MXB7846EEE+T Datasheet MXB7846EEE+T, MXB7846EEE+, MXB7846EUE+T | P1-P3

MXB7846

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

with Internal Reference and Temperature Sensor

________________________________________________________________

Maxim Integrated Products

Pin Configuration

19-2436; Rev 2; 1/08

For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

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

DCLK

DIN

BUSY

DOUT

PENIRQ

REF

TOP VIEW

MXB7846

QSOP/TSSOP

X+

Y+

GND

X-

Y-

BAT

AUX

Ordering Information

PART TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MXB7846EEE -40°C to +85°C 16 QSOP E16-6

MXB7846EUE -40°C to +85°C 16 TSSOP U16-1

TRANSZORB is a trademark of Vishay Intertechnology, Inc.

SPI/QSPI are trademarks of Motorola, Inc.

Typical Application Circuit appears at end of data sheet.

MXB7846

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

with Internal Reference and Temperature Sensor

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

, VBAT, DIN, CS, DCLK to GND ........................-0.3V to +6V

Digital Outputs to GND...............................-0.3V to (V

+ 0.3V)

REF

, X+, X-, Y+, Y-, AUX to GND..............-0.3V to (V

+ 0.3V)

Maximum Current into Any Pin .........................................±50mA

Maximum ESD per IEC-61000-4-2 (per MIL STD-883 HBM)

X+, X-, Y+, Y-, VBAT, AUX ......................................15kV (4kV)

All Other Pins ..........................................................2kV (500V)

Continuous Power Dissipation (T

= +70°C)

16-Pin QSOP (derate 8.30mW/°C above +70°C).........667mW

16-Pin TSSOP (derate 5.70mW/°C above +70°C) .......456mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

= 2.7V to 3.6V, V

REF

= 2.5V, f

DCLK

= 2MHz (50% duty cycle), f

SAMPLE

= 125kHz, 12-bit mode, 0.1µF capacitor at REF, T

MIN

to T

MAX

, unless otherwise noted. Typical values are at T

= +25°C.)

PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS

DC ACCURACY (Note 1)

Resolution 12 Bits

No Missing Codes 11 12 Bits

Relative Accuracy INL (Note 2) ±1 ±2 LSB

Differential Nonlinearity DNL ±1 LSB

Offset Error ±6 LSB

Gain Error (Note 3) ±4 LSB

Noise Including internal reference 70 µV

RMS

CONVERSION RATE

Conversion Time t

CONV

12 clock cycles (Note 4) 6 µs

Track/Hold Acquisition Time t

ACQ

3 clock cycles 1.5 µs

Throughput Rate f

SAMPLE

16 clock conversion 125 kHz

Multiplexer Settling Time 500 ns

Aperture Delay 30 ns

Aperture Jitter 100 p s

Channel-to-Channel Isolation V

= 2.5V

P-P

at 50kHz 100 dB

Serial Clock Frequency f

DCLK

0.1 2.0 MHz

Duty Cycle 40 60 %

ANALOG INPUT (X+, X-, Y+, Y-, AUX)

Input Voltage Range 0V

REF

Input Capacitance 25 pF

Input Leakage Current On/off leakage, V

= 0 to V

±0.1 ±1 µA

SWITCH DRIVERS

Y+, X+ 7

On-Resistance (Note 5)

Y-, X- 9

INTERNAL REFERENCE

Reference Output Voltage V

REF

= 2.7V to 5.25V, T

= +25°C 2.45 2.50 2.55 V

REF Output Tempco TCV

REF

50 ppm°/C

REF Short-Circuit Current 18 mA

REF Output Impedance 250 Ω

MXB7846

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

with Internal Reference and Temperature Sensor

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

= 2.7V to 3.6V, V

REF

= 2.5V, f

DCLK

= 2MHz (50% duty cycle), f

SAMPLE

= 125kHz, 12-bit mode, 0.1µF capacitor at REF, T

MIN

to T

MAX

, unless otherwise noted. Typical values are at T

= +25°C.)

PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS

EXTERNAL REFERENCE (Internal reference disabled, reference applied to REF)

Reference Input Voltage Range (Note 7) 1 V

Input Resistance 1GΩ

SAMPLE

= 125kHz 13 40

SAMPLE

= 12.5kHz 2.5

µA

Input Current

DCLK

= 0 ±3

BATTERY MONITOR (BAT)

Input Voltage Range 06V

Input Resistance During acquisition 10 kΩ

REF

= 2.5V ±2

Accuracy

Internal reference ±3

TEMPERATURE MEASUREMENT

Differential method (Note 8) 1.6 °C

Resolution

Single-conversion method 0.3 °C

Differential method (Note 8) ±2°C

Accuracy

Single-conversion method ±3°C

DIGITAL INPUTS (DCLK, CS, DIN)

Input High Voltage V

0.7 V

Input Low Voltage V

0.8 V

Input Hysteresis V

HYST

100 mV

Input Leakage Current I

±1 µA

Input Capacitance C

15 pF

DIGITAL OUTPUT (DOUT, BUSY)

Output Voltage Low V

SINK

= 250µA 0.4 V

Output Voltage High V

SOURCE

= 250µA V

0.5 V

PENIRQ Output Low Voltage V

50kΩ pullup to V

0.8 V

Three-State Leakage Current I

CS = V

1 ±10 µA

Three-State Output Capacitance C

OUT

CS = V

15 pF

POWER REQUIREMENTS

External reference 2.375 5.250

Supply Voltage V

Internal reference 2.70 5.25

SAMPLE

= 125ksps 270 650

SAMPLE

= 12.5ksps 220

External

reference

SAMPLE

= 0 150

µA

SAMPLE

= 125ksps 780 950

SAMPLE

= 12.5ksps 720

Supply Current I

Internal

reference

SAMPLE

= 0 650

µA

Shutdown Supply Current I

SHDN

DCLK = CS = V

3µA

Power-Supply Rejection Ratio P

SRR

= 2.7V to 3.6V full scale 70 dB

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24

MXB7846EEE+T

Mfr. #:

Buy MXB7846EEE+T

Manufacturer:

Maxim Integrated

Description:

Touch Screen Controllers 2.375-5.25V 4-Wire Touch-Screen Ctlr

Lifecycle:

New from this manufacturer.

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MXB7846EEE+T

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