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MK715
Touch Screen Controller
General Description
The MK715 Touch Screen Controller IC provides all the screen drive, Analog to Digital converter (ADC) and control circuits to easily interface to 4-wire analog resistive touch screens. It also includes a general purpose A to D converter and a clock synthesizer. The IC continually monitors the screen waiting for a touch. In this mode, the supply current is typically 4A. When the screen is touched, the IC performs analog to digital conversions to determine the location of the touch, stores the X and Y locations in the registers, and issues an interrupt. This process is repeated up to 303 times per second until no further screen touches are detected, at which time the low current mode is resumed. The device has a general purpose input into the 10-bit ADC, allowing for the measurement of other inputs such as battery voltage. The MK715 can be powered from a 3.3V supply, and uses an inexpensive 32.768kHz watch crystal as the input reference. An internal Phase-Lock Loop clock synthesizer provides the high speed clock for the ADC, and the option to have a clock output to drive other digital chips in the system. The tiny package is the same body size as the 14 pin SOIC, with 25 mil spacings on the leads.
Features
Tiny 20 pin SSOP (150 mil body) 4 microamp standby current Less than 3mA active current at 3.3V, including screen drive Touch pressure can be measured One or two general purpose A to D inputs On-chip voltage reference 32.768kHz crystal/clock input MHz clock outputs available Operates with four wire touch screens Ratiometric conversion eliminates screen calibration Automatic wake up upon screen touch Programmable conversion rate to a maximum of 303 points per second 3.3V or 5V supply (2.7V version available) 10 bit A/D converter Full powerdown control Touch screen is directly driven - no external transistors are required A to D Converter guaranteed monotonic 3 or 4 wire serial interface
Applications
Notebook Computers Handheld Computers PDAs Touch-screen kiosks
Pin Assignment
SK D0 DI TOUCH# XH XL YH YL PL GP 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 CS CLKOUT INT VDD X2 X1 GND CAP2 CAP1 CAP3
MK715 20 pin SSOP
MK715RevD020200
ICS reserves the right to make changes in the device data identified in this publication without further notice. ICS advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate.
MK715
Pin Descriptions
P in# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 N ame SK DO DI TOUC H# XH XL YH YL PL GP C AP3 C AP1 C AP2 GND X1 X2 VD D INT C LK OUT CS Ty pe I O I O TS TS TS TS I I P I I P O O I D escription S eri al C lock. D ata Out. For 3 wi re seri al port, connect to pi n 3. D ata In. For 3 wi re seri al port, connect to pi n 2. T uch S i gnal. Goes low when screen i s touched. Opti onal C lock out. o C onnect to X - hi gh on touch screen (ri ght si de). C onnect to X - low on touch screen (left si de). C onnect to Y - hi gh on touch screen (top). C onnect to Y - low on touch screen (bottom). General purpose A D C i nput. General purpose A D C i nput. C onnect a 0.01uF capaci tor to ground. Loop fi lter connecti on. Loop fi lter connecti on. C onnect to ground. C onnect to 32.768 kHz crystal, or ground for clock i nput. C onnect to 32.768 kHz crystal or clock i nput. C onnect to +5 V or +3.3 V. Interrupt. Goes hi gh to si gnal i nterrupt. Opti onal clock output. C lock output. Typi cally 32.768 kHz. C an also be MHz output. C hi p select A cti ve hi gh.
Key: I = Input, O = Output, I/O = Input and Output, P = Power, TS = Touch Screen pin.
