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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： | 15/16頁 |
| 文件大小： | 193K |
| 代理商： | AD7843 |
REV. 0
AD7843
–15–
been enabled (see Table III), when the touch screen connected
to the AD7843 is touched via a pen or finger, the
PENIRQ
output
will go low initiating an interrupt to a microprocessor which may
then instruct a control word to be written to the AD7843 to
initiate a conversion. This output can also be enabled between
conversions during power-down (see Table III) allowing power-
up to be initiated only when the screen is touched. The result of
the first touch screen coordinate conversion after power-up will
be valid assuming any external reference is settled to the 12- or
8-bit level as required.
EXTERNAL
PULL-UP
TOUCH
SCREEN
100k
X+
Y
–
Y+
PENIRQ
ENABLE
+V
CC
PENIRQ
ON
+V
CC
Figure 13.
PENIRQ
Functional Block Diagram
Figure 14 assumes the
PENIRQ
function has been enabled in
the last write or the part has just been powered up so
PENIRQ
is enabled by default. Once the screen is touched, the
PENIRQ
output will go low a time t
PEN
later. This delay is approximately
5
μ
s, assuming a 10 nF touch screen capacitance, and will vary
with the touch screen resistance actually used. Once the START
bit is detected, the pen interrupt function is disabled and the
PENIRQ
will not respond to screen touches. The
PENIRQ
CS
DCLK
1
16
DIN
t
PEN
8
1
A2
A1
A0
MODESER/
1
0
S
NO RESPONSE TO TOUCH
(START)
PENIRQ
INTERRUPT
PROCESSOR
SCREEN
TOUCHED
HERE
PD1 = 1, PD0 = 0,
PENIRQ
ENABLED AGAIN
13
Figure 14.
PENIRQ
Timing Diagram
output will remain low until the fourth falling edge of DCLK
after the START bit has been clocked in, at which point it will
return high as soon as possible, regardless of the touch screen
capacitance. This does not mean the pen interrupt function is
now enabled again as the power-down bits have not yet been
loaded to the control register. So regardless of whether
PENIRQ
is to be enabled again or not the
PENIRQ
output will always
idle high normally. Assuming the
PENIRQ
is enabled again as
shown in Figure 14, once the conversion is complete, the
PENIRQ
output will respond to a screen touch again. The fact
that
PENIRQ
returns high almost immediately after the fourth
falling edge of DCLK, means the user will avoid any spurious
interrupts on the microprocessor or DSP which could occur if
the interrupt request line on the micro/DSP was unmasked
during or toward the end of conversion with the
PENIRQ
pin
still low. Once the next START bit is detected by the AD7843
the
PENIRQ
function is disabled again.
If the control register write operation will overlap with the data
read, a START bit will always be detected prior to the end of
conversion, meaning that even if the
PENIRQ
function has been
enabled in the Control Register it will be disabled by the START
bit again before the end of the conversion is reached, so the
PENIRQ
function effectively cannot be used in this mode.
However, as conversions are occurring continuously, the
PENIRQ
function is not necessary and, therefore, redundant.
GROUNDING AND LAYOUT
For information on grounding and layout considerations for the
AD7843 refer to the “Layout and Grounding Recommendations
for Touch Screen Digitizers” Technical Note.
相關PDF資料 |
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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