BUF634P - 250mA, 180MHz High-Speed Buffer | Texas Instruments
MPN： BUF634P ✓ 啟用中BUF634P 概覽
A buffer amplifier (also called a unity-gain voltage follower) is an analog IC that replicates its input voltage at its output while providing high input impedance and low output impedance. In the signal-chain hierarchy, the buffer sits downstream of op amps, DACs, and sensors, isolating gain stages from heavy or reactive loads. Buffers are a subset of operational amplifier analog front ends within the broader category of amplifiers and linear ICs.
Key differentiating features include the 250 mA continuous output current capability, the unique pin-selectable bandwidth: connecting the BW pin to V+ yields the full 180 MHz bandwidth, while leaving it open reduces bandwidth to 30 MHz and cuts quiescent current to only 1.5 mA. Internal current limiting and thermal shutdown protection provide robust fault tolerance, and the +/-18 V supply range supports high-voltage analog systems.
Architecturally, the BUF634 is an open-loop, unity-gain buffer with no external compensation requirements, making it inherently stable and free of phase-reversal issues. Because it operates open-loop, inserting it inside an op amp feedback loop increases output current, eliminates thermal feedback errors at the op amp input stage, and dramatically improves capacitive-load drive capability - a technique documented in the manufacturer datasheet application section.
Typical applications include headphone amplifiers (where 250 mA drives low-impedance headphones directly), op amp output current boosting in test and measurement equipment, video distribution and cable driving, and PLC/analog output modules. The BUF634P is also a perennial favorite in high-end DIY audio buffer stages.
Design-wise, keep the BW pin short to V+ only when slew and bandwidth demand it; the 30 MHz mode saves over 20 mA of quiescent current in multi-channel designs. On 8-pin PDIP, thermal resistance limits continuous dissipation - verify power at high load currents.
This page synthesizes verified distributor data, family cross-references, and practical design guidance not found in the manufacturer datasheet alone.
直接替換替代品，適用於 BUF634P — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： BUF634P （相同外形與佔位） — 差異在於 Package, Bandwidth, Function, Mounting Type, Quiescent Current.
BUF634U
✅ 直接替換聯絡詢價
查看資料表 →BUF634U-VB
✅ 直接替換聯絡詢價
查看資料表 →BUF634T
✅ 直接替換聯絡詢價
查看資料表 →BUF634AIDR
✅ 直接替換聯絡詢價
查看資料表 →BUF634AIDDAR
✅ 直接替換聯絡詢價
查看資料表 →BUF634P 最大額定值與電氣特性
| 功能 | High-speed unity-gain buffer |
| Number of Channels | 1 |
| Output Current | 250 mA |
| Slew Rate | 2000 V/us |
| Bandwidth (pin-selected) | 180 MHz (BW to V+) / 30 MHz (BW open) |
| 靜態電流 | 1.5 mA (30 MHz BW mode) |
| Supply Voltage Range | +/-2.25 V to +/-18 V |
| Gain | 1 V/V (unity, open-loop buffer) |
| Protection Features | Internal current limit, thermal shutdown |
| 封裝 | 8-PDIP (P) |
| 安裝類型 | Through Hole |
| Upgrade Path | BUF634A (higher slew 3750 V/us, 210 MHz BW, 8.5 mA IQ) |
BUF634P 腳位配置
| 腳位 1 | V+ — Positive power supply |
| 腳位 2 | NC — Not connected (per datasheet) |
| 腳位 3 | IN — Buffer input |
| 腳位 4 | BW — Bandwidth select: tie to V+ for 180 MHz; leave open for 30 MHz low-power mode |
| 腳位 5 | V- — Negative power supply |
| 腳位 6 | OUT — Buffer output, up to 250 mA |
| 腳位 7 | NC — Not connected (per datasheet) |
| 腳位 8 | NC — Not connected (per datasheet) |
典型應用
BUF634P 適用於 6 應用s: Headphone Amplifier Output Stage, Op Amp Output Current Boosting, Video Distribution and Cable Driving, Test and Measurement Instrumentation Outputs, PLC and Industrial Analog Output Modules, Sensor and S/H Circuit Buffering.
Headphone Amplifier Output Stage
The BUF634P is a reference choice for headphone amplifier output stages because its 250 mA output current directly drives 16-ohm to 600-ohm headphones without additional pass elements. In a typical topology, an op amp such as the OPA2134 provides voltage gain while the BUF634P sits inside the feedback loop as the current booster; the 180 MHz bandwidth and 2000 V/us slew rate keep loop gain high at audio frequencies, minimizing distortion. Placing the buffer inside the loop also eliminates thermal feedback errors in the op amp input stage, improving DC offset stability. In 30 MHz BW mode the 1.5 mA quiescent current suits portable designs, while tying BW to V+ maximizes performance for desktop amps. The PDIP package is especially popular in DIY audio for easy socketed assembly.
推薦
Op Amp Output Current Boosting
When a precision op amp cannot supply the required load current, the BUF634P is inserted inside its feedback loop to raise drive capability to 250 mA while preserving the op amp's input precision. Per the TI datasheet, this configuration simultaneously eliminates thermal feedback - load-current-induced die heating that degrades input offset - and improves capacitive load drive, since the open-loop buffer isolates the op amp output from reactive loads. The 2000 V/us slew rate ensures the buffer never limits the composite circuit's large-signal response, and the +/-18 V supply range covers standard +/-15 V analog rails. The BW pin lets designers reduce bandwidth to 30 MHz in noise-sensitive precision circuits, saving quiescent current in multi-channel instrumentation.
