AK4181AVTP-E2 - AKM Semiconductor

[AK4181A]

MS0313-E-02 2010/09

AK4181A Touch Screen Controller

AIN+

AIN-

Internal VREF(2.5V)

12bit

ADC

(SAR type)

VREF+ VREF-

VBAT

VREF

DCLK

CSN

DIN

DOUT

IN1

BUSY

PENIRQN

VCC GND

Control

Logic

IN2

Temp.

Sensor

PEN

INTERRUPT

Block Diagram

Features:

 Sampling Frequency: 125kHz(max)

 Pen Pressure Measurem ent

 On-Chip Thermo Sensor

 Two Auxiliary Analog Inputs

 Direct Battery Measurement

 4-wire I/F

 On-Chip Voltage Reference (2.5V)

 12 bit SAR type A/D Converter with S/H circuit

 Low Power Consumption (250μA)

 Low Voltage Operation (2.7V - 3.6V)

 Package 16pin TSSOP

General Description:

The AK4181A is a 4-wire touch screen controller that

incorporates a 12-bit 125k Hz sampling SAR A/D converter.

The AK4181A can detect the p ressed screen location by

performing two A/D conversions. In addition to location, the

AK4181A also measures touch screen pressure.

On-chip VREF can be utilized for two analog auxiliary

inputs and battery monitoring, with the ability to measure

voltages from 0V to 5V.

The AK4181A also has an o n-chip temperature sensor.

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 Ordering Guide

AK4181AVT -20°C ∼ +70°C 16pinTSSOP

 Pin Layout

Top View

1 VCC

GND

VBAT 7

IN1 8

16 DCLK

CSN

DIN

BUSY

DOUT

PENIRQN

10 IN2

9 VREF

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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/IN1/IN2 Measurement: OPEN state

 Pen Waiting State: Pulled up by an internal resistor (typ.50k ohm).

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/IN1/IN2 Measurement: 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/IN1/IN2 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/IN1/IN2 Measurement: OPEN state

 Pen Waiting State: connected to GND.

6 GND - Ground

7 VBAT I Analog Input for Battery Monitor

8 IN1 I Auxiliary 1 Analog Input

9 VREF I/O Voltage Reference Input/Output

Outputs 2.5V

10 IN2 I Auxiliary 2 Analog Input

11 PENIRQN O Pen Interrupt Output

This pin should be pulled up via a 100k-ohm resistor. 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 8th DCLK and the falling edge of 9th 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”

AK4181A 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

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Absolute Maximum Ratings

GND=0V (Note 1)

Parameter Symbol Min max Units

Power Supplies VCC -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 -20 70 °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

Note 1. All voltages with respect to ground.

WARNING: AKM assumes no responsibility for the usage beyond the conditions in this datasheet.

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Analog Characteristics

Ta=-20°C to 70°C, VCC=2.7V, External Vref =2.5V, fs=125kHz, fDCLK=16*fs, 12bit mode

Parameter min typ max Units

ADC for Touch Screen

Resolution 12 Bits

No Missing Codes 11 12 Bits

Integral Linearity Error ±2 LSB

DNL

±1 LSB

Analog Input Voltage Range 0 Vref V

Offset Error ±6 LSB

Gain Error ±4 LSB

Touch Panel Driver

XP, YP, RL=300Ω

XN, YN, RL=300Ω

XP Pull Up Register (when pen interrupt enable) 50 KΩ

PSRR (10KHz 100mVpp) 70 dB

Reference Output

Internal Reference 2.44 2.50 2.56 V

Drift 30

ppm/°C

Load Capacitance 0.1 μF

Reference Input

Input Voltage Range VCC V

Battery Monitor

Input Voltage Range 5.0 V

Input Impedance (Battery Measure Mode) 5 10 KΩ

Accuracy (Note 2) External VREF = 2.5V is used ±2 %

Accuracy (Note 2) Internal Reference is used. ±3 %

Temperature Measuremen t

Temperature Range -20 70 °C

Resolution (Note 3) 1.6

°C

Accuracy (Note 4) ±3 °C

Power Supply Current

Normal Mode (Internal Reference OFF) 250 500 μA

Normal Mode (Internal Reference ON) 520 800 μA

Full Power Down(when writing control command with PD1=PD0= “0”) 0 3 μA

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.

