CDP1871 View Datasheet(PDF) - Intersil

Part Name

Description

Manufacturer

CDP1871

CMOS Keyboard Encoder

Intersil 

CDP1871A, CDP1871AC

TPB

KEY

CLOSURE

DA

RPT

DEBOUNCE

tCWH

tCC

tCWL

CLOSED

tDAL

RNCX

D1-D11 PRESENT COUNT

OPEN

RXCX

tDAH

tCD1

NEXT COUNT

CS

(NOTE)

BUS0-BUS7

tCDV

NOTE: CS = CS1 • CS2 • CS3 • CS4

CS1, CS2, CS3 = (CPU N-LINES)

CS4 (MRD) is High for CPU Input Instruction

FIGURE 3. CDP1871A DYNAMIC TIMING DIAGRAM (NON-REPEAT)

tCDH

VALID

TPB

KEY

DEPRESSED

DA

RPT

DEBOUNCE

D1-D11

CLOSED

tDAH

tRPL

PRESENT COUNT

OPEN

tRPH

RXCX

NEXT COUNT

CS

(NOTE)

BUS0-BUS7

tCDV

tCDH

VALID

NOTE: CS = CS1 • CS2 • CS3 • CS4

CS1, CS2, CS3 = (CPU N-LINES)

CS4 (MRD) is High for CPU Input Instruction

FIGURE 4. FIGURE 4. CDP1871A DYNAMIC TIMING DIAGRAM (REPEAT)

4-74

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