Gennum Corporation GS4981-ITA, GS4981-IKA, GS4981-IDA, GS4981-CTA, GS4981-CKA Datasheet

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GS1881, GS4881, GS4981

Monolithic Video Sync Separators

DATA SHEET

FEATURES

• noise tolerant odd/even flag, back porch and
horizontal sync pulse

• fast recovery from impulse noise

• excellent temperature stability

• 0.5 V to 4 Vpp input signal amplitude with 5 V
supply

• well-controlled clamp discharge current and
slicing level

• programmable horizontal scan rate (up to 130 kHz)

• composite, vertical, back porch, odd/even
(GS1881, GS4881), horizontal (GS4981) outputs

• predictable vertical output pulse width with
default trigger for non-standard video signals

• 5 V to 12 V supply voltage range

• pin compatible with LM1881 sync separator

SELECTION CHART

APPLICATION CHOOSE DEVICE:

Direct LM1881 Replacement GS1881
with Improved Performance

New Applications GS4881
Substitution for LM1881

New Applications Requiring GS4981
Horizontal Sync Output

DESCRIPTION

The GS1881, GS4881 and GS4981 are general purpose sync
separators for use in a wide variety of video applications. The
devices extract the timing information from composite video
signals with scan rates from 15 to 130 kHz.

The GS1881 is a drop-in replacement for the industry standard
LM1881 with much improved performance. The device
generates composite sync, vertical sync, back porch and
odd/even field signals. The GS4881 is identical to the GS1881
but features a noise immune back porch pulse which maintains
a constant H rate during the vertical interval. The GS4981 is
identical to the GS4881, except that it provides horizontal sync
in place of the odd/even output.

All three devices feature a self-adjusting windowing circuit for
noise immunity, which synchronizes to H rate. This
windowing circuit determines the odd or even field
in the GS1881 and GS4881, gates the back porch pulse in
the GS4881 and GS4981, and generates the horizontal sync
output in the GS4981.

The devices feature an improved input stage which ensures
that the input signal is sliced at a predictable point due to
well-controlled input clamp discharge current and sync
slicing level. A missing pulse detector enables the devices to
recover quickly from impulse noise disturbances by temporarily
increasing the clamp discharge current by roughly ten times.
The input stage will operate with signals from 0.5 to 4 volts
peak to peak with a 5 volt supply.

The GS1881, GS4881 and GS4981 also feature a predictable
vertical output pulse width with a default trigger for non-standard
video signals. All three are available in commercial and
industrial temperature ranges and are packaged in both DIP
and SOIC.

PIN CONNECTIONS

GS1881, GS4881

COMPOSITE

SYNC OUT

COMPOSITE

VIDEO IN

VERTICAL

SYNC OUT

GROUND

Patent No. 5,432,559
Revision Date: October 1995

GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. [phone] fax: [phone]

Japan Branch: A-302 Miyamae Village, 2-10-42 Miyamae, Suginami-ku, Tokyo 168, Japan tel. [phone] fax [phone]

1

2

3

4

8 PIN DIP

8 PIN SOIC

8

7

6

5

V

cc

ODD/EVEN

R

SET

BACK PORCH

COMPOSITE

SYNC OUT

COMPOSITE

VIDEO IN

VERTICAL

SYNC OUT

GROUND

GS4981

1

2

3

4

8 PIN DIP

8 PIN SOIC

V

8

cc

HORIZONTAL

7

6

R

SET

5

BACK PORCH

Document No. 520 - 23 - 03

GS1881 ELECTRICAL CHARACTERISTICS

(VCC= 5 V, R

= 680 kΩ, TA = 25° C, unless otherwise specified)

SET

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply Voltage 4.5 5 13.2 V
Supply Current Outputs at Logic 1 V

V

= 5 V - 4.6 6.5 mA

CC

= 12 V - 5.0 7.0 mA

CC

Video Input (Pin 2)
(a) Signal Level V

= 5 V 0.5 - 4 Vp-p

CC

(b) Clamp Current Charge 500 650 850 µA

Discharge - normal 9 11 13 µA

- Nosync flag raised 65 95 115 µ A

(c) Delay to raising of Nosync flag Video input held high 64 95 130 µs
(d) Sync Tip Clamp Voltage - 1.55 - V
Sync Slice Level Relative to sync tip clamp voltage 70 77 84 mV
R

