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Ordering number : ENN5971A
CMOS IC
LC75893M
1/3 Duty LCD Display Driver with Key Input Function
Overview
The LC75893M is a 1/3 duty LCD display driver that can directly drive up to 48 segments and can control up to four general-purpose output ports. This product also incorporates a key scan circuit that accepts input from up to 20 keys to reduce printed circuit board wiring.
Package Dimensions
unit: mm 3204-MFP36S
[LC75893M]
36 19
Features
* Key input function for up to 20 keys (A key scan is performed only when a key is pressed.) * 1/3 duty - 1/2 bias and 1/3 duty - 1/3 bias drive schemes can be controlled from serial data (up to 48 segments). * Sleep mode and all segments off functions that are controlled from serial data * Segment output port/general-purpose output port function switching that is controlled from serial data * Serial data I/O supports CCB format communication with the system controller. * Direct display of display data without the use of a decoder provides high generality. * Provision of an on-chip voltage-detection type reset circuit prevents incorrect displays. * RC oscillator circuit
10.5 7.9 9.2 0.65 0.15
1
15.3
18
0.35
0.8
0.85
* CCB is a trademark of SANYO ELECTRIC CO., LTD. * CCB is SANYO's original bus format and all the bus addresses are controlled by SANYO.
Any and all SANYO products described or contained herein do not have specifications that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft's control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO representative nearest you before using any SANYO products described or contained herein in such applications. SANYO assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all SANYO products described or contained herein.
SANYO Electric Co.,Ltd. Semiconductor Company
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN
N2999RM (OT) No. 5971-1/23
0.1
2.15 2.5max
SANYO: MFP36S
LC75893M
Specifications
Absolute Maximum Ratings at Ta = 25C, VSS = 0V
Parameter Maximum supply voltage Input voltage Symbol VDD max VIN1 VIN2 VOUT1 VOUT2 IOUT1 Output current IOUT2 IOUT3 IOUT4 Allowable power dissipation Operating temperature Storage temperature Pd max Topr Tstg VDD CE, CL, DI OSC, KI1 to KI5, TEST, VDD1, VDD2 DO OSC, S1 to S16, COM1 to COM3, KS1 to KS4, P1 to P4 S1 to S16 COM1 to COM3 KS1 to KS4 P1 to P4 Ta = 85C Conditions Ratings -0.3 to +7.0 -0.3 to +7.0 -0.3 to VDD +0.3 -0.3 to +7.0 -0.3 to VDD +0.3 300 3 1 5 100 -40 to +85 -55 to +125 Unit V V V V V A mA mA mA mW C C
Output voltage
Allowable Operating Ranges at Ta = -40 to +85C, VSS = 0 V
Parameter Supply voltage Input voltage Symbol VDD VDD1 VDD2 VIH1 VIH2 VIL ROSC COSC fOSC tds tdh tcp tcs tch toH toL tr tf tdc tdr VDD VDD1 VDD2 CE, CL, DI KI1 to KI5 CE, CL, DI, KI1 to KI5 OSC OSC OSC CL, DI: Figure 2 CL, DI: Figure 2 CE, CL: Figure 2 CE, CL: Figure 2 CE, CL: Figure 2 CL: Figure 2 CL:Figure 2 CE, CL, DI: Figure 2 CE, CL, DI: Figure 2 DO: RPU = 4.7 k, CL = 10 pF*1: Figure 2 DO: RPU = 4.7 k, CL = 10 pF*1: Figure 2 19 160 160 160 160 160 160 160 160 160 1.5 1.5 0.8 VDD 0.6 VDD 0 68 820 38 76 Conditions Ratings min 4.5 2/3 VDD 1/3 VDD typ max 6.0 VDD VDD 6.0 VDD 0.2 VDD Unit V V V V V V k pF kHz ns ns ns ns ns ns ns ns ns s s
Input high level voltage Input low level voltage Recommended external resistance Recommended external capacitance Guaranteed oscillation range Data setup time Data hold time CE wait time CE setup time CE hold time High level clock pulse width Low level clock pulse width Rise time Fall time DO output delay time DO rise time
Note *1: Since DO is an open-drain output, these values depend on the resistance of the pull-up resistor RPU and the load capacitance CL.
