DS8627 - National Semiconductor

TL/F/5009

DS8627/DS8628 130/225 MHz Low Power Prescalers

June 1986

DS8627/DS8628 130/225 MHz Low Power Prescalers

General Description

The DS8627 and DS8628 are low power fixed ratio prescal-

ers which divide by 24 and 20, respectively. The inputs can

be driven either single or double-ended and they are buff-

ered, providing 40/100 mVrms input sensitivity. The output

provided is open-collector and is capable of interfacing with

TTL and CMOS.

The device can be used in phase-locked loop applications

such as FM radio or other communications bands to pre-

scale the input frequency down to a more usable level. A

digital frequency display system can also be derived

separately or in conjunction with a phase-locked loop, and it

can extend the useful range of many inexpensive frequency

counters to 225 MHz.

Features

YInput frequency: 130 MHz (-4, -3); 225 mHz (-2, std)

YLow power: 10 mA (-4, -2); 7 mA (-3, std)

YInput sensitivity: 100 mVrms (-4, -3); 40 mVrms (-2, std)

Logic and Connection Diagrams

DS8627 (d24)

TL/F/5009– 1

DS8628 (d20)

TL/F/5009– 2

Dual-In-Line Package

TL/F/5009– 3

Top View

Order Number DS8627N or DS8628N (-4, -3, -2)

See NS Package Number N08E

C1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

VCC Supply Voltage 7V

VIN Input Voltage kVCC

Open-Collector Output Voltage 7V

Operating Free Air Temperature Range b30§Ctoa

70§C

Storage Temperature Range b65§Ctoa

150§C

Recommended Operating Conditions

DS8627-4 DS8627-3 DS8627-2 DS8627

Symbol Parameter Conditions DS8628-4 DS8628-3 DS8628-2 DS8628 Units

Min Max Min Max Min Max Min Max

VCC Supply Voltage 4.5 5.5 4.5 5.5 4.5 5.5 4.5 5.5 V

fMAX Toggle Frequency VIN e100 mVrms 20 130 20 130 20 225 20 225 MHz

VIN Input Signal Amplitude 100 300 100 300 40 300 40 300 mVrms

VSLW Slew Rate 20 20 20 20 V/ms

IOL Low Level Output Current 3 3 3 mA

DC Electrical Characteristics (Notes 2 and 3)

DS8627-4 DS8627-3 DS8627-2 DS8627

Symbol Parameter Conditions DS8628-4 DS8628-3 DS8628-2 DS8628 Units

Min Max Min Max Min Max Min Max

ICEX Open-Collector High Level Output Output e5.5V 100 100 100 100 mA

VOL Low Level Output Voltage VCC e4.5V, 0.4 0.4 0.4 0.4 V

IOL e3mA

CC Supply Current VCC e5.5V 10 7 10 7 mA

AC Electrical Characteristics VCC e5V g10%, TAeb

30§Ctoa

70§C

Symbol Parameter Conditions Min Max Units

RIN AC Input Resistance VIN e100 MHz and 50 mVrms 1.0 kX

CIN Input Capacitance 3 10 pF

Note 1: ‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed. Except for ‘‘Operating Temperature Range’’

they are not meant to imply that the devices should be operated at these limits. The table of ‘‘Electrical Characteristics’’ provides conditions for actual device

operation.

Note 2: Unless otherwise specified min/max limits apply across the b30§Ctoa

70§C temperature range.

Note 3: All currents into device pins are shown as positive, out of device pins as negative, all voltages referenced to ground unless otherwise noted. All values

shown as max or min on absolute value basis.

Application Hints

OPERATING NOTES

The signal source is usually capacitively coupled to the in-

put. At higher frequencies a 0.001 mF input capacitor is usu-

ally sufficient, with larger values used at the lower frequen-

cies. If the input signal is likely to be interrupted, it may be

desirable to connect a 100 kXresistor between one input

and ground to stabilize the device. In the single-ended

mode, it is preferable to connect the resistor to the unused

input. In the differential mode, the resistor can be connected

to either input. The addition of the 100 kXpull-down resistor

causes a loss of input sensitivity, but prevents circuit oscilla-

tions under no signal (open circuit) conditions. In addition, in

the single ended mode, a capacitor of 0.001 mF should be

connected between the unused input and the ground plane

to provide a good high frequency bypass. The capacitor

should be made larger for lower frequencies.

The input waveform may be sinusoidal, but below about 20

MHz the operation of the circuit becomes dependent on the

slew rate of the input rather than amplitude. A square wave

input with a slew rate of greater than 20 V/ms will permit

correct operation down to lower frequencies, provided the

proper input coupling capacitor is provided.

Schematic Diagrams

TL/F/5009– 4

TL/F/5009– 5

Typical Application

TL/F/5009– 6

DS8627/DS8628 130/225 MHz Low Power Prescalers

Physical Dimensions inches (millimeters)

Molded Dual-In-Line Package (N)

Order Number DS8627N or DS8628N (-4, -3, -2)

NS Package Number N08E

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL

SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or 2. A critical component is any component of a life

systems which, (a) are intended for surgical implant support device or system whose failure to perform can

into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life

failure to perform, when properly used in accordance support device or system, or to affect its safety or

with instructions for use provided in the labeling, can effectiveness.

be reasonably expected to result in a significant injury

to the user.

National Semiconductor National Semiconductor National Semiconductor National Semiconductor

Corporation Europe Hong Kong Ltd. Japan Ltd.

1111 West Bardin Road Fax: (

49) 0-180-530 85 86 13th Floor, Straight Block, Tel: 81-043-299-2309

Arlington, TX 76017 Email: cnjwge

tevm2.nsc.com Ocean Centre, 5 Canton Rd. Fax: 81-043-299-2408

Tel: 1(800) 272-9959 Deutsch Tel: (

49) 0-180-530 85 85 Tsimshatsui, Kowloon

Fax: 1(800) 737-7018 English Tel: (

49) 0-180-532 78 32 Hong Kong

Fran3ais Tel: (

49) 0-180-532 93 58 Tel: (852) 2737-1600

Italiano Tel: (

49) 0-180-534 16 80 Fax: (852) 2736-9960

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.