MK712RITR

MK712 IDT | Alldatasheet

Document overview

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Technical content

Features

• Packaged in 28-pin SSOP (150 mil) or 28-pin SOIC (300 mil)
• Industrial (-30°C to +70°C) and commercial (0 to +70°C) and automotive (-35°C to +85°C) temperature ranges
• Available in Pb (lead) free
• Fully integrated, lowest power solution
• Low standby current of 0.5µA (typical) at 5.0 V
• Active current while converting less than 10 mA
• Resolves 350 dots/inch on 10.5” display
• Maximum speed of 197 points/second
• Ratio metric conversion may eliminate screen calibration
• Automatically wakes up and goes back to standby
• 3.3 V or 5 V supply
• 12 bit A/D converter
• Simplifies the writing of software for touch screens
• Extended temperature range available
• Capacitors are the only external components required
• Touch screen is directly driven - no external transistors are required
• Programmable conversion rate
• A to D Converter is monotonic
• Parallel interface Pin Assignment XL YH YL GND GND GND CLKIN WR A0 RD A1 CS VDD VDD XH D5 TOUCH VDD D3 NC INT D1

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 2 MK712 REV L 070805 Pin Descriptions Interrupts Interrupts are controlled by register 6 (see Register Description). The INT pin (pin 2) goes high to signal an interrupt. Interrupts are then cleared by reading any register. However, if the MK712 is in the process of generating an interrupt during a read cycle, then the interrupt is not cleared and INT will stay high. This internal process may take 100ns, and so to guarantee that the interrupt is cleared, two successive read cycles may be necessary. Pin Number Pin Name Pin Type Pin Description 1 NC — No connect. Do not connect this pin to anything. 2 INT Output Interrupt. Goes high to signal an interrupt. Cleared on next read.

3 TOUCH

Output Touch signal. Goes low when screen is touched. Goes high when not touched. 4 VDD Power Power Supply. Connect to +5 V or +3.3 V. (Connect all VDDs to same voltage) 5 VDD Power Power Supply. Connect to +3.3 V. 6 XH Touch Screen Pin Connect to X-high on touch screen. (Right side) 7 XL Touch Screen Pin Connect to X-low on touch screen. (Left side) 8 YH Touch Screen Pin Connect to Y -high on touch screen. (Top) 9 YL Touch Screen Pin Connect to Y -low on touch screen. (Bottom) 10 GND Power Connect to ground. 11 GND Power Connect to ground. 12 WR Input Write enable. Active low. 13 RD Input Read enable. Active low. 14 CS Input Chip select. Active low. 15 A2 Input Register address 2. 16 A1 Input Register address 1. 17 A0 Input Register address 0. 18 CLKIN Input Clock input. Typically 14.3 MHz. Best if driven by an ICS clock synthesizer. 19 D7 I/O Data bit 7. 20 D6 I/O Data bit 6. 21 GND Power Connect to ground. 22 VDD Power Power Supply. Connect to +5 V or +3.3 V. (Connect all VDDs to same voltage) 23 D5 I/O Data bit 5. 24 D4 I/O Data bit 4. 25 D3 I/O Data bit 3. 26 D2 I/O Data bit 2. 27 D1 I/O Data bit 1. 28 D0 I/O Data bit 0.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 3 MK712 REV L 070805 IC Operation

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 4 MK712 REV L 070805 Register Description The MK712 register set is designed to be compatible with the Gazelle pen digitizer registers allowing a software driver for the Gazelle digitizer to be used with the MicroClock MK712. The eight 8-bit registers are defined below:

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 5 MK712 REV L 070805 Rate Register (Register 7) Programming Calculating Points Per Second The formula for determining P .P .S. is: Power-On Reset On application of power, an internal reset is generated that clears all bits in registers 0, 1, and 6. Register 7 is set to 32 giving a rate of 86 PPS. Note that clearing register 6 puts the IC into the power down condition. Initializing the MK712 The interrupt on the MK712 can only be cleared by reading a register or by writing register 6 to the power down condition. After a fault condition, initialize the MK712 by writing register 6 to zero and then writing register 6 to the desired value. This will always clear pending interrupts.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 6 MK712 REV L 070805 Recommended Circuit Pen Bounce When the screen is untouched, the Y plate is driven high and the X plate is driven low. When the screen is touched, the X plate is pulled high, which is detected by the MK712. This initiates a conversion (as long as periodic conversions are enabled). Some de-bounce is provided by the time constant of the screen decoupling capacitors combined with the screen resistance. However, once conversions have started, pen bounce will not be detected until after both the X and Y points have been taken. If the pen is lifted during a conversion, this will also not be detected until the conversion is complete. This is typically indicated by a point with the correct Y coordinates, but minimum (for that screen) X coordinates. Screen Decoupling The component values suggested should give excellent results. However, for screens with a high resistance operating at a high conversion rate, extra interrupts may be issued. This is because the time constant of the screen decoupling capacitors and screen resistance is high, resulting in the screen appearing to be untouched and then touched between conversions. These extra interrupts can be eliminated by reducing the size of the screen decoupling capacitors on pins XH, XL, YH, and YL. This will, however, slightly reduce the noise rejection, which could decrease the accuracy of the conversion.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 7 MK712 REV L 070805 Optimizing Performance when Reading and Writing Registers Reading and writing the MK712 generates digital noise that may reduce the accuracy of the A to D converter. This noise has several causes, including board layout, data bus loading, and power supply voltage. By appropriately timing the register operations, the effects of this noise can be minimized. After an interrupt is issued, the MK712 allows a minimum of 1 millisecond to elapse before initiating the conversion cycle. This allows the screen drivers to settle. For best performance, complete all register operations within this 1ms window after an interrupt. Power Down/Stopping the Clock If the screen is untouched, the supply current is under 3µA. If the input clock is stopped, the supply current is also less than 3µA. When the screen is touched with no clock, TOUCH goes low and INT goes high, but no further operations occur until the clock starts. A to D conversions are invalid until after the clock has stabilized at the correct frequency and one full conversion cycle has been completed. Input Clock The MK712 is highly tolerant of different clock frequencies (from 12 to 20 MHz), rise times, and duty cycles. However, any input clock undershoot or overshoot will cause the MK712 to draw extra current. This can be eliminated by using a MicroClock clock synthesizer and properly terminating the clock driver. MicroClock makes low power clock synthesizers with 14.3 MHz power down. Resistive Touch Screen (4-wire) Resistive touch screens consist of 2 resistive plates that are separated by a small gap. Each plate has an electrode at each end and when the screen is touched, the two plates are shorted together at that point. If a voltage is applied, for example, between XL and XH, then a voltage divider is formed on the X PLATE. When the Y PLATE is touched to the X PLATE, a voltage will be developed on the Y PLATE that is proportional to distance of the touch from XL and XH. By accurately measuring this voltage, the position of the touch can be determined.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 8 MK712 REV L 070805 Recommended Method for Reading Points If the user is pressing lightly on the touch screen, it is likely that the screen contact will be intermittent. The screen will bounce, causing false points. This effect can be reduced by insuring that the screen is touched both before and after a conversion. By doing this, the first and last point in a series of points are discarded. The following algorithm checks that a point has valid touches both before and after a conversion, and it distinguishes between change-in-touch interrupts and conversion complete interrupts. Register 6 bits 0, 1, and 2 must all be true (logical 1) in order to use this method.Warning–When Using a Switching Regulator Power Supply When using the MK712 in a system where the power is supplied by a switching regulator, do not perform screen conversions when the regulator is operating in the power saving mode. Some switching regulators feature a low power mode (for example, Linear Technology’s “Burst Mode”) where the output is turned on and off in order to save power. The extra power supply noise generated when using this mode causes spurious data points to be returned from the MK712, so it should be disabled when the MK712 is doing screen conversions.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 9 MK712 REV L 070805 Analog to Digital Converter Option The 12-bit ADC converts X and Y co-ordinates at a rate determined by registers 6 and 7. The converter uses a ratiometric technique to give absolute co-ordinates on the screen, largely independent of variations in screen resistance, temperature or power supply voltage. The total voltage applied across the screen is defined as full-scale for the converter (i.e. 4095) and any point touched on the screen is proportional to this. For example, if the screen is touched exactly in the center, the converter will read 2047. This feature may allow for the elimination of calibration upon startup. However, the full scale voltage is defined at the IC pins and so any parasitic interconnect resistance will be included in full scale. In addition, the interconnect resistances on the screen also account for about 20% of the total resistance. This means that approximately the bottom 10% and top 10% of full scale are inaccessible. The converter is guaranteed to be monotonic, with no missing codes.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 10 MK712 REV L 070805 Absolute Maximum Ratings Stresses above the ratings listed below can cause permanent damage to the MK712. These ratings, which are standard values for ICS commercially rated parts, are stress ratings only. Functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical parameters are guaranteed only over the recommended operating temperature range. Recommended Operation Conditions Item Rating Supply Voltage, VDD (referenced to ground) 7 V All Inputs and Outputs (referenced to ground) -0.5 V to VDD+0.5 V Ambient Operating Temperature (commercial) 0 to +70 ° C Ambient Operating Temperature (industrial) -30 to +70 ° C Ambient Operating Temperature (automotive) -35 to +85 ° C Storage Temperature -65 to +150 ° C Junction Temperature 125 ° C Soldering Temperature (10 to 20 seconds max) 260 ° C Parameter Min. Typ. Max. Units Ambient Operating Temperature (commercial) 0 +70 ° C Ambient Operating Temperature (industrial) -30 +70 ° C Ambient Operating Temperature (automotive) -35 +85 ° C Power Supply Voltage (measured in respect to GND) (commercial and industrial) +3.0 +5.5 V Power Supply Voltage (measured in respect to GND) (automotive) +3.135 +5.5 V