No. 5971-2/23
LC75893M Electrical Characteristics for the Allowable Operating Ranges
Parameter Hysteresis Power-down detection voltage Input high level current Input low level current Input floating voltage Pull-down resistance Output off leakage current Symbol VH VDET IIH IIL VIF RPD IOFFH VOH1 Output high level voltage VOH2 VOH3 VOH4 VOL1 VOL2 Output low level voltage VOL3 VOL4 VOL5 VMID1 VMID2 Output middle level voltage*2 VMID3 VMID4 VMID5 Oscillator frequency fOSC IDD1 Current drain IDD2 IDD3 CE, CL, DI: VI = 6.0 V CE, CL, DI: VI = 0 V KI1 to KI5 KI1 to KI5: VDD = 5.0 V DO: VO = 6.0 V KS1 to KS4: IO = -500 A P1 to P4: IO = -1 mA S1 to S16: IO = -20 A COM1 to COM3: IO = -100 A KS1 to KS4: IO = 25 A P1 to P4: IO = 1 mA S1 to S16: IO = 20 A COM1 to COM3: IO = 100 A DO: IO = 1 mA COM1 to COM3: 1/2 bias, IO = 100 A S1 to S16: 1/3 bias, IO = 20 A S1 to S16: 1/3 bias, IO = 20 A COM1 to COM3: 1/3 bias, IO = 100 A COM1 to COM3: 1/3 bias, IO = 100 A OSC: ROSC = 68 k, COSC = 820 pF Sleep mode VDD = 6.0 V, output open, 1/2 bias, fOSC = 38 kHz VDD = 6.0 V, output open, 1/3 bias, fOSC = 38 kHz 200 170 1/2 VDD - 1.0 2/3 VDD - 1.0 1/3 VDD - 1.0 2/3 VDD - 1.0 1/3 VDD - 1.0 30.4 38 0.1 VDD - 1.2 VDD - 1.0 VDD - 1.0 VDD - 1.0 0.2 0.5 1.5 1.0 1.0 1.0 0.5 1/2 VDD + 1.0 2/3 VDD + 1.0 1/3 VDD + 1.0 2/3 VDD + 1.0 1/3 VDD + 1.0 45.6 100 400 340 VDD - 0.5 50 100 -5.0 0.05 VDD 250 6.0 VDD - 0.2 CE, CL, DI, KI1 to KI5 2.7 Conditions Ratings min typ 0.1 VDD 3.0 3.3 5.0 max Unit V V A A V k A V V V V V V V V V V V V V V kHz A A A
Note *2: Excluding the bias voltage generation divider resistor built into VDD1 and VDD2. (See Figure 1.)
No. 5971-3/23
LC75893M
To the common segment driver
Excluding these resistors.
Figure 1 * When CL is stopped at the low level
* When CL is stopped at the high level
Figure 2
No. 5971-4/23
LC75893M Pin Assignment
Block Diagram
No. 5971-5/23
LC75893M Pin Functions
Pin Pin No. Function Segment outputs for displaying the display data transferred by serial data input. The S1/P1 to S4/P4 pins can be used as general-purpose output ports under serial data control. Active I/O Handling when unused
S1/P1 to S4/P4 S5 to S14
1 to 4 5 to 14
--
O
Open
COM1 COM2 COM3
15 16 17 Common driver outputs The frame frequency fO is given by: fO = (fOSC/384) Hz. -- O Open
KS1/S15 KS2/S16 KS3 KS4
18 19 20 21
Key scan outputs Although normal key scan timing lines require diodes to be inserted in the timing lines to prevent shorts, since these outputs are unbalanced CMOS transistor outputs, these outputs will not be damaged by shorting when these outputs are used to form a key matrix. The KS1/S15 and KS2/S16 pins can be used as segment outputs when so specified by the control data.
