Datasheet BA7242F Datasheet (ROHM)

1

Multimedia ICs

Color TV signal encoder

BA7242F

The BA7242F is an IC which converts analog RGB signals to NTSC and PAL color TV signals. In addition to com­posite output, luminance output, chrominance output, and analog RGB output are available. Each type of output is
equipped with an internal 75Ω driver.

•

Applications

TV peripheral devices

•

Features

1) Supports both NTSC and PAL systems.

2) Internal flip-flop circuit for PAL common mode
switching

3) Equipped with Y / C separated output pin.

4) Internal 75Ω driver

5) Supports subcarrier pulse for color input

•

Block diagram

1

2

3

4

5

6

7

BIN

GIN

RIN

V

CC1

SYNC

BFP

GND1

V

CC2

Y

OUT

VOUT

GND2

C

OUT

NT / PAL

SCIN

14

13

12

11

10

9

8

CLAMP

BFP

BFP

BFP

VCC

SYNC

NT / PAL

BURST

FLAG

R-Y

MOD

F • F

B-Y

MOD

CHROMA

GEN

Y / C

MIX

SYNC

MIX

SYNC

V

CCGNDNT / PAL

MATRIX

PHASE

GEN

FILTER

GND

CLAMP

CLAMP

2

Multimedia ICs BA7242F

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Absolute maximum ratings (Ta = 25°C)

Parameter Symbol Limits

7

450

∗

– 20 ~ + 70
– 55 ~ + 125

Unit

V

mW

°C
°C

V

CC

Pd
Topr
Tstg

Power supply voltage
Power dissipation
Operating temperature
Storage temperature

∗

Reduced by 4.5mW for each increase in Ta of 1°C over 25°C.

(When mounted on a 70mm × 70mm × 1.6mm glass epoxy board.)

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Limits

4.5 ~ 5.5
0 ~ 0.7
0 ~ 0.7
0 ~ 0.7

0.45 ~ 0.60

Unit

V

V

P–P

VP–P
VP–P
VP–P

VCC

υRI
υGI
υBI

υSC

Power supply voltage
RIN input level
GIN input level
BIN input level
SCIN input level

•

Pin descriptions

Pin No.

1

Pin name Function

BIN Input for analog B signal. Operate with low impedance.

Input for analog G signal. Operate with low impedance.
Input for analog R signal. Operate with low impedance.
V

CC for all except 75Ω driver.

GND for all except 75Ω driver.

3.58MHz or 4.43MHz pulse signal input.
Video signal output mode setting. HIGH level = NTSC, LOW level = PAL.
Chrominance signal output. Internal 75Ω driver.
GND for 75Ω driver.
Composite video signal output. Internal 75Ω driver.
Luminance signal output. Internal 75Ω driver.
V

CC for 75Ω driver.

2 GIN
3 RIN
4V

CC1

5 SYNC

6 BFP
7 GND1

8 SCIN
9 NT / PAL

10 C

OUT

11 GND2
12 V

OUT

13 YOUT
14 VCC2

Input for composite SYNC signal. Outputs SYNC signal to VOUT and YOUT pins
when input is LOW.

Input for burst timing signal. Simultaneously performs the burst output and initiates
the pedestal clamp for the RIN, GIN, and BIN input signals when input is LOW.

3

Multimedia ICs BA7242F

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Electrical characteristics (unless otherwise noted, Ta = 25°C, VCC = 5V, SCIN = 3.579545MHz, NT / PAL = 5V)

Parameter Symbol Min.

23

0.63

0.19

0.37

Typ.

0.70

0.21

0.41

Max.

45

0.77

0.23

I

CC

υL
υL(R)
υL(G)

Current consumption

Luminance level
Luminance level R
Luminance level G

Unit

mA

V

P-P

VP-P
VP-P

Conditions

υ

RI = υ GI = υ BI = 0.7VP-P

υRI = 0.7VP-P

∗

2

υGI = 0.7VP-P

∗

2

υBI = 0.7VP-P

∗

2

0.07 0.08

0.45

υL(B)Luminance level B VP-P

0.27 0.30

0.09

υS

R S / L

Synchronization level VP-P

0.38

2.84

2.65

94

2.01

231
337

0.26
—

125
215 225

145

0.9

1.60

2.20

1.35 1.75 2.15

3.00
V

2.0 — — V

0.43

3.16

2.95

2.24
104
241
347

0.29

—

135

1.0

2.00

2.60

0.33

0.48

3.48

3.25

2.47
114
251
357

0.32

35

235 deg

1.1

2.40

R

R / BU

R G / BU
R B / BU

θR
θG

θB
υBU
υCL

θBU +
θBU –

R BU
V YO
V CO
V VO

V IH

V IL —

V

IH —

V

IL —

—

—

—

0.8

300

200

V

µA

µA With 0V applied

With 5V applied

Synchronization /
luminance level ratio

Red / burst level ratio
Green / burst level ratio
Blue / burst level ratio
Red phase
Green phase
Blue phase
Burst level

