MXB7846 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – 2.375V to 5.25V, 4-Wire Touch-Screen Controller with Internal Reference and Temperature Sensor

19-2436; Rev 1; 5/04
2.375V to 5.25V, 4-Wire Touch-Screen Controller
with Internal Reference and Temperature Sensor
General Description
The MXB7846 is an industry-standard 4-wire touch-
screen controller. It contains a 12-bit sampling analog-
to-digital converter (ADC) with a synchronous serial
interface and low on-resistance switches for driving
resistive touch screens. The MXB7846 uses an internal
+2.5V reference or an external reference. The
MXB7846 can make absolute or ratiometric measure-
ments. In addition, this device has an on-chip tempera-
ture sensor, a battery-monitoring channel, and has the
ability to perform touch-pressure measurements without
external components. The MXB7846 has one auxiliary
ADC input. All analog inputs are fully ESD protected,
eliminating the need for external TransZorb™ devices.
The MXB7846 is guaranteed to operate with a supply
voltage down to +2.375V when used with an external
reference or +2.7V with an internal reference. In shut-
down mode, the typical power consumption is reduced
to under 0.5µW, while the typical power consumption at
125ksps throughput and a +2.7V supply is 650µW.
Low-power operation makes the MXB7846 ideal for bat-
tery-operated systems, such as personal digital assis-
tants with resistive touch screens and other portable
equipment. The MXB7846 is available in 16-pin QSOP
and TSSOP packages, and is guaranteed over the
-40°C to +85°C temperature range.
Applications
Personal Digital Assistants
Portable Instruments
Point-of-Sales Terminals
Pagers
Touch-Screen Monitors
Cellular Phones
Typical Application Circuit appears at end of data sheet.
TransZorb is a trademark of Vishay Intertechnology, Inc.
SPI/QSPI are trademarks of Motorola, Inc.
Features
♦ ESD-Protected ADC Inputs
±15kV IEC 61000-4-2 Air-Gap Discharge
±8kV IEC 61000-4-2 Contact Discharge
♦ Pin Compatible with MXB7843
♦ +2.375V to +5.25V Single Supply
♦ Internal +2.5V Reference
♦ Direct Battery Measurement (0 to 6V)
♦ On-Chip Temperature Measurement
♦ Touch-Pressure Measurement
♦ 4-Wire Touch-Screen Interface
♦ Ratiometric Conversion
♦ SPI™/QSPI™, 3-Wire Serial Interface
♦ Programmable 8-/12-Bit Resolution
♦ Auxiliary Analog Input
♦ Automatic Shutdown Between Conversions
♦ Low Power (External Reference)
270µA at 125ksps
115µA at 50ksps
25µA at 10ksps
5µA at 1ksps
2µA Shutdown Current
PART
MXB7846EEE
MXB7846EUE
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 TSSOP
Pin Configuration
TOP VIEW
V_{DD 1}
X+ 2
Y+ 3
X- 4
Y- 5
GND 6
BAT 7
AUX 8
MXB7846
16 DCLK
15 CS
14 DIN
13 BUSY
12 DOUT
11 PENIRQ
10 V_DD
9 REF
QSOP/TSSOP
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.