--
O
Open
KI1 to KI5
22 to 26
Key scan inputs These pins have built-in pull-down resistors. Oscillator connection An oscillator circuit is formed by connecting an external resistor and capacitor at this pin. Serial data interface connections to the controller. Note that DO, being an open-drain output, requires a pull-up resistor. CE: Chip enable CL: Synchronization clock DI: Transfer data DO: Output data This pin must be connected to ground. Used for applying the LCD drive 2/3 bias voltage externally. Must be connected to VDD2 when a 1/2 bias drive scheme is used. Used for applying the LCD drive 1/3 bias voltage externally. Must be connected to VDD1 when a 1/2 bias drive scheme is used. Power supply connection. Provide a voltage of between 4.5 and 6.0 V. Power supply connection. Connect to ground.
H
I
GND
OSC CE CL DI DO TEST VDD1
32
--
I/O
VDD
34 35 36 33 27
H
I I GND
-- -- --
I O I Open --
29
--
I
Open
VDD2 VDD VSS
30
--
I
Open
28 31
-- --
-- --
-- --
No. 5971-6/23
LC75893M Serial Data Input 1. When CL is stopped at the low level
Display data
Control data
Display data
Fixed data
Note: B0 to B3 and A0 to A3 *********** CCB address DD ***************************************** Direction data
2. When CL is stopped at the high level
Display data
Control data
Display data
Fixed data
Note: B0 to B3 and A0 to A3 ***********CCB address DD *****************************************Direction data
* CCB address ****42H * D1 to D48**********Display data * S0, S1 ***************Sleep control data * K0, K1 ***************Key scan output/segment output selection data * P0 to P2 ************Segment output port/general-purpose output port selection data * SC*********************Segment on/off control data * DR*********************1/2 bias or 1/3 bias drive selection data
No. 5971-7/23
LC75893M Control Data Functions 1. S0, S1: Sleep control data These control data bits switch between normal mode and sleep mode and set the states of the KS1 to KS4 key scan outputs during key scan standby.
Control data S0 0 0 1 1 S1 0 1 0 1 Mode Normal Sleep Sleep Sleep OSC oscillator Operating Stopped Stopped Stopped Segment outputs Common outputs Operating L L L KS1 H L L H Output pin states during key scan standby KS2 H L L H KS3 H L H H KS4 H H H H
Note: This assumes that the KS1/S15 and KS2/S16 output pins are selected for key scan output.
2. K0, K1: Key scan output/segment output selection data These control data bits switch the functions of the KS1/S15 and KS2/S16 output pins between key scan output and segment output.
Control data K0 0 0 1 X: don't care K1 0 1 X Output pin state KS1/S15 KS2/S16 KS1 S15 S15 KS2 KS2 S16 Maximum number of input keys 20 15 10 Note: KSn (n = 1, 2): Key scan output Sn (n = 15, 16): Segment output
3. P0 to P2: Segment output port/general-purpose output port selection data These control data bits switch the functions of the S1/P1 to S4/P4 output pins between the segment output port and the general-purpose output port.
Control data P0 0 0 0 0 1 P1 0 0 1 1 0 P2 0 1 0 1 0 S1/P1 S1 P1 P1 P1 P1 Output pin state S2/P2 S2 S2 P2 P2 P2 S3/P3 S3 S3 S3 P3 P3 S4/P4 S4 S4 S4 S4 P4 Note: Sn (n = 1 to 4): Segment output port Pn (n = 1 to 4): General-purpose output port
The table below lists the correspondence between the display data and the output pins when these pins are selected to be general-purpose output ports.
Output pin S1/P1 S2/P2 S3/P3 S4/P4 Corresponding display data D1 D4 D7 D10
For example, if the S4/P4 output pin is selected to be a general-purpose output port, the S4/P4 output pin will output a high level (VDD) when the display data D10 is 1, and will output a low level (VSS) when D10 is 0. 4. SC: Segment on/off control data This control data bit controls the on/off state of the segments.
SC 0 1 Display state On Off
However, note that when the segments are turned off by setting SC to 1, the segments are turned off by outputting segment off waveforms from the segment output pins.
