EL4390C
Triple 80 MHz Video Amplifier with DC Restore
Table 1. Charge Storage Capacitor Value vs. Droop and Charging Rates
Cap Value
(nF)
Droop in
Charge in
Charge in
60mS (mV)
2mS (mV)
4mS (mV)
10
22
30
13.6
6.4
400
182
85
800
364
170
80
47
100
220
3.0
40
1.36
18
36
These numbers represent the worst case bias current, and the worst case charging current. Note that to
l
a
get the full (2mA ) charging current, the clamp input must have 250mV of error voltage.
Note that the magnitude of the bias current will decrease as temperature increases.
The basic droop formula is :
e
c
b
(Line time Charge time) / capacitor value
V (droop)
I
B
a
and the basic charging formula is:
e
c
Charge time / capacitor value
V (charge)
I
OUT
Where I
I
is:
OUT
e
(Clamp voltage
b a
IN voltage) / 120
OUT
4
ELANTEC [ ELANTEC SEMICONDUCTOR ]
