ASAHI KASEI
[AK4182]
MS0411-E-00
2005/08
1
AK4182
Touch Screen Controller
Level
Shifter
DCLK
CSN
DOUT
DIN
BUSY
PEN
INTERRUPT
PENIRQN
VREF GND
Temp.
Sensor
12bit
ADC
(SAR type)
VREF+
AIN+
Internal VREF(2.5V)
VREF-
Control
Logic
R1
R2
AIN-
IOVDD
VCC
YN
XN
YP
XP
VBAT
IN
Block Diagram
Features:
12 bit SAR type A/D Converter with S/H circuit
Low Voltage Operation (VCC = 2.2V
3.6V)
Low Voltage Digital I/F (1.5V
VCC)
4-wire I/F
Sampling Frequency: 125 kHz (max)
On-Chip Voltage Reference (2.5V)
Pen Pressure Measurement
On-Chip Thermo Sensor
Direct Battery Measurement
Low Power Consumption (260
A)
Package 16pin
QFN
General Description:
The AK4182 is a 4-wire resistive touch screen controller
that incorporates a 12-bit 125 kHz sampling SAR type
A/D converter.
The AK4182 operates down to 2.2V supply voltage and
supports digital I/O interface voltage from 1.5V to VCC in
order to connect low voltage uP.
The AK4182 can detect the pressed screen location by
performing two A/D conversions. In addition to location,
the AK4182 also measures touch screen pressure.
On-chip VREF can be utilized for analog auxiliary input,
temperature measurement and battery monitoring with
the ability to measure voltage from 0V to 5V.
The AK4182 also has an on-chip temperature sensor.
The AK4182 is available in 16pin QFN thin package
(0.75mm in height) and has the operating temperature
range of -40
C
to +85
C
ASAHI KASEI
[AK4182]
MS0411-E-00
2005/08
2
Ordering Guide
AK4182VN -40
C +85C
16pinQFN
Pin Layout
VCC
XP
YP
XN
YN
G
ND
VB
AT
IN
PENIRQN
IOVDD
VREF
DOUT
DCLK
CS
N
BUSY
DIN
ASAHI KASEI
[AK4182]
MS0411-E-00
2005/08
3
Pin/Function
No. Signal
Name I/O
Description
1 VCC
- Power
Supply
2
XP
I/O
Touch Screen X+ plate Voltage supply
X axis Measurement: Supplies the voltage to X+ position input
Y axis Measurement: This pin is used as the input for the A/D converter
Pen Pressure Measurement: This pin is the input for the A/D converter at Z1 measurement.
Temperature/VBAT/IN Measurement: OPEN state
Pen Waiting State: Pulled up by an internal resistor (typ.50K
).
3
YP
I/O
Touch Screen Y+ plate Voltage supply
Y axis Measurement: Supplies the voltage to Y+ position input
X axis Measurement: This pin is used as the input for the A/D converter
Pen Pressure Measurement: Supplies the voltage.
Temperature/VBAT/IN Measurement: OPEN state
Pen Waiting State: OPEN state
4
XN
I/O
Touch Screen X- plate Voltage supply
X axis Measurement: Supplies the voltage to X- position input
Y axis Measurement: OPEN state
Pen Pressure Measurement: Supplies the voltage.
Temperature/VBAT/IN Measurement: OPEN state
5
YN
I/O
Touch Screen Y- plate Voltage supply
Y axis Measurement: Supplies the voltage to Y- position input
X axis Measurement: OPEN state
Pen Pressure Measurement: This pin is the input for the A/D converter at Z2 measurement.
Temperature/VBAT/IN Measurement: OPEN state
Pen Waiting State: connected to GND.
6 GND
- Ground
7
VBAT
I
Analog Input for Battery Monitor
8 IN
I Auxiliary
Analog
Input
9
VREF
I/O
Voltage Reference Input/Output
2.5V reference voltage output at PD1 = "1". Voltage reference input at PD1 = "0".
