EL4390C
Triple 80 MHz Video Amplifier with DC Restore
Table 1 Charge Storage Capacitor Value vs Droop and Charging Rates
Cap Value
(nF)
10
22
47
100
220
Droop in
60mS (mV)
30
13 6
64
30
1 36
Charge in
2mS (mV)
400
182
85
40
18
Charge in
4mS (mV)
800
364
170
80
36
These numbers represent the worst case bias current and the worst case charging current Note that to
get the full (2mA
a
) charging current the clamp input must have
l
250mV of error voltage
Note that the magnitude of the bias current will decrease as temperature increases
The basic droop formula is
V (droop)
e
I
B
a
c
(Line time
b
Charge time)
and the basic charging formula is
V (charge)
e
I
OUT
c
Charge time
capacitor value
capacitor value
120
Where I
OUT
is
I
OUT
e
(Clamp voltage
b
IN
a
voltage)
4
ELANTEC [ ELANTEC SEMICONDUCTOR ]
