Philips TDA4884 Service Manual

INTEGRATED CIRCUITS

DATA SH EET

TDA4884

Three gain control video pre-amplifier for OSD

Preliminary speciﬁcation File under Integrated Circuits, IC02

June 1994

Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

FEATURES

• 85 MHz video controller

• Fully DC controllable

• 3 separate video channels

• Input black level clamping

• White level adjustment for 3 channels

GENERAL DESCRIPTION

The TDA4884 is a monolithic integrated RGB amplifier for colour monitor systems with super VGA performance, intended for DC or AC coupling of the colour signals to the cathodes of the CRT. With special advantages the circuit can be used in conjunction with the TDA485x monitor deflection IC family.

• Contrast control for all 3 channels simultaneously

• Cathode feedback to internal reference for cut-off

control, which allows unstabilized video supply voltage

• Current outputs for RGB signal currents

• RGB voltage outputs to external peaking circuits

• Blanking and switch-off input for screen protection

• Sync on green operation possible

• OSD application very easily.

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

l(b-w)

O(b-w)

positive supply voltage (pin 7) 7.2 8.0 8.8 V supply current − 48 − mA input voltage (black-to-white; pins 2, 5 and 8) − 0.7 1.0 V output voltage (black-to-white; pins 19, 16 and 13) nominal contrast;

− 0.79 − V pins 3, 1 and 11 open-circuit

O(b-w)

output current (black-to-white; pins 20, 17 and 14) − 50 − mA

peak output current (pins 20, 17 and 14) −− 100 mA B bandwidth −3 dB 70 85 − MHz G

nom

nominal gain (pins 2, 5 and 8 to pins 19, 16 and 13) nominal contrast;

− 1 − dB pins 3, 1 and 11 open-circuit

G C C T

v v OSD

amb

gain control for all channels (relative to G

) −5 −+2.6 dB

nom

contrast control V6= 1 to 6 V −22 −+3.4 dB minimum contrast for OSD V6= 0.7 V −−40 − dB operating ambient temperature −20 −+70 °C

ORDERING INFORMATION

EXTENDED

TYPE NUMBER

PINS PIN POSITION MATERIAL CODE

PACKAGE

TDA4884 20 DIL plastic SOT146

Note

1. SOT146-1; 1996 November 22.

June 1994 2

(1)

Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

Fig.1 Block diagram and basic application circuit for DC and AC coupling.

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Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

PINNING

SYMBOL PIN DESCRIPTION

GND 4 ground V

HBL 9 horizontal blanking, switch-off CL 10 input clamping, vertical blanking, test

1 gain control Channel 2 2 signal input Channel 1 3 gain control Channel 1

5 signal input Channel 2 6 contrast control, OSD switch 7 supply voltage 8 signal input Channel 3

mode 11 gain control Channel 3 12 feedback Channel 3 13 voltage output Channel 3 14 current output Channel 3 15 feedback Channel 2 16 voltage output Channel 2 17 current output Channel 2 18 feedback Channel 1 19 voltage output Channel 1 20 current output Channel 1

Fig.2 Pin configuration.

FUNCTIONAL DESCRIPTION

The RGB input signals (0.7 V

) are capacitively coupled

(p-p)

into the TDA4884 (pins 2, 5 and 8) from a low ohmic source and are clamped to an internal DC voltage (artificial black level). Composite signals will not disturb normal operations because an internal clipping circuit cuts all signal parts below black level. All channels have a maximum total voltage gain of 7 dB (maximum contrast and maximum individual channel gain). With the nominal channel gain of 1 dB and nominal contrast setting the nominal black-to-white output amplitude is 0.79 V

(p-p)

. DC voltages are used for contrast and gain control. Contrast control is achieved by a voltage at pin 6 and

affects the three channels simultaneously. To provide the correct white point, an individual gain control (pins 3, 1 and 11) adjusts the signals of Channels 1, 2 and 3.

Each output stage provides a current output (pins 20, 17 and 14) and a voltage output (pins 19, 16 and 13). External cascode transistors reduce power consumption of the IC and prevent breakdown of the output transistors. Signal

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output currents and peaking characteristics are determined by external components at the voltage outputs and the video supply. The channels have separate internal feedback loops which ensure large signal linearity and marginal signal distortion in spite of output transistor thermal V

variation.