No. 5971-8/23
LC75893M 5. DR: 1/2 bias or 1/3 bias drive selection data This control data bit switches between LCD 1/2 bias or 1/3 bias drive.
DR 0 1 Drive scheme 1/3 bias drive 1/2 bias drive
Display Data and Output Pin Correspondence
Output pin S1/P1 S2/P2 S3/P3 S4/P4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 KS1/S15 KS2/S16 COM1 D1 D4 D7 D10 D13 D16 D19 D22 D25 D28 D31 D34 D37 D40 D43 D46 COM2 D2 D5 D8 D11 D14 D17 D20 D23 D26 D29 D32 D35 D38 D41 D44 D47 COM3 D3 D6 D9 D12 D15 D18 D21 D24 D27 D30 D33 D36 D39 D42 D45 D48
Note: This is for the case where the output pins S1/P1 to S4/P4, KS1/S15 and KS2/S16 are selected for use as segment outputs.
For example, the table below lists the segment output states for the S11 output pin.
Display data D31 0 0 0 0 1 1 1 1 D32 0 0 1 1 0 0 1 1 D33 0 1 0 1 0 1 0 1 Output pin state (S11) The LCD segments for COM1, COM2, and COM3 are off The LCD segment for COM3 is on The LCD segment for COM2 is on The LCD segments for COM2 and COM3 are on The LCD segment for COM1 is on The LCD segments for COM1 and COM3 are on The LCD segments for COM1 and COM2 are on The LCD segments for COM1, COM2, and COM3 are on
No. 5971-9/23
LC75893M Serial Data Output 1. When CL is stopped at the low level
Output data
Note: B0 to B3 and A0 to A3 ************ CCB address
2. When CL is stopped at the high level
Output data
Note: B0 to B3 and A0 to A3 *********** CCB address
* CCB address********** 43H * KD1 to KD20 ********** Key data * SA ************************** Sleep acknowledge data Note: If a key data read operation is executed when DO is high, the read key data (KD1 to KD20) and sleep acknowledge data (SA) will be invalid.
Output Data 1.KD1 to KD20 : Key data When a key matrix of up to 20 keys is formed from the KS1 to KS4 output pins and the KI1 to KI5 input pins and one of those keys is pressed, the key output data corresponding to that key will be set to 1. The table shows the relationship between those pins and the key data bits.
KI1 KS1/S15 KS2/S16 KS3 KS4 KD1 KD6 KD11 KD16 KI2 KD2 KD7 KD12 KD17 KI3 KD3 KD8 KD13 KD18 KI4 KD4 KD9 KD14 KD19 KI5 KD5 KD10 KD15 KD20
When the KS1/S15 and KS2/S16 output pins are selected to be segment outputs by control data bits K0 and K1 and a key matrix of up to 10 keys is formed using the KS3 and KS4 output pins and the KI1 to KI5 input pins, the KD1 to KD10 key data bits will be set to 0. 2.SA: Sleep acknowledge data This output data bit is set to the state when the key was pressed. Also, while DO will be low in this case, if serial data is input and the mode is set (to normal or sleep mode) during this period, that mode will be set. SA will be 1 in sleep mode and 0 in normal mode. Sleep Mode Functions Sleep mode is set up by setting S0 or S1 in the control data to 1. The segment outputs will all go low and the common outputs will also go low, and the oscillator on the OSC pin will stop (it will be started by a key press). This reduces power dissipation. This mode is cleared by sending control data with both S0 and S1 set to 0. However, note that the S1/P1 to S4/P4 outputs can be used as general-purpose output ports according to the state of the P0 to P2 control data bits, even in sleep mode. (See the control data description for details.)
No. 5971-10/23
LC75893M Key Scan Operation Functions 1. Key scan timing The key scan period is 192 T (s). To reliably determine the on/off state of the keys, the LC75893M scans the keys twice and determines that a key has been pressed when the key data agrees. It outputs a key data read request (a low level on DO) 420 T (s) after starting a key scan. If the key data does not agree and a key was pressed at that point, it scans the keys again. Thus the LC75893M cannot detect a key press shorter than 420 T (s).
