ADS7845
FEATURES
l 5-WIRE TOUCH SCREEN INTERFACE
l RATIOMETRIC CONVERSION
l SINGLE SUPPLY: 2V to 5V
l UP TO 125kHz CONVERSION RATE
l SERIAL INTERFACE
l PROGRAMMABLE 8- OR 12-BIT RESOLUTION
l AUXILIARY ANALOG INPUTS
l FULL POWER-DOWN CONTROL
®
DESCRIPTION
The ADS7845 is a 12-bit sampling analog-to-digital
converter (ADC) with a synchronous serial interface
and low on-resistance switches for driving touch
screens. Typical power dissipation is 750µW at a
125kHz throughput rate and a +2.7V supply. The
reference voltage (V
REF
) can be varied between 1V and
+V
CC
, providing a corresponding input voltage range
of 0V to V
REF
. The device includes a shutdown mode
which reduces typical power dissipation to under
0.5µW. The ADS7845 is guaranteed down to 2.7V
operation.
Low power, high speed, and on-board switches make
the ADS7845 ideal for battery-operated systems such
as personal digital assistants with resistive touch screens
and other portable equipment. The ADS7845 is avail-
able in a 16-lead SSOP package and is guaranteed
over the –40°C to +85°C temperature range.
APPLICATIONS
l PERSONAL DIGITAL ASSISTANTS
l PORTABLE INSTRUMENTS
l POINT-OF-SALES TERMINALS
l PAGERS
l TOUCH-SCREEN MONITORS
©
1998 Burr-Brown Corporation PDS-1497A Printed in U.S.A. December, 1998
TOUCH SCREEN CONTROLLER
CDAC
SAR
ADS7845
Comparator
MUX
Serial
Data
Interface
and
Control
DOUT
BUSY
CS
DCLK
DIN
UR
LR
UL
LL
AUX IN
WIPER
PENIRQ
V
REF
GND
Driver
+V
CC
+V
CC
GND
+V
CC GND
International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111
Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
ADS7845