BUF634FKTTT - 250mA 180MHz High-Speed Buffer | TI
MPN: BUF634FKTTT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.62 | $4.62 |
| 10 | $4.16 | $41.60 |
| 100 | $3.7 | $370.00 |
| 500 | $3.24 | $1,620.00 |
| 1,000 | $2.87 | $2,870.00 |
BUF634FKTTT Overview
A buffer amplifier is a unity-gain analog stage whose sole purpose is to provide current drive and isolation between a high-impedance source and a low-impedance load. In the power-management and signal-chain hierarchy, buffers sit between precision op amps and their loads, preventing the output stage of the amplifier from dissipating load current internally - a phenomenon known as thermal feedback that degrades offset and drift specifications.
The defining feature of the BUF634 is its ability to operate inside the feedback loop of an op amp to multiply available output current up to 250 mA, eliminate thermal feedback, and dramatically improve capacitive load drive. Its 2000 V/us slew rate and 180 MHz bandwidth preserve the speed of the host amplifier, while the wide supply range of +/-2.25V to +/-18V (4.5V to 36V total) covers virtually all precision analog rails.
Internally, the BUF634 is a complementary class-AB emitter-follower architecture with a bandwidth-select pin (BW). Tying BW to V- engages the full 180 MHz / 10 mA-standby mode; leaving BW open reduces quiescent current for power-sensitive designs at reduced bandwidth. The KTT DDPAK-5 tab provides a low-thermal-resistance path to the PCB copper for sustained 250 mA output currents.
Typical applications include output-current boosting of precision op amps in test and measurement front ends, cable and capacitive-load drivers in data acquisition systems, video and IF signal distribution, and loop-powered actuator drivers in industrial control.
Design consideration: place a small series resistor or short snubber at the output when driving long cables, and keep the BW pin connection as short as possible to avoid RF pickup in high-speed mode.
This page synthesizes verified distributor data, the TI BUF634 family cross-reference, and practical design guidance in one place - information not consolidated in the manufacturer datasheet alone.
Drop-in alternatives for BUF634FKTTT — 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 BUF634FKTTT (same form factor and footprint) — differing in Bandwidth, Package, Slew Rate, Supply Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BUF634AKTTT
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
BUF634AIDDAR
✅ Drop-In✓ In Stock
$2.15 / Unit
View Datasheet →BUF634AIDR
✅ Drop-In✓ In Stock
$1.56 / Unit
View Datasheet →BUF634FKTTT Maximum Ratings & Electrical Characteristics
| Amplifier Type | Unity-Gain Open-Loop Buffer |
| Number of Channels | 1 |
| Output Current | 250 mA |
| Bandwidth | 180 MHz |
| Slew Rate | 2000 V/us |
| Supply Voltage Range | +/-2.25 V to +/-18 V (4.5 V to 36 V total) |
| Operating Temperature | -40C to +125C |
| Package | TO-263 (DDPAK / KTT), 5+tab pins |
| Mounting Type | Surface Mount |
| Bandwidth Select Pin | Yes (BW pin) |
| Thermal Feedback | Eliminated when used inside op amp feedback loop |
| Capacitive Load Drive | Improved vs op amp alone (buffered output) |
| Supplier Device Package | KTT |
BUF634FKTTT ktt Pin Configuration Guide
Pin configuration for BUF634FKTTT (ktt 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 BUF634FKTTT.
Refer to the datasheet for full pin configuration.
Typical Applications
BUF634FKTTT is suitable for 6 applications: Op Amp Output Current Boosting, Test and Measurement Front Ends, Capacitive Load and Cable Driving, Industrial Control Signal Output, Video and High-Speed Signal Distribution, Audio Line Output Drivers.
Op Amp Output Current Boosting
The primary application of the BUF634FKTTT is extending the output current of precision op amps from the typical tens of milliamperes up to 250 mA. Placed inside the op amp feedback loop, the buffer carries the load current while the op amp only supplies the buffer input, so the amplifier's internal output stage stays cool and thermal feedback - the dominant cause of offset drift - is eliminated. With 180 MHz bandwidth and 2000 V/us slew rate, the buffer adds no speed penalty to the host amplifier. The +/-2.25V to +/-18V supply range matches virtually all precision op amp rails, making integration a two-pin-series change in most designs.
Recommended
Test and Measurement Front Ends
Bench instruments, data acquisition systems, and automated test equipment require output stages that combine precision with drive capability. The BUF634FKTTT's 250 mA output current drives low-impedance probes, coaxial cables, and stimulus loads, while its open-loop unity-gain topology introduces no gain error of its own - closed-loop accuracy is set entirely by the surrounding op amp. The 2000 V/us slew rate preserves fast pulse edges in stimulus generation, and the BW pin lets engineers trade standby current for bandwidth in battery-powered portable instruments. The TO-263 package handles the sustained dissipation typical of continuous test cycles.
