AK4185 AKM [Asahi Kasei Microsystems], AK4185 Datasheet
AK4185
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AK4185 Summary of contents
Page 1
... 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. ...
Page 2
... Ordering Guide AK4185ECB −40 ∼ +85°C AKD4185 AK4185 Evaluation Board ■ Pin Layout MS0954-E-00 12pin CSP (1.96mm x 1.46mm, 0.5mm pitch) 3 Top View XP/BR YP/TR XN/TL VDD CSN DIN IN/WIPER PENIRQN DOUT TOP View - 2 - [AK4185] Black Type YN/BL VSS SCLK ...
Page 3
... 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. Data is clocked at SCLK falling edge. This pin is Hi-Z when CSN keeps “H” Function [AK4185] 2008/05 ...
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... WARNING: AKEMD assumes no responsibility for the usage beyond the conditions in this datasheet. MS0954-E-00 ABSOLUTE MAXIMUM RATINGS Symbol VDD IIN IOUTDRV VIN Ta Tstg RECOMMEND OPERATING CONDITIONS Symbol VDD - 4 - Setting This pin must be open. min max -0.3 4.6 - ± −0.3 VDD+0.3 or 4.6 -40 85 -65 150 min typ max 1.6 1.8 3.6 [AK4185] Units °C °C Units V 2008/05 ...
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... VDD-0 0 [AK4185] Units Bits Bits LSB LSB LSB LSB Ω Ω kΩ V °C °C °C μA μA μA μA μA Units V V μ μA μA 2008/05 ...
Page 6
... PD0 Figure 2. Timing Diagram - 6 - min typ max 2.5 3.6 5.1 - 300 - 30 - 5000 0 150 - - tCSI tDOD D11 D10 D0 [AK4185] Units MHz kHz KHz % μs 1/fSCLK tCSW 50%VDD 50%VDD 50%VDD tCCZ VOH VOL 2008/05 ...
Page 7
... The SAR A/D converter output is a straight binary format as shown below: (ΔVREF-2.5LSB) ~ (ΔVREF-1.5LSB) The AK4185 can select SCLK of the digital interface and internal clock within oscillator for A/D conversion clock. The full scale (ΔVREF) of the A/D converter depends on the input mode. Position and pen pressure is actually measured by differential mode, then IN and temperature is actually measured by single-ended mode ...
Page 8
... Figure 3. Axis Measurements for 4-wire Touch Screen MS0954-E-00 X-Plate YP-Driver Y-Plate VREF+ YP ADC VREF Y-Position Measurement Differential Mode 4-wire Touch Screen Construction - 8 - VDD XP AIN+ YP AIN- XN Touch Screen YN YN-Driver SW ON X-Plate (Top side) Y-Plate (Bottom side) [AK4185] X-Plate Y-Plate 2008/05 ...
Page 9
... Connect the metal contact of the top layer to the WIPER pin, which connected inside of the AK4185, to AIN+ to measure the Y-axis of current position. The top right and top left contacts at the 4 corners are connected to VDD and the bottom right and bottom left contacts connected to VSS ...
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... Y ⎟ ⎟ − − ⋅ ⎜ Position Y - plate Z ⎝ 4096 ⎠ 1 touch VREF+ ADC VREF- Figure 5. Pen Pressure Measurements - 10 - ⎞ ⎟ ⎠ VDD AIN+ AIN Z2-Position Measurement Differential Mode [AK4185] touch 2008/05 ...
Page 11
... The diode characteristic is approximately shown as a diode junction voltage. That is theoretically to the temperature; the ambient temperature can be predicated by knowing this voltage. As the AK4185 has two different fixed current circuits and a diode (temperature sensor), the temperature can be measured by using two different methods. ...
Page 12
... Digital I/F The AK4185 operates with the microprocessor via SPI with serial clock. The AK4185 operates off of supply voltage down to 1.6V in order to connect a low voltage microprocessor. 4/5-wire touch panel Standard Sequence: 8bit Control Command However Setup Command (write) writes Setup Function (4bit) after 8bit Control Command. ...
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... R/W =“0” omm and DIN Data Byte D7 D0 4bit Setup Function Figure 13. Setup Command Write R/W =“1” omm and DIN Byte Data DOUT Figure 14. Setup Command Read - D11 A/D Data (Z2 A/D Data (Z1) [AK4185] 2008/05 ...
Page 14
... This command can select the touch panel and ADC conversion clock. This 8bit control command includes channel selection, resolution, and power-down mode, and outputs in synchronization of the falling edge of SCLK after CSN = “L”. The AK4185 latches the serial command at the rising edge of SCLK. Refer to the control command of the AK4185 as shown in ...