—
—

—
—

deg

∗

2

∗

2

∗

2

∗

4

∗

3

deg
deg
V

P-P

mVP-P

deg

—

V
V

R

YO = υYS / υYL

υRI = 0.7VP-P

∗

2

υGI = 0.7VP-P

∗

2

υBI = 0.7VP-P

∗

2

NT / PAL = 0V

∗

2

NT / PAL = 0V

∗

2

NT / PAL = 0V

∗

2

Carrier leak

PAL burst phase

PAL burst ratio
YOUT DC voltage
COUT DC voltage
VOUT DC Voltage
High level input voltage

SYNC, BFP, NT / PAL
Low level input voltage

SYNC, BFP, NT / PAL
Input current during high

SYNC, BFP, NT / PAL
Input current during low

SYNC, BFP, NT / PAL

34

YOUT
VOUT

COUT
VOUT

∗

2 Guaranteed design with these parameters

∗

3 Measured using a 3.58MHz BPF for 3.5µs after the burst.

∗

4 Measured using a 3.58MHz BPF.

䊊 Not designed for radiation resistance

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Multimedia ICs BA7242F

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Measurement circuit

1

2

3

4

5

6

7

BIN input

GIN input

RIN input

V

CC

Composite SYNC

(BFP)

Burst flag pulse

YOUT
measurement point

Vcc

14

13

11

10

99

8

CLAMP

BFP

BFP

BFP

VCCSYNC

NT / PAL

BURST

FLAG

R-Y

MOD

F • F

B-Y

MOD

CHROMA

GEN

Y / C

MIX

SYNC

MIX

SYNC

V

CCGND

NT / PAL

MATRIX

PHASE

GEN

FILTER

GND

CLAMP

CLAMP

0.1µ

0.1µ

0.1µ

VCC

VOUT
measurement point

75

75

75

75

75

220µ

220µ

COUT
measurement point

75

0.47µ

0.1µ

560

4.7k
Color subcarrier

12

(1) The composite SYNC is input to the SYNCIN pin.
During Low level input, the SYNC signal is output to
the YOUT, VOUT, and SYNCOUT pins.
(2) The burst flag pulse is input to the BFPIN pin.
During Low level input, the burst signal is output to the
COUT and VOUT pins. For PAL, the phase inversion of
the chroma signal occurs according to this signal.
Furthermore, this signal also acts as the timing for the
pedestal clamp for the RIN, GIN, and BIN pins. By
using an external condenser for charging during Low
level input, the pedestal levels for the RIN, GIN, and
BIN pins are maintained at a uniform level.
(3) The NT / PAL pin is for selecting either NTSC or

PAL. For NTSC, this pin is connected to V

CC and for

PAL, this pin is connected to GND.
(4) The SCIN pin is the color subcarrier input pin. Input
either a pulse wave or a sine wave of frequency

3.579545MHz for NTSC or of frequency 4.433619MHz
for PAL.
(5) The COUT pin is the output pin for the chroma sig­nal, and the YOUT pin is the output pin for the lumi­nance signal. This is compatible with the S pin because
the chroma signal and the luminance signal can be out­put separately. Both pins have internal 75Ω drivers.
(6) The VOUT pin is the output pin for a color TV signal
and has an internal 75Ω driver.

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Operation description

5

Multimedia ICs BA7242F

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Application example (When using NTSC color TV signal)

1

2

3

4

5

6

7

Analog B signal

Analog G signal

Analog R signal

V

CC

Composite SYNC

(BFP)

Burst flag pulse

V

CC

14

13

12

11

10

9

8

CLAMP

BFP

BFP

BFP

VCCSYNC

NT / PAL

BURST

FLAG

R-Y

MOD

F • F

B-Y

MOD

CHROMA

GEN

Y / C

MIX

SYNC

MIX

SYNC

V

CC

GND

NT / PAL

MATRIX

PHASE

GEN

FILTER

GND

CLAMP

CLAMP

0.1µ

0.1µ

0.1µ

VCC

Color TV signal output

75

220µ

0.1µ

560

4.7k
Color subcarrier

+

•

Operation notes

(1) Since analog RGB signals perform clamping at the
input pin, input them with a low impedance.
(2) Input a signal of duty 50% for the color subcarrier. If
the duty fluctuates, it will affect the chroma phase.
Furthermore, for the application example, a voltage­dividing resistor is assumed for the CMOS input of 5V

P-P.

For other input formats, regulate the SCIN pin for

0.5V

P-P.

(3) Input the composite SYNC and burst flag pulse
according to the standard value. If the timing is off, the
TV receiver may not show any color. As well, set the
input level the same as the TTL level. The input imped­ance is 8kΩ.

•

External dimensions (Units: mm)

SOP14

0.4 ± 0.11.27

1

14

8.7 ± 0.2

7

8

4.4 ± 0.2

6.2 ± 0.3

0.11

1.5 ± 0.1

0.15

0.15 ± 0.1

0.3Min.