Burr Brown Corporation ADS7846N-2K5, ADS7846N, ADS7846E-2K5, ADS7846 Datasheet

®

For most current data sheet and other product

information, visit www.burr-brown.com

TOUCH-SCREEN CONTROLLER

ADS7846

ADS7846

FEATURES

● SAME PINOUT AS ADS7843

● 2.2V TO 5.25V OPERATION

● INTERNAL 2.5V REFERENCE

● DIRECT BATTERY MEASUREMENT (0V to 6V)

● ON-CHIP TEMPERATURE MEASUREMENT

● TOUCH-PRESSURE MEASUREMENT

● QSPI/SPI 3-WIRE INTERFACE

● AUTO POWER DOWN

● TSSOP-16 AND SSOP-16 PACKAGES

APPLICATIONS

● PERSONAL DIGITAL ASSISTANTS

● PORTABLE INSTRUMENTS

● POINT-OF-SALES TERMINALS

● PAGERS

● TOUCH-SCREEN MONITORS

● CELLULAR PHONES

PENIRQ

DESCRIPTION

The ADS7846 is a next-generation version to the industry
standard ADS7843 4-wire touch-screen controller. The
ADS7846 is 100% pin-compatible with the existing
ADS7843, and will drop into the same socket. This allows
for easy upgrade of current applications to the new ver­sion. Only software changes will be required to take
advantage of the added features of direct battery measure­ment, temperature measurement, and touch-pressure mea­surement. The ADS7846 also has an on-chip 2.5V refer­ence that can be utilized for the auxiliary input, battery
monitor, and temperature measurement modes. The refer­ence can also be powered down when not used to conserve
power. The internal reference will operate down to 2.7V
supply voltage while monitoring the battery voltage from
0V to 6V.

The low power consumption of < 0.5mW typ at 2.7V
(reference OFF), high speed (> 125kHz clock rate), and
on-chip drivers make the ADS7846 an ideal choice for
battery-operated systems such as Personal Digital Assis­tants (PDAs) with resistive touch screens, pagers, cellu­lar phones, and other portable equipment. The ADS7846
is available in the small TSSOP-16 and SSOP-16 pack­ages and is guaranteed over the –40°C to +85°C tem­perature range.

+V

CC

X+
X–

Y+
Y–

V

BAT

AUX

V

REF

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: [phone]

Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]

©

1999 Burr-Brown Corporation PDS-1545B Printed in U.S.A. June, 2000

Battery
Monitor

Temperature

Sensor

6-Channel

MUX

CDAC

SAR

ADS7846

Comparator

Internal 2.5V

Reference

Serial

Data

Out

1

DOUT

BUSY

CS

DCLK

DIN

ADS7846

®

PRELIMINARY SPECIFICATIONS

At TA =–40°C to +85°C, +VCC = +2.7V, V

, unless otherwise noted.

+V

CC

PARAMETER CONDITIONS MIN TYP MAX UNITS
ANALOG INPUT

Full-Scale Input Span Positive Input - Negative Input 0 V
Absolute Input Range Positive Input –0.2 +V

Capacitance 25 pF
Leakage Current 0.1 µA

SYSTEM PERFORMANCE

Resolution 12 Bits
No Missing Codes 11 Bits
Integral Linearity Error ±2 LSB
Offset Error ±6 LSB
Gain Error External V
Noise Including Internal V
Power Supply Rejection 70 dB

SAMPLING DYNAMICS

Conversion Time 12 CLK Cycles
Acquisition Time 3 CLK Cycles
Throughput Rate 125 kHz
Multiplexer Settling Time 500 ns
Aperture Delay 30 ns
Aperture Jitter 100 ps
Channel-to-Channel Isolation V

SWITCH DRIVERS

On-Resistance

Y+, X+ 5 Ω
Y–, X– 6 Ω

Drive Current

(2)

REFERENCE OUTPUT

Internal Reference Voltage 2.45 2.50 2.55 V
Internal Reference Drift 15 ppm/°C
Input Impedance Internal Reference ON 250 Ω