Note: *3. In sleep mode the high/low state of these pins is determined by the S0 and S1 bits in the control data. Key scan output signals are not output from pins that are set low.
2. In normal mode * The pins KS1 to KS4 are set high. * When a key is pressed a key scan is started and the keys are scanned until all keys are released. Multiple key presses are recognized by determining whether multiple key data bits are set. 1 * If a key is pressed for longer than 420 T (s) (where T = ) the LC75893M output a key data read fOSC request (a low level on DO) to the controller. The controller acknowledges this request and reads the key data. However, if CE is high during a serial data transfer, DO will be set high. * After the controller reads the key data, the key data read request is cleared (DO is set high) and the LC75893M performs another key scan. Also note that DO, being an open-drain output, requires a pull-up resistor (between 1 and 10 k).
No. 5971-11/23
LC75893M 3. In sleep mode * The pins KS1 to KS4 are set to high or low by the S0 and S1 bits in the control data. (See the control data description for details.) * If a key on one of the lines corresponding to a KS1 to KS4 pin which is set high is pressed, the oscillator on the OSC pin is started and a key scan is performed. Keys are scanned until all keys are released. Multiple key presses are recognized by determining whether multiple key data bits are set. 1 * If a key is pressed for longer than 420 T (s) (where T = ) the LC75893M outputs a key data read fOSC request (a low level on DO) to the controller. The controller acknowledges this request and reads the key data. However, if CE is high during a serial data transfer, DO will be set high. * After the controller reads the key data, the key data read request is cleared (DO is set high) and the LC75893M performs another key scan. However, this does not clear sleep mode. Also note that DO, being an open-drain output, requires a pull-up resistor (between 1 and 10 k). * Sleep mode key scan example Example: When S0 = 0, S1 = 1 (Sleep with only KS4 high)
When any one of these keys is pressed, the oscillator on the OSC pin is started and the keys are scanned.
Note: *4. These diodes are required to reliable recognize multiple key presses on the KS4 line when sleep mode state with only KS4 high, as in the above example. That is, these diodes prevent incorrect operations due to sneak currents in the KS4 key scan output signal when keys on the KS1 to KS3 lines are pressed at the same time.
Multiple Key Presses Although the LC75893M is capable of key scanning without inserting diodes for dual key presses, triple key presses on the KI1 to KI5 input pin lines, or multiple key presses on the KS1 to KS4 output pin lines, multiple presses other than these cases may result in keys that were not pressed recognized as having been pressed. Therefore, a diode must be inserted in series with each key. Applications that do not recognize multiple key presses of three or more keys should check the key data for three or more 1 bits and ignore such data.
No. 5971-12/23
LC75893M 1/3 Duty, 1/2 Bias Drive Technique
COM1
COM2
COM3
LCD drive output when all LCD segments corresponding to COM1, COM2, and COM3 are turned off. LCD drive output when only LCD segments corresponding to COM1 are on. LCD drive output when only LCD segments corresponding to COM2 are on. LCD drive output when LCD segments corresponding to COM1 and COM2 are on. LCD drive output when only LCD segments corresponding to COM3 are on. LCD drive output when LCD segments corresponding to COM1 and COM3 are on. LCD drive output when LCD segments corresponding to COM2 and COM3 are on. LCD drive output when all LCD segments corresponding to COM1, COM2, and COM3 are on.
1/3 Duty, 1/2 Bias Waveforms
No. 5971-13/23
LC75893M 1/3 Duty, 1/3 Bias Drive Technique
COM1
COM2
COM3
LCD drive output when all LCD segments corresponding to COM1, COM2, and COM3 are turned off.
LCD drive output when only LCD segments corresponding to COM1 are on.
LCD drive output when only LCD segments corresponding to COM2 are on.
LCD drive output when LCD segments corresponding to COM1 and COM2 are on.
LCD drive output when only LCD segments corresponding to COM3 are on.
LCD drive output when LCD segments corresponding to COM1 and COM3 are on.