2
MK715
Chip Overview
The MK715 communicates via a 4 pin serial port. This may be connected as either a 3 or 4 wire serial port. The port is connected to 4 registers that control the various modes and function of the chip. The primary function of the MK715 is to control resistive touchscreens. There are two ways to read screen points, both controlled by the registers. In the first method, which is enabled by setting the ENCONR bit, the MK715 performs periodic conversions at a rate set by the rate register. The chip monitors the touch screen in a low power condition (about 4 mA) until the screen is touched. When a touch is detected, the chip powers up and starts converting screen points. The TOUCH# pin goes low and INT goes high to indicate a change in touch status. The converter outputs a Y co-ordinate, then an X co-ordinate, then a Y coordinate, and so on. The X and Y co-ordinates are stored in the same register (RESULT) and each conversion over-writes the previous conversion. When a co-ordinate is stored, the conversion complete bit is asserted in the STATUS register. This bit is cleared when the RESULT register is read. The inverted state of the TOUCH# pin also appears in the STATUS register. After each coordinate conversion, INT goes high and the screen is checked to see if it is still touched. If not, conversions stop, TOUCH# goes high, INT goes high (to indicate a change in touch status) and the chip reverts to the low power mode. The second method to read a screen is to set the RD1PT (read one point) bit in the CONTROL register. The chip will perform two conversions, a Y co-ordinate followed by an X co-ordinate. The X co-ordinate overwrites the Y co-ordinate and so the X co-ordinate must be read before this happens. Finally, RD1PT is cleared. The conversion pair takes about 3.5 ms. The converter may also be used to measure voltages presented on the GP or PL pins. The range of the converter is 0 to 1.279 V and so voltages outside this range must be scaled appropriately. Again, the RD1PT bit is set to start the conversion but first either SELGP or SELPL must be set to select the correct input. Only one conversion is performed. The result is stored in the RESULT register and then RD1PT is cleared. The conversion takes about 1.7ms. The final conversion mode is used to measure touch pressure. This is controlled identically to the second method outlined above except that either RDPRESA or RDPRESB must first be set. The MK715 allows for several different clocks to be generated, controlled by the registers. On the CLKOUT pin, the output is either a a 32768 Hz clock from the crystal oscillator or a MHz - frequency clock synthesized from the PLL. Similarly, this MHz - frequency clock can appear on the INT or TOUCH# pins instead of their usual functions. In these cases, if the MHz clock needs to run continuously, then the ENPLL bit must be set in order to override the automatic powerdown of the PLL. Refer to page 12 for more details.
3
MK715
Block Diagram
Registers
DI D0 CS SK
Serial Port
12
Status Rate Result Control
0 1 2 3 Screen Drive
XH XL YH YL PL
Controller
CAP3 GP CAP1
Voltage Reference
10 Bit A-D Converter
1 0
INT
CAP2
X1
32.768kHz Oscillator
Phase Locked Loop
1 0
TOUCH#
1 0
CLKOUT
X2
4
MK715
IC Operation
(Periodic Conversions Enabled) N
Power ON
Is screen touched?
Y
Write D6 Reg 0 to 1 and TOUCH# = 0 Issue Interrupt, power-up ADC and PLL
Convert Y co-ordinates Store Y co-ordinates in Register 2 Write D7 register 0 to 1 Issue interrupt Is screen touched?
N
Y
Convert X co-ordinates Store X co-ordinates in Register 2 Write D7 register 0 to 1 Issue Interrupt Wait. Duration controlled by Rate Register
Y
Is screen touched?
N
Write D6 Reg 0 to 0 and TOUCH# = 1 Issue Interrupt, power-down ADC and PLL
5
MK715
Register Description
The MK715 has four 12 bit registers. However, only 8 bits in each register can be written (D0-D7). The other 4 bits (D8D11) can never be written and are always read only.The RESULT register contains 2 levels, a read only level and a write only level. Reading this register gives the conversion results. Writing this register changes 4 control bits. DESCRIPTION STATUS (ADDRESS 0) Read 11 10 9 8 7 6 5 4 3 2 1 and Write
0
RD1PT. Read one point. Cleared when conversion complete. ENCONR. Enable periodic screen conversions at rate set by RATE register. PD. Power Down. Chip powers down. See CONTROL register bit 7. ENPLL. Overrides automatic powerdown of PLL between conversions and forces continuous running. SELGP. Select GP input to ADC. SELPL. Select PL input to ADC. Touch Status. 1 = touch. Conversion complete. Cleared on next read of RESULT register. Always set to zero.
TYPE R/W R/W R/W R/W R/W R/W RO RO RO
Power-up State 0 0 0 0 0 0 0 0 0
Read and Write
RATE (ADDRESS 1)
11 10 9 8 7 6 5 4 3 2 1 0
Controls frequency of screen conversions when periodic conversions are enabled. Always set to zero. R/W RO 32 0
Read
RESULT (ADDRESS 2)
11 10 9 8 7 6 5 4 3 2 1 0
10-bit conversion result. XSEL. Screen conversion status. 0 = Y coordinate, 1 = X coordinate. Conversion type. 0 = non-screen conversion, 1 = screen conversion. RO RO RO X 0 1
Write
RESULT (ADDRESS 2)
11 10 9 8 7 6 5 4 3 2 1 0
RDPRESA. Read pressure A. See description of measuring touch pressure. RDPRESB. Read pressure B. See description of measuring touch pressure. PLZERO. Forces PL pin to ground. Can be used to control an external resistor divider. Test mode. ALWAYS WRITE TO 0. Don't Care. WO WO WO WO 0 0 0 0 X
6
MK715
Register Description (cont.)