The clamping pulse (pin 10) is used for input clamping only. The input signals have to be at black level during the clamping pulse and are clamped to an internal artificial black level. The coupling capacitors are used in this way for black level storage. Because the threshold for the clamping pulse is higher than that for vertical blanking (pin

10) the rise and fall times of the clamping pulse have to be faster than 75 ns/V during transition from 1 V to 3.5 V.

The vertical blanking pulse will be detected if the input voltage (pin 10) is higher than the threshold voltage for approximately 320 ns but does not exceed the threshold for the clamping pulse in the time between. During the vertical blanking pulse the input clamping is disabled in order to avoid misclamping in the event of composite input signals.

Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

The input signal is blanked and the artificial black level is inserted instead, thus the output signal is at reference black level. The DC value of the reference black level will be adjusted by cut-off stabilization (see below).

During horizontal blanking (pin 9) the output signal is set to reference black level as previously described and output clamping is activated. If the voltage at pin 9 exceeds the switch-off threshold the signal is blanked and switched to ultra black level for screen protection and spot suppression during V-flyback. Ultra black level is the lowest possible output voltage (at voltage outputs) and does not depend on cut-off stabilization.

For cut-off stabilization (DC coupling to the CRT) respectively black level stabilization (AC coupling) the video signal at the cathode or the coupling capacitor is divided by an adjustable voltage divider and fed to the feedback inputs (pins 18, 15 and 12). During the horizontal

blanking time this signal is compared with an internal DC voltage of approximately 5.8 V. Any difference will lead to a reference black level correction by charging or discharging the integrated capacitor which stores the reference black level information between the horizontal blanking pulses.

For OSD fast switching of control pin 6 to less than 1 V (e.g. 0.7 V) blanks the input signals. The OSD signals can easily be inserted to the external cascode transistor (see Fig.3).

During test mode (pins 9 and 10 connected to VP) the black levels at the voltage outputs (pins 12, 16 and 13) are internally set to typical 0.5 V (3 V DC at signal inputs (pins 2, 5 and 8)).

Fig.3 OSD application.

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Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

LIMITING VALUES

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

SYMBOL PARAMETER MIN. MAX. UNIT

V V V

I I P T T T V

P I ext

O M

tot stg amb j ESD

supply voltage (pin 7) 0 8.8 V input voltage (pins 2, 5 and 8) −0.1 V

V external DC voltage pins 20, 17 and 14 −0.1 V

V pins 19, 16 and 13 no external voltages pins 1, 3, 6 and 11 −0.1 V pin 9 −0.1 V pin 10 −0.1 V

+ 0.7 V

average output current (pins 20, 17 and 14; note 1) 0 50 mA peak output current (pins 20, 17 and 14) 0 100 mA total power dissipation − 1200 mW storage temperature −25 +150 °C operating ambient temperature −20 +70 °C junction temperature −25 +150 °C electrostatic handling for all pins (note 2) −500 +500 V

Notes to the limiting values

1. Signal amplitude of 50 mA black-to-white is possible if the average current (including blanking times and signal variation against time) does not exceed 50 mA. The maximum power dissipation of 1200 mW has to be considered.

2. Equivalent to discharging a 200 pF capacitor through a 0 Ω series resistor.

THERMAL RESISTANCE

SYMBOL PARAMETER THERMAL RESISTANCE

th j-a

from junction to ambient in free air 65 K/W

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Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

CHARACTERISTICS

= 8.0 V; T

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Video signal inputs (Channel 1: pin 2, Channel 2: pin 5 and Channel 3: pin 8)

I(b-w)

IC2,5,8

2,5,8

Contrast control (pin 6; note 2)

Tr tracking of output signals of

dfC

drC

= +25 °C; all voltages measured to GND (pin 4); unless otherwise speciﬁed.

amb

positive supply voltage (pin 7) 7.2 8.0 8.8 V supply current (pin 7) 36 48 60 mA

input voltage (black-to-white value;

− 0.7 1.0 V

pins 2, 5 and 8) DC voltage during input clamping

note 1 2.8 3.1 3.4 V

(artiﬁcial black + VBE) DC current no clamping;

2,5,8=VIC2,5,8;

= −20 to +70 °C

amb

during clamping; V

2,5,8=VIC2,5,8

± 0.7 V

−0.05 +0.05 +0.250 µA

±50 ±75 ±120 µA

input voltage 1.0 − 6.0 V maximum input voltage −−V

−1V

input voltage for nominal contrast note 3 − 4.3 − V input current V6= 4.3 V −5 −1 −0.1 µA contrast relative to nominal contrast V6= 6.0 V; pins 3, 1 and

