TDA4884 Datasheet, PDF (12/28 Pages) NXP Semiconductors – Advanced monitor video controller for OSD

Philips Semiconductors
Three gain control video pre-amplifier for OSD
Product specification
TDA4884
13. The output current approximately follows the equation
I_o
=
V_o


R---1--_O^--
+
2----.--2--1---k---Ω^{--- }
–
500
µA
for V_o > V_bl(SO) and with
R_O = external resistor at voltage output to ground.
The external RC combination at pins 19, 16 and 13 (see Fig.1) enables peak currents during transients.
14. Frequency response, crosstalk and pulse response have been measured at voltage outputs in a special
printed-circuit board with 50 Ω line in/out connections and without peaking (see Chapter “Application and test
information”). Typical frequency response see Fig.9, typical pulse response see Fig.11 and typical characteristic of
contrast control as a function of frequency see Fig.12.
15. Crosstalk between any two output pins (e.g. channels 1 and 2):
a) Input conditions: one channel (channel 1) with nominal input signal and minimum rise time. The inputs of the
other channels capacitively coupled to ground (channels 2 and 3). Gain pins 3, 1 and 11 open-circuit.
b) Output conditions: output signal of channel 1 is set by contrast control voltage (pin 6) to
V_o(b-w) = V_o(VOUT1) = 0.7 V, the rise time should be 5 ns. Output signal of channel 2 then is V_o(b-w) = V_o(VOUT2).
c) Transient crosstalk: α_{cr (tr)} = 20 × log ^VV-----oo--⁽⁽--^VV---^OO---^UU----^TT--²¹---⁾⁾ dB
d) Crosstalk as a function of frequency has been measured without peaking circuit, with nominal input signal and
nominal settings. Typical frequency dependent crosstalk between channels see Figs 13, 14 and 15.
16. The internal threshold voltages are derived from a stabilized voltage. The internal pulses are generated while the
input pulses are higher than the thresholds. Voltages less than −0.1 V at pins 9 and 10 can influence black-level
control and should be avoided.
17. For 75 ns/V < t_r(CL), t_f(CL) < 240 ns/V, generation of internal input clamping and blanking pulse is not defined.
Pulses not exceeding the threshold of input clamping (typical 3 V) will be detected as blanking pulse. Timing of pulses
at pin 10 see Fig.16.
1997 Nov 26
12