10
IOVDD
Digital I/O Power Supply
11
PENIRQN
O
Pen Interrupt Output
This pin is "L" during the pen down on pen interrupt enable state with CSN ="H" otherwise this
pin is "H". This pin is "H" during pen interrupt disable state with the CSN = "H" regardless pen
touch. See Power-down Control and Pen Interrupt for the reference.
12
DOUT
O
Serial A/D Data Output
Output A/D data serially at the falling edge of DCLK. MSB is output at the falling edge of
BUSY signal.
Output "L" at CSN= "L" during A/D data does not output.
This pin is Hi-Z state at CSN="H"
13 BUSY
O BUSY
Output
This pin goes to low at CSN = "L". BUSY signal is "H" only for the period between the falling
edge of 8
th
DCLK and the falling edge of 9
th
DCLK.
This pin is Hi-Z state at CSN= "H"
14 DIN
I Serial
Data
Input
Inputs 8-bit control command data serially when CSN= "L"
AK4182 latches at the rising edge of DCLK. Must keep "L" while not issuing commands.
15 CSN
I Chip
Select
Input
Enables writing data to the registers when CSN= "L".
16 DCLK
I External
Clock
Input
ASAHI KASEI
[AK4182]
MS0411-E-00
2005/08
4
Absolute Maximum Ratings
GND = 0V (Note 1)
Parameter Symbol
Min
max
Units
Power Supplies
VCC
-0.3
6.0
V
Digital I/O Power Supply
IOVDD
-0.3
6.0
V
Input Current (any pins except for supplies)
IIN
-
10
mA
Input Voltage
VIN
-0.3
6.0(VCC+0.3)
V
Touch Panel Drive Current IOUTDRV
50
mA
Ambient Temperature (power supplied)
Ta
-40
85
C
Storage Temperature
Tstg
-65
150
C
Note 1.All voltages with respect to ground.
WARNING: Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
Recommended Operating Conditions
GND = 0V (Note 1)
Parameter
Symbol
Min
typ
max
Units
Power Supplies
VCC
2.7
3.3
3.6
V
Digital I/O Power Supply
IOVDD
1.5
3.3
VCC
V
Note 1. All voltages with respect to ground.
WARNING: AKM assumes no responsibility for the usage beyond the conditions in this datasheet.
ASAHI KASEI
[AK4182]
MS0411-E-00
2005/08
5
Analog Characteristics
Ta=-40
C to 85C, VCC = IOVDD = 2.7V, External Vref=2.5V, fs = 125 KHz, fDCLK = 16 x fs, 12bit mode
Parameter min
typ
max
Units
ADC for Touch Screen
Resolution
12
Bits
No Missing Codes
11
12
Bits
Integral Nonlinearity (INL) Error
2
LSB
Differential Nonlinearity (DNL) Error
1
LSB
Analog Input Voltage Range
0
Vref
V
Offset Error
6
LSB
Gain Error
4
LSB
Touch Panel Driver
XP, YP, RL=300
XN, YN, RL=300
5
5
XP Pull Up Register (when pen interrupt enable)
50
K
PSRR (10KHz 100mVpp)
70
dB
Reference Output
Internal Reference
2.44 2.50 2.56 V
Drift
30
ppm/
C
Load Capacitance
0.1
F
Reference Input
Input Voltage Range
VCC
V
Battery Monitor
Input Voltage Range
5.0
V
Input Impedance (Battery Measure Mode)
5
10
K
Accuracy (Note 2) External VREF = 2.5V is used
2
%
Accuracy (Note 2) Internal Reference is used.
3
%
Temperature Measurement
Temperature Range
-40
85
C
Resolution (Note 3)
1.6
C
Accuracy (Note 4)
3
C
Power Supply Current
Normal Mode (Internal Reference OFF)
260
500
A
Normal Mode (Internal Reference ON)
540
800
A
Full Power Down(when writing control command with PD1=PD0= "0")
0
3
A
Note 2. Accuracy is the difference between the output code when 5 volts is input to the VBAT pin and the "ideal" code at 1.25
volts.
Note 3. "Ideal" value derived from theory
Note 4. Accuracy is defined as the difference between the voltage measured by two current sources, and the ideal voltage derived
from theory at specific temperatures.
PDF 
ZIP