Frame Manual
500ADA-EQ-L Equalizing Analog Video Distribution Amplifier
500ADA-EQ-L - 6
Revision
1.2
5. CIRCUIT
DESCRIPTION
The input signal enters the board through looping BNCs with isolated ground so that balanced input
processing may be done to remove any common mode hum that may have been added to the signal and
ground shield. On-board jumpers allow you to configure the input impedance and input coupling (AC/DC).
For video applications, the synchronization pulses are analyzed for position and size information. A clamp
pulse is generated from the sync information and a clamp signal is delivered to a DC restorer circuit that
positions the blanking level to ground. This feature can be enabled with a jumper, the time-constant of the
clamping action may be fast or slow and the DC level may be set with a card edge POT.
An adjustable gain stage feeds the cable equalizer that can adjust the frequency response to match the
attenuation of up to 300m of coaxial cable. One OP-Amp drives the eight output BNC's with 75-Ohm
output impedance.
The digital power supply is separated from the analog power supply. In the case of a failure in the analog
power supply, the digital circuitry can report the fault to the global frame status bus and to the frame
controller card.
The power supply monitoring circuitry monitors the over-voltage conditions on 3.3V, 5 V and 12V power
supplies and under-voltage condition on 3.3V, 5V, and -5V power supplier. When an over-voltage or
under-voltage condition is detected, the local fault indicator will be turned on.
Over-voltage
Threshold
Under-voltage
Threshold
12V 15.2V
N/A
5V 6.2V
3.6V
-5V N/A
-3.3V
3V 4.1V
2V