BUF634U/2K5 - 250mA 180MHz High-Speed Buffer | TI
MPN: BUF634U/2K5 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $19.75 | $19.75 |
| 10 | $18.2 | $182.00 |
| 100 | $16.8 | $1,680.00 |
| 500 | $15.4 | $7,700.00 |
| 1,000 | $14.1 | $14,100.00 |
Drop-in alternatives for BUF634U/2K5 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BUF634AIDR
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View Datasheet →BUF634U/2K5 Maximum Ratings & Electrical Characteristics
| Amplifier Type | Buffer (unity-gain, open-loop) |
| Number of Circuits | 1 |
| Output Current | 250 mA |
| Bandwidth (-3dB) | 180 MHz (full BW mode) |
| Alternate Bandwidth Setting | 30 MHz (BW pin tied to V-) |
| Slew Rate | 2000 V/us |
| Supply Voltage Range (Single) | 4.5 V to 36 V |
| Supply Voltage Range (Dual) | +/-2.25 V to +/-18 V |
| Quiescent Current | 1.5 mA (30 MHz BW mode) |
| Input Bias Current | 5 uA |
| Input Offset Voltage | 30 mV |
| Protection Features | Internal current limit, thermal shutdown |
| Operating Temperature Range | -40C to +125C |
| Package | 8-pin SOIC (D) |
| Mounting Type | Surface Mount (SMD/SMT) |
| Packaging | Tape & Reel (2K5 = 2500 units/reel) |
BUF634U/2K5 Pin Configuration
| Pin 1 | BW — Bandwidth select: open for 180MHz, tie to V- for 30MHz low-power mode |
| Pin 2 | IN — Buffer input |
| Pin 3 | NC — Not connected (per datasheet) |
| Pin 4 | V- — Negative supply |
| Pin 5 | NC — Not connected (per datasheet) |
| Pin 6 | OUT — Buffer output, 250mA capability |
| Pin 7 | NC — Not connected (per datasheet) |
| Pin 8 | V+ — Positive supply |
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
BUF634U/2K5 is suitable for 6 applications: Op Amp Output Current Boost, Headphone and Audio Line Drivers, Automatic Test Equipment (ATE) Drivers, Piezo and Capacitive Load Drive, Video Distribution and Cable Driving, Instrumentation Output Stages.
Op Amp Output Current Boost
The primary application of the BUF634U/2K5 is embedding the buffer inside an op amp feedback loop to raise output current to 250mA while the loop gain corrects the buffer's 30mV offset and unity-gain error. With 2000 V/us slew rate and 180MHz bandwidth, the composite amplifier retains the precision DC accuracy of the op amp and the current drive of the buffer. Placed directly at the op amp output with short traces and local 0.1uF/10uF supply decoupling, it also isolates the op amp from reactive loads, eliminating thermal-feedback-induced offset drift on the input pair and improving capacitive load drive dramatically.
Recommended
Headphone and Audio Line Drivers
In high-fidelity headphone amplifiers, the BUF634U/2K5 provides the high 250mA output current needed for low-impedance headphones while a precision op amp sets gain and distortion. The 30MHz bandwidth-select mode with only 1.5mA quiescent current is popular in portable headphone designs because it halves power draw versus full 180MHz mode while still exceeding audio requirements by three orders of magnitude. The 2000 V/us slew rate ensures large audio transients are reproduced without slew-induced distortion, and the buffer's open-loop architecture inside the op amp loop keeps THD at the level set by the surrounding amplifier.
Recommended
Automatic Test Equipment (ATE) Drivers
ATE pin drivers and cable drivers demand both fast edges and high current: the BUF634U/2K5's 180MHz bandwidth and 2000 V/us slew rate drive long cables and capacitive loads with 250mA peak capability. The wide +/-18V supply range accommodates legacy bipolar test levels, and the internal current limit protects the driver during fault conditions with low-impedance loads. The buffer can be placed inside a loop with a precision op amp to define accurate output levels, while the BUF634 supplies the muscle; thermal shutdown provides a final safeguard during sustained high-current test patterns.
Recommended
Piezo and Capacitive Load Drive
Piezo actuators and long coaxial cables present large, mostly capacitive loads that destabilize conventional op amps. The TI datasheet specifically recommends the BUF634 inside the op amp feedback loop to improve capacitive load drive: the buffer isolates the load from the op amp output while the loop maintains DC accuracy. With 250mA available, charging and discharging nanofarad-scale capacitance is fast - for example, driving 10nF with 250mA yields slew-equivalent rates on the order of tens of volts per microsecond. A small series isolation resistor at the buffer output further damps resonance peaks.