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DC Characteristics (L ogic I/O)

Ta=-20 to 70°C, VCC=2.7V to 3.6V

Parameter Symbol min typ max Units

“H” level input voltage VIH 0.8xVCC - V

“L” level input voltage VIL - 0.2xVCC V

Input Leakage Current IILK -10 10 μA

“H” level output voltage (@ Iout = -250uA) VOH VCC-0.4 - V

“L” level output voltage (@ Iout= 250uA) VOL - - 0.4 V

Tri-state Leakage Current

All pins except for XP, YP, XN, YN pins

XP, YP, XN, YN pins

IOLK

-10

-50

μA

PENIRQN “L” level output voltage (100KΩ Pull-Up) VOLP 0.8 V

Switching Characteristics

Ta=-20°C to 70°C, VCC=2.7V to 3.6V

Parameter Symbol min typ max Units

Touch Panel (A/D Converter)

Throughput Rate Fs 125 kHz

DCLK

frequency

duty

fDCLK

duty

2100

kHz

Tracking Time (Rin=600Ω) (Note 5) tTRK 1.428 μs

Conversion Time tCONV 12 1/fDCLK

CSN “↓” to First DCLK “↑” t1 100 ns

CSN “↓” to BUSY Tri-State Disabled t2 200 ns

CSN “↓” to DOUT Tri-State Disabled t3 200 ns

DCLK High Pulse Width t4 190 ns

DCLK Low Pulse Width t5 190 ns

DCLK “↓” to BUSY “↑” t6 160 ns

Data Setup Time t7 100 ns

Data Valid to DCLK Hold Time t8 10 ns

Data Access Time after DCLK “↓” t9 160 ns

CSN “↑” to DCLK Ignored t10 0 ns

CSN “↑” to BUSY High-Z state t11 200 ns

CSN “↑” to DOUT High-Z state t12 200 ns

Note 5. The actual tracking periods are 3tDCLK. (tDCLK=1/fDCLK)

CSN

DCLK

DIN

BUSY

DOUT

t4 t5

t7 t8

t6 t6 t9 t10

t11

t12

PD0

D11 D10 D0

50%VCC

VOH

VOL

50%VCC

VOL

VOH

Figure 1 AK4181A Timing Diagram

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 A/D Converter for Touch Screen

The AK4181A incorporates a 12-bit successive approximation resistor (SAR) A/D converter for position measurement,

temperature, and battery voltage. The architecture is based on capacitive redistribution algorithm, and an internal capacitor array

functions as the sample/hold (S/H) circuit.

The SAR A/D converter output is a straight binary format as shown below:

Input Voltage Output Code

(ΔVREF-1.5LSB)~ ΔVREF FFFH

(ΔVREF-2.5LSB) ~ (ΔVREF-1.5LSB) FFEH

--------- ---------

0.5LSB ~ 1.5LSB 001H

0 ~ 0.5LSB 000H

ΔVREF: (VREF+) – (VREF-)

Table 1 Output Code

The full scale (ΔVREF) of the A/D converter depends on the input mode. The AK4181A is controlled by the 8 bit serial command

on DIN.

 Analog Inputs

Analog input is selected via the A2, A1, A0 and SER/ DFR bits in the control register. If the analog inputs are selected to the X

or Y-axis, SER/ DFR = “0”, which means differential mode, the full scale (ΔVREF) is the differential voltage between the non-

inverting terminal and the inverting terminal of the measured axis (e.g. X-axis measurement:(XP) – (XN)). Analog non-inverting

input to A/D converter is the non-inverting terminal of the non-measured axis while the inverting input is the inverting terminal of

the measured axis. If the SER/ DFR bit is set to “1” which means single-ended mode, the full scale of A/D converter (ΔVREF)

is the internal reference voltage or external reference voltage. Note that SER/ DFR bit should be set to ”0” if IN2 is selected as

analog input; nevertheless, IN2 is actually measured by single-ended mode.