2.4 3.4 − dB

11 open-circuit V

= 1.0 V; pins 3, 1 and

−26 −22 −19 dB

11 open-circuit

input voltage for minimum contrast pins 3, 1 and 11

− 0.7 − V

open-circuit 1 V < V

< 6 V; note 4 − 0 0.5 dB

Channels 1, 2 and 3 delay between leading edges (falling)

of step in contrast voltage and output signals at voltage outputs (pins 19,

V6= 4.3 V to 0.7 V; input fall time at pin 6: t

= 2 ns; note 5

fCC

− 720ns

16 and 13) delay between trailing edges (rising)

of step in contrast voltage and output signals at voltage outputs (pins 19,

V6= 0.7 V to 4.3 V; input rise time at pin 6: t

= 2 ns; note 5

rCC

− 15 25 ns

16 and 13) fall time of output signals at voltage

outputs (pins 19, 16 and 13)

rise time of output signals at voltage outputs (pins 19, 16 and 13)

90% to 10% amplitude; input fall time at pin 6: t

= 2 ns; note 5

fCC

10% to 90% amplitude; input rise time at pin 6: t

= 2 ns; note 5

rCC

− 615ns

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Philips Semiconductors Preliminary speciﬁcation

Three gain control video pre-ampliﬁer for OSD TDA4884

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Gain control (pin 3 for Channel 1, pin 1 for Channel 2 and pin 11 for Channel 3; note 6)

3,1,11

N3,1,11

3,1,11

Feedback input (Channel 1: pin 18, Channel 2: pin 15 and Channel 3: pin 12; note 7)

int

18,15,12

∆V

CRT

∆

TVint

∆

VVint

Voltage outputs (Channel 1: pin 19, Channel 2: pin 16 and Channel 3: pin 13; note 1)

O(b-w)

blx

blSO

blT

S/N signal-to-noise ratio note 10 − 50 44 dB D

∆

LFVbl

off

∆

TVO(b-w)

input voltage 1.0 − 6.0 V input voltage for nominal gain pins 3, 1 and 11

3.6 3.75 3.95 V

open-circuit input resistance 44 55 66 kΩ gain relative to nominal gain V6= 4.3 V; V

= 4.3 V; V

= 6 V 2 2.6 3.3 dB

3,1,11

=1V −5.5 −5 −4.5 dB

3, 1, 11

internal reference voltage 5.6 5.8 6.1 V maximum output current during output clamping;

18,15,12

= 3 V

−500 −100 −60 nA

∆ black level at CRT note 8 0 40 200 mV

variation of V

in the temperature

int

= −20 to +70 °C 0 20 50 mV

amb

range variation of V

nominal signal output voltage (black-to-white value)

with supply voltage 7.2 V ≤ VP≤ 8.8 V 0 60 100 mV

int

V6= 4.3 V; V

l(b-w)

= 0.7 V;

0.69 0.79 0.89 V pins 3, 1 and 11 open-circuit

maximum adjustable black level voltage

black level voltage during switch-off, equal to minimum

during output clamping; T

= −20 to +70 °C

amb

V9= VP; RO=33Ω; T

= −20 to +70 °C

amb

1 1.2 1.4 V

30 45 100 mV

adjustable black level voltage black level voltage during test

mode

output thermal distortion I ∆ black level between clamping

V9=VP; V10=VP;

0.3 0.7 1.2 V pin 1 open-circuit; V

= V

2,5,8

= 50 mA; note 11 − 0.6 1 %

O(b-w)

IC2,5,8

; note 9

line frequency 30 kHz − 0.5 4.5 mV

pulses maximum offset during sync

2,5,8

< V

; note 12 0 7 15 mV

IC2,5,8

clipping variation of nominal output signal

(black-to-white value) with temperature

V6= 4.3 V; V T

= −20 to +70 °C;

amb

l(b-w)

pins 3, 1 and 11

= 0.7 V;

0 2.5 10 %

open-circuit

Current outputs (Channel 1: pin 20, Channel 2: pin 17 and Channel 3: pin 14; note 13)

O(b-w)

;

20-19

17-16;V14-13

blSO

signal current (black-to-white value)

start of HF-saturation of output transistors

with peaking −−100 mA IO= 50 mA −−2.0 V

= 100 mA −−2.2 V

− 50 − mA

output current during switch-off V9= VP; RO= 33 Ω 0 20 900 µA

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