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器件描述：Touch Screen Digitizer
器件厂商：AD [Analog Devices]
厂商主页：http://www.analog.com/
文件大小：657.3KB
文件页数：28
PDF阅读：AD7873.pdf (点击阅读器件资料)
摘要：
Touch Screen Digitizer
AD7873
Rev. D
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.326.8703 ? 2004 Analog Devices, Inc. All rights reserved.
FEATURES
4-wire touch screen interface
On-chip temperature sensor: ?40°C to +85°C
On-chip 2.5 V reference
Direct battery measurement (0 V to 6 V)
Touch-pressure measurement
Specified throughput rate of 125 kSPS
Single supply, VCC of 2.2 V to 5.25 V
Ratiometric conversion
High speed serial interface
Programmable 8-bit or 12-bit resolution
One auxiliary analog input
Shutdown mode: 1 ?A max
16-lead QSOP, TSSOP, and LFCSP packages
APPLICATIONS
Personal digital assistants
Smart hand-held devices
Touch screen monitors
Point-of-sale terminals
Pagers
GENERAL DESCRIPTION
The AD7873 is a 12-bit successive approximation ADC with a
synchronous serial interface and low on resistance switches for
driving touch screens. The AD7873 operates from a single 2.2 V
to 5.25 V power supply and features throughput rates greater
than 125 kSPS.
The AD7873 features direct battery measurement, temperature
measurement, and touch-pressure measurement. The AD7873
also has an on-board reference of 2.5 V that can be used for the
auxiliary input, battery monitor, and temperature measurement
modes. When not in use, the internal reference can be shut
down to conserve power. An external reference can also be
applied and can be varied from 1 V to VCC, while the analog
input range is from 0 V to VREF. The device includes a shutdown
mode that reduces the current consumption to less than 1 ?A.
The AD7873 features on-board switches. This, coupled with low
power and high speed operation, makes the device ideal for
battery-powered systems such as personal digital assistants with
resistive touch screens and other portable equipment. The part
is available in a 16-lead 0.15" quarter size outline package
(QSOP), a 16-lead thin shrink small outline package (TSSOP),
and a 16-lead lead frame chip scale package (LFCSP).
FUNCTIONAL BLOCK DIAGRAM
02164-D-001
AD7873
+V
CC
+V
CC
PENIRQ
SPORT
DIN CS DOUT DCLK BUSY
PEN
INTERRUPT
CHARGE
REDISTRIBUTION
DAC
SAR + ADC
CONTROL LOGIC
6-TO-1
I/P
MUX
T/H
COMP
GND
TEMP
SENSOR
BATTERY
MONITOR
Y+
Y–
AUX
2.5V
REF
X+
X–
V
REF
V
BAT
BUF
Figure 1.
PRODUCT HIGHLIGHTS
1. Ratiometric conversion mode available, eliminating errors
due to on-board switch resistances.
2. On-board temperature sensor: ?40°C to +85°C.
3. Battery monitor input.
4. Touch-pressure measurement capability.
5. Low power consumption of 1.37 mW max with the
reference off, or 2.41 mW typ with the reference on, at
125 kSPS and VCC at 3.6 V.
6. Package options include 4 mm × 4 mm LFCSP.
7. Analog input range from 0 V to VREF.
8. Versatile serial I/O ports.
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