Tracking time is the period from the falling edge of 5th DCLK to that of 8th DCLK after the detection of START bit during

CSN=”L”.

The required settling time to charge the internal capacitor array depends on the source impedance (Rin). If the source impedance is

600 ohm, the settling time needs at least 1.428μs (3tDCLKat 2.1MHz). The maximum throughput of A/D converter is 125 kHz.

If the source impedance of analog input or battery input is larger than 600 ohm, longer tracking time is required.

 The Position Detection of Touch Sc reen

The position on the touch screen is detected by taking the voltage of one axis when the voltage is supplied between the two

terminals of another axis. At least two A/D conversions are needed to get the two-dimensional (X/Y axis) position.

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VREF

VREF-

ADC AIN+

AIN-

a) X-Position Measurement Differentia l Mode b) Y-Position Measurement Differential Mode

VREF

VREF-

ADC AIN+

AIN-

Figure 2 Axis Measurement

The differential mode position detection is typically more accurate than the single-ended mode. As the full scale of single-ended

mode is fixed to the internal (or external) reference voltage, input voltage may exceed the full-scale reference voltage. This

problem does not occur in differential mode. In addition to this, the differential mode is less influenced by power supply voltage

variation due to the ratio-metric meas urem ent.

However, note that the touch screen driver switch is still ON and the current flows even for the A/D conversion time. On the other

hand, the touch scre en driver switch is ON only for the tracking time, 3tDCLK. From the poi nt of power consumption, singl e-

ended mode has more advantages.

 The Pen Pressure Measurement

The touch screen pen pressure can be derived from the measurement of the contact resistor between two plates. The contact

resistance depends on the size of the depressed area and the pressure. The area of the spot is proportional to the contact resistance.

This resistance (Rtouch) can be calculated using two different methods.

The first method is that when the total resistance of the X-plate sheet is already known. The resistance, Rtouch, is calculated from

the results of three conversions, X-position, Z1-Position, and Z2-Position, and then using the following formula:

Rtouch = (Rxplate) * (Xposition/4096) * [ (Z2/Z1) – 1]

The second method is that when both the resistances of the X-plate and Y-plate are known. The resistance, Rtouch, is calculated

from the results of three conversions, X-position, Y-Position, and Z1-Position, and then using the following formula:

Rtouch = (Rxplate*Xposition/4096)*[(4096/Z1) – 1] – Ryplate*[1 – (Yposition/4096)]

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ON YN

VREF+

VREF-

ADC AIN+

AIN-

a) Z1-Position Measurement Differential Mode

touch

ON YN

VREF+

VREF-

ADC AIN+

AIN-

b) Z2-Position Measurement Differential Mode

touch

Figure 3 Pen Pressure Measurements

 Voltage Reference

The AK4181A has an internal 2.5V voltage reference. This reference can be turned ON when PD1 = “1”, and OFF when PD1 =

“0”. This reference is used in the single-ended mode for the battery monitoring, temperature measurement, or for auxiliary input.

A 0.1μF or larger capacitor should be connected for stable operation of the VREF circuit. Settling time depends on this external

capacitance, but 400μs or longer time is required if the external capacitance is 0.1μF.

If an external voltage reference is used, PD1 bit should be set to “0”.

 Battery Measureme nt

The AK4181A can directly measure the battery voltage up to 5V while the AK4181A operates at 2.7V to 3.3V. The input voltage

is internally divided down by 4 and applied to the input of AD converter (AIN+). Minimum 5μs is required as tracking time. If

the source impedance is larger, more tracking time is required.