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 11 MK712 REV L 070805 Unless stated otherwise,VDD = 3.3 V or 5V, TA = 0 to +70° C (commercial), -30°C to +70°C (industrial), -35°C to +85°C (automotive) Parameter Symbol Conditions Min. Typ. Max. Units Operating Voltage VDD Commercial and industrial 3.0 5.5 V Operating Voltage VDD Automotive 3.135 5.5 V Input High Voltage V IH VDD=5 V 2 V Input Low Voltage V IL VDD=5 V 0.8 V Output High Voltage V OH IOH = -2 mA VDD-0.4 V Output High Voltage V OH VDD=5 V, IOH = -12 mA 2.4 V Output Low Voltage V OL VDD=5 V, IOL = 12 mA 0.4 V Input High Voltage V IH VDD=3.3 V 1.9 V Input Low Voltage V IL VDD=3.3 V 0.4 V Output High Voltage V OH VDD=3.3 V, IOH = -8 mA 2.4 V Output Low Voltage V OL VDD=3.3 V, IOL = 8 mA 0.4 V Operating Supply Current IDD At VDD=5 V, 300 Ω screen, 100 PPS 5m A At VDD=3.3 V, Note 3 3 mA Standby, Clock, Note 4 0.5 3 µA Standby, Note 5 0.5 3 µA Power down, PD =0 or PD=1, no clock 0.2 3 µA Short Circuit Current I OS Each output ±50 mA Input Capacitance C IN 7p F

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 12 MK712 REV L 070805 Unless stated otherwise,VDD = 3.3 V or 5 V, TA = 0 to +70° C (commercial), -30°C to +70°C (industrial), -35°C to +85°C (automotive) Note 1: Consult with ICS about the best device to use to generate the input clock. Note 2: With no missing codes. Note 3: Assumes no 14.3 MHz input clock overshoot, 300Ω screen, 100 PPS. Note 4: Assumes no 14.3 MHz input clock overshoot, no touch. Note 5: With no touch, no clock. Parameter Symbol Conditions Min. Typ. Max. Units Input Clock Frequency, pin 18 Note 1 12 14.32 20 MHz Input Clock Duty Cycle, pin 18 At 1.5 V 25 75 % Output Rise Time t OR 0.8 to 2.0 V, VDD=5 V 3 ns Output Fall Time t OF 2.0 to 0.8 V, VDD=5 V 3 ns Resolution 12 bits Non-linearity Monotonic, Note 2 ±2 LSB Touch Screen Resistance 100 2000 Ω

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 13 MK712 REV L 070805 Register Interface Timing Notes: 1. RD edges may precede or follow CS edges. 2. WR edges may precede or follow CS edges. 3. Either TRDW or TRDWC specification must be met. 4. Either TRDHW or TRDHWC specification must be met. 5. It is not permitted to have both RD and WR low at the same time. Number Symbol Description Min. Max. Units Note Read and Write Cycles

