics

STM8T141
7.4.4
7.5
7.6
Extreme Low Power mode
With the STM8T141 in Extreme Low Power mode, burst cycles only occur every 17th
t
t
This reduces the amount of burst cycles in Extreme Low Power mode even more than Low
Power mode which in turn saves even more power but comes at the expense of a higher
system response time
Figure 19. Charge cycle timing diagram in Extreme Low Power mode
Charge transfer frequency
The STM8T141 offers two charge transfer frequencies. The charge transfer frequency must
be adjusted depending on the C
raised to 250 kHz in order to reduce t
●
●
Bit 1 of option byte OPT1 is used to select the correct charge transfer frequency.
Sampling period
The default sampling period (t
compromises between power consumption and conversion rates:
●
●
When using a faster sampling rate (t
modes will occur at twice the speed.
BIt 2 of option byte OPT1 is used to select the correct conversion period.
SAMPLING
SAMPLING
C
S
1
125 kHz
250 kHz
20-ms sampling rate to reduce average power consumption
10-ms sampling rate to increase detection response time
2
period (or 5.88% of the Normal Power mode), thus adding 16 extra delays of
between charge cycles to conserve power.
3
4
5
(Figure
6
Burst cycle every 17th t
7
SAMPLING
Doc ID 15699 Rev 7
19).
S
8
capacitor. The charge transfer frequency may need to be
t
SAMPLING
LP
9
BURST
) is configurable in order to allow different
10
SAMPLING
when the C
11
= 10 ms), all the timing values of the Power
12
period
13
S
capacitance is large.
14
15
16
17
Device operation
18
19
20
25/50
t