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參數(shù)資料
| 型號(hào)： | AK4183VT |
| 廠商： | Asahi Kasei Microsystems Co.,Ltd |
| 英文描述： | I2C Touch Screen Controller |
| 中文描述： | 觸摸屏控制器的I2C |
| 文件頁數(shù)： | 6/17頁 |
| 文件大?。?/td> | 173K |
| 代理商： | AK4183VT |
ASAHI KASEI
[AK4183]
A/D Converter for Touch Screen
The AK4183 incorporates a 12-bit successive approximation resistor (SAR) A/D converter for position measurement. The
architecture is based on a capacitive redistribution algorithm, and an internal capacitor array functions as the sample/hold (S/H)
circuit.
The SAR A/D converter output is a straight binary format as shown below:
Input Voltage
(
VREF-1.5LSB)~
VREF
(
VREF-2.5LSB) ~ (
VREF-1.5LSB)
---------
0.5LSB ~ 1.5LSB
0 ~ 0.5LSB
VREF: (VREF+) – (VREF-)
MS0500-E-00
2006/04
6
Output Code
FFFH
FFEH
---------
001H
000H
Table 1 Output Code
The Position Detection of Touch Screen
A position detecting (X, Y position) on the touch panel is selected by the control command via the A2, A1, A0 bits in the control
register. The mode of the position detecting is differential mode, the full scale (
VREF) is the differential voltage between the non-
inverting terminal and the inverting terminal of the measured axis (e.g. X-axis measurement:
VREF = V
XP
– V
XN
). The voltage
difference on the A/D converter (
AIN) is the voltage between non-inverting terminals of the non-measured axis and the inverting
terminal of the measured axis. (E.g.
AIN= (AIN+) - (AIN-) = V
YP
-V
XN
) The voltage difference (
AIN) is charged to the internal
capacitor array during the sampling period. No current flows into the internal capacitor after the capacitor has been charged
completely.
The required settling time to charge the internal capacitor array depends on the source impedance (Rin). If the source impedance is
600 ohm, the settling time needs at least 2.5
μ
s (1 clock cycle period of SCL 400 KHz)
The position on the touch screen is detected by taking the voltage of one axis when the voltage is supplied between the two
terminals of another axis. At least two A/D conversions are needed to get the two-dimensional (X/Y axis) position.
The X-plate and Y-plate are connected on the dotted line when the panel is touched.
XP
XN
X-Plate (Top side)
Y-Plate (Bottom side)
c) 4-wire Touch Screen Construction
X-Plate
Y-Plate
X-Plate
YP
YN
YN
XN
YP
XN-Driver SW ON
VREF+
VREF-
ADC
AIN+
AIN-
XP
XP-Driver SW ON
a) X-Position Measurement Differential Mode
b) Y-Position Measurement Differential Mode
YN
XN
YP
YN-Driver SW ON
VREF+
VREF-
ADC
AIN+
AIN-
XP
YP-Driver SW ON
VCC
VCC
Touch Screen
Y-Plate
Figure 2 Axis Measurements
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AK4184 | TSC with Keypad Scanner and GPIO Expander |
| AK4184VG | TSC with Keypad Scanner and GPIO Expander |
| AK4220 | 7:3 Audio Switch and 6:3 Video Switch |
| AK4220VQ | 7:3 Audio Switch and 6:3 Video Switch |
| AK4250 | Output Coupling Capacitor-less Video Amp with LPF |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AK4184 | 制造商:AKM 制造商全稱:AKM 功能描述:Analog I/F IC which includes 4-wire resistive Touch Screen Controller |
| AK4184A | 制造商:AKM 制造商全稱:AKM 功能描述:TSC with Keypad Scanner and GPIO Expander |
| AK4184AEG | 制造商:AKM 制造商全稱:AKM 功能描述:TSC with Keypad Scanner and GPIO Expander |
| AK4184VG | 制造商:AKM 制造商全稱:AKM 功能描述:TSC with Keypad Scanner and GPIO Expander |
| AK4185 | 制造商:AKM 制造商全稱:AKM 功能描述:Low Power Touch Screen Controller with SPI? Interface |
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