MAX4412EXK-T(2000) Просмотр технического описания (PDF) - Maxim Integrated

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MAX4412EXK-T
(Rev.:2000)

Low-Cost, Low-Power, Ultra-Small, 3V/5V, 500MHz Single-Supply Op Amps with Rail-to-Rail Outputs

Maxim Integrated 

Low-Cost, Low-Power, Ultra-Small, 3V/5V, 500MHz

Single-Supply Op Amps with Rail-to-Rail Outputs

PIN

MAX4412 MAX4413

1





1



7

2

4

3





3



5

4





2



6

5

8

NAME

OUT

OUTA

OUTB

VEE

IN+

INA+

INB+

IN-

INA-

INB-

VCC

Amplifier Output

Amplifier A Output

Amplifier B Output

Negative Power Supply

Amplifier Noninverting Input

Amplifier A Noninverting Input

Amplifier B Noninverting Input

Amplifier Inverting Input

Amplifier A Inverting Input

Amplifier B Inverting Input

Positive Power Supply

FUNCTION

Pin Description

Detailed Description

The MAX4412/MAX4413 single-supply, rail-to-rail, volt-

age-feedback amplifiers achieve 220V/µs slew rates

and 500MHz -3dB bandwidths, while consuming only

1.7mA of supply current per amplifier. Excellent har-

monic distortion and differential gain/phase perfor-

mance make these amplifiers an ideal choice for a wide

variety of video and RF signal-processing applications.

Internal feedback around the output stage ensures low

open-loop output impedance, reducing gain sensitivity

to load variations. This feedback also produces

demand-driven current bias to the output transistors.

Rail-to-Rail Outputs,

Ground-Sensing Input

The MAX4412/MAX4413 input common-mode range

extends from (VEE - 0.1V) to (VCC - 1.5V) with excellent

common-mode rejection. Beyond this range, the ampli-

fier output is a nonlinear function of the input, but does

not undergo phase reversal or latchup.

The output swings to within 105mV of either power-sup-

ply rail with a 1kΩ load. Input ground sensing and rail-

to-rail outputs substantially increase the dynamic

range. With a symmetric input in a single +5V applica-

tion, the input can swing 3.6Vp-p, and the output can

swing 4.6Vp-p with minimal distortion.

Output Capacitive Loading

and Stability

The MAX4412/MAX4413 are optimized for AC perfor-

mance. They are not designed to drive highly reactive

loads. Such loads decrease phase margin and may

produce excessive ringing and oscillation. The use of

an isolation resistor eliminates this problem (Figure 1).

Figure 2 is a graph of the Optimal Isolation Resistor

(RISO) vs. Capacitive Load.

The Small Signal Gain vs. Frequency with Capacitive

Load and No Isolation Resistor graph in the Typical

Operating Characteristics shows how a capacitive load

causes excessive peaking of the amplifier’s frequency

response if the capacitor is not isolated from the ampli-

fier by a resistor. A small isolation resistor (usually 20Ω

to 30Ω) placed before the reactive load prevents ring-

ing and oscillation. At higher capacitive loads, AC per-

formance is controlled by the interaction of the load

capacitance and the isolation resistor. The Small-Signal

Gain vs. Frequency with Capacitive Load and 22Ω

Isolation Resistor graph shows the effect of a 22Ω isola-

tion 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.

___________Applications Information

Choosing Resistor Values

Unity-Gain Configuration

The MAX4412/MAX4413 are internally compensated for

unity gain. When configured for unity gain, the devices

require a 24Ω feedback resistor (RF). This resistor

improves AC response by reducing the Q of the paral-

lel LC circuit formed by the parasitic feedback capaci-

tance and inductance.

_______________________________________________________________________________________ 9

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