Recommended
Video Distribution and Cable Driving
Video and high-speed signal chains require drivers whose bandwidth far exceeds the signal content; the BUF634U/2K5's 180MHz -3dB bandwidth and 2000 V/us slew rate comfortably support high-resolution video and fast pulse signals over 75-ohm coaxial lines. The wide +/-18V supply range supports standard video signal swings with headroom, and the open-loop buffer topology adds minimal phase shift, which is important when the buffer sits inside the enclosing feedback loop. The SOIC-8 surface-mount package suits dense multi-channel video distribution cards where channel count and board area are at a premium.
Recommended
Instrumentation Output Stages
Bench instruments, programmable power references, and sensor excitation sources need output stages that combine precision and current drive. The BUF634U/2K5 placed inside the feedback loop of a precision amplifier yields a composite output stage with the amplifier's microvolt-level accuracy and the buffer's 250mA drive. Thermal shutdown and current limit protect against accidental shorts during probing, an important robustness feature in lab instruments. Operating from +/-15V rails typical of analog instrumentation, the buffer's -40C to +125C temperature range ensures behavior is stable across bench and environmental testing conditions.
Recommended
Recommended Products Summary
Engineering reference data for BUF634U/2K5 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BUF634AIDR | BUF634AIDDAR | BUF634U |
|---|---|---|---|---|
| Package | SOIC-8 (D) | SOIC-8 (D) - same | SOIC-8 (D) - same | SOIC-8 (D) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 250 mA | 250 mA | 250 mA | 250 mA |
| Bandwidth | 180 MHz / 30 MHz selectable | 180 MHz / 30 MHz selectable | 180 MHz / 30 MHz selectable | 180 MHz / 30 MHz selectable |
| Slew Rate | 2000 V/us | 2000 V/us | 2000 V/us | 2000 V/us |
| Supply Range | +/-2.25V to +/-18V | +/-2.25V to +/-18V | +/-2.25V to +/-18V | +/-2.25V to +/-18V |
| Quiescent Current (30MHz BW) | 1.5 mA | 1.5 mA | 1.5 mA | 1.5 mA |
| Lifecycle / Upgrade Status | Active (BUF634A is recommended upgrade) | Active - recommended new-design choice | Active - recommended new-design choice | Active - original die |
| Packaging Option | Tape & Reel, 2500 units (2K5) | Tape & Reel (DR = 2500/reel) | Tape & Reel, larger reel (DDAR) | Tube / small-quantity tray |
Key Differentiators
- Pin-selected bandwidth/power trade-off (vs OPA633)
- Higher output current than op amp output stages (vs THS4062ID)
- Trade-off: open-loop accuracy (vs BUF634AIDR)
Design Notes
The 8-pin SOIC package has modest thermal capability. Estimated: with +/-15V rails and 100mA average output into a grounded-referenced load, dissipation approaches (15V - VOUT)*IOUT plus quiescent terms; at higher currents the junction can exceed safe limits quickly. Use generous copper pour tied to the SOIC-8 footprint's thermal relief, and treat the internal thermal shutdown as a fault protection limit rather than a continuous operating mechanism. For sustained multi-hundred-milliamp duty, the TO-220 BUF634T variant offers far better thermal performance on the same die.
Exploit the BW pin (pin 1) as a power/speed trade-off: open (or high) gives the full 180MHz bandwidth, while tying it to V- selects the 30MHz mode and cuts quiescent current to 1.5mA. Decouple both supply pins with 0.1uF ceramic capacitors placed within a few millimeters of pins 4 and 8, plus 10uF bulk capacitance per rail. Because the buffer delivers 250mA pulses, supply trace inductance directly converts di/dt into rail bounce on neighboring circuitry - use a solid ground plane and short wide supply traces.
The BUF634 is an open-loop unity-gain buffer with 30mV input offset and 5uA bias current - do not use it standalone where DC accuracy matters; always place it inside an op amp feedback loop so loop gain corrects these errors. When doing so, verify overall loop stability: the buffer's phase lag combines with the op amp's, so many precision op amps need a small compensation network (per the datasheet typical application circuits) to maintain phase margin. Also confirm BW-pin strapping intent during layout - leaving pin 1 accidentally connected to a low-impedance node changes bandwidth mode.
Compliance Information
RoHS/REACH status not explicitly stated in the provided web data; verify on the TI product page environmental datasheet before ordering.
