®
ADS
784
ADS7845
5
TOUCH SCREEN CONTROLLER
FEATURES
q
5-WIRE TOUCH SCREEN INTERFACE
q
RATIOMETRIC CONVERSION
q
SINGLE SUPPLY: 2V to 5V
q
UP TO 125kHz CONVERSION RATE
q
SERIAL INTERFACE
q
PROGRAMMABLE 8- OR 12-BIT RESOLUTION
q
AUXILIARY ANALOG INPUTS
q
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
q
PERSONAL DIGITAL ASSISTANTS
q
PORTABLE INSTRUMENTS
q
POINT-OF-SALES TERMINALS
q
PAGERS
q
TOUCH-SCREEN MONITORS
+V
CC
GND
UR
LR
GND
Driver
+V
CC
UL
LL
SAR
ADS7845
DOUT
BUSY
Comparator
+V
CC
GND
CDAC
Serial
Data
Interface
and
Control
CS
AUX IN
WIPER
PENIRQ
MUX
DCLK
DIN
V
REF
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
©
1998 Burr-Brown Corporation
PDS-1497A
Printed in U.S.A. December, 1998