INPUT/OUTPUT PORTS

VCC

 

 

 

.

Ω

.

Ω

R=100k.

R=10k.

ON P3

 

ON P2

 

INTERNAL

BUS

READOFF N

(A) "1" data writing equivalent circuit

VCC

 

 

VCC

 

.

Ω

.

Ω

 

R=100k.

R=10k.

 

 

 

 

ON

ON

P3

ON

P2

10kΩ

 

 

 

IIH

 

 

 

 

INTERNAL

 

 

 

 

BUS

 

 

 

 

READ

 

OFF

N

OFF

 

 

(B) "1" data input equivalent circuit

 

VCC

 

 

VCC

 

.

Ω

.

Ω

 

R=100k.

R=10k.

 

 

 

 

OFF

ON

P3

OFF

P2

10kΩ

 

 

 

IOH

 

 

 

 

INTERNAL

 

 

 

 

BUS

 

 

 

 

READ

 

OFF

N

ON

 

 

(C) "0" data input equivalent circuit

Figure 5-7 Quasi-bidirectional port input equivalent circuit

199

Page 206
Image 206
Sonic Alert msm85c154hvs, msm83c154s, msm80154s user manual 199, On P3 On P2 Internal BUS Readoff N