MC33172D - Low-Power Dual Op Amp | STMicroelectronics
MPN: MC33172D ✓ ActiveMC33172D Overview
An operational amplifier is a voltage-controlled differential amplifier that compares two input voltages and amplifies their difference. Operational amplifiers form part of the broader analog IC and active-signal-processing hierarchy. The MC33172D uses bipolar transistor input stages and is suitable for functions such as buffering, gain amplification, comparisons, filtering, and instrumentation interfaces when configured with suitable external resistors and capacitors.
Each MC33172D channel provides a practical combination of low power consumption and general-purpose signal handling. The device contains two amplifier circuits in one 8-SOIC package, reducing component count and board area in designs requiring paired amplification. Its listed maximum input offset voltage is 6.5 mV, while its unity-gain bandwidth is 1.8 MHz. These characteristics suit signal paths that do not require the very low offset, very high bandwidth, or very low noise associated with specialized precision amplifiers.
The bipolar architecture is appropriate for low-frequency control, measurement, and conditioning circuits where the amplifier operates mainly in a closed-loop configuration. Noise, offset, input common-mode range, output swing, supply current, and stability characteristics must be checked against the actual signal amplitude and frequency before the device is used. Negative feedback, adequate output loading, and input-referenced compensation should follow the manufacturer's recommended application circuits.
Typical applications include dual-axis sensor signal conditioning, active filtering, audio preamplification, threshold detection, low-frequency instrumentation, and general industrial control. Two channels can also implement differential or complementary signal processing when their inputs and outputs are configured appropriately. The 8-SOIC package is easy to assemble with conventional surface-mount production equipment and can simplify upgrades compared with discrete single-amplifier packages.
Designers should verify the supported supply voltage, common-mode input range, output swing, input bias current, and operating temperature against the manufacturer's datasheet. Input and output voltages must remain within the electrical limits, and unused amplifier inputs should be biased rather than left floating. Stable feedback-network values are essential at higher frequencies.
This product page combines package details, searchable technical questions, application guidance, and a drop-in comparison focused on practical amplifier selection. It helps engineers distinguish the dual bipolar MC33172D from higher-speed rail-to-rail alternatives before committing a circuit board to an 8-SOIC footprint.
Drop-in alternatives for MC33172D — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MC33172D (same form factor and footprint) — differing in Package.
MC33172D
✅ Drop-InContact for price
View Datasheet →LM358DT
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$0.0509 / Unit
View Datasheet →MC33172D Maximum Ratings & Electrical Characteristics
| Amplifier Type | General-purpose operational amplifier |
| Number of Amplifier Circuits | 2 circuits |
| Input Transistor Technology | Bipolar |
| Power Category | Low power |
| Unity-Gain Bandwidth | 1.8 MHz |
| Maximum Input Offset Voltage | 6.5 mV |
| Package | 8-SOIC |
| Number of Pins | 8 pins |
| Mounting Type | Surface mount |
| Output Type | Single-ended |
MC33172D 8-soic Pin Configuration Guide
Pin configuration for MC33172D (8-soic package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for MC33172D.
Refer to the datasheet for full pin configuration.
Typical Applications
MC33172D is suitable for 6 applications: Dual-Axis Sensor Signal Conditioning, Active Audio Preamplification, Industrial Threshold Detection, Active Filtering and Frequency Control, Low-Frequency Instrumentation, Embedded Control Signal Conditioning.
Dual-Axis Sensor Signal Conditioning
The MC33172D fits dual-axis sensor interfaces because two bipolar amplifier channels are integrated in one 8-SOIC package. Each channel can amplify a low-frequency sensor signal before it reaches an ADC, while the listed 1.8 MHz bandwidth provides ample margin for many position, force, and level sensors. The 6.5 mV maximum input offset must be compared with the smallest sensor output, because offset that appears small relative to a full-scale signal can become significant near the measurement floor. Verify the sensor's output voltage against the input common-mode range and choose resistor values that preserve closed-loop stability.
Recommended
Active Audio Preamplification
The MC33172D can support two low-frequency audio preamplifier channels when the source impedance, signal level, and required bandwidth remain modest. Its bipolar input stage is appropriate for general-purpose voltage amplification, and the listed 1.8 MHz unity-gain bandwidth comfortably exceeds the bandwidth of many line-level and instrument preamplifier stages. The dual 8-SOIC construction also reduces board area compared with two separate single-amplifier packages. Keep the gain network within the manufacturer's recommended range, check output swing against the target level, and add output isolation if the next stage presents an unexpectedly low load.
