FHP3350 Datasheet, PDF (13/19 Pages) Fairchild Semiconductor – Triple and Quad Voltage Feedback Amplifiers

Applications Information
General Description
The FHP3350 and FHP3450 are low cost, high performance,
voltage feedback amplifiers designed for video applications.
These triple and quad amplifiers consume only 3.6mA of supply
current per channel and are capable of driving dual (75Ω) video
loads while providing 0.1dB of gain flatness to 30MHz.
Consumer video applications will also benefit from their low
0.07% differential gain and 0.03˚ differential phase errors. The
FHP3350 offers three outputs that can be put into a high
impedance disable state to allow for video multiplexing or
minimize power consumption.
These amplifiers are designed to operate from 5V (±2.5V) to
12V (±6V) supplies. The outputs swing to within 1.3V of either
supply rail to accommodate video signals on a single 5V supply.
The FHP3350 and FHP3450 are designed on a complementary
bipolar process. They provide 210MHz of full power bandwidth
and 1,100V/µs of slew rate at a supply voltage of ±5V. The
combination of high performance, low power, and excellent
video performance make these amplifiers well suited for use in
many digital consumer video appliances as well as many
general purpose high speed applications.
Driving Capacitive Loads
The Frequency Response vs. C_L plot on page 8, illustrates the
response of the FHP3350 Family. A small series resistance
(R_s) at the output of the amplifier, illustrated in Figure 1, will
improve stability and settling performance. R_s values in the
Frequency Response vs. C_L plot were chosen to achieve
maximum bandwidth with less than 1dB of peaking. For
maximum flatness, use a larger R_s.
Rs
Rf
CL
RL
Rg
Figure 31. Typical Topology for driving
capacitive loads
Power Dissipation
The maximum internal power dissipation allowed is directly
related to the maximum junction temperature. If the maximum
junction temperature exceeds 150˚C for an extended time,
device failure may occur. The FHP3350 and FHP3450 are short
circuit protected. However, this may not guarantee that the
maximum junction temperature (+150˚C) is not exceeded under
all conditions. RMS Power Dissipation can be calculated using
the following equation:
Power Dissipation = I_s * (V_s+ - V_s-) + (V_s+ - V_o(RMS)) * I_OUT(RMS)
Where I_s is the supply current, V_s+ is the positive supply pin
voltage, V_s- is the negative supply pin voltage, V_o(RMS) is the
RMS output voltage and I_OUT(RMS) is the RMS output current
delivered to the load. Follow the maximum power derating
curves shown in Figure 32 below to ensure proper operation.
1.4
1.2
TSSOP-14
1.0
SOIC-14
0.8
0.6
0.4
0.2
0
-40 -20 0 20 40 60 80
Ambient Temperature (°C)
Figure 32. Maximum Power Derating
Overdrive Recovery
For an amplifier, an overdrive condition occurs when the output
and/or input ranges are exceeded. The recovery time varies
based on whether the input or output is overdriven and by how
much the ranges are exceeded. The FHP3350/3450 will
typically recover in less than 50ns from an overdrive condition.
Figure 33 shows the FHP3350 in an overdriven condition.
2
Vs = ±2.5V
1.5 ^{G = +5}
Output
1
Input
0.5
0
-0.5
-1
-1.5
-2
0 0.1 02 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Time (µs)
Figure 33. Overdrive Recovery
FHP3350, FHP3450 Rev. 1A
13
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