Voltage Controller. AD7889 Datasheet

AD7889 Controller. Datasheet pdf. Equivalent

AD7889 Datasheet
Recommendation AD7889 Datasheet
Part AD7889
Description Low Voltage Controller
Feature AD7889; a Preliminary Technical Information FEATURES www.datasheet4u.com Fast 12-Bit ADC with 1.4 µs Convers.
Manufacture Analog Devices
Datasheet
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Analog Devices AD7889
Data Sheet
Low Voltage Controller for Touch Screens
AD7879/AD7889
FEATURES
4-wire touch screen interface
1.6 V to 3.6 V operation
Median and averaging filter to reduce noise
Automatic conversion sequencer and timer
User-programmable conversion parameters
Auxiliary analog input/battery monitor (0.5 V to 5 V)
1 optional GPIO
Interrupt outputs (INT, PENIRQ)
Touch-pressure measurement
Wake-up on touch function
Shutdown mode: 6 μA maximum
12-ball, 1.6 mm × 2 mm WLCSP
16-lead, 4 mm × 4 mm LFCSP
APPLICATIONS
Personal digital assistants
Smart handheld devices
Touch screen monitors
Point-of-sale terminals
Medical devices
Cell phones
GENERAL DESCRIPTION
The AD7879/AD7889 are 12-bit successive approximation
analog-to-digital converters (SAR ADCs) with a synchronous
serial interface and low on-resistance switches for driving 4-wire
resistive touch screens. The AD7879/AD7889 work with a very
low power supply—a single 1.6 V to 3.6 V supply—and feature a
throughput rate of 105 kSPS. The devices include a shutdown
mode that reduces current consumption to less than 6 μA.
To reduce the effects of noise from LCDs and other sources, the
AD7879/AD7889 contain a preprocessing block. The
preprocessing function consists of a median filter and an
averaging filter. The combination of these two filters provides a
more robust solution, discarding the spurious noise in the signal
and keeping only the data of interest. The size of both filters is
programmable. Other user-programmable conversion controls
include variable acquisition time and first conversion delay; up
to 16 averages can be taken per conversion. The AD7879/AD7889
can run in slave mode or standalone (master) mode, using an
automatic conversion sequencer and timer.
FUNCTIONAL BLOCK DIAGRAM
VCC/REF
X+
X–
Y+
Y–
GND
REF–
TEMPERATURE
SENSOR
X– Y– X+ Y+
REF– REF+
12-BIT
SAR ADC
AD7879/
AD7879-1
AD7889/
AD7889-1
RESULT
REGISTERS
CONTROL
REGISTERS
TO
RESULT
REGISTERS
SERIAL PORT
CS/ DIN/ DOUT/ SCL
ADD0 ADD1 SDA
Figure 1.
SEQUENCER
AND TIMER
The AD7879/AD7889 have a programmable pin that can
operate as an auxiliary input to the ADCs, as a battery monitor,
or as a general-purpose input/output (GPIO). In addition, a
programmable interrupt output can operate in three modes: as a
general-purpose interrupt to signal when new data is available
(DAV), as an interrupt to indicate when limits are exceeded
(INT), or as a pen-down interrupt when the screen is touched
(PENIRQ). The AD7879/AD7889 offer temperature
measurement and touch pressure measurement.
The AD7879 is available in a 12-ball, 1.6 mm × 2 mm WLCSP
and in a 16-lead, 4 mm × 4 mm LFCSP. The AD7889 is available
in a backside coated version of the WLCSP. Both devices support
an SPI interface (AD7879/AD7889) or an I2C interface (AD7879-1/
AD7889-1).
Note that throughout this data sheet, multifunction pins, such
as PENIRQ/INT/DAV, are referred to either by the entire pin
name or by a single function of the pin, for example, PENIRQ,
when only that function is relevant.
Rev. D
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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Tel: 781.329.4700 ©2008–2016 Analog Devices, Inc. All rights reserved.
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Analog Devices AD7889
AD7879/AD7889
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
SPI Timing Specifications (AD7879/AD7889) ........................ 4
I2C Timing Specifications (AD7879-1/AD7889-1) ................. 5
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution.................................................................................. 6
Pin Configurations and Function Descriptions ........................... 7
Typical Performance Characteristics ............................................. 9
Terminology .................................................................................... 12
Theory of Operation ...................................................................... 13
Touch Screen Principles ............................................................ 13
Measuring Touch Screen Inputs ............................................... 14
Touch Pressure Measurement................................................... 15
Temperature Measurement ....................................................... 15
Median and Averaging Filters ....................................................... 17
AUX/VBAT/GPIO Pin................................................................... 18
REVISION HISTORY
8/2016—Rev. C to Rev. D
Changed CP-16-10 to CP-16-20 .................................. Throughout
Changes to General Description Section ...................................... 1
Changes to Figure 7, Figure 8, and Table 7 ................................... 8
Moved Figure 34; Renumbered Sequentially .............................. 30
Updated Outline Dimensions ....................................................... 39
Changes to Ordering Guide .......................................................... 39
11/2010—Rev. B to Rev. C
Changes to Table 2............................................................................ 3
Added Conversion Timing Section.............................................. 20
Added Figure 34.............................................................................. 29
1/2010—Rev. A to Rev. B
Updated Outline Dimensions ....................................................... 37
Changes to Ordering Guide .......................................................... 38
3/2009—Rev. 0 to Rev. A
Added AD7889 and Backside-Coated WLCSP ..............Universal
Change to Battery Monitor, Input Voltage Range Parameter..... 3
Changes to Table 4............................................................................ 6
Added Thermal Resistance Section and Table 5; Renumbered
Sequentially ....................................................................................... 6
Data Sheet
Auxiliary Input ........................................................................... 18
Battery Input ............................................................................... 18
Limit Comparison...................................................................... 18
GPIO ............................................................................................ 18
Conversion Timing ........................................................................ 20
Register Map ................................................................................... 21
Detailed Register Descriptions ..................................................... 22
Control Registers ............................................................................ 26
Control Register 1 ...................................................................... 26
Control Register 2 ...................................................................... 28
Control Register 3 ...................................................................... 30
Interrupts..................................................................................... 31
Synchronizing the AD7879/AD7889 to the Host CPU......... 32
Serial Interface ................................................................................ 33
SPI Interface ................................................................................ 33
I2C-Compatible Interface .......................................................... 35
Grounding and Layout .................................................................. 38
Lead Frame Chip Scale Packages ............................................. 38
WLCSP Assembly Considerations........................................... 38
Outline Dimensions ....................................................................... 39
Ordering Guide .......................................................................... 40
Changes to Pin Configurations and Function Descriptions Section ..7
Added Table 7 ....................................................................................8
Changes to First Method Section ................................................. 15
Changes to Median and Averaging Filters Section .................... 17
Changes to GPIO Interrupt Enable (Bit 12, Control Register 3,
Address 0x03) Section ................................................................... 19
Changes to Table 13 ....................................................................... 22
Changes to ADC Channel (Control Register 1, Bits[14:12])
Section.............................................................................................. 26
Changes to Power Management (Control Register 2,
Bits[15:14]) Section ........................................................................ 27
Changes to DAV—Data Available Interrupt Section................. 29
Changes to INT—Out-of-Limit Interrupt Section .................... 29
Changes to Writing Data Section................................................. 31
Changes to Reading Data Section and Figure 40 ....................... 32
Changes to Figure 41...................................................................... 33
Changes to Writing Data over the I2C Bus Section.................... 34
Changes to Figure 44...................................................................... 35
Updated Outline Dimensions....................................................... 37
Changes to Ordering Guide. ......................................................... 38
10/2008—Revision 0: Initial Version
Rev. D | Page 2 of 40



