FEATURES

• accurate clamping to within

• ultra low differential gain (0.03% typ.)

• wideband unity gain, can typically be flattened to

• can be configured as a gain stage with reduced

bandwidth.

• drives 100pF loads

• convenient 8 pin SIP packaging

Pin No.

GB4551

Function

1

+IN

non-inverting input

2V

CC

positive power supply

3

STB

strobe

4

GND

ground

5C

X

external capacitor

6V

EE

negative power supply

7

- IN

inverting input

8

OUT

output

ORDERING INFORMATION

Part Number

Package Type

Temperature Range

GB4551-CSA

8 Pin SIP

GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3

tel. (905) 632-2996 fax: (905) 632-2055

Japan Branch: B-201 Miyamae Village, 2-10-42 Miyamae, Suginami-ku Tokyo 168, Japan

tel. (03) 3247-8838

fax: (03) 3247-8839

DATA SHEET

GB4551 Video Buffer with

Strobed DC Restore

Document No. 520 - 52 - 2

DESCRIPTION

The GB4551 is a high performance video buffer with DC

restore primarily used for accurate back porch clamping.

The circuit features a wideband differential amplifier that

can be configured as a gain stage. The output signal

voltage is limited to +2V above the clamp level in order to

prevent damage to crosspoints or other circuits connected

to the output.

The clamping action occurs when the STROBE (STB)

input is taken to ground. A typical application would be for

DC restoration during the back porch period. In this case

the negative-going back porch pulse would be derived

from an external sync separator circuit.

The GB4551 will operate from

± 9V to ±12V power supplies

and will directly interface with Gennum’s video crosspoint

switches. The 8 pin SIP package is ideally suited for

space restricted board layouts.

APPLICATIONS

• Input buffering and DC restoration to crosspoint switches

• Accurate back porch video signal clamping

• Inter-circuit buffering and DC restoration.

500

10k

–IN

OUT

30k

+IN

STROBE

12pF

10k

GND

(+2V OUTPUT CLAMP)

7mA

NOM.

+

-

+

-

SIMPLIFIED CIRCUIT DIAGRAM

All resistors in ohms, all capacitors in microfarads unless otherwise stated.

PIN CONNECTIONS

1

2

3

4

5

6

7

8

GB4551