DESCRIPTION CONTROL (ADDRESS 3) Read 11 10 9 8 7 6 5 4 3 2 1 and Write
0
SEL0. Clock select 0. See page 11. SEL1. Clock select 1. See page 11. SEL2. Clock select 2. See page 11. SEL3. Clock select 3. See page 11. SEL4. Clock select 4. See page 11. CLKSEL. Clock frequency select. See page 11. 0 = 14.3196 MHz 1 = 14.7456 MHz Set to 0. DIS32. Determines state of 32.768 kHz oscillator when PD asserted (STATUS register). Always set to zero.
TYPE R/W R/W R/W R/W R/W R/W R/W R/W RO
Power-up State 0 0 0 0 0 0 0 0 0
R/W = Read/Write, RO = Read Only, WO = Write Only
Converter Control
R D PR ESB R D PR ESA S E LP L S E LGP E N C ON R R D 1P T C ON VE R S ION P E R FOR ME D P erforms 2 conversi ons on the screen - a Y and then an X conversi on. RP 1P T i s then cleared. E nable conversi ons at rate as set i n RATE regi ster. When screen i s touched, converter operates conti nously unti l no touch i s detected. C hi p then automati cally goes to low power, standby state. P erforms one conversi on on GP i nput. RD 1P T i s cleared. P erforms one conversi on on P L i nput. RD 1P T i s cleared. P erforms two conversi ons, a Y and then an X , to gi ve touch pressure data. S ee secti on on touch pressure measurement. RD 1P T i s cleared. P erforms two conversi ons, a Y and then an X , to gi ve touch pressure data. S ee secti on on touch pressure measurement. RD 1P T i s cleared.
0
0
0
0
0
0 to 1
0
0
0
0
1
0
0 0
0 0
0 1
1 0
0 0
0 to 1 0 to 1
0
1
0
0
0
0 to 1
1
0
0
0
0
0 to 1
The converter must be sequenced correctly - before writing RD1PT to one, the appropriate bit (e.g. SELGP) must first be set in a previous write. Only the combinations shown above are permitted. Other combinations will give unpredictable behavior.
7
MK715
Rate Register (Register 2) Programming
C ount P.P.S. C ount 0 to 5 Not permi tted 25 6 303 26 7 280 27 8 259 28 9 242 29 10 227 30 11 213 31 12 201 32 13 191 33 14 181 34 15 172 35 16 165 40 17 157 45 18 151 50 19 145 55 20 139 60 21 134 65 22 129 70 23 125 75 24 120 80 P.P.S. 117 113 109 106 103 100 98 95 93 90 88 78 71 64 59 55 51 47 45 42 C ount 85 90 95 100 105 110 115 120 125 135 145 155 165 175 185 195 205 215 235 255 P.P.S. 40 38 36 34 32 31 30 29 28 26 24 22 21 20 19 18 17 16 15 14
P.P.S. = Points Per Second. With 14.7456 MHz clock selected.
Calculating Points Per Second
The formula for determining P.P.S. is: P.P.S. = fin 24072+(4096xCOUNT) Where fin is the frequency of the internal clock (14.3196 MHz or 14.7456 MHz) and COUNT is the value of the rate register.
Power-On Reset
On application of power, an internal reset is generated that clears all bits in registers 0, 2, and 3. Register 1 is set to 32 giving a rate of 92 PPS with 14.3196 MHz selected.
Initializing the MK715
The interrupt on the MK715 can only be cleared by reading any register or, alternatively, by writing PD (register 0, bit 2) to one, which forces a powerdown. After a fault condition, initialize the MK715 by writing PD to one, then writing PD to zero. This will always clear pending interrupts.
8
MK715
Warning - Operation under a Power Supply Switching Regulator
When using the MK715 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 MK715, so it should be disabled when the MK715 is doing screen conversions.
Interrupts
The MK715 generates an interrupt to signal a change in touch status or to signal that a conversion is complete. The INT pin (pin 2) goes high to signal an interrupt. Interrupts are then cleared by reading any register. However, if the MK715 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.