Analog Devices AD7889
Data Sheet
AD7879/AD7889
SPECIFICATIONS
VCC = 1.6 V to 3.6 V, TA = −40°C to +85°C, unless otherwise noted.
Table 1.
Parameter
DC ACCURACY
Resolution
No Missing Codes
Integral Nonlinearity (INL)1
Differential Nonlinearity (DNL)1
Negative DNL
Positive DNL
Offset Error1, 2
Gain Error1, 2
Noise3
Power Supply Rejection3
Internal Clock Frequency
Internal Clock Accuracy
SWITCH DRIVERS
On Resistance1
Y+, X+
Y−, X−
ANALOG INPUTS
Input Voltage Range
DC Leakage Current
Input Capacitance
Accuracy
TEMPERATURE MEASUREMENT
Temperature Range
Resolution
Accuracy2
BATTERY MONITOR
Input Voltage Range
Input Impedance3
Accuracy
LOGIC INPUTS (DIN, SCL, CS, SDA, GPIO)
Input High Voltage, VINH
Input Low Voltage, VINL
Input Current, IIN
Input Capacitance, CIN3
LOGIC OUTPUTS (DOUT, GPIO, SCL, SDA, INT)
Output High Voltage, VOH
Output Low Voltage, VOL
Floating State Leakage Current
Floating State Output Capacitance2
CONVERSION RATE3
Conversion Time
Min
12
11
1.8
0
−40
0.5
0.7 × VCC
VCC − 0.2
Typ
12
±2
70
60
2
6
5
±0.1
30
0.3
0.3
±2
16
2
0.01
10
±0.1
5
9.5
Throughput Rate
105
Max
±3
−0.99
2
±6
±4
2.2
Unit
Bits
Bits
LSB
LSB
LSB
LSB
LSB
µV rms
dB
MHz
MHz
VCC V
µA
pF
%
+85 °C
°C
°C
5V
kΩ
5%
0.3 × VCC
V
V
µA
pF
V
0.4 V
µA
pF
µs
kSPS
Test Conditions/Comments
LSB size = 390 µV
LSB size = 390 µV
Calibrated at 25°C
Uncalibrated accuracy
VIN = 0 V or VCC
Including 2 µs of acquisition time, median
and averaging (MAV) filter off; 2 µs of add-
itional time is required if the MAV filter is on
Rev. D | Page 3 of 40





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