LCD drive output when LCD segments corresponding to COM2 and COM3 are on.
LCD drive output when all LCD segments corresponding to COM1, COM2, and COM3 are on.
1/3 Duty, 1/3 Bias Waveforms
No. 5971-14/23
LC75893M Voltage Detection Type Reset Circuit (VDET) This circuit generates an output signal and resets the system when power is first applied and when the voltage drops, i.e., when the power supply voltage is less than or equal to the power down detection voltage VDET, which is 3.0 V, typical. To assure that this function operates reliably, a capacitor must be added to the power supply line so that the power supply voltage VDD rise time when power is first applied and the power supply voltage VDD fall time when the voltage drops are both at least 1 ms. (See Figure 3.) System Reset The LC75893M supports the reset method described below. When a system reset is applied, display is turned off, key scanning is stopped, and all the key data is reset to low. When the reset is cleared, display is turned on and key scanning become possible. 1. Reset method If at least 1 ms is assured as the supply voltage VDD rise time when power is applied, a system reset will be applied by the VDET output signal when the supply voltage is brought up. If at least 1 ms is assured as the supply voltage VDD fall time when power drops, a system reset will be applied in the same manner by the VDET output signal when the supply voltage is lowered. Note that the reset is cleared at the point when all the serial data (the display data D1 to D48 and the control data) has been transferred, i.e., on the fall of the CE signal on the transfer of the last direction data, after all the direction data has been transferred. (See Figure 3.)
Figure 3 2. LC75893M internal block states during the reset period * CLOCK GENERATOR Reset is applied and the base clock is stopped. However the OSC pin state (normal or sleep mode) is determined after the S0 and S1 control data bits are transferred. * COMMON DRIVER, SEGMENT DRIVER & LATCH Reset is applied and the display is turned off. However, display data can be input to the latch circuit in this state. * KEY SCAN Reset is applied, the circuit is set to the initial state, and at the same time the key scan operation is disabled. * KEY BUFFER Reset is applied and all the key data is set to low. * CCB INTERFACE, CONTROL REGISTER, SHIFT REGISTER Since serial data transfer is possible, these circuits are not reset.
No. 5971-15/23
LC75893M
Blocks that are reset
3. Output pin states during the reset period
Output pin S1/P1 to S4/P4 S5 to S14 COM1 to COM3 KS1/S15, KS2/S16 KS3 KS4 DO State during reset L *5 L L L *5 X *6 H H *7
X: Don't care Note: *5. These output pins are forcibly set to the segment output function and held low. *6. When power is first applied, these output pins are undefined until the S0 and S1 control data bits have been transferred. *7. Since this output pin is an-open drain output, a pull-up resistor of between 1 and 10 k is required. This pin remains high during the reset period even if a key data read operation is performed.
No. 5971-16/23
LC75893M Sample Application Circuit 1 1/2 bias (for use with normal panels)
Note: *8.Add a capacitor to the power supply line so that the power supply voltage VDD rise time when power is applied and the power supply voltage VDD fall time when power drops are both at least 1 ms, as the LC75893M is reset by the VDET. *9.The DO pin, being an open-drain output, requires a pull-up resistor. Select a resistance (between 1 to 10 k) appropriate for the capacitance of the external wiring so that signal waveforms are not degraded.
No. 5971-17/23
LC75893M Sample Application Circuit 2 1/2 bias (for use with large panels)
Note: *8.Add a capacitor to the power supply line so that the power supply voltage VDD rise time when power is applied and the power supply voltage VDD fall time when power drops are both at least 1 ms, as the LC75893M is reset by the VDET. *9.The DO pin, being an open-drain output, requires a pull-up resistor. Select a resistance (between 1 to 10 k) appropriate for the capacitance of the external wiring so that signal waveforms are not degraded.
No. 5971-18/23
LC75893M Sample Application Circuit 3 1/3 bias (for use with normal panels)
Note: *8.Add a capacitor to the power supply line so that the power supply voltage VDD rise time when power is applied and the power supply voltage VDD fall time when power drops are both at least 1 ms, as the LC75893M is reset by the VDET. *9.The DO pin, being an open-drain output, requires a pull-up resistor. Select a resistance (between 1 to 10 k) appropriate for the capacitance of the external wiring so that signal waveforms are not degraded.
