OPA637AM - Precision High-Speed DiFET Op Amp | Texas Instruments
MPN: OPA637AM β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $38.48 | $38.48 |
| 10 | $36.55 | $365.50 |
| 100 | $34.73 | $3,473.00 |
| 500 | $33 | $16,500.00 |
| 1,000 | $31.34 | $31,340.00 |
Drop-in alternatives for OPA637AM β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
OPA627AM
β Drop-Inπ Reference alternative (not in catalog)
OPA637SM
β Drop-Inπ Reference alternative (not in catalog)
OPA627SM
β Drop-Inβ In Stock
$145 / Unit
View Datasheet βOPA637AM Maximum Ratings & Electrical Characteristics
| Amplifier Type | Precision High-Speed DiFET Operational Amplifier |
| Number of Channels | 1 |
| Input Offset Voltage (max) | 100 uV |
| Offset Voltage Drift (max) | 0.8 uV/C |
| Input Bias Current (max) | 5 pA |
| Output Noise | Very low noise at 10 kHz (see datasheet for typ value) |
| Settling Time (0.01%) | Fast settling (see datasheet for typ value) |
| Stability | Stable in gain of 5 or greater (de-compensated) |
| Package | TO-99-8 (metal can) |
| Mounting Type | Through Hole |
| Manufacturer Process | DiFET (dielectrically isolated FET input) |
OPA637AM Pin Configuration
| Pin 1 | NC β Not connected (per datasheet) |
| Pin 2 | IN- β Inverting input |
| Pin 3 | IN+ β Non-inverting input |
| Pin 4 | V- β Negative power supply |
| Pin 5 | NC β Not connected (per datasheet) |
| Pin 6 | OUT β Amplifier output |
| Pin 7 | V+ β Positive power supply |
| Pin 8 | NC β Not connected (per datasheet) |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
OPA637AM is suitable for 6 applications: High-Speed Data Acquisition, Photodiode Transimpedance Amplification, Professional Audio Signal Chains, Precision Instrumentation Front Ends, Pulse Amplification and Integrators, Active Filters in High-Gain Topologies.
High-Speed Data Acquisition
The OPA637AM fits high-speed data acquisition front ends because its DiFET input combines a 100 uV maximum offset with fast settling to 0.01%, allowing ADC driver stages to reach accurate final values within short acquisition windows. In a typical gain-of-10 non-inverting stage, the de-compensated OPA637 delivers more bandwidth than the unity-gain-stable OPA627 would in the same socket. The 5 pA maximum bias current prevents high-impedance sensor sources from being loaded, preserving accuracy. Designers should verify that closed-loop gain remains at 5 or above and use low-inductance ground returns around the TO-99-8 can to protect the noise floor at 10 kHz and beyond.
Recommended
Photodiode Transimpedance Amplification
The OPA637AM is well suited to high-gain photodiode transimpedance stages, where its 5 pA maximum input bias current keeps photodiode leakage-equivalent error negligible and its 0.8 uV/C maximum drift preserves DC calibration over temperature. A transimpedance amplifier using a large feedback resistor typically presents effective closed-loop gain far above the minimum of 5 required for OPA637 stability, so the de-compensated design contributes additional bandwidth for faster pulse response. The metal TO-99-8 can shields the high-impedance summing node from electrostatic pickup. Place the feedback resistor close to the input pins and guard the IN- node to fully exploit the femtoampere-class input current performance.
Recommended
Professional Audio Signal Chains
In professional audio preamplifier and equalizer stages requiring gain of 5 or more, the OPA637AM offers the very low noise at 10 kHz that the datasheet highlights, together with precision DC characteristics that avoid offset-induced clicks and pops. The 100 uV maximum offset voltage means direct-coupled gain stages stay within acceptable output offset limits without servo correction in many designs. The DiFET input's 5 pA bias current allows use of high-value input networks without adding significant bias-induced offset. The metal can package additionally shields sensitive gain stages from hum and RF pickup in console environments with transformers and long signal lines.