PD1

Internal

VREF(2.5V)

R1=7.5K

R2=2.5K

VBAT

ADC

Enable

R0 AIN+

AIN-

VREF+

VREF-

VREF

Figure 4 Battery Monitoring

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 Temperature Measure ment

Equation <1> describes the forward characteristics of the diode.

iD=I0exp(vD/VT) ( VT = kT/q) <1>

I0: reverse saturation current

q : 1.602189×10-19 (electron charge)

k : 1.38054×10-23 (Boltzmann’s constant)

vD: voltage across diode

T: absolute temperature K

The diode characteristic is approximately shown as a diode junction voltage. That is theoretically proportional to the temperature;

the ambient temperature can be predicted by knowing this voltage.

Temp.

Sensor

TEMP0 TEMP1

I 82I

Figure 5 Temperature Measurement

As the AK4181A has two different fixed current circuits and a diode (temperature sensor), the tem perature can be measured by

using two different methods.

The first method needs two conversions, but can derive the temperature directly without knowing the voltage at a specific

temperature.

From equation <1>

(iD2 / iD1) = exp{(v(NI) - v(I))/VT} N = (iD2 / iD1) = 82 (ratio of the current)

T°C = (ΔVbe * q)/(k * ln N) – 273

ΔVbe = V(82I) – V(I)

T°C = 2.63×103 × ΔVbe – 273

The second method needs only one conversion as the following equation, but requires knowing the junction voltage at the specific

temperature.

T = (k/q)* vD/ln(iD/I0) <2>

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 Control Command

The control command, 8 bits, provided to the AK4181A via DIN is shown in the following table. This command includes start bit,

channel selection, resolution, measurement configuration, and power-down mode. The AK4181A latches the serial command at

the rising edge of DCLK. Table 2 gives detailed information regarding the bit order, function, the status of driver switch, ADC

input, reference voltage.

D7 D6 D5 D4 D3 D2 D1 D0

S A2 A1 A0 MODE

SER/ DFR PD1 PD0

BIT Name Function

7 S Start Bit. This bit must be “H” because the AK4181A initiates the command recognition

6-4 A2-A0 Channel Selection Bits. Analog inputs to the A/D converter and the activated driver switches are

selected. Please see the following table for the detail.

3 MODE Resolution of A/D converter. ”L”: 12 bit output “H”: 8 bit output

2 SER/ DFR Measurement Mode (Single-Ended/Differential)

3 PD1-PD0 Power-down Mode (reference to “ Power-down Control”)

Control Command Status of Driver Switch ADC input (ΔAIN) Reference Voltage

(ΔVREF)

A2 A1 A0 SER/

DFR

XP XN YP YN AIN+ AIN- VREF+ VREF- Note

0 0 0 1 OFF OFF OFF OFF TEMP0 GND VREF GND TEMP0

0 0 1 1 OFF OFF ON ON XP GND VREF GND Y-axis

0 1 0 1 OFF OFF OFF OFF VBAT GND VREF GND Battery Monitor

0 1 1 1 OFF ON ON OFF XP(Z1) GND VREF GND Z1 (Pen Pressure)

1 0 0 1 OFF ON ON OFF YN(Z2) GND VREF GND Z2 (Pen Pressure)

1 0 1 1 ON ON OFF OFF YP GND VREF GND X-axis

1 1 0 1 OFF OFF OFF OFF IN1 GND VREF GND IN1

1 1 1 1 OFF OFF OFF OFF TEMP1 GND VREF GND TEMP1

0 0 0 0 NA

0 0 1 0 OFF OFF ON ON XP YN YP YN Y-axis

0 1 0 0 NA

0 1 1 0 OFF ON ON OFF XP(Z1) XN YP XN Z1 (Pen Pressure)

1 0 0 0 OFF ON ON OFF YN(Z2) XN YP XN Z2 (Pen Pressure)

1 0 1 0 ON ON OFF OFF YP XN XP XN X-axis

1 1 0 0 OFF OFF OFF OFF IN2 GND VREF GND IN2 (Note 6)

1 1 1 0 NA

Note 6. Note that IN2 auxiliary input is measured by single-ended mode although SER/ DFR bit is “0”.