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... Table 6. Control Command List (5-wire) (The combination other than above is invalid.) (3) Setup Command configuration BIT Name D7 S Start Bit. This bit must be “H” because the AK4185 initiates the command recognition. D6-D4 A2-A0 Setup command. must write “010” D3-D1 Addr Addr Selection “000”: Function 1 “ ...
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... Description 00: Normal Mode (default) 01: Sleep Mode 1 (PENIRQN disabled and output “H”. Touch Panel is open.) 10: Sleep Mode 2 (PENIRQN disabled and open. Touch Panel is open.) 11: Reserved [Read only] 00: Not Busy 01: Sampling Wait 10: Sequence Busy 11: Data Available Table 12. Setup Function 4 description - 16 - [AK4185] 2008/05 ...
Page 17
... The AK4185 changes to sleep mode when the micro-controller writes to SLEEP1-0 bits of AK4185’s register. After writing the sleep command, this sleep mode starts when the CSN pin is “H”. The AK4185 returns to normal operation out of sleep mode when the CSN pin is “L” and receives the normal control command. ...
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... SCLK. The AK4185 outputs 12bit or 8bit A/D data with MSB first via the DOUT pin from the falling edge of 9th SCLK. The AK4185 can output one A/D data per 15 SCLK clock cycles for the fastest way as shown in the dotted line. Please see “ ...
Page 19
... Figure 17. External Clock Mode Control Sequence (Continuous Mode: DDLY bit = “0”) If DDLY bit = “1”, the AK4185 outputs MSB first 12bit A/D data from the falling edge of the 9th SCLK. In this mode, the AK4185 continuously outputs A/D data according to the number of times by COUNT bit ( times A/D conversion) from the falling edge of the 9th SCLK per 16SCLK cycles ...
Page 20
... The micro-processor sends the read command (10101111b) to read the A/D conversion data. Then the AK4185 outputs the A/D data in order of the register selected by SEQM1-0 bits. When the micro-processor reads data as many as more than the actual data number, the AK4185 outputs a zero data. The A/D data is cleared after reading all the A/D data. ...
Page 21
... The other commands are ignored. The micro-processor can set CSN = “H” during the sequence. However, the AK4185 can accept sequence commands even if the AK4185 is in the sleep mode. When the sleep mode is selected, the AK4185 goes to the sleep mode after the sequence is finished and CSN = “H”. MS0954-E-00 ...
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... Pen Interrupt The AK4185 has pen interrupt function to detect the pen touch. Pen interrupt function is enabled at power-down state. The YN pin (4-wire pin (5-wire) is connected to VSS at the PEN interrupt enabled state. And the XP pin (4-wire) or WIPER pin (5-wire) is pulled up via an internal resistor (R WIPER pin (5-wire) inside. If touch plate is pressed by a pen, the current flows via < ...
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... CONV Internal MS0954-E-00 VDD R = IRQ EN2 50kΩ Driver OFF Driver PD0 Figure 23. PENIRQN Functional Timing Chart - 23 - PENIRQN VDD XP/WIPER YN/BL iii [AK4185] 2008/05 ...
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... Auxiliary Analog Input Notes: - VSS of the AK4185 should be distributed separately from the ground of external controllers. - All digital input pins (CSN, SCLK, DIN pins) must not be left floating. - The DOUT pin is floating except when communicating with the micro-controller. Therefore, a pull-up or pull-down resistor around 100kΩ must be connected to the DOUT pin of the AK4185. ...
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... Decoupling capacitors should be as near to the AK4185 as possible, with the small value ceramic capacitor being the nearest. 2. Analog Inputs When an EMI source is close to the touch panel analog signal line, EMI noise affects analog characteristics performance. Connect noise canceling capacitors as close as possible to each pin (XP, XN, YP, YN pins) of the AK4185 to avoid this noise. (Figure 24, ...
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... CSP: 1.96mm x 1.46mm Top View 1.96 ± 0. ■ Material & Lead finish Package molding compound: Epoxy resin Solder ball material: SnAgCu MS0954-E-00 PACKAGE 3 1.46 ± Bottom View 0 φ 0.3 ± 0.05 φ 0. [AK4185] AB 2008/05 ...
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... MS0954-E-00 MARKING 4185 XXXX A1 XXXX: Date code identifier (4 digit) Pin #A1 indication REVISION HISTORY Reason Page Contents First Edition IMPORTANT NOTICE , and AKEMD assumes no responsibility for such use, except for the use Note2 [AK4185] in any safety, life support, or Note1) 2008/05 ...