SGM358_15 Datasheet, PDF (8/17 Pages) SG Micro Corp – Low-Cost, Microprocessor Supervisory Circuit

SGM321/SGM358/SGM324
1MHz, 60μA, Rail-to-Rail I/O
CMOS Operational Amplifiers
TYPICAL APPLICATION CIRCUITS
Differential Amplifier
The circuit shown in Figure 4 performs the difference function. If
the resistor ratios are equal to (R₄ / R₃ = R₂ / R₁), then
VOUT = (Vp - Vn) × R2 / R1 + VREF.
R2
R1
Vn
Vp
R3
SGM321
R₄
VREF
V_OUT
Figure 4. Differential Amplifier
Low Pass Active Filter
The low pass filter shown in Figure 6 has a DC gain of (-R2 / R1)
and the -3dB corner frequency is 1/2R₂C. Make sure the filter
bandwidth is within the bandwidth of the amplifier. The large
values of feedback resistors can couple with parasitic
capacitance and cause undesired effects such as ringing or
oscillation in high-speed amplifiers. Keep resistor values as low
as possible and consistent with output loading consideration.
R₁
V_IN
C
R₂
SGM321
V_OUT
Instrumentation Amplifier
The circuit in Figure 5 performs the same function as that in
Figure 4 but with a high input impedance.
SGM321
Vn
R₂
R₁
SGM321
V_OUT
R₃ = R₁ // R₂
Figure 6. Low Pass Active Filter
Vp
R3
SGM321
R₄
VREF
Figure 5. Instrumentation Amplifier
SG Micro Corp
8
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