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參數資料
| 型號： | AD7843 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Touch Screen Digitizer |
| 中文描述： | 觸摸屏數字轉換器 |
| 文件頁數： | 9/16頁 |
| 文件大小： | 193K |
| 代理商： | AD7843 |
REV. 0
AD7843
–9–
ANALOG INPUT
Figure 4 shows an equivalent circuit of the analog input struc-
ture of the AD7843 which contains a block diagram of the input
multiplexer, the differential input of the A/D converter and the
differential reference.
Table I shows the multiplexer address corresponding to each
analog input, both for the SER/
DFR
bit in the control register
set high and low. The control bits are provided serially to the
device via the DIN pin. For more information on the control
register see the Control Register section.
When the converter enters the hold mode, the voltage difference
between the +IN and –IN inputs (see Figure 4) is captured on
the internal capacitor array. The input current on the analog
inputs depends on the conversion rate of the device. During the
sample period, the source must charge the internal sampling
capacitor (typically 37 pF). Once the capacitor has been fully
charged, there is no further input current. The rate of charge
transfer from the analog source to the converter is a function of
conversion rate.
Acquisition Time
The track and hold amplifier enters its tracking mode on the
falling edge of the fifth DCLK after the START bit has been
detected (see Figure 13). The time required for the track and
hold amplifier to acquire an input signal will depend how
quickly the 37 pF input capacitance is charged. With zero
source impedance on the analog input three DCLK cycles will
always be sufficient to acquire the signal to the 12-bit level.
With a source impedance R
IN
on the analog input, the actual
acquisition time required is calculated using the formula:
t
ACQ
= 8.4
×
(
R
IN
+100
)
×
37
pF
where
R
IN
is the source impedance of the input signal, and
100
, 37 pF is the input RC value. Depending on the frequency
of DCLK used, three DCLK cycles may or may not be suffi-
cient to acquire the analog input signal with various source
impedance values.
4-TO-1
MUX
X+
Y+
IN3
IN4
DATA OUT
3-TO-1
MUX
3-TO-1
MUX
X+ Y+
REF
EXT
X
–
Y
–
GND
V
CC
X+
X
–
Y+
Y
–
ON-CHIP SWITCHES
REF
–
ADC CORE
IN
–
REF+
IN+
IN+
Figure 4. Equivalent Analog Input Circuit
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PDF描述 |
|---|---|
| AD7843ARQ | Touch Screen Digitizer |
| AD7843ARU | Touch Screen Digitizer |
| AD7843ARU-REEL7 | Touch Screen Digitizer |
| AD7843ARQ-REEL | Touch Screen Digitizer |
| AD7843ARQ-REEL7 | Touch Screen Digitizer |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD7843ARQ | 制造商:Analog Devices 功能描述:TOUCH SCREEN DIGITIZER 制造商:Rochester Electronics LLC 功能描述:2.7V 12-BIT TOUCH SCREN DIGITIZER I.C. - Bulk 制造商:Analog Devices 功能描述:IC 12-BIT ADC |
| AD7843ARQ-REEL | 制造商:Analog Devices 功能描述:TOUCH SCREEN DIGITIZER 制造商:Rochester Electronics LLC 功能描述:2.7V 12-BIT TOUCH SCREN DIGITIZER I.C. - Tape and Reel |
| AD7843ARQ-REEL7 | 制造商:Analog Devices 功能描述:TOUCH SCREEN DIGITIZER 制造商:Rochester Electronics LLC 功能描述:2.7V 12-BIT TOUCH SCREN DIGITIZER I.C. - Tape and Reel |
| AD7843ARQZ | 功能描述:IC ADC 12BIT TOUCHSCREEN 16-QSOP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 觸摸屏控制器 系列:- 標準包裝:96 系列:- 類型:- 觸摸面板接口:- 輸入數/鍵:- 分辨率（位）:- 評估套件:* 數據接口:- 數據速率/采樣率 (SPS，BPS):- 電壓基準:- 電源電壓:- 電流 - 電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:16-TSSOP 包裝:帶卷 (TR) |
| AD7843ARQZ2 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Touch Screen Digitizer |
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