推薦
Video Distribution and Cable Driving
Video and high-speed signal distribution demands buffers that drive back-terminated 75-ohm coax or multiple parallel loads without slew limiting. The BUF634P's 2000 V/us slew rate and 180 MHz pin-selected bandwidth support NTSC/PAL composite video and fast pulse applications with minimal edge degradation. Its 250 mA current capacity easily drives heavily loaded distribution buses or long cables, while internal current limit protects against short circuits on field-wired outputs. In industrial video and test setups, the through-hole PDIP package simplifies repair and prototyping. Designers should ensure adequate copper around the output for thermal dissipation when driving sustained high currents at video duty cycles, and select the 180 MHz BW mode whenever signal bandwidth exceeds a few megahertz.
推薦
Test and Measurement Instrumentation Outputs
Bench instruments, function generators, and data-acquisition front ends require output stages that combine precision with robustness. The BUF634P, placed after a precision amplifier, provides 250 mA fault-tolerant drive with internal current limiting and thermal shutdown - valuable when instrument outputs face accidental shorts or unknown external loads. The +/-2.25 V to +/-18 V supply range supports signal swings up to roughly 34 Vpp on +/-15 V rails, and the 180 MHz bandwidth preserves waveform fidelity for fast edges. Using the buffer inside the amplifier feedback loop, as recommended in the TI datasheet, keeps output offset governed by the amplifier rather than the buffer. The 30 MHz low-power mode suits battery-powered portable instruments where several buffer channels operate simultaneously.
推薦
PLC and Industrial Analog Output Modules
Industrial analog output modules driving actuators, valves, and long field wiring benefit from the BUF634P's combination of 250 mA drive, +/-18 V supply tolerance, and built-in fault protection. Current limiting and thermal shutdown protect the module during wiring faults, while the wide bandwidth comfortably handles the kHz-range signals typical of 0-10 V and +/-10 V industrial standards. The buffer-in-the-loop technique with a precision op amp keeps output accuracy within process-control tolerances, and the open-loop buffer architecture avoids oscillation with capacitive cable loads - a common failure mode in field wiring. The through-hole PDIP package eases servicing of DIN-rail modules and legacy equipment retrofits where SMD rework is impractical.
推薦
Sensor and S/H Circuit Buffering
High-impedance sensor outputs, sample-and-hold capacitors, and ADC inputs need buffers with low loading and strong drive. The BUF634P's open-loop unity-gain architecture presents a benign load to upstream circuitry while supplying 250 mA to charge large hold or filter capacitors rapidly - the 2000 V/us slew rate enables fast acquisition settling in data converters. Its 180 MHz bandwidth maintains flat response for wideband sensor signal chains, and the 30 MHz/1.5 mA mode optimizes power in multichannel scanning systems. Because the buffer adds no feedback-network noise, signal-to-noise ratio is preserved for precision measurements. Designers should provide clean, decoupled +/-rails and observe thermal limits when charging large capacitors repetitively at high rates.
推薦
推薦產品摘要
工程參考資料，適用於 BUF634P — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | BUF634U | BUF634T | BUF634AIDR | BUF634AIDDAR |
|---|---|---|---|---|---|
| Package | 8-PDIP (P) | SOIC-8 (adapter needed for PDIP footprint) | TO-220-5 (different footprint) | SOIC-8 (adapter needed for PDIP footprint) | SOIC-8 (adapter needed for PDIP footprint) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 250 mA | 250 mA | 250 mA | 250 mA | 250 mA |
| Slew Rate | 2000 V/us | 2000 V/us | 2000 V/us | 3750 V/us (+88%) | 3750 V/us (+88%) |
| Bandwidth | 180 MHz / 30 MHz (pin-selected) | 180 MHz / 30 MHz (pin-selected) | 180 MHz / 30 MHz (pin-selected) | 210 MHz (upgraded) | 210 MHz (upgraded) |
| Thermal Capability | PDIP-8 (limited dissipation) | SOIC-8 (moderate) | TO-220-5 (best - heatsink mountable) | SOIC-8 (moderate) | SOIC-8 (moderate) |
主要差異化特點
- Only PDIP-8 member of the BUF634 family (對比BUF634U)
- Pin-selectable bandwidth for power optimization (對比BUF634AIDR)
- Superior thermal option exists via same-die TO-220 (對比BUF634T)
設計說明
Estimated: at 250 mA output with a 5 V headroom across the buffer (e.g., +/-15 V rails, output near +/-10 V), device dissipation reaches ~1.25 W continuous. The 8-pin PDIP package has limited thermal capability compared to the TO-220-5 (BUF634T); for sustained high-current duty, prefer BUF634T with heatsinking or reduce duty cycle. Verify junction temperature using datasheet theta-JA for the P package before finalizing the design.
The BW pin (pin 4) is functional, not a no-connect: leaving it open selects the 30 MHz / 1.5 mA low-power mode, while tying it to V+ selects 180 MHz. Accidentally floating this pin in a wideband design halves system bandwidth; conversely, tying it high in a battery design wastes >20 mA per channel. Also remember BUF634U (SOIC) is not footprint-compatible with BUF634P (PDIP) - plan adapters or footprints early.
Decouple both supply pins with 0.1 uF ceramics placed within a few millimeters of pins 1 and 5, plus bulk 4.7-10 uF local to the board. In buffer-in-loop configurations with an op amp, keep the feedback takeoff point at the buffer output and route the loop with minimal capacitance to preserve phase margin; the TI datasheet application section shows the recommended topology for capacitive-load driving.
合規資訊
Compliance status for the BUF634P PDIP suffix not stated in provided web data; verify on the TI product page or DigiKey listing before procurement.
