SX8652ICSTRT Semtech, SX8652ICSTRT Datasheet - Page 29

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

8.5.2. Conversion Time
The maximum possible throughput can be estimated with the following equation
with:
Table 15 gives some examples of Coordinate Rate and Sample Rate for various setting in PENTRIG mode.
8.5.3. AUTO MODE
In AUTO mode, the coordinate throughput rate is the RATE set in RegCtrl0 if the host retrieve channel data at this RATE.
The RATE set should be superior or equal to the CoordRate.
8.6. ESD event
In case of ESD event, the chip can 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, a pressure measurement can be done. The conditions Z1<10 and Z2>4070 indicate an
ESD event.
Revision V1.6/July 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 7).
= {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 15. Coordinate throughput examples
+
N
PowDly
[uS]
0.5
71
140
chan
POWDLY
SetDly
[uS]
15kV ESD Low Power 4-Wire / 5-Wire Resistive
0.5
0.5
-
Page 29
+
SETDLY N
Touchscreen Controller with SPI Interface
Tconv
[uS]
190
740
51
filt
Tcomm
[uS]
–
1
14
8
8
+
T
osc
CoordRate
[kSPS]
21N
16.7
5.0
1.3
filt
+
1
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