8-4

August 1998

MIC50395/50396/50397

Micrel

General Description

The MIC50395 is an ion-implanted, P-channel MOS six-

decade synchronous up/down-counter/display driver with

compare-register and storage-latches. The counter as well

as the register can be loaded digit-by-digit with BCD data.

The counter has an asynchronous-clear function.

Scanning is controlled by the scan oscillator input which is

self-oscillating or can be driven by an external signal. The

six-decade register is constantly compared to the state of

the six-decade counter and when both the register and the

counter have the same content, an EQUAL signal is gener-

ated. The contents of the counter can be transferred into the

6-digit latch which is then multiplexed from MSD to LSD in

BCD and 7-segment format to the output. The seven-

segment decoder incorporates a leading-zero blanking

circuit which can be disabled by an external signal. This

device is intended to interface directly with the standard

CMOS logic families.

The MIC50396 and MIC50397 operate identically to the

MIC50395 except that two digits in each were reprogrammed

to provide divide by six circuitry instead of divide by ten. The

MIC50396 is well suited for industrial timer applications while

the MIC50397 is best suited for stop watch or real time

computer clock applications.

Features

•

Single power supply

•

Schmitt-Trigger on the count-input

•

Drives common anode or cathode displays (CA with buffer)

•

Six decades of synchronous up/down counting

•

Look-ahead carry or borrow

•

Loadable counter

•

Loadable compare-register with comparator output

•

Multiplexed BCD and seven-segment outputs

•

Internal scan oscillator

•

Direct LED segment drive

•

Interfaces directly with CMOS logic

•

Leading zero blanking

•

MIC50396 programmed to count time:

– 99 hrs. 59 min. 59 sec.

•

MIC50397 programmed to count time:

– 59 hrs. 59 min. 99/100 min.

MIC50395/50396/50397

Six Decade Counter / Display Decoder

Pin Connection

Ordering Information

Part Number

Temp. Range

Package

MIC50395CN

0

°C to 70°C

40-pin Plastic DIP

MIC50396CN

0

°C to 70°C

40-pin Plastic DIP

MIC50397CN

0

°C to 70°C

40-pin Plastic DIP

1

40

2

39

3

38

4

37

5

36

6

35

7

34

8

33

9

32

10

31

11

30

12

29

13

28

14

27

15

26

16

25

17

24

18

23

19

22

20

21

UP/DOWN

ZERO

CARRY

COUNT INHIBIT

COUNT

R A

R B

R C

R D

REGISTER

BCD

IN

LOAD COUNTER

LOAD REGISTER

D 6

D 5

D 4

D 3

MSD

DIGIT

D 2

D 1

STROBES

LSD

EQUAL

SCAN

V DD

MIC50395CN

MIC50396CN

MIC50397CN

SET

LZB

a

b

c

d

e

f

g

A

B

C

D

C D

C C

C B

C A

CLEAR

STORE

SEGMENTS

BCD

OUT

COUNTER

BCD

IN

V SS

a

g

d

f

e

b

c

Segment Identification

Not Recommended for New Designs