Quiescent Current 500 µA

REFERENCE INPUT

Range 1.0 V
Resistance PD1 = 0, Internal Reference OFF 1 G Ω

BATTERY MONITOR

Input Voltage Range 0.5 6.0 V
Input Impedance

Sampling Battery 10 KΩ
Battery Monitor OFF 1GΩ

Accuracy V

TEMPERATURE MEASUREMENT

Temperature Range –40°C +85 °C
Resolution Differential Method

Accuracy Differential Method

DIGITAL INPUT/OUTPUT

Logic Family CMOS
Logic Levels, Except PENIRQ

V

IH

V

IL

V

OH

V

OL

PENIRQ

V

OL

Data Format Straight Binary

= 2.5V internal voltage, f

REF

Negative Input –0.2 +0.2 V

= 2.5Vp-p at 50kHz 100 dB

IN

Duration 100ms 50 mA

Internal Reference OFF 1 GΩ

Internal Reference –3 +3 %

TA = 0°C to +85°C, 50kΩ Pull-Up 0.8 V

SAMPLE

= 125kHz, f

CLK

= 16 • f

= 2MHz, 12-bit mode, and digital inputs = GND or

SAMPLE

ADS7846E

REF

+0.2 V

CC

REF

REF

= 2.5V –2 +2 %

REF

(3)

(4)

TEMP0

TEMP0

| I

| ≤ +5µA+V

IH

| I

| ≤ +5µA –0.3 +0.8 V

IL

IOH = –250µA+V

IOL = 250µA 0.4 V

(3)

(4)

• 0.7 +VCC +0.3

CC

• 0.8 V

CC

70 µVrms

1.6 °C

0.3 °C

±2 °C
±3 °C

±4 LSB

CC

V

V

(1)

®

ADS7846

2

SPECIFICATIONS (Cont.)

=–40°C to +85°C, +VCC = +2.7V, V

At T

A

, unless otherwise noted.

+V

CC

PARAMETER CONDITONS MIN TYP MAX UNITS

POWER SUPPLY REQUIREMENTS

(5)

+V

CC

Quiescent Current Internal Reference OFF 280 650 µA

Power Dissipation +VCC = +2.7V 1.8 mW

TEMPERATURE RANGE

Specified Performance –40 +85 °C

NOTES: (1) LSB means Least Significant Bit. With V
may result in device degradation. (3) Difference between TEMP0 and TEMP1 measurement. No calibration necessary. (4) Temperature drift is –2.1mV/°C.
(5) ADS7846 will operate down to 2.2V.

= 2.5V internal voltage, f

REF

Specified Performance 2.7 3.6 V

Internal Reference ON 780 µA

Shut Down Mode with 3 µA

DCLK = DIN = +V

equal to +2.5V, one LSB is 610µV. (2) Guaranteed by design, but not tested. Exceeding 50mA source current

REF

SAMPLE

= 125kHz, f

CLK

= 16 • f

= 2MHz, 12-bit mode, and digital inputs = GND or

SAMPLE

ADS7846E

Operating Range 2.2 5.25 V

= 12.5kHz 220 µA

f

SAMPLE

CC

PIN CONFIGURATION

Top View SSOP

+V

X+
Y+
X–
Y–

GND

V

BAT

1

CC

2
3
4
5

ADS7846

6
7
8

IN

16
15
14
13
12
11
10

9

DCLK
CS
DIN
BUSY
DOUT
PENIRQ
+V

CC

V

REF

PIN DESCRIPTION

PIN NAME DESCRIPTION

1+V
2 X+ X+ Position Input. ADC Input Channel 1.
3 Y+ Y+ Position Input. ADC Input Channel 2.
4 X– X– Position Input
5 Y– Y– Position Input
6 GND Ground
7V

BAT

8 IN Auxiliary Input to ADC Input, Channel 4.
9V

REF

10 +V
11 PENIRQ Pen Interrupt. Open anode output (requires 10kΩ to

12 DOUT Serial Data Output. Data is shifted on the falling

13 BUSY Busy Output. This output is high impedance when

14 DIN Serial Data Input. If CS is LOW, data is latched on

15 CS Chip Select Input. Controls conversion timing and

16 DCLK External Clock Input. This clock runs the SAR conver-

Power Supply

CC

Battery Monitor Input

Voltage Reference Input/Output
Power Supply

CC

100kΩ pull-up resistor externally).

edge of DCLK. This output is high impedance when
CS is HIGH.

CS is HIGH.

rising edge of DCLK.

enables the serial input/output register. CS HIGH =
power-down mode (ADC only).

sion process and synchronizes serial data I/O.

®

3

ADS7846

ABSOLUTE MAXIMUM RATINGS

+V

to GND ........................................................................ –0.3V to +6V

CC

Analog Inputs to GND ............................................ –0.3V to +V

Digital Inputs to GND .............................................–0.3V to +VCC + 0.3V

Power Dissipation .......................................................................... 250mW

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

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

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

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

NOTE: (1) Stresses above those listed under “Absolute Maximum Ratings”
may cause permanent damage to the device. Exposure to absolute maximum
conditions for extended periods may affect device reliability.

