[AK4185]
AK4185
Low Power Touch Screen Controller with SPI™ Interface
GENERAL DESCRIPTION
The AK4185 is a 4-wire/ 5-wire resistive touch screen controller that incorporates 12bit SAR A/D
converter. The AK4185 operates down to 1.6V supply voltage in order to connect a low voltage
microprocessor. The AK4185 can detect the pressed screen location by performing two A/D conversions
and it can also measure touch pressure. The AK4185 is the best fit for cellular phone, DSC, DVC, smart
phone, or other portable devices.
FEATURES
4-wire or 5-wire Touch Screen Interface
SPI
TM
Serial Interface
12bit SAR A/D Converter with S/H circuit
Sampling Frequency: 300Ksps
Pen Pressure Measurement (4-wire)
Continuous Read Function (External Clock Mode)
Integrated Internal Osc (Sequence Mode)
Low Voltage Operation: VDD = 1.6V ~ 3.6V
PENIRQN Buffer Output
Low Power Consumption: 240μA at 1.8V
Auto Power Down
Package: 12pin CSP (1.96mm x 1.46mm, pitch 0.5mm)
Software Compatible with AK4182A
VDD
XP/BR
YP/TR
XN/TL
YN/BL
IN/
WIPER
TEMP
Internal
Osc
CSN
4/5wire
Touch
Screen
Drivers
Interface
SPI
Serial I/F
&
Control
Logic
DIN
SCLK
DOUT
PENIRQN
VREF+
AIN+
MUX
AIN-
SAR
ADC
VREF-
VSS
Figure 1. Block Diagram
SPI
TM
is a registered trademark of Motorola, Inc.
MS0954-E-00
-1-
2008/05
[AK4185]
■
Ordering Guide
AK4185ECB
−40 ∼
+85°C
12pin CSP (1.96mm x 1.46mm, 0.5mm pitch)
AKD4185
AK4185 Evaluation Board
Black Type
■
Pin Layout
3
Top View
2
1
A
B
C
D
3
2
1
XP/BR
VDD
IN/WIPER
A
YP/TR
CSN
PENIRQN
B
XN/TL
DIN
DOUT
C
YN/BL
VSS
SCLK
D
TOP View
MS0954-E-00
-2-
2008/05
[AK4185]
PIN/FUNCTION
No.
C2
B2
D1
A2
A3
B3
C3
D3
D2
A1
B1
Pin Name
DIN
CSN
SCLK
VDD
XP
BR
YP
TR
XN
TL
YN
BL
VSS
IN
WIPER
PENIRQN
I/O
I
I
I
-
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
-
I
I
O
Function
Serial Data Input
Data is clocked on the rising edge of SCLK. Must keep “L” while not issuing
command.
Chip Select Input
Enables writing data to registers when CSN = “L”.
Serial Clock Input
Power Supply and External Reference Input: 1.6V ~ 3.6V
Touch Panel X+ Input (4-wire, PANEL bit = “0”)
Touch Panel Bottom Right Input (5-wire, PANEL bit = “1”)
Touch Panel Y+ Input (4-wire, PANEL bit = “0”)
Touch Panel Top Right Input (5-wire, PANEL bit = “1”)
Touch Panel X- Input (4-wire, PANEL bit = “0”)
Touch Panel Top Left Input (5-wire, PANEL bit = “1”)
Touch Panel Y- Input (4-wire, PANEL bit = “0”)
Touch Panel Bottom Right Input (5-wire, PANEL bit = “1”)
Ground
Auxiliary Analog Input (4-wire, PANEL bit = “0”)
Top Touch Panel Input (5-wire, PANEL bit = “1”)
Pen Interrupt Output (CMOS output)
The PENIRQN pin is “L” when touch-screen press is detected and CSN = “H”. This
pin is always “H” irrespective of touch-screen press when pen interrupt is not
enabled.
Serial A/D Data Output
Data is clocked at SCLK falling edge. This pin is Hi-Z when CSN keeps “H”.
C1
DOUT
O
Note 1. All digital input pins (DIN, CSN, SCLK) must not be left floating.
MS0954-E-00
-3-
2008/05
[AK4185]
■
Handling of Unused Pin
The unused I/O pin must be processed appropriately as below.
Classification
Analog
Pin Name
IN/WIPER
Setting
This pin must be open.