Pin Reference Voltage (Pin 6) See Note 1 1.14 1.24 1.34 V

SET

Composite Sync Out (Pin 1) See Note 2 40 60 80 ns
Delay from Video CL = 15p
Back Porch Pulse Out (Pin 5) CL = 15p
(a) Delay from Rising
Edge of Sync 400 500 650 ns
(b) Pulse Width 2.0 2.5 3.2 µs
Vertical Sync Out (Pin 3)
(a) Pulse Width Serrations during vertical interval 197.7 197.7 197.7 µs
(b) Default Starting Time No serrations during the vertical interval 48 65 82 µs
Horizontal Scan Rate Modified R

SET

15 - 130 kHz
Logic Outputs
(a) V

OH

I

= 40 µA VCC = 5 V 4.2 4.6 - V

OH

VCC = 12 V 11.2 11.6 - V

IOH = 1.6 mA VCC = 5 V 2.4 3.4 - V
VCC = 12 V 9.4 10.4 - V

(b) V

OL

IOL = -1.6 mA - 0.3 0.6 V

Note 1: When placing the R

as possible to pin 6. Care should also be taken to avoid parasitic capacitive coupling from any output pin (pins 1, 3, 5 and 7) to pin 6.

Note 2: Measured from slicing point of input falling edge to 50% point of composite sync falling edge.

resistor and the 0.1µF decoupling capacitor careful attention should be made to ensure that they are as close

SET

ORDERING INFORMATION

Part Number Package Type Temperature Range

GS1881 - CDA 8 PDIP 0° to 70° C

GS1881 - CKA 8 SOIC 0° to 70° C
GS1881 - CTA 8 TAPE 0° to 70° C
GS1881 - IDA 8 PDIP -25° to 85° C
GS1881 - IKA 8 SOIC -25° to 85° C
GS1881 - ITA 8 TAPE -25° to 85° C

520 - 23 - 03

2

CAUTION

ELECTROSTATIC

SENSITIVE DEVICES

DO NOT OPEN PACKAGES OR HANDLE

EXCEPT AT A STATIC-FREE WORKSTATION

GS4881 ELECTRICAL CHARACTERISTICS

(VCC= 5 V, R

= 680 kΩ, TA = 25° C, unless otherwise specified)

SET

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply Voltage 4.5 5 13.2 V
Supply Current Outputs at Logic 1 V

V

= 5 V - 4.6 6.5 mA

CC

= 12 V - 5.0 7.0 mA

CC

Video Input (Pin 2)
(a) Signal Level V

= 5 V 0.5 - 4 Vp-p

CC

(b) Clamp Current Charge 500 650 850 µA

Discharge - normal 9 11 13 µA

- Nosync flag raised 65 95 115 µA

(c) Delay to raising of Nosync flag Video input held high 64 95 130 µs
(d) Sync Tip Clamp Voltage - 1.55 - V
Sync Slice Level Relative to sync tip clamp voltage 70 77 84 mV
R

Pin Reference Voltage (Pin 6) See Note 1 1.14 1.24 1.34 V

SET

Composite Sync Out (Pin 1) See Note 2 40 60 80 ns
Delay from Video CL = 15p
Back Porch Pulse Out (Pin 5) CL = 15p
(a) Delay from Rising
Edge of Sync 400 500 650 ns
(b) Pulse Width 2.0 2.5 3.2 µs
(c) Occurence Rate H H H
Vertical Sync Out (Pin 3)
(a) Pulse Width Serrations during vertical interval 197.7 197.7 197.7 µs
(b) Default Starting Time No serrations during the vertical interval 48 65 82 µs
Horizontal Scan Rate Modified R

SET

15 - 130 kHz
Logic Outputs
(a) V

OH

I

= 40 µA VCC = 5 V 4.2 4.6 - V

OH

VCC = 12 V 11.2 11.6 - V

IOH = 1.6 mA VCC = 5 V 2.4 3.4 - V
VCC = 12 V 9.4 10.4 - V

(b) V

OL

IOL = -1.6 mA - 0.3 0.6 V

Note 1: When placing the R

as possible to pin 6. Care should also be taken to avoid parasitic capacitive coupling from any output pin (pins 1, 3, 5 and 7) to pin 6.

