MAX4490 查看數據表（PDF） - Maxim Integrated
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MAX4490 Datasheet PDF : 8 Pages
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Low-Cost, High-Slew-Rate,
Rail-to-Rail I/O Op Amps in SC70
pole at frequency (2πR′CIN)-1, where R′ is the parallel
combination of the gain-setting resistors for the invert-
ing or noninverting amplifier configuration (Figure 2). If
the pole frequency is less than or comparable to the
unity-gain bandwidth (10MHz), the phase margin will
be reduced, and the amplifier will exhibit degraded
AC performance through either ringing in the step
response or sustained oscillations. The pole frequency is
10MHz when R′ = 3.2kΩ. To maximize stability, R′ <3kΩ
is recommended.
Applications that require rail-to-rail operation with mini-
mal loading (for small VDD - VOH and VOL - VSS) will
typically require R′ values >3kΩ. To improve step
response under these conditions, connect a small
capacitor Cf between the inverting input and output.
Choose Cf as follows:
Cf = 5(R / Rf) [pf]
where Rf is the feedback resistor and R is the gain-set-
ting resistor (Figure 2).
Figure 3 shows the step response for a noninverting
amplifier subject to R′ = 4kΩ with and without the Cf
feedback capacitor.
6
5
4
VDD = +2.7V
VDD - VOH = 200mV
VDD - VOH = 100mV
VDD - VOH = 50mV
VDD = +5.0V
3
2
1
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Figure 1a. Output Source Current vs. Temperature
9
VDD - VOH = 200mV
8
VDD - VOH = 100mV
7
VDD - VOH = 50mV
VDD = +5.0V
6
VDD = +2.7V
5
4
3
2
1
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Figure 1b. Output Sink Current vs. Temperature
INVERTING
VIN
R
Cf
Rf
MAX4490
VOUT
R′ = R || Rf
RfCf = RCIN
NONINVERTING
VIN
VOUT
MAX4490
Rf
Cf
R
R′ = R || Rf
RfCf = RCIN
Figure 2. Inverting and Noninverting Amplifier with Feedback
Compensation
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