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参数资料
| 型号： | TSC2003I |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | ADC |
| 英文描述： | 3-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PDSO16 |
| 封装： | PLASTIC, TSSOP-16 |
| 文件页数： | 3/20页 |
| 文件大小： | 309K |
| 代理商： | TSC2003I |
TSC2003
11
SBAS162A
www.ti.com
discussion, it's useful to consider the basic operation of the
TSC2003 (see Figure 1). This particular application shows
the device being used to digitize a resistive touch screen. A
measurement of the current Y position of the pointing device
is made by connecting the X+ input to the A/D converter,
turning on the Y+ and Y– drivers, and digitizing the voltage
on X+, as shown in Figure 4. For this measurement, the
resistance in the X+ lead does not affect the conversion; it
does, however, affect the settling time, but the resistance is
usually small enough that this is not a concern. However,
since the resistance between Y+ and Y– is fairly low, the
on-resistance of the Y drivers does make a small difference.
Under the situation outlined so far, it would not be possible
to achieve a 0V input or a full-scale input regardless of
where the pointing device is on the touch screen because
some voltage is lost across the internal switches. In addition,
the internal switch resistance is unlikely to track the resis-
tance of the touch screen, providing an additional source of
error.
This situation is remedied, as shown in Figure 5, by using
the differential mode: the +REF and –REF inputs are con-
nected directly to Y+ and Y–, respectively. This makes the
A/D converter ratiometric. The result of the conversion is
always a percentage of the external reference, regardless of
how it changes in relation to the on-resistance of the internal
switches.
REFERENCE INPUT
The voltage difference between +REF and –REF (see
Figure 2) sets the analog input range. The TSC2003 will
operate with a reference in the range of 2V to +VDD. There are
several critical items concerning the reference input and its
wide-voltage range. As the reference voltage is reduced, the
analog voltage weight of each digital output code is also
reduced. This is often referred to as the LSB (Least Significant
Bit) size, and is equal to the reference voltage divided by 4096
(256 if in 8-bit mode). Any Offset or Gain error inherent in the
A/D converter will appear to increase, in terms of LSB size,
as the reference voltage is reduced. For example, if the offset
of a given converter is 2LSBs with a 2.5V reference, it will
typically be 2.5LSBs with a 2V reference. In each case, the
actual offset of the device is the same, 1.22mV. With a lower
reference voltage, more care must be taken to provide a clean
layout including adequate bypassing, a clean (low-noise, low-
ripple) power supply, a low-noise reference (if an external
reference is used), and a low-noise input signal.
The voltage into the VREF input is not buffered, and directly
drives the Capacitor Digital-to-Analog Converter (CDAC)
portion of the TSC2003. Therefore, the input current is very
low, typically < 6
A.
REFERENCE MODE
There is a critical item regarding the reference when making
measurements while the switch drivers are ON. For this
FIGURE 4. Simplified Diagram of Single-Ended Reference.
FIGURE 5. Simplified Diagram of Differential Reference
(Y Switches Enabled, X+ is Analog Input).
Converter
+IN
+REF
Y+
+V
DD
X+
Y–
GND
–REF
–IN
Converter
+IN
+REF
Y+
+V
DD
V
REF
X+
Y–
GND
–REF
–IN
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相关代理商/技术参数 |
参数描述 |
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| TSC2003IPW | 功能描述:触摸屏转换器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20 |
| TSC2003IPWG4 | 功能描述:触摸屏转换器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20 |
| TSC2003IPWR | 功能描述:触摸屏转换器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20 |
| TSC2003IPWR | 制造商:Texas Instruments 功能描述:Controller IC |
| TSC2003IPWRG4 | 功能描述:触摸屏转换器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20 |
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