Recommended
Industrial Threshold Detection
The MC33172D is suitable for industrial threshold detection when two independent comparisons or monitoring functions are required. Its two amplifier channels can form comparator-style circuits with external feedback and reference networks, while the 1.8 MHz bandwidth is more than adequate for most slow process-control signals. The 6.5 mV maximum input offset should be included when setting a narrow alarm threshold around a low-level sensor signal. Ensure the reference voltage and signal stay inside the device's common-mode range, and include output-swing margin for the logic interface or relay-driver stage.
Recommended
Active Filtering and Frequency Control
The MC33172D can implement first-order and carefully compensated higher-order active filters when the signal bandwidth is well below the listed 1.8 MHz unity-gain bandwidth. Two channels make cascaded sections practical without splitting the circuit across separate packages. Component tolerances, op-amp gain-bandwidth behavior, and the maximum offset voltage directly influence cutoff accuracy and low-level response. Validate the filter against its intended load and verify that the feedback network does not introduce unintended peaking near the amplifier's gain-bandwidth limit. Stable resistor and capacitor choices are especially important when precision cutoff placement is required.
Recommended
Low-Frequency Instrumentation
The MC33172D is appropriate for instrumentation that handles low-frequency or audio-band signals and needs two general-purpose amplifier channels in a single package. Its 1.8 MHz bandwidth supports buffering and moderate-gain functions around measurement transducers, although input bias current must be checked against high-impedance sources. The device's 6.5 mV maximum input offset is a key consideration for bridge or level measurements with small full-scale outputs. Use short, shielded interconnects for noisy analog environments and confirm that grounding does not create feedback through the source impedance.
Recommended
Embedded Control Signal Conditioning
The MC33172D can condition two low-speed control or feedback signals between sensors and an embedded controller. One channel may amplify a feedback measurement while the other shapes an actuator command, and the 8-SOIC package simplifies assembly in compact control boards. The amplifier's bandwidth is sufficient for many servo, thermal-control, and motor-position loops, but loop stability must be checked with the actual sensors, filters, and actuator loads. Keep control signals within the input and output ranges and account for the amplifier's offset when precise setpoints or small error voltages matter.
Recommended
Recommended Products Summary
Engineering reference data for MC33172D — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC33172D | LM358 |
|---|---|---|---|
| Brand | STMicroelectronics | onsemi | onsemi |
| Package | 8-SOIC | 8-SOIC | 8-SOIC |
| Amplifier Count | 2 circuits | 2 circuits | 2 circuits |
| General-Purpose Amplifier | Yes | Yes | Yes |
Key Differentiators
- Higher cited maximum supply capability than the LM358 alternative (vs LM358)
- Dual low-power bipolar channels in one standard 8-SOIC package (vs MC33172D)
- Direct onsemi-branded source for the same base ordering number (vs MC33172D)
Design Notes
Treat the MC33172D as a bipolar-input general-purpose amplifier rather than a rail-to-rail device. Before connecting sensors or control signals, verify that both input voltages remain within the common-mode range and that the required output level has adequate swing under the expected load. The listed 6.5 mV maximum input offset can materially affect precision measurements near the signal floor, and the 1.8 MHz bandwidth should be treated as a closed-loop guideline rather than unlimited signal capability.
Follow the manufacturer's pin-description drawing when assigning the 8-SOIC footprint. Keep the two amplifier channels separate in the layout when they carry unrelated signals, because sharing ground-current paths can inject one channel's output current into the other input reference. Place input and feedback components close to their associated pins, maintain a quiet ground return for sensitive inputs, and avoid routing high-current actuator or switching paths beneath the analog package.
Calculate the closed-loop gain and required signal bandwidth together. For an inverting or non-inverting stage, the closed-loop bandwidth is approximately the unity-gain bandwidth divided by the closed-loop noise gain, so a 1.8 MHz device has less usable bandwidth as feedback reduces the signal gain. Add output isolation for capacitive loads, keep feedback-loop area small, and test stability with the real sensor, filter, and downstream load because reactive loading can materially change the response.
Confirm that the selected supply rail satisfies the manufacturer's recommended operating range and that every input and output remains inside its absolute maximum limits. The cited cross-reference notes a 44 V MC33172 capability, compared with a lower LM358 limit, but the complete operating range should still be taken from the datasheet. Use local bypass capacitance, provide adequate return-current paths, and account for input and output currents when estimating total supply demand.
Compliance Information
No explicit RoHS, REACH, lead-free, halogen-free, or conflict-minerals status was identified. AEC-Q100 is treated as not applicable because the product is a general-purpose analog IC without an automotive qualification indication.