Recommended
Capacitive Load and Cable Driving
Long coaxial cables, ADC input sampling networks, and reference bypass capacitance present capacitive loads that destabilize standalone op amps by adding a pole inside the loop. Buffering with the BUF634FKTTT isolates the op amp from the load capacitance: the op amp closes its loop around the buffer output, and the capacitive load pole is moved outside the loop-gain path. According to the TI datasheet, improved capacitive load drive is an explicitly intended function of this part. A small series output resistor is still recommended with very long cables to damp transmission-line reflections at the 180 MHz bandwidth edge.
Recommended
Industrial Control Signal Output
Industrial controllers drive actuators, valve positioners, and process transmitters that often need more current than a precision op amp can supply. The BUF634FKTTT boosts controller outputs to 250 mA while the surrounding op amp maintains loop accuracy and thermal stability. Its -40C to +125C operating range meets industrial ambient requirements, and the 4.5V to 36V total supply span accommodates both 5V logic-referenced and 24V-backplane-referenced analog subsystems. The KTT DDPAK tab solders directly to a PCB copper area, providing passive cooling without a heatsink at moderate dissipation levels.
Recommended
Video and High-Speed Signal Distribution
With 180 MHz bandwidth and 2000 V/us slew rate, the BUF634FKTTT distributes wideband video, IF, and RF-envelope signals to multiple low-impedance loads without rate limiting. Because the buffer is open-loop, it adds no closed-loop phase shift, preserving phase margin of the surrounding amplifier. The dual-supply range of +/-2.25V to +/-18V supports AC-coupled video levels and bipolar modulation formats. For fan-out designs, one buffer per output leg prevents channel-to-channel crosstalk; the BW pin should be tied to V- for full-speed operation, accepting the higher quiescent current of the high-bandwidth mode.
Recommended
Audio Line Output Drivers
In the low-bandwidth mode (BW pin open), the BUF634FKTTT reduces standby current while retaining enough bandwidth for professional audio, making it suitable for headphone and line-output stages driven by low-power precision op amps. The 250 mA capability drives low-impedance headphones and long balanced-line runs directly, while buffering inside the op amp loop keeps distortion and offset dominated by the precision amplifier, not the output stage. Wide +/-18V operation provides ample headroom for high-level balanced studio signals, and the TO-263 package dissipates output-stage heat through the PCB copper without additional thermal hardware.
Recommended
Recommended Products Summary
Engineering reference data for BUF634FKTTT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BUF634AKTTT | BUF634AIDDAR | BUF634AIDR |
|---|---|---|---|---|
| Package | TO-263 (DDPAK / KTT), 5+tab | TO-263 (DDPAK / KTT) - same | SOIC-8 (D) - different footprint | SOIC-8 (D) - different footprint |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 250 mA | 250 mA | 250 mA | 250 mA |
| Bandwidth | 180 MHz | 180 MHz (upgraded performance per TI) | 180 MHz (upgraded performance per TI) | 180 MHz (upgraded performance per TI) |
| Supply Voltage Range | +/-2.25 V to +/-18 V | +/-2.25 V to +/-18 V | +/-2.25 V to +/-18 V | +/-2.25 V to +/-18 V |
| Operating Temperature | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C |
| Lifecycle | Active (TI recommends BUF634A for new designs) | Active - TI's upgraded drop-in successor | Active - upgraded family | Active - upgraded family |
Key Differentiators
- In-loop buffering eliminates thermal feedback (vs BUF634AKTTT)
- Selectable standby power via BW pin (vs BUF634AIDDAR)
- Sustained 250 mA without heatsink hardware (vs BUF634AIDR)
Design Notes
When closing an op amp loop around the BUF634FKTTT, ensure the op amp phase margin is analyzed with the buffer inside the loop. Although the open-loop buffer adds minimal phase shift, the BW pin setting changes the buffer's small-signal behavior: BW tied to V- gives the full 180 MHz mode with higher quiescent current, while BW open reduces standby power at reduced bandwidth. Choose the mode deliberately - leaving BW floating unintentionally due to a layout error is a common source of reduced bandwidth.
Estimated: at +/-15V supplies delivering 100 mA into a mid-rail load, dissipation is roughly (V+ - VOUT) * IOUT, on the order of 1-2 W sustained. The KTT DDPAK tab must be soldered to at least 1 square inch of 2-oz copper pour to keep junction temperature within the -40C to +125C rating. Verify the exact theta-JA value in the TI BUF634 datasheet thermal section for your specific board stackup before finalizing power budget.
Place 0.1uF ceramic decoupling capacitors within 3 mm of both supply pins, with a 4.7uF-10uF bulk capacitor nearby. Keep the BW pin trace short and, in noisy environments, route it away from switching regulators. For capacitive loads beyond a few hundred pF or long cables, add a small series output resistor (10-50 ohm) to isolate transmission-line effects at the 180 MHz bandwidth edge. The exposed tab is electrically connected internally per the datasheet - verify tab net before connecting it to a copper pour.
Compliance Information
Compliance data was not present in the verified web data retrieved for this part. Consult the TI product page for BUF634FKTTT environmental certification details.