1 TRASC Address Setup to CS Low 5 ns

2 TRAHC Address Hold from CS High 0 ns

3 TRCCY CS High to CS Low 40 ns

4 TRSCR CS Low to RD Low 10 ns

5 TRRD RD Pulse Width 40 ns

6 TRCHR1 RD High to CS High 0 ns

7 TRCHR2 RD High to CS Low 40 ns

8 TRDC CS Low to Data 35 ns

9 TRDR RD Low to Data 35 ns

10 TRDHC CS High to Data Release 2 20 ns 1

11 TRDHR RD High to Data Release 2 20 ns 1

12 TRCSW CS Low to WR Low 10 ns

13 TRWR WR Pulse Width 40 ns

14 TRCHW WR High to CS High 0 ns 2

15 TRWH WR High to CS Low 40 ns

16 TRWCY WR High to WR Low 40 ns

17 TRDW Data Setup to WR High 15 ns 3

18 TRDHW Data Hold from WR High 15 ns 4

19 TRDWC Data Setup to CS High 15 ns 3

20 TRDHWC Data Hold from CS High 15 ns 4

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 14 MK712 REV L 070805 Register Read Register Write

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 15 MK712 REV L 070805 Touchscreen Resistance Graph 1 Touchscreen Resistance Graph 2

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 16 MK712 REV L 070805 Touchscreen Resistance Graph 3

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 17 MK712 REV L 070805 Suggested Layout Notes: 1. The 14.318 MHz input clock on pin 18 should have a 33Ω series termination resistor at its source. Consult ICS for the best way to generate this clock. 2. All digital signals should be kept well away from pins 4, 5, 6, 7, 8, 9, 10, and 11, and any traces connected to those pins.

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 18 MK712 REV L 070805 Package Outline and Package Dimensions (28-pin SOIC, 300 Mil. Wide Body) Package dimensions are kept current with JEDEC Publication No. 95 INDEX AREA 1 2 D E SEATING PLANE A e - C - B .10 (.004) C C L H h x 45 Millimeters Inches Symbol Min Max Min Max A — 2.65 — 0.104 A1 0.10 — 0.004 0.010 B 0.33 0.51 0.013 0.020 C 0.18 0.32 0.007 0.013 D 17.70 18.40 0.697 0.724 E 7.40 7.60 0.291 0.299 e 1.27 Basic .050 Basic H 10.00 10.65 0.394 0.419 h 0.25 0.75 0.010 0.029 L 0.40 1.27 0.016 0.050 α 0° 8° 0° 8°

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 19 MK712 REV L 070805 Package Outline and Package Dimensions (28-pin SSOP, 150 Mil. Wide Body) Package dimensions are kept current with JEDEC Publication No. 95 INDEX AREA 1 2 D E1 E SEATING PLANE A AA e - C - b aaa C c L Millimeters Inches Symbol Min Max Min Max A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 A2 -- 1.50 -- .059 b 0.20 0.30 0.008 0.012 C 0.18 0.25 0.007 0.010 D 9.80 10.00 0.386 0.394 E 5.80 6.20 0.228 0.244 E1 3.80 4.00 0.150 0.157 e .635 Basic .025 Basic L 0.40 1.27 0.016 0.050 α 0° 8° 0° 8°

TOUCH SCREEN CONTROLLER TOUCH SCREEN CONTROL IDT™ / ICS™ TOUCH SCREEN CONTROLLER 20 MK712 REV L 070805

Ordering Information

Parts that are ordered with a “LF” suffix to the part number are the Pb-Free configuration and are RoHS compliant. While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (ICS) assumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or critical medical instruments. Part / Order Number Marking Shipping Packaging Package Temperature MK712S MK712S Tubes 28-pin SOIC 0 to +70 ° C MK712STR MK712S Tape and Reel 28-pin SOIC 0 to +70 ° C MK712SI MK712SI Tubes 28-pin SOIC -30 to +70 ° C MK712SITR MK712SI Tape and Reel 28-pin SOIC -30 to +70 ° C MK712R MK712R Tubes 28-pin SSOP 0 to +70 ° C MK712RTR MK712R Tape and Reel 28-pin SSOP 0 to +70 ° C MK712RLF MK712RLF Tubes 28-pin SSOP 0 to +70 ° C MK712RLFTR MK712RLF Tape and Reel 28-pin SSOP 0 to +70 ° C MK712RI MK712RI Tubes 28-pin SSOP -30 to +70 ° C MK712RITR MK712RI Tape and Reel 28-pin SSOP -30 to +70 ° C MK712RWLF MK712RWLF Tubes 28-pin SSOP -35 to +85 ° C MK712RWLFTR MK712RWLF Tape and Reel 28-pin SSOP -35 to +85 ° C

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