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

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

2.375V to 5.25V, 4-Wire Touch-Screen Controller

with Internal Reference and Temperature Sensor

________________________________________________________________ Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

DCLK

CS

DIN

BUSY

DOUT

PENIRQ

REF

TOP VIEW

MXB7846

QSOP/TSSOP

X+

Y+

GND

X-

Y-

BAT

AUX

Pin Configuration

Ordering Information

19-2436; Rev 1; 5/04

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.

PART

TEMP RANGE

PIN-PACKAGE

MXB7846EEE

-40

°C to +85°C

16 QSOP

MXB7846EUE

-40

°C to +85°C

16 TSSOP

TransZorb is a trademark of Vishay Intertechnology, Inc.

SPI/QSPI are trademarks of Motorola, Inc.

Typical Application Circuit appears at end of data sheet.