Table 2 Control Command List

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 Power-down Control

Power-down is controlled by two bits, PD0 bit and PD1 bit. The power-down state of internal voltage reference is controlled by

PD1 bit, and is updated at the rising edge of 7th DCLK with CSN = “L”.

The power-down state of A/D converter, and touch screen driver switches is controlled by PD0 bit, and is updated at the rising

edge of 8th DCLK with CSN = “L”.

If PD0 bit is set to “1”, the state of the driver switches is maintained until the 5th DCLK↑ of the next conversion if CSN is “L”. If

CSN is “H”, all driver switches except for YN switch switches are turned off and are open states. Only YN driver switch is turned

ON and YN pin is forced to the ground in this case.

PD1 PD0 PENIRQN Function

0 0 Enabled Auto Power-down Mode.

A/D converter is automatically powered up at the start of the conversion, and goes to power- down

state automatically at the end of the conversion. And the AK4181A is always powered down at this

mode if CSN= “H”. All touch screen driver switches except for YN switch are turned off and

relative pins are open state. Only YN driver switch is turned ON and YN pin is forced to the ground

in this case. PEN interrupt function is enabled except for the tracking time and conversion time even

CSN= “L”. Please se e “ PEN Interrupt” for the detail. The internal voltage reference is always

power-down state.

0 1 Enabled ADC ON Mode

A/D converter is always powered up while CSN = “L”. The internal voltage reference is always

power-down state. If X-axis or Y-axis is selected as analog input, touch screen driver switches are

always turned ON and the current flows through the touch plate if CSN= “L”. This is effective if

more settling time is required to suppress the electrical bouncing of touch plate.

1 0 Enabled VREF ON Mode

The internal voltage reference is always powered up regardless of CSN state. ADC is auto power-

down mode. PEN interrupt function is enabled at all the period except for the period from the

5DCLK↓ to 20DCLK↓ regardless of CSN state.

1 1 Disabled ADC and VREF ON Mode

A/D converter and the internal voltage reference is power-up state

PEN interrupt function is disabled and PENIRQN is forced to “H” state if CSN= “H”. The behavior

of PENIRQN is the same as “ADC ON Mode”

Table 3 Power-down Control

 Serial Interface

The AK4181A is controlled via 4-wire serial interface, CSN, DCLK, DIN, DOUT.

Please see “ Switching Characteristics” for the detail.

SER/

DFR

BUSY

DOUT

S A2 A0 A1 MO PD1

PD0

SER/

DFR

DCLK

DIN

11 9 8 7 6 5 4 3 2 1 0 10

CSN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Driver SW

SER/ DFR =”1”

Driver SW

SER/ DFR =”0”

S A2 A0 A1 MO

PD1 PD0

Hi-Z

Hi-Z 10

Figure 6 Serial Interface

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BUSY and DOUT goes to “L” from Hi-Z state at the falling edge of CSN. The AK4181A latches the 8bit control word serially via

DIN at the rising edge of DCLK. As the AK4181A starts the command decoding at the first “H” bit after CSN= “↓”, MSB (S bit)

of the command must be “H”.

Tracking time is the period from the falling edge of 5th DCLK to the falling edge of 8th DCLK. If SER/ DFR = “1”, PD0= “0”,

and if analog input is X-axis or Y-axis (the measurement is the pen position or pen pressure), the touch screen driver switches are

turned ON for this 3DCLK period. If SER/ DFR = “0”, the switches are turned ON for the period from 5DCLK↓ to 20 DCLK↓.

BUSY is “H” for one DCLK period, which is from 8DCLK↓ to 9DCLK↓. BUSY is “L” for other period.

