MAX4490AUK-T 查看數據表（PDF） - Maxim Integrated

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MAX4490AUK-T

Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70

Maxim Integrated 

Low-Cost, High-Slew-Rate,

Rail-to-Rail I/O Op Amps in SC70

Driving Capacitive Loads

In conjunction with op amp output resistance, capaci-

tive loads introduce a pole frequency that can reduce

phase margin and lead to unstable operation. The

MAX4490/MAX4491/MAX4492 drive capacitive loads

up to 300pF without significant degradation of step

response and slew rate (Figure 4). Capacitive Load

Stability (page 1) shows regions of stable and margin-

ally stable (step overshoot <10%) operation for different

combinations of capacitive and resistive loads.

Improve stability for large capacitive loads by adding

an isolation resistor (typically 10Ω) in series with the

output (Figure 5). Note that the isolation resistor forms a

voltage divider with potential for gain error.

Chip Information

MAX4490 TRANSISTOR COUNT: 60

MAX4491 TRANSISTOR COUNT: 120

MAX4492 TRANSISTOR COUNT: 240

SUBSTRATE CONNECTED TO VSS

3a)

4a)

WITHOUT FEEDBACK COMPENSATION

AV = -1, RL = 4kΩ, Cf = 0

3b)

WITHOUT CAPACITIVE LOADING

AV = +1, RL = 100kΩ, CL = 0

4b)

WITH FEEDBACK COMPENSATION

AV = -1, RL = 4kΩ, Cf = 5pF

Figure 3. Step Response With and Without Feedback

Compensation

WITH CAPACITIVE LOADING

AV = +1, RL = 100kΩ, CL = 300pF

Figure 4. Step Response With and Without Capacitive Loading

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