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參數(shù)資料
| 型號(hào)： | ADS7846IGQCR |
| 英文描述： | TOUCH-SCREEN CONTROLLER |
| 中文描述： | 觸摸屏控制器 |
| 文件頁(yè)數(shù)： | 13/23頁(yè) |
| 文件大?。?/td> | 520K |
| 代理商： | ADS7846IGQCR |
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ADS7846
SBAS125H
13
www.ti.com
sample-and-hold goes into the hold mode and the touch
panel drivers turn off (in single-ended mode). The next 12
clock cycles accomplish the actual analog-to-digital conver-
sion. If the conversion is ratiometric (
SER/DFR
= 0), the
drivers are on during the conversion and a 13th clock cycle
is needed for the last bit of the conversion result. Three more
clock cycles are needed to complete the last byte (DOUT will
be low), which are ignored by the converter.
Control Byte
The control byte (on DIN), as shown in Table III, provides the
start conversion, addressing, ADC resolution, configuration,
and power-down of the ADS7846. Figure 9 and Tables III
and IV give detailed information regarding the order and
description of these control bits within the control byte.
SER/DFR
The
SER/DFR
bit controls the reference mode,
either single-ended (high) or differential (low). The differential
mode is also referred to as the ratiometric conversion mode
and is preferred for X-Position, Y-Position, and Pressure-
Touch measurements for optimum performance. The refer-
ence is derived from the voltage at the switch drivers, which
is almost the same as the voltage to the touch screen. In this
case a reference voltage is not needed, as the reference
voltage to the ADC is the voltage across the touch screen. In
the single-ended mode, the converter reference voltage is
always the difference between the V
REF
and GND pins (see
Tables I and II, and Figures 2 through 5 for further informa-
tion).
If X-Position, Y-Position, and Pressure-Touch are measured
in the single-ended mode, an external reference voltage is
needed. The ADS7846 should also be powered from the
external reference. Caution must be observed when using
the single-ended mode such that the input voltage to the
ADC does not exceed the internal reference voltage, espe-
cially if the supply voltage is greater than 2.7V.
NOTE: The differential mode can only be used for X-Position,
Y-Position, and Pressure-Touch measurements. All other
measurements require the single-ended mode.
PD0 and PD1
—
Table V describes the power-down and the
internal reference voltage configurations. The internal refer-
ence voltage can be turned on or off independently of the
ADC. This can allow extra time for the internal reference
voltage to settle to the final value prior to making a conver-
sion. Make sure to also allow this extra wake-up time if the
internal reference is powered down. The ADC requires no
wake-up time and can be instantaneously used. Also note
that the status of the internal reference power-down is
latched into the part (internally) with BUSY going high.
Therefore, in order to turn the reference off, an additional
write to the ADS7846 is required after the channel is con-
verted.
Bit 7
(MSB)
Bit 0
(LSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
S
A2
A1
A0
MODE
SER/DFR
PD1
PD0
TABLE III. Order of the Control Bits in the Control Byte.
BIT
NAME
DESCRIPTION
7
S
Start Bit. Control byte starts with first high bit on DIN.
A new control byte can start every 15th clock cycle
in 12-bit conversion mode or every 11th clock cycle
in 8-bit conversion mode (see Figure 12).
6-4
A2-A0
Channel Select Bits. Along with the
SER/DFR
bit,
these bits control the setting of the multiplexer input,
touch driver switches, and reference inputs (see
Tables I and II).
3
MODE
12-Bit/8-Bit Conversion Select Bit. This bit controls
the number of bits for the next conversion: 12-bits
(low) or 8-bits (high).
2
SER/DFR
Single-Ended/Differential Reference Select Bit. Along
with bits A2-A0, this bit controls the setting of the
multiplexer input, touch driver switches, and reference
inputs (see Tables I and I).
1-0
PD1-PD0
Power-Down Mode Select Bits. See Table V for
details.
TABLE IV. Descriptions of the Control Bits within the Control
Byte.
Initiate START
—
The first bit, the S bit, must always be high
and initiates the start of the control byte. The ADS7846
ignores inputs on the DIN pin until the start bit is detected.
Addressing
—
The next three bits (A2, A1, and A0) select the
active input channel(s) of the input multiplexer (see Tables I,
II, and Figure 2), touch screen drivers, and the reference
inputs.
MODE
—
The mode bit sets the resolution of the ADC. With
this bit low, the next conversion has 12 bits of resolution; with
this bit high, the next conversion has 8 bits of resolution.
PD1
PD0
PENIRQ
DESCRIPTION
0
0
Enabled
Power-Down Between Conversions. When each
conversion is finished, the converter enters a
low-power mode. At the start of the next conver-
sion, the device instantly powers up to full power.
There is no need for additional delays to assure
full operation and the very first conversion is
valid. The Y
–
switch is on when in power-down.
0
1
Disabled
Reference is off and ADC is on.
1
0
Enabled
Reference is on and ADC is off.
1
1
Disabled
Device is always powered. Reference is on and
ADC is on.
TABLE V. Power-Down and Internal Reference Selection.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS7846IRGVR | 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(lèi)型:Resistive Touch Controllers 輸入類(lèi)型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類(lèi)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 |
| 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(lèi)型:Resistive Touch Controllers 輸入類(lèi)型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類(lèi)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(lèi)型:Resistive Touch Controllers 輸入類(lèi)型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類(lèi)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(lèi)型:Resistive Touch Controllers 輸入類(lèi)型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類(lèi)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 |
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