LC6514B Просмотр технического описания (PDF) - SANYO -> Panasonic

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производитель

LC6514B

Single-Chip 4-bit Microcontroller (Low-Threshold Input, On-Chip FLT Driver)

SANYO -> Panasonic 

LC6514B

Proper Cares in using the IC

[Digit drive signal-used key scan]

When key-scanning with the FLT digit drive signal in Fig. 9 and inputting the return signal to port A, the following

must be observed.

(a) Estimate voltage drop (VON) in the output transistor using the current flowing in an FLT used and the V-1 charac-

teristic of the output port of the LC6514B.

(b) Estimate voltage drop (VSW) in the switch circuit.

(c) Check to see that (VON + VSW) meets the VIH/VIL requirement of the input port.

Fig. 9 Sample Key Scan Application

For the key scan application in Fig. 9, make the program considering the deley in the external circuit and the input

delay shown below.

N : Number of instruction cycles existing between instruction (OP, SPB, RPB) used to output data to output port and

insutruction (IP, BP, BNP) used to input data from input port. (Number of instruction cycles to be programmed

according to the length of tDL, tDH)

tDL, tDH : Delay in external circuit from output port to input port.

When the IP instruction is used to input the return signal as shown in Fig. 10, the input delay must be considered and

three instructions are placed between the IP instruction and the crossing of input port waveform and VIL1 or VIL2,

VIH1 or VIH2, respectively.

Some instructions must be placed additionally according to the length of delay (tDL, tDH) in the external circuit after

the digit drive signal is delivered with the execution of the OP instruction ( a and c ).

No.1802–9/17

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