Recommended
Precision Instrumentation Front Ends
Test and measurement instrumentation benefits from the OPA637AM's combination of 100 uV maximum offset, 0.8 uV/C drift, and fast 0.01% settling, which together allow a single amplifier stage to provide both DC accuracy and wideband response in high-gain (>=5) configurations such as oscilloscope vertical amplifiers and precision detector preamps. The low 5 pA bias current permits direct connection to high-impedance probes and sensors. Because drift and offset are tightly specified, calibration intervals can be extended compared with general-purpose high-speed amplifiers. Designers should account for the through-hole TO-99-8 footprint when laying out mixed through-hole/SMT measurement boards.
Recommended
Pulse Amplification and Integrators
The fast settling time to 0.01% accuracy specified for the OPA637AM makes it appropriate for pulse amplification and precision integrator circuits where an accurate final value must be reached quickly after a transient. In integrator topologies the effective noise gain at high frequency typically satisfies the gain-5-or-greater stability condition, letting designers exploit the de-compensated bandwidth. The 5 pA maximum input bias current minimizes integrator droop caused by input current charging the integration capacitor, and the 100 uV maximum offset limits output error accumulation. Choose capacitor dielectrics with low leakage and low voltage coefficient to match the amplifier's precision level.
Recommended
Active Filters in High-Gain Topologies
Active filter stages designed with passband gain of 5 or above can use the OPA637AM to combine precision DC characteristics with the wideband dynamics needed for fast-settling filter responses. The very low noise at 10 kHz preserves signal-to-noise ratio in narrow-band measurement filters, while the 100 uV maximum offset keeps filter center-point errors small in direct-coupled designs. The FET input's 5 pA bias current permits large resistor values in low-frequency filters without significant bias-current error. Verify each filter topology's noise gain at high frequency exceeds 5 for stability; Sallen-Key unity-gain sections should instead use the OPA627AM in the same socket.
Recommended
Recommended Products Summary
Engineering reference data for OPA637AM β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | OPA627AM | OPA637SM | OPA627SM |
|---|---|---|---|---|
| Package | TO-99-8 (metal can) | TO-99-8 (metal can) - same | TO-99-8 (metal can) - same | TO-99-8 (metal can) - same |
| Brand | Texas Instruments (Burr Brown heritage) | Texas Instruments | Texas Instruments | Texas Instruments |
| Input Offset Voltage (max) | 100 uV | 100 uV | [DATA_NEEDED] | [DATA_NEEDED] |
| Input Bias Current (max) | 5 pA | 5 pA | [DATA_NEEDED] | [DATA_NEEDED] |
| Stability | Stable at gain >= 5 (de-compensated) | Unity-gain stable | Stable at gain >= 5 | Unity-gain stable |
| Offset Drift (max) | 0.8 uV/C | 0.8 uV/C | [DATA_NEEDED] | [DATA_NEEDED] |
| Settling Time (0.01%) | Fast settling (see datasheet) | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Temperature Grade | Commercial/industrial (AM suffix) | Commercial/industrial | Military grade (SM suffix) | Military grade (SM suffix) |
Key Differentiators
- Higher bandwidth in high-gain circuits (vs OPA627AM)
- Superior EMI shielding via metal can (vs OPA637AU (SOIC-8))
- Trade-off: not unity-gain stable (vs OPA627AM)
Design Notes
The most frequent design error with the OPA637AM is using it in a unity-gain or low-gain (<5) configuration. The device is de-compensated and stable only at closed-loop gains of 5 or greater; below this it will oscillate. For buffer or gain-of-1 circuits, use the pin-compatible OPA627AM in the same TO-99-8 socket. Also check the high-frequency noise gain of feedback networks in integrator and transimpedance topologies to confirm the stability condition is met.
The TO-99-8 metal can is a through-hole package; provide a clean ground plane beneath it and keep the inverting input trace as short as possible to protect the 5 pA bias-current precision from leakage paths. Clean flux residue thoroughly around high-impedance nodes, or add a guard ring driven from the IN+ potential. The metal case can be tied to ground for additional EMI shielding in noisy environments.
Decouple the V+ and V- supply pins (pins 7 and 4) with 0.1 uF ceramic capacitors placed as close to the pins as the TO-99 layout permits, plus bulk tantalum capacitance on each rail. Good supply decoupling preserves the low noise performance at 10 kHz cited in the datasheet and prevents supply-coupled oscillation in the wideband de-compensated design.
Compliance Information
Compliance status not stated in the provided distributor listings; verify via TI product page at ti.com/product/OPA637 or distributor compliance certificates.
