MAX4351ESA Maxim Integrated, MAX4351ESA Datasheet - Page 8

• Manufacturer Part Number: MAX4351ESA
• Description: High Speed Operational Amplifiers
• Manufacturer: Maxim Integrated

ful attention to inputs and outputs to avoid large para-
sitic capacitance. Whether or not you use a constant-
impedance board, observe the following design guide-
lines:
• Don’t use wire-wrap boards; they are too inductive.
• Don’t use IC sockets; they increase parasitic capaci-
• Use surface-mount instead of through-hole compo-
• Use a PC board with at least two layers; it should be
• Keep signal lines as short and as straight as possi-
The input common-mode range extends from
V
rejection. Beyond this range, the amplifier output is a
nonlinear function of the input, but does not undergo
phase reversal or latchup. The output swings to within
125mV of either power-supply rail with a 2kΩ load.
Ultra-Small, Low-Cost, 210MHz, Dual-Supply
Op Amps with Rail-to-Rail Outputs
Figure 2. Driving a Capacitive Load Through an Isolation Resistor
8
EE
tance and inductance.
nents for better high-frequency performance.
as free from voids as possible.
ble. Do not make 90° turns; round all corners.
_______________________________________________________________________________________
to (V
CC
- 2.25V) with excellent common-mode
R
V
G
IN
R
TIN
50Ω
MAX435 _
Ground-Sensing Input
R
Rail-to-Rail Outputs,
F
R
ISO
C
L
V
OUT
The MAX4350/MAX4351 are optimized for AC perfor-
mance. They are not designed to drive highly reactive
loads, which decrease phase margin and may produce
excessive ringing and oscillation. Figure 2 shows a cir-
cuit that eliminates this problem. Figure 3 is a graph of
the Isolation Resistance (R
Figure 4 shows how a capacitive load causes exces-
sive peaking of the amplifier’s frequency response if
the capacitor is not isolated from the amplifier by a
resistor. A small isolation resistor (usually 20Ω to 30Ω)
placed before the reactive load prevents ringing and
oscillation. At higher capacitive loads, AC performance
is controlled by the interaction of the load capacitance
and the isolation resistor. Figure 5 shows the effect of a
27Ω isolation resistor on closed-loop response.
Coaxial cable and other transmission lines are easily
driven when properly terminated at both ends with their
characteristic impedance. Driving back-terminated
transmission lines essentially eliminates the line’s
capacitance.
Figure 3. Isolation Resistance vs. Capacitive Load
Output Capacitive Load and Stability
30
25
20
15
10
5
0
0
50
CAPACITIVE LOAD (pF)
100
ISO
150
) vs. Capacitive Load.
200
250