TDA4655 查看數據表（PDF） - Philips Electronics

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TDA4655

Generic multi-standard decoder

Philips Electronics 

Philips Semiconductors

Generic multi-standard decoder

Preliminary specification

TDA4655

demodulated signal. The result is an

identification signal (PIDT, pin 15) that

is positive for a PAL signal in PAL

mode, for a SECAM signal in SECAM

mode and for a PAL signal in

NTSC 4.4 mode.

If PIDT is positive in SECAM mode,

the scanner switches back to the PAL

mode in order to prevent a PAL signal

being erroneously identified as a

SECAM signal (PAL priority). If then

PIDT is not positive, the scanner

returns to SECAM mode and remains

there until PIDT is positive again. In

the event of a field frequency of 60 Hz

the signal can not be identified as a

SECAM signal, even if PIDT is

positive. In this event the scanner

switches forward in the NTSC 3.5

mode. If the H/2 signal has the wrong

polarity, the identification signal is

negative and the H/2 flip-flop is set to

the correct phase.

The third demodulator operates in

NTSC mode and is active during the

burstkey pulse. The resulting

identification signal (NIDT, pin 14) is

positive for PAL and NTSC 4.4

signals in NTSC 4.4 mode and for

NTSC 3.5 signals in the NTSC 3.5

mode. The reference signal has the

(B−Y) phase.

The two identification signals allow an

unequivocal identification of the

received signal. In the event of a

signal being identified, the scanning is

stopped and after a delay time the

colour is switched on.

The standard outputs (active HIGH)

are available at the pins 20, 21, 22

and 23. During scanning the HIGH

level is 2.5 V and when a signal has

been identified the HIGH level is

switched to 6 V. The standard pins

can also be used as inputs in order to

force the IC into a desired mode

(Forced Standard Setting).

Sandcastle detector and pulse

processing

In the sandcastle detector the super

sandcastle pulse (SC) present at pin

24 is compared with three internal

threshold levels by means of three

differential amplifiers. The derived

signals are the burstkey pulse, the

horizontal blanking pulse and the

combined horizontal and vertical

blanking pulse. These signals are

processed into various control pulses

required for the timing of the IC.

Bandgap reference

In order to ensure that the CD output

signals and the threshold levels of the

sandcastle detector are independent

of supply voltage variations a

bandgap reference voltage has been

integrated.

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 134).

SYMBOL

PARAMETER

CONDITIONS

Tstg

Tamb

Vp

Ptot

V24

storage temperature

operating ambient temperature

supply voltage

power dissipation

voltage at pin 24

voltage at all other pins

without load

Imax = 10 µA

Imax = 100 µA

MIN.

−25

0

−

−

−

−

MAX.

+150

+70

8.8

330

15

VP +

Vbe

UNIT

°C

°C

V

mW

V

V

THERMAL RESISTANCE

SYMBOL

Rth j-a

PARAMETER

thermal resistance on printed-circuit board from

junction to ambient in free air (without heat spreader)

SO 24

SDIL 24

THERMAL RESISTANCE

90 K/W

70 K/W

June 1993

6

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