Touch Screen Serial Port (Four Wire)
Data is written to, and read from, the MK715 via the serial port. When writing, only 8 data bits can be written to each 12 bit register. The 4 highest order bits (D8-D11) in each register are read only and can never be writtern. When reading, all 12 bits are returned. The serial port has 4 pins - serial clock (SK), chip select (CS), data in (DI), and data out (DO). The SK acts on the rising edge. The CS acts as a reset for the serial port with CS going high initiating a cycle. The cycle consists of 2 parts a write followed by a read. Each part consists of 12 bits. Refer to the serial port diagram on page 10 and timing diagram on page 20. After CS goes high, any number of leading zeros can occur on DI. When a one is presented (even if this is the first bit after CS goes high), this becomes the start bit. The start bit is followed by 3 op-code bits. The first is a write bit (WR), which determines whether the data following is actually loaded into the appropriate register or not. The next two bits are address bits, which select 1 of 4 on-chip registers. The last 8 bits are data. If WR was low, then these data bits are ignored. On the fourteenth SK rising edge after a start bit, DO is released from tri-state and data is clocked out of the part. This is the read part of the cycle. The register to be read is selected with the op-code address. The data are 12 bits long. For the result of a conversion (which is stored in register 2), this data consists of 10 bits from the ADC, a bit identifying an X or a Y coordinate, and a bit identifying a screen conversion or a general purpose conversion. For the other 3 registers, the data are only 8 bits long, so the 12 bit output word contains four leading zeros. After the 12 data bits are clocked out, the DO pin stays active and bits will continue to appear until CS goes low. See the following page for the timing diagram.
Three-Wire Serial Port
To configure the serial port for 3 wires, DI must be connected to DO to form a bi-directional data line. All other timing and configuration remain unchanged.
9
MK715
Using the General Purpose Inputs to the A to D Converter
The GP pin is a general purpose input to the 10 bit ADC. An on-chip 1.297 V reference is used, where 1.297 V is full scale. In addition, when using a 4-wire touch screen, the PL pin is available as a general purpose input, or it can be used as a power control for an external resistor divider: Voltage to be measured
SELGP
MK715 SELGP, SELPL, and PLZERO are all register bits.
GP Optional Capacitor
SELPL
ADC
PL
PLZERO
For two voltages, the connection is as follows: MK715
Voltage 1
SELGP
Voltage 2
GP
SELPL
ADC
PL Optional Capacitor
PLZERO=0 (transistor off)
If PL or GP are unused, they should be connected to ground. The capacitors connected to GP and PL are optional and will reduce noise on the ADC input.
10
MK715
Clock Control
PD ENPLL
To A-D Converter
/8 /4 /2
14.3196 or 3 2 1
X1
32.768kHz
PD DIS32
Phase Locked
CLKSEL
CLOCKMHZ
1
CLKOUT
SEL2 SEL0, SEL1 INT
1
X2
INT
SEL3 TOUCH#
1
TOUCH#
Clock Selection Tables
S E L2 0 0 0 0 1 1 1 1 PD 0 0 1 1 0 0 1 1 E N P LL x x x x 0 1 0 1 D IS32 0 1 0 1 x x x x C LK OU T FR EQ 32.768 32.768 32.768 OFF MHZ MHZ OFF OFF
SEL4
N OTES Power-up State
Runs only when screen touched Always Runni ng
C K SEL 0 0 0 0 1 1 1 1
S E L1 0 0 1 1 0 0 1 1
S E L0 0 1 0 1 0 1 0 1
C LOC K MH Z 14.3196 7.160 3.580 1.790 14.7456 7.3728 3.6864 1.8432
S E L2 0 1
C LOC K OU T 32.768 kHz C LOC KMHZ S E L4 0 1
S E L3 0 1 TOU C H # TOUC H# C LOC KMHZ
IN T INT C LOC KMHZ
Clocks may be programmed to be on any of three pins per the description above. The clocks are controlled by the following register bits (see register description for more details): STATUS register, bits 2 and 3; and CONTROL register bits 0, 1, 2, 3, 4, 5, 7. 11
MK715
Power and Clock Control
The power consumed by the MK715 can be controlled by programming various register bits.