(1)

+ 0.3V

CC

ELECTROSTATIC
DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and
installation procedures can cause damage.

ESD damage can range from subtle performance degradation to
complete device failure. Precision integrated circuits may be
more susceptible to damage because very small parametric
changes could cause the device not to meet its published specifi­cations.

PACKAGE/ORDERING INFORMATION

MAXIMUM

INTEGRAL PACKAGE SPECIFICATION

PRODUCT ERROR (LSB) PACKAGE NUMBER RANGE NUMBER

LINEARITY DRAWING TEMPERATURE ORDERING TRANSPORT

ADS7846E ±2 SSOP-16 322 –40°C to +85°C ADS7846E Rails

"" "" "ADS7846E/2K5 Tape and Reel

ADS7846N ±2 TSSOP-16 363 –40°C to +85°C ADS7846N Rails

"" "" "ADS7846N/2K5 Tape and Reel

NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces
of “ADS7846E/2K5” will get a single 2500-piece Tape and Reel.

(1)

MEDIA

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.

®

ADS7846

4

TYPICAL PERFORMANCE CURVES

CHANGE IN OFFSET vs TEMPERATURE

20–40 100–20 0 40

Temperature (˚C)

Delta from +25˚C (LSB)

0.6

0.4

0.2

0.0

–0.2

–0.4

–0.6

60 80

MAXIMUM SAMPLE RATE vs +V

CC

3.5252.5 4

+V

CC

(V)

Sample Rate (Hz)

1M

100k

10k

1k

4.53

At TA = +25°C, +VCC = +2.7V, V

SUPPLY CURRENT vs TEMPERATURE

400

= External +2.5V, f

REF

= 125kHz, and f

SAMPLE

CLK

= 16 • f

= 2MHz, unless otherwise noted.

SAMPLE

POWER DOWN SUPPLY CURRENT

140

vs TEMPERATURE

350

300

250

200

Supply Current (µA)

150

100

20–40 100–20 0 40

60 80

Temperature (˚C)

SUPPLY CURRENT vs +V

CC

120

100

80

60

Supply Current (nA)

40

20

20–40 100–20 0 40

Temperature (˚C)

60 80

390

370

f

= 12.5kHz

SAMPLE

350

330

310

290

Supply Current (µA)

270

250

CHANGE IN GAIN vs TEMPERATURE

0.15

0.10

0.05

0.00

–0.05

Delta from +25˚C (LSB)

–0.10

–0.15

3.5252.5 4

+V

(V)

CC

20–40 100–20 0 40

Temperature (˚C)

4.53

60 80

®

5

ADS7846

TYPICAL PERFORMANCE CURVES (Cont.)

At TA = +25°C, +VCC = +2.7V, V

= External +2.5V, f

REF

= 125kHz, and f

SAMPLE

CLK

= 16 • f

= 2MHz, unless otherwise noted.

SAMPLE

REFERENCE CURRENT vs SAMPLE RATE

14

12

10

18

16

14

REFERENCE CURRENT vs TEMPERATURE

8

12

6

4

Reference Current (µA)

2

0

750 12525 50 100

Sample Rate (kHz)

SWITCH ON RESISTANCE vs +V

(X+, Y+: +VCC to Pin; X–, Y–: Pin to GND)

CC

8

7

6

5

(Ω)

ON

4

R

3

Y–
X–

X+Y+

10

Reference Current (µA)

8

6

20–40 100–20 0 40

60 80

Temperature (˚C)

SWITCH ON RESISTANCE vs TEMPERATURE

8

(X+, Y+: +V

to Pin; X–, Y–: Pin to GND)

CC

7

Y–X–

6

5

(Ω)

ON

4

R

X+

Y+

3

2

1

+V

3.5252.5

CC

4

(V)

MAXIMUM SAMPLING RATE vs R

2

1.8

1.6

1.4

INL: R = 2k
INL: R = 500
DNL: R = 2k
DNL: R = 500

1.2
1

0.8

Error (LSB)

0.6

0.4

0.2
0

20 40 60 80 100 120 140 160 180 200

Sampling Rate (kHz)

2

1

4.53

40

20–40 100–20

60 800

Temperature (˚C)

IN

INTERNAL V

vs TEMPERATURE

REF

2.4920

2.4915

2.4910

2.4905

(V)

REF

2.4900

2.4895

2.4890

Internal V

2.4885

2.4880

2.4875

–40

–35

–30

–25

–20

–15

–10

–05

0

0510152025303540455055606570758085

Temperature (°C)

®

ADS7846

6