The AK4181A outputs A/D data with MSB first via DOUT from the falling edge of 9th DCLK.

DIN must keep low stat e for mi nimum 7 DCLK times (9th-15th DCLK) after command is sent on the DIN.

The AK4181A can output one A/D data per 15 DCLK clock cycles for the fastest way as shown in the dotted line of the Figure 6.

 Pen Interrupt

The AK4181A has pen interrupt function to detect the pen touch. Pen interrupt function is enabled at power-down state. YN pin is

connected to GND at the PEN interrupt enabled state. And XP pin is pulled up via an internal resistor (Ri), typically 50k ohm.

PENIRQN pulled up via an external resistor, 100k ohm, is also connected to XP pin. If touch plate is pressed by pen the current

flows via <VCC> – <Ri> – <XP> –<the plates> - <YN>. The resistance of the plate is generally 1k ohm or less, PENIRQN is

forced to “L” level. If the pen is released, PENIRQN returns “H” level because two plates are disconnected, and the current

doesn’t flow via two plates.

If the plate is touched with pen or finger, PENIRQN goes to “L” at CSN = “H” unless previous command issued with both PD1

and PD0 is “1”. PENIRQN is disabled and keeps “H” level regardless of the touched/non-touched state if CSN = “H”.

The operation of PENIRQN is related to PD0 bit. PD0 bit is updated at the rising edge of 8th DCLK (please see “ Power-down

Control” for the detail). Therefore, the last PD0 bit is valid until this timing. (The internal voltage reference is controlled by only

PD1 bit regardless of PD0 bit and CSN state.)

i. The period from the 5th DCLK↓ to the 20th DCLK↓

The behavior of PENIRQN is related to the selected analog input. If the X-axis or Y-axis is selected as analog input, PENIRQN

is forced to “L” regardless of the touched/non-touched state. If the temperature, VBAT, or auxiliary inputs is selected,

PENIRQN is forced to “H” regardless of the touched/non-touched state.

ii. The period from CSN↓ to the 5th DCLK.

The behavior of PENIRQN is related to the combination of the last selected analog input channel, and the last PD0 bit. If the

last PD0 bit was set to “0”, PENIRQN is “H” while the plate is not pressed, and “L” while the plate is pressed regardless of the

last analog input. If the last PD0 bit was set to “1”, the last analog input decides the level of PENIRQN. If the last analog input

channel is ether X-axis or Y-axis, PENIRQN is “L” for all the time in this period regardless of the touched/non-touched state.

On the other hand, if the last analog input is te mperature, VBAT, or auxiliary inputs, PENIRQN is “H” for all the time in this

period regardless of the touched/non-touched state.

iii. The period from the 20th DCLK↓ to CSN↑

The behavior of PENIRQN is related to the combination of the current selected analog input channel, and the current PD0 bit.

If the current PD0 bit is set to “0”, PENIRQN is “H” while the plate is not pressed, and “L” while the plate is pressed regardless

of the current selected analog input. If the current PD0 bit is set to “1”, the current analog input decides the operation of

PENIRQN. If the current analog input channel is ether X-axis or Y-axis, PENIRQN is “L” for all the time in this period

regardless of the touched/non-touched state. On the other hand, if the current analog input is temperature, VBAT, or auxiliary

inputs, PENIRQN is “H” for all the time in this period regardless of the touched/non-touched state.

It is recommended that the micro controller mask the pseudo-interrupts while the control command is issued or A/D data is output.

Full power down (CSN = “H”, DIN = “H”, DCLK= “L” or “H”) should force internal register to initial value 00H and XP, YP, XN

pin to Hi-z state. In addition to this, the current does not flow even if the plate is touched with pen or finger. PENIRQN goes to

“H” regardless of pen touch at full power.