Note 2: Measured from slicing point of input falling edge to 50% point of composite sync falling edge.

resistor and the 0.1µF decoupling capacitor careful attention should be made to ensure that they are as close

SET

ORDERING INFORMATION

Part Number Package Type Temperature Range

GS4881 - CDA 8 PDIP 0° to 70° C

GS4881 - CKA 8 SOIC 0° to 70° C
GS4881 - CTA 8 TAPE 0° to 70° C
GS4881 - IDA 8 PDIP -25° to 85° C
GS4881 - IKA 8 SOIC -25° to 85° C
GS4881 - ITA 8 TAPE -25° to 85° C

3

520 - 23 - 03

GS4981 ELECTRICAL CHARACTERISTICS

(VCC= 5 V, R

= 680 kΩ, TA = 25° C, unless otherwise specified)

SET

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply Voltage 4.5 5 13.2 V
Supply Current Outputs at Logic 1 V

V

= 5 V - 4.6 6.5 mA

CC

= 12 V - 5.0 7.0 mA

CC

Video Input (Pin 2)
(a) Signal Level V

= 5 V 0.5 - 4 Vp-p

CC

(b) Clamp Current Charge 500 650 850 µA

Discharge - normal 9 11 13 µA

- Nosync flag raised 65 95 115 µA

(c) Delay to raising of Nosync flag Video input held high 64 95 130 µs
(d) Sync Tip Clamp Voltage - 1.55 - V
Sync Slice Level Relative to sync tip clamp voltage 70 77 84 mV
R

Pin Reference Voltage (Pin 6) See Note 1 1.14 1.24 1.34 V

SET

Composite Sync Out (Pin 1) See Note 2 40 60 80 ns
Delay from Video CL = 15p
Back Porch Pulse Out (Pin 5) CL = 15p
(a) Delay from Rising
Edge of Sync 400 500 650 ns
(b) Pulse Width 2.0 2.5 3.2 µs
(c) Occurence Rate H H H
Vertical Sync Out (Pin 3)
(a) Pulse Width Serrations during vertical interval 197.7 197.7 197.7 µs
(b) Default Starting Time No serrations during the vertical interval 48 65 82 µs
Horizontal Sync Out (Pin 7) CL = 15p
(a) Delay from Video 90 190 290 ns
(b) Pulse Width 5.0 7.0 9.0 µs
Horizontal Scan Rate Modified R

SET

15 - 130 kHz
Logic Outputs
(a) V

OH

I

= 40 µA VCC = 5 V 4.2 4.6 - V

OH

VCC = 12 V 11.2 11.6 - V

IOH = 1.6 mA VCC = 5 V 2.4 3.4 - V

Note 3 VCC = 12 V 9.4 10.4 - V

(b) V

OL

Note 1: When placing the R

as possible to pin 6. Care should also be taken to avoid parasitic capacitive coupling from any output pin (pins 1, 3, 5 and 7) to pin 6.

Note 2: Measured from slicing point of input falling edge to 50% point of composite sync falling edge.
Note 3: Applies only to composite sync, vertical sync, and back porch outputs. Horizontal sync has a passive 10 kΩ pull-up to V

resistor and the 0.1µF decoupling capacitor careful attention should be made to ensure that they are as close

SET

IOL = -1.6 mA - 0.3 0.6 V

.

CC

ORDERING INFORMATION

Part Number Package Type Temperature Range

GS4981 - CDA 8 PDIP 0° to 70° C
GS4981 - CKA 8 SOIC 0° to 70° C
GS4981 - CTA 8 TAPE 0° to 70° C
GS4981 - IDA 8 PDIP -25° to 85° C
GS4981 - IKA 8 SOIC -25° to 85° C
GS4981 - ITA 8 TAPE -25° to 85° C

520 - 23 - 03

4

TYPICAL PERFORMANCE CHARACTERISTICS (VS = 5V, TA = 25° C unless otherwise shown)

700

600

500

400

(kΩ)

SET

R

300

200

100

0

15 35 55 75 95 115 135

SCAN RATE (kHz)

Fig. 1 R

700

600

500

400

300

200

vs Scan Rate

SET

BACK PORCH DELAY (ns)

100

70

60

50

40

30

20

VERTICAL DEFAULT TIME (µs)

10

0

0 100 200 300 400 500 600 700

R

(kΩ)

SET

Fig. 2 Vertical Sync Default Starting Time

vs R

SET

3000

2500

2000

1500

1000

BACK PORCH WIDTH (ns)

500

0

0 100 200 300 400 500 600 700

R

(kΩ)

SET

Fig. 3 Back Porch Delay vs R

8000

7000

6000

5000

4000

3000

HORIZONTAL WIDTH (µs)

2000

1000

0

0 100 200 300 400 500 600 700

R

(kΩ)

SET

Fig. 5 Horizontal Width vs R

SET

SET

0

0 100 200 300 400 500 600 700

R

(kΩ)

SET

Fig. 4 Back Porch Width vs R

110
100

90
80
70
60
50
40
30

NOSYNC DELAY TIME (µs)

20
10

0

0 100 200 300 400 500 600 700

R

(kΩ)

SET

Fig. 6 Nosync Delay Time vs R

SET

SET

5

520 - 23 - 03