PD 1 1
D IS 32 0 1
E N P LL X X
E N C ON R X X
Is the S creen Touched? X X
C hip C ondition E verythi ng off E verythi ng off except crystal osci llator and 32kHz output (i f selected) E verythi ng off except crystal ocsi llator and 32 kHz output.TOUC H# and INT pi ns respond to changes i n touch status. E verythi ng off except crystal ocsi llator and 32 kHz output.TOUC H# and INT pi ns respond to changes i n touch status. E verythi ng off except crystal osci llator, P LL and clock outputs. TOUC H# and INT pi ns respond to changes i n TOUC H status. E verythi ng off except crystal osci llator and clock outputs. E verythi ng off except crystal osci llator, P LL and clock outputs. A D C , P LL, etc. operati ng.
Ty pical ID D 0 4mA
0
X
0
0
No
4mA
0
X
0
0
Yes
40mA
0
X
1
0
X
2mA (depends on clock frequency and loadi ng 4mA 2mA 5mA (S ee P ower S upply C urrent graphs)
0 0
X X
0 1
1 1
No NO
0
X
X
1
Yes
12
MK715
Recommended Circuit
From Microprocessor 32.768 kHz Crystal
Analog Voltage
DI D0 CS SK X2 X1 PL GP VDD CAP3 GND
TOUCH# INT CLKOUT XH XL YH YL
To Power Management To Interrupt Controller To Microcontroller To Touch Screen
+ 3.3V or +5V
1mF
0.01mF
0.01mF
All 0.01mF
CAP2 470 pF
CAP1
100kW 0.01mF
The capacitors connected to CAP1 and CAP3 must be low leakage, ceramic type capacitors.
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 MK715. This initiates a conversion, as long as conversions at rate (ENCONR) 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 the current X or Y points have been taken. If the pen is lifted during a conversion, this will also not be detected until the conversion is complete.
13
MK715
Optimizing Performance when Reading and Writing Registers
Reading and writing the MK715 generates digital noise that may reduce the accuracy of the A to D converter. This noise has several causes, including board layout, and power supply voltage. By appropriately timing the register operations, the effects of this noise can be minimized. After an interrupt is issued or RDIPT is asserted, the MK715 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.
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.
14
MK715
Analog to Digital Converter Operation with a Touchscreen
The 10-bit ADC converts X and Y co-ordinates at a rate determined by register 1. 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. 1023) 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 511. 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 up to 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.
Board and Wire Interconnect XH Full Scale (1023) Screen Interconnect
MK715
YL
Screen
X Coordinate XL Board and Wire Interconnect
Screen Interconnect
15
MK715
Measuring Touch Pressure
Measuring touch pressure can only be performed on 4-wire touchscreens. In normal operation, the screen drivers force XH high and XL to ground and measure the voltage on the other plate. A schematic of this is as follows:
Voltage measured on YH is the same as at K and L giving the X co-ordinate.
When RDPRESA is asserted, the screen drive changes as follows (XSEL=1):
Voltage measured on YH is now the voltage at L. Voltage measured at XL is now the voltage at K. The difference is proportional to the touch pressure.
When RD1PT is asserted, the converter automatically performs two conversions. The status of the XSEL bit identifies the conversions. The following table gives the four measurements available.
R D PR ESB R D PR ESA 0 0 1 1 1 1 0 0
XSEL 0 1 0 1
D R IVE YH, X L XH, YL YH, X L XH, YL
PIN MEASU R ED XH YH YL XL
Both points returned in one conversion pair. Both points returned in one conversion pair.