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PENIRQN

Driver ON

100kΩ

EN2

50kΩ Driver OFF

EN1

Figure 7 PENIRQ Functional Block Diagram

BUSY

DOUT

S A2 A0

A1 MO PD1 PD0

SER/

DFR

DCLK

DIN

11 9 8 7 6 5 4 3 2 1 0 10

CSN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

CONV

Internal

AXIS = ((!A2) & (!A1) & (A0)) /* X-axis Measurement */

| ((!A2) & (A1) & (A0)) /* Z1 Measurement */

| ((A2) & (!A1) & (!A0)) /* Z2 Measurement */

| ((A2) & (!A1) & (A0)); /* Y-axis Measurement */

EN1 = ((!CSN) & (!CONV) & AXIS & PD0)

/* CSN=”L”, X/Y/Z1/Z2 Measurement, PD0 = 1, NOT “CONV period” */

| ((!CSN) & AXIS & CONV);

/* CSN=”L”, X/Y/Z1/Z2 Measurement, “CONV period” */

EN2 = ((!CSN) & (!CONV) & (!PD0))

/* CSN=”L”, PD0 = 1, NOT “CONV period” */

| (CSN & (!(PD1& PD0));

/* CSN=”H”, (PD0, PD1) is not (1,1) */

 Power on Sequence

On the AK4181A first powers up, the register value including power down mode, internal reference (PD1, PD0) holds unfixed

before sending first control command. On this condition pen interrupt function may be disable, i nternal re ference may also be ON

state ([PD1, PD0] = [1,1]). 8bit control command must be sent as quick as possible when first power up to fix the internal register

value. The sequence is that 1) Power On with CSN = “L” or “H” then CSN = “H”. 2) Send control command after CSN = “L”. 3)

CSN = “H” again. Once sending command to fix the internal register after first power up, the state of AK4181A is held on the

condition of state as last command issued.

[AK4181A]

MS0313-E-02 2010/09

Package

0-10°

Detail A

Seating Plane 0.10

0.17±0.05

0.22±0.1 0.65

*5.0±0.1 1.1 (max )

1 8

9 16

16pin TSSOP (Unit: mm)

*4.4±0.1

6.4±0.2

0.5±0.2

0.1±0.1

NOTE: Dimension "*" does not include mold flash.

0.13 M

 Package & Lead frame material

Package molding compound: Epoxy

Lead frame materia l : Cu

Lead frame surface treatment: Solder (Pb free) plate

[AK4181A]

MS0313-E-02 2010/09

Marking

AKM

4181AVT

XXYYY

Contents of XXYYY

XX: Lot #

YYY: Date Code

Date (YY/MM/DD) Revision Reason Page Contents

04/08/30 01 First Edition

10/09/17 02 Specification

Change 15 Package

The package dimensions were changed.

REVISION HISTORY

[AK4181A]

MS0313-E-02 2010/09

IMPORTANT NOTICE

z These products and their specifications are subject to change without notice.

When you consider an y us e or application of these products, please make inquiries the sales office of Asahi Kasei

Microdevices Corporation (AKM) or authorized distributors as to current status of the products.

z Descriptions of external circuits, application circuits, software and other related information contained in this

document are provided only to illustrate the operation and application examples of the semiconductor products.

You are fully responsible for the incorporation of these external circuits, application circuits, software and other

related information in the design of your equipments. AKM assumes no responsibility for any losses incurred by

you or third parties arising from the use of these information herein. AKM assumes no liability for infringement

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or other hazard related device or systemNote2), and AKM assumes no responsibility for such use, except for the

use approved with the express written consent by Representative Director of AKM. As used here:

Note1) A critical component is one whose failure to function or perform may reasonably be expected to

result, whether directly or indirectly, in the loss of the safety or effectiveness of the device or system

containing it, and which must therefore meet very high standards of performance and reliability.

Note2) A hazard related device or system is one designed or intended for life support or maintenance of

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places the product with a third party, to notify such third party in advance of the above content and conditions,

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from any and all claims arising from the use of said product in the absence of such notification.