SX8652ICSTRT Semtech, SX8652ICSTRT Datasheet - Page 26

• Manufacturer Part Number: SX8652ICSTRT
• Description: 4/5-wire Resistive Touch Screen Controller (SPI)
• Manufacturer: Semtech

10.6.2. Conversion Time
The maximum possible throughput can be estimated with the following equation
with:
Table 16 gives some examples of Coordinate Rate and Sample Rate for various setting in PENTRIG mode.
10.7. ESD event
In case of ESD event, the chip may reset to protect its internal circuitry. The bit RSTEVENT indicates that a reset event has
occurs.
ESD event may trig the pen detection circuitry. In this case wrong data will be send to the host. To detect this false
coordinates on 4-wire touchscreen, Z1 and Z2 can be read. The conditions Z1<LowThreshold and Z2>HighThreshold
indicate an ESD event. The values LowThreshold and HighThreshold are given for indication only on the table below and
should be fine tune according to the system.
Revision V1.7/October 2010
©2010 Semtech Corp.
ADVANCED COMMUNICATIONS & SENSING
N
N
POWDLY = 0.5us to 18.19ms, settling time as defined in RegCtrl0
SETDLY = 0.5us to 18.19ms, settling time when filtering as defined in RegCtrl2
Tosc is the oscillator period (555ns +/- 15%)
filt
chan
= {1,3,5,7} based on the order defined for the filter FILT (see Figure 8).
= {1,2,3,4,5} based on the number of channels defined in RegChanMsk
T
conv
Nch
[1..5 ]
2
2
4
=
47 T
Nfilt
[1 3 5 7]
1
3
3
osc
Table 17. Threshold to detect false coordinates
Table 16. Coordinate throughput examples
+
N
PowDly
[uS]
0.5
71
140
chan
LowThreshold
POWDLY
10
SetDly
[uS]
15kV ESD Low Power 4-Wire / 5-Wire Resistive
0.5
0.5
-
Page 26
+
SETDLY N
Touchscreen Controller with SPI Interface
Tconv
HighThreshold
[uS]
190
740
51
4070
filt
Tcomm
[uS]
–
1
14
8
8
+
T
osc
CoordRate
[kSPS]
21N
16.7
5.0
1.3
filt
+
1
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