From these four measurements, the resistance of the touch can be calculated as a proportion of x-plate and y-plate resistance. See the next section for suggestions about calculating the touch resistance. From this, the touch pressure can be inferred. See the table on page 7 for the correct register sequencing of the converter. 16
MK715
Calculating Touch Resistance
There are a total of six measurements possible:
R D PR ESB R D PR ESA 0 0 0 0 1 1 0 0 1 1 0 0
XSEL 0 1 0 1 0 1
D R IVE YH, YL XH, XL YH, XL XH, YL YH, XL XH, YL
PIN MEASU R ED XH YH XH YH YL XL
R ESU LT C D E F G H
where the result is a number from 0 to 1023. From simple network theory, RTOUCH can be represented in many ways, 3 are given below:
RTOUCH = RX *
D G * ( - 1) 1023 E
where RX = X plate resistance
or
RTOUCH = RY *
C H * ( - 1) 1023 F
where RY = Y plate resistance
or
RTOUCH =
RY * C D RX * * (1023 - E) - RY + 1023 1023 E
17
MK715
Electrical Specifications
P arameter AB S OLU TE MAXIMU M R ATIN GS (N ote 1) Inputs and C lock Outputs A mbi ent Operati ng Temperature S olderi ng Temperature Storage Temperature D C C H AR AC TE R IS TIC S (VD D = 3.3 V OR 5 V (unless noted) Operati ng Voltage, V D D Input Hi gh Voltage Input Low Voltage, V IL Output Hi gh Voltage, V OH Output Hi gh Voltage, V OH Output Low Voltage, V OL Input Hi gh Voltage, V IH Input Low Voltage, V IL Output Hi gh Voltage, V OH Output Low Voltage, V OL Operati ng S upply C urrent, ID D , at V D D =5 V Operati ng S upply C urrent, ID D , at V D D =3.3 V Operati ng S upply C urrent ID D standby, clock on Operati ng S upply C urrent, ID D power down S hort C i rcui t C urrent Input C apaci tance Resoluti on Non-li neari ty Touch S creen Resi stance Voltage Reference V D D = 3.3 V, 25 C AC C H AR AC TE R IS TIC S (VD D = 3.3 V OR 5 V (unless noted) Input C lock or C rystal Frequency Output Ri se Ti me Output Fall TIme 0.8 to 2.0 V, V D D = 5 V 2.0 to 0.8 V, V D D =5 V 32.768 3 3 kHz ns ns Monotoni c, note 4 100 1.266 1.279 VD D = 5 V VD D = 5 V IOH = -2mA V D D = 5 V, IOH = 12mA V D D = 5 V, IOL = 12mA V D D = 3.3 V V D D = 3.3 V V D D = 3.3 V, IOH = -6mA V D D = 3.3 V, IOL = 6mA note 2 note 2 note 3 P D =1, no clock E ach output 5 3 3 0.2 3 2.4 0.4 1.9 0.4 V D D -0.4 2.4 .04 3 2 0.8 5.5 V V V V V V V V V V mA mA Max of 20 seconds -65 Referenced to GND -0.5 0 V D D +0.5 70 260 150 V C C C C onditions Minimum Ty pical Maximum U nits
mA mA
mA pF 10 bi ts LS B
50
7
2
2000 1.292
W
V
Notes: 1. Stresses beyond those listed under Absolute Maximum Ratings could cause permanent damage to the device. Prolonged exposure to levels above the operating limits but below the Absolute Maximums may affect device relaibility. 2. Assumes 300 W screen, 100 pps. 3. Assumes no touch. 4. With no missing codes.
18
MK715
MK715 TIMING DIAGRAM
A B
1 SK CS DI C DO Tri-State D E
2
3
4
WR
A1
14 SK CS
15
16
25
DI DO F A B C D E F G D11 F
Don't Care D10 D9 D1 D0 G MIN 50 15 15 15 15 20 50 MAX (SK Period) -15
SK Period SK High TIme CS Setup to SK high DI Setup to SK high DI Hold from SK high DO valid from SK high CS hold from last SK high
ns ns ns ns ns ns ns
19
MK715
20
MK715
Pin 1 2 G
0.01F
20 19 18 17 16
0.01F 0.01F
3 4 5
V
32768 Hz
To Touch Screen
6 7 8 9 10 G
15 14 13
1000 pF
G
12
100kW
11
0.01F
G
G = Connection to ground plane V
= Connection to VDD plane
Notes: 1. All digital signals should be kept well away from pins 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16 and any traces connected to those pins.
21
MK715
Package Outline and Package Dimensions
(For current dimensional specifications, see JEDEC Publication No. 95.) 20 pin SSOP ( in inches)
Sy mbol A A1 B C D E e H L Min 0.053 0.004 0.008 0.007 0.337 0.150 0.025 0.228 0.016 Max 0.069 0.010 0.012 0.010 0.344 0.157 BSC 0.244 0.050
A 1 L B
C
L
Ordering Information
Part/Order N umber MK715R MK715RTR Marking MK715R MK715R Shipping Tubes Tape and Reel
Integrated Circuit Systems, Inc. 525 Race Street San Jose CA95126 (408)295-9800tel www.icst.com
22
ICS reserves the right to make changes in the device data identified in this publication without further notice. ICS advises its customers to obtain the latest version of all device data to verify that any information being relied upon by the customer is current and accurate.

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