參數(shù)資料
型號(hào)： ADS7846IRGVR
英文描述： TOUCH-SCREEN CONTROLLER
中文描述： 觸摸屏控制器
文件頁(yè)數(shù)： 8/23頁(yè)
文件大?。?/td> 520K
代理商： ADS7846IRGVR
ADS7846
SBAS125H
8
www.ti.com
THEORY OF OPERATION
The ADS7846 is a classic successive approximation register
(SAR) analog-to-digital converter (ADC). The architecture is
based on capacitive redistribution which inherently includes
a sample-and-hold function. The converter is fabricated on a
0.6
μ
m CMOS process.
The basic operation of the ADS7846 is shown in Figure 1.
The device features an internal 2.5V reference and an
external clock. Operation is maintained from a single supply
of 2.7V to 5.25V. The internal reference can be overdriven
with an external, low impedance source between 1V and
+V
CC
. The value of the reference voltage directly sets the
input range of the converter.
The analog input (X-, Y-, and Z-position coordinates, auxil-
iary input, battery voltage, and chip temperature) to the
converter is provided via a multiplexer. A unique configura-
tion of low on-resistance touch panel driver switches allows
an unselected ADC input channel to provide power and its
accompanying pin to provide ground for an external device,
such as a touch screen. By maintaining a differential input to
the converter and a differential reference architecture, it is
possible to negate the error from each touch panel driver
switch
’
s on-resistance (if this is a source of error for the
particular measurement).
ANALOG INPUT
See Figure 2 for a block diagram of the input multiplexer on
the ADS7846, the differential input of the ADC, and the
differential reference of the converter. Table I and Table II
show the relationship between the A2, A1, A0, and
SER/DFR
control bits and the configuration of the ADS7846. The
control bits are provided serially via the DIN pin
—
see the
Digital Interface section of this data sheet for more details.
When the converter enters the hold mode, the voltage
difference between the +IN and
–
IN inputs (see Figure 2) is
captured on the internal capacitor array. The input current
into the analog inputs depends on the conversion rate of the
device. During the sample period, the source must charge
the internal sampling capacitor (typically 25pF). After 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.
FIGURE 1. Basic Operation of the ADS7846.
A2
A1
A0
V
BAT
AUX
IN
TEMP
Y
–
X+
Y+
Y-POSITION
X-POSITION
Z
1
-POSITION
Z
2
-POSITION
X-DRIVERS
Y-DRIVERS
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
+IN (TEMP0)
Off
Off
Off
Off
On
Off
+IN
Measure
+IN
+IN
Measure
X
–
, On
X
–
, On
On
Off
Off
Y+, On
Y+, On
Off
Off
Off
+IN
Measure
+IN
Measure
+IN
+IN (TEMP1)
TABLE I. Input Configuration (DIN), Single-Ended Reference Mode (
SER/DFR
high).
TABLE II. Input Configuration (DIN), Differential Reference Mode (
SER/DFR
low).
A2
A1
A0
+REF
–
REF
Y
–
X+
Y+
Y-POSITION
X-POSITION
Z
1
-POSITION
Z
2
-POSITION
DRIVERS ON
0
0
1
1
0
1
0
0
1
1
0
1
Y+
Y+
Y+
X+
Y
–
X
–
X
–
X
–
+IN
+IN
Measure
Y+, Y
–
Y+, X
–
Y+, X
–
X+, X
–
Measure
+IN
Measure
+IN
Measure
+V
CC
X+
Y+
X
–
Y
–
GND
V
BAT
AUX
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
DCLK
CS
DIN
BUSY
DOUT
PENIRQ
+V
CC
V
REF
Serial/Conversion Clock
Chip Select
Serial Data In
Converter Status
Serial Data Out
+
1
μ
F
to
10
μ
F
(Optional)
+2.7V to +5V
ADS7846
Auxiliary Input
To Battery
Voltage
Regulator
Touch
Screen
0.1
μ
F
Pen Interrupt
50k
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參數(shù)描述
ADS7846IRGVRG4 功能描述:觸摸屏轉(zhuǎn)換器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20
ADS7846IRGVT 功能描述:觸摸屏轉(zhuǎn)換器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20
ADS7846IRGVT 制造商:Texas Instruments 功能描述:IC CONTROLLER TOUCH SCREEN SMD 制造商:Texas Instruments 功能描述:IC, CONTROLLER, TOUCH SCREEN, SMD
ADS7846IRGVTG4 功能描述:觸摸屏轉(zhuǎn)換器和控制器 4-wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20
ADS7846IZQCR 制造商:Texas Instruments 功能描述:
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