ABSOLUTE MAXIMUM RATINGS
(VSS = 0V (Note
2))
Parameter
Power Supply
Input Current, Any Pins except for supply
Touch Panel Drive Current
Input Voltage (Note
3)
Ambient Temperature (power applied)
Storage Temperature
Symbol
VDD
IIN
IOUTDRV
VIN
Ta
Tstg
min
-0.3
-
-
−0.3
-40
-65
max
4.6
±10
50
VDD+0.3 or 4.6
85
150
Units
V
mA
mA
V
°C
°C
Note 2. All voltages with respect to ground.
Note 3. XP/BR, XN/TL, YP/TR, YN/TL, IN/WIPER, CSN, DIN and SCLK pins. The maximum value is smaller value
between (VDD+0.3)V and 4.6V.
WARNING: Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
RECOMMEND OPERATING CONDITIONS
(VSS = 0V (Note
2))
Parameter
Power Supply
Note 2. All voltages with respect to ground.
WARNING: AKEMD assumes no responsibility for the usage beyond the conditions in this datasheet.
Symbol
VDD
min
1.6
typ
1.8
max
3.6
Units
V
MS0954-E-00
-4-
2008/05
[AK4185]
ANALOG CHARACTERISTICS
(Ta = -40°C to 85°C, VDD = 1.8V, fSCLK = fs x 16=5.0MHz, 12bit mode)
Parameter
min
A/D Converter
Resolution
-
No Missing Codes
11
Integral Nonlinearity (INL) Error
-
Differential Nonlinearity (DNL) Error
-2
Offset Error
-
Gain Error
-
Touch Panel Drivers Switch On-Resistance
XP, YP
-
XN, YN
-
PENIRQ Pull Up Resistor R
IRQ
-
Auxiliary IN Input
Input Voltage Range
0
Temperature Measurement
Temperature Range
-40
Resolution (Note
4)
-
Accuracy (Note
5)
-
Power Supply Current
Normal Mode (Internal Oscillator mode) (Note
6)
VDD=18V
-
VDD=3.6V
-
Normal Mode (Bus clock mode) PD0 = “0” (Note
7)
VDD=1.8V
-
VDD=3.6V
-
Full Power Down (when writing control command with PD0 = “0”)
-
typ
12
12
-
±1
-
-
5
5
50
max
Units
Bits
Bits
LSB
LSB
LSB
LSB
Ω
Ω
kΩ
V
°C
°C
°C
μA
μA
μA
μA
μA
±2
+3
±6
±4
-
-
-
VDD
85
-
-
-
550
-
800
3
1.2
±3
240
-
340
-
0
Note 4. “Ideal” value derived from a theory when VDD = 1.8V. This value according to the supplied VDD voltage is
0.6466 x VDD.
Note 5. The typical value has +6°C(typ) offset.
Note 6. The signal of 1kHz, 1.6Vpp (-1dB) is input to the IN/WIPER pin, when COUNT bit = “0”, INTERVAL = 0µs and
command cycle is 50µs. DOUT C
L
= 0pF, the current of touch panel drivers is excluded.
Note 7. The signal of 1kHz, 1.6Vpp (-1dB) is input to the IN/WIPER pin, when Single Mode for external clock
(CONTINUE bit = “0”) and 15 SCLK clock cycles. DOUT C
L
= 0pF, the current of touch panel drivers is
excluded.
DC CHARACTERISTTICS (Logic I/O)
(Ta=-40°C to 85°C, VDD =1.6V to 3.6V)
Parameter
Symbol
min
Digital Input (CSN, SCLK, DIN)
“H” level input voltage
VIH
0.8xVDD
“L” level input voltage
VIL
-
Input Leakage Current.
IILK
-10
Digital Output (DOUT, PENIRQN)
VOH
VDD-0.4
“H” level output voltage (@ Iout = -250μA)
VOL
-
“L” level output voltage (@ Iout = 250μA)
Tri-state Leakage Current
IOLK
All pins except for XP, YP, XN, YN pins
-10
XP, YP, XN, YN pins
-10
typ
-
-
max
-
0.2xVDD
10
-
0.4
10
10
Units
V
V
μA
V
V
μA
μA
-
-
-
-
MS0954-E-00
-5-
2008/05
京公网安备 11010802033920号
EEWORLD
