MOTOROLA CMOS LOGIC DATA

1

MC14521B

24-Stage Frequency Divider

The MC14521B consists of a chain of 24 flip–flops with an input circuit that

allows three modes of operation. The input will function as a crystal

oscillator, an RC oscillator, or as an input buffer for an external oscillator.

Each flip–flop divides the frequency of the previous flip–flop by two,

consequently this part will count up to 224 = 16,777,216. The count advances

on the negative going edge of the clock. The outputs of the last

seven–stages are available for added flexibility.

• All Stages are Resettable

• Reset Disables the RC Oscillator for Low Standby Power Drain

• RC and Crystal Oscillator Outputs Are Capable of Driving External

Loads

• Test Mode to Reduce Test Time

• VDD′ and VSS′ Pins Brought Out on Crystal Oscillator Inverter to Allow

the Connection of External Resistors for Low–Power Operation

• Supply Voltage Range = 3.0 Vdc to 18 Vdc

• Capable of Driving Two Low–power TTL Loads or One Low–power

Schottky TTL Load over the Rated Temperature Range.

Symbol

Parameter

Value

Unit

VDD

DC Supply Voltage

– 0.5 to + 18.0

V

Vin, Vout Input or Output Voltage (DC or Transient)

– 0.5 to VDD + 0.5

V

Iin, Iout

Input or Output Current (DC or Transient),

per Pin

± 10

mA

PD

Power Dissipation, per Package†

500

mW

Tstg

Storage Temperature

– 65 to + 150

_C

TL

Lead Temperature (8–Second Soldering)

260

_C

* Maximum Ratings are those values beyond which damage to the device may occur.

†Temperature Derating:

Plastic “P and D/DW” Packages: – 7.0 mW/

_C From 65_C To 125_C

Ceramic “L” Packages: – 12 mW/

_C From 100_C To 125_C

BLOCK DIAGRAM

Output

Count Capacity

Q18

218 = 262,144

Q19

219 = 524,288

Q20

220 = 1,048,576

Q21

221 = 2,097,152

Q22

222 = 4,194,304

Q23

223 = 8,388,608

Q24

224 = 16,777,216

STAGES

18 THRU 24

STAGES

1 THRU 17

Q18 Q19 Q20 Q21 Q22 Q23 Q24

10

11

12

13

14

15

1

2

6

IN 2

9

IN 1

7

RESET

VDD = PIN 16

VSS = PIN 8

5

3

4

OUT 1

VDD′

VSS′

OUT2

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

REV 3

1/94

MC14520B

See Page 6-292

MC14521B

L SUFFIX

CERAMIC

CASE 620

ORDERING INFORMATION

MC14XXXBCP

Plastic

MC14XXXBCL

Ceramic

MC14XXXBD

SOIC

TA = – 55° to 125°C for all packages.

P SUFFIX

PLASTIC

CASE 648

D SUFFIX

SOIC

CASE 751B

PIN ASSIGNMENT

13

14

15

16

9

10

11

12

5

4

3

2

1

8

7

6

Q20

Q21

Q22

VDD

IN 1

Q18

Q19

OUT 2

VSS′

RESET

Q24

VSS

OUT 1

IN 2

VDD′

Q23