No. 5971-19/23
LC75893M Sample Application Circuit 4 1/3 bias (for use with large panels)
Note: *8.Add a capacitor to the power supply line so that the power supply voltage VDD rise time when power is applied and the power supply voltage VDD fall time when power drops are both at least 1 ms, as the LC75893M is reset by the VDET. *9.The DO pin, being an open-drain output, requires a pull-up resistor. Select a resistance (between 1 to 10 k) appropriate for the capacitance of the external wiring so that signal waveforms are not degraded.
Notes on transferring display data from the controller The display data (D1 to D48) is transferred to the LC75893M in two operations. All of the display data should be transferred within 30 ms to maintain the quality of the displayed image.
No. 5971-20/23
LC75893M Notes on the controller key data read techniques 1. Timer based key data acquisition * Flowchart
CE = [L]
DO = [L]
* Timing chart
t3*******Key scan execution time when the key data agreed for two key scans (420T[s]). t4*******Key scan execution time when the key data did not agree for two key scans and the key scan was executed again (840T[s]). t5*******Key address (43H) transfer time 1 T = ---- t6*******Key data read time fosc
* Explanation In this technique, the controller uses a timer to determine key on/off states and read the key data. The controller must check the DO state when CE is low every t7 period without fail. If DO is low, the controller recognizes that a key has been pressed and executes the key data read operation. The period t7 in this technique must satisfy the following condition. t7 > (t5 + t6 + t4) If a key data read operation is executed when DO is high, the read key data (KD1 to KD20) and sleep acknowledge data (SA) will be invalid.
No. 5971-21/23
LC75893M 2. Interrupt based key data acquisition * Flowchart
CE = [L]
DO = [L]
CE = [L]
DO = [H]
* Timing chart
t3*******Key scan execution time when the key data agreed for two key scans (420T[s]). t4*******Key scan execution time when the key data did not agree for two key scans and the key scan was executed again (840T[s]). t5*******Key address (43H) transfer time 1 T = ---- t6*******Key data read time fosc
* Explanation In this technique, the controller uses interrupts to determine key on/off states and read the key data. The controller must check the DO state when CE is low. If DO is low, the controller recognizes that a key has been pressed and executes the key data read operation. After that the next key on/off determination is performed after the time t8 has elapsed by checking the DO state when CE is low and reading the key data. The period t8 in this technique must satisfy the following condition. t8 > t4 If a key data read operation is executed when DO is high, the read key data (KD1 to KD20) and sleep acknowledge data (SA) will be invalid.
No. 5971-22/23
LC75893M
Specifications of any and all SANYO products described or contained herein stipulate the performance, characteristics, and functions of the described products in the independent state, and are not guarantees of the performance, characteristics, and functions of the described products as mounted in the customer's products or equipment. To verify symptoms and states that cannot be evaluated in an independent device, the customer should always evaluate and test devices mounted in the customer's products or equipment. SANYO Electric Co., Ltd. strives to supply high-quality high-reliability products. However, any and all semiconductor products fail with some probability. It is possible that these probabilistic failures could give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire, or that could cause damage to other property. When designing equipment, adopt safety measures so that these kinds of accidents or events cannot occur. Such measures include but are not limited to protective circuits and error prevention circuits for safe design, redundant design, and structural design. In the event that any or all SANYO products (including technical data, services) described or contained herein are controlled under any of applicable local export control laws and regulations, such products must not be exported without obtaining the export license from the authorities concerned in accordance with the above law. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or any information storage or retrieval system, or otherwise, without the prior written permission of SANYO Electric Co., Ltd. Any and all information described or contained herein are subject to change without notice due to product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification" for the SANYO product that you intend to use. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties.
This catalog provides information as of November, 1999. Specifications and information herein are subject to change without notice. PS No. 5971-23/23

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