Cypress CapSense CY8CMBR2044, Руководство по конструкции

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Low-Power Design Considerations
AN66308 - CY8CMBR2044 CapSense® Design Guide, Doc. No. 001-66308 Rev. *F 34
Response time, T
RES,
is the amount of time the CY8CMBR2044 takes to produce a valid signal on GPOx after CSx
senses a TOUCH state. The CY8CMBR2044 device has two different response times. The first is the time it takes to
respond when the device wakes up from low power mode:
Equation 6
Where:
T
R
= Scan Rate
And the second is the time it takes to respond to any subsequent TOUCH after it wakes up, 80 ms.
Scan Time (T
S
)
Approximate scan time can be calculated using:
Equation 7
Where:
K
CSX
= button sensitivity constant for CSx.
T
FW
= Firmware execution time, from Table 5-2 .
Table 5-1. Button Sensitivity Constant
C
P
(pF)
Button Sensitivity Constant
(K)
Button connected to Ground 0
5 pF ≤ C
P
≤ 10 pF
1
10 pF < C
P
≤ 22 pF
2
23 pF < C
P
≤ 40 pF
4
Table 5-2. Average Current Parameters
Parameter Typ Max
T
FW
1.50 ms 1.57 ms
I
SLEEP
1.07 µA 1.5 µA
T
S
From Equation 7 +5% from TYP value
T
R
Table 3-4
±10 from Value
I
ACTIVE
2.67 mA 3.8 mA