Texas Instruments BUF634F

Overview

BUF634F from Texas Instruments is a unity-gain, open-loop high-speed buffer IC designed for output current boosting and capacitive load driving in precision analog signal paths. It delivers 250mA continuous output current, 2000V/µs slew rate, and pin-selectable bandwidth (30–180MHz) in TO-220 (KC) and TO-263 (KTT) packages. It operates across ±2.25V to ±18V supplies and integrates thermal shutdown and internal current limiting - used in valve drivers, ATE pin drivers, and video line drivers.

For engineers reviewing the BUF634F datasheet, BUF634F pinout, BUF634F application, or BUF634F equivalent, key selection criteria include its adjustable bandwidth via external resistor, low-quiescent-current mode (1.5mA), rugged protection features, and compatibility with op amp feedback loops for current gain without thermal coupling.

Technical Context

The BUF634F implements an open-loop complementary emitter-follower architecture with no internal feedback, enabling direct integration into op amp feedback networks to decouple thermal effects and boost drive capability. Its bandwidth is externally set by a resistor between V– and the BW pin, allowing precise trade-off between speed (up to 180MHz) and quiescent current (1.5–15mA).

It features dual operating modes: low-quiescent-current mode (30MHz, 1.5mA) and wide-bandwidth mode (180MHz, 15mA), both supporting ±250mA output with rail-to-rail headroom of ≤2.5V at 150mA. Protection includes foldback current limiting and thermal shutdown triggered at 175°C junction temperature.

Key Specifications

Pinout & Package

BUF634F is offered in two thermally robust power packages: 5-pin TO-220 (KC) and 5-pin TO-263 (KTT), both with exposed metal pads for heatsink attachment. Pin functions are identical across both packages.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar unity-gain buffer applications.

Compared with BUF634A and LMH6321, the BUF634F uniquely balances pin-selectable bandwidth, ultra-low 1.5mA quiescent current mode, and rugged thermal/current protection - making it optimal for cost-sensitive, thermally constrained, or multi-speed industrial analog systems.

Availability

BUF634F is available at Aetrix Electronics and suitable for valve drivers, ATE pin drivers, video line drivers, and op amp current booster applications requiring stable component supply across industrial temperature ranges (–40°C to +85°C) and long-lifecycle production programs.

Supply support for BUF634F includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and communications markets.

The BUF634 product line was engineered as a high-current, high-speed unity-gain buffer to solve op amp output stage limitations - specifically enabling current boosting without thermal feedback or stability compromise in precision analog systems.

FAQ

What is the maximum continuous output current of the BUF634F?

The BUF634F delivers ±250mA continuous output current in both TO-220 (KC) and TO-263 (KTT) packages under recommended operating conditions (TA ≤ 85°C, adequate heatsinking). Short-circuit current reaches ±350mA to ±550mA depending on operating mode and junction temperature, with thermal shutdown engaging at 175°C to prevent damage.

How does the BW pin function on the BUF634F?

The BW pin on the BUF634F sets quiescent current and bandwidth by connecting an external resistor to V–. An open connection yields 1.5mA IQ and 30MHz bandwidth; a 0Ω connection yields 15mA IQ and 180MHz bandwidth. The relationship is monotonic and documented in Figure 6-9 of the datasheet - enabling precise speed/power tuning without changing PCB layout.

Can the BUF634F be used in single-supply configurations?

Yes, the BUF634F supports single-supply operation by referencing VIN and VO to a mid-rail voltage (e.g., VCC/2) while connecting V+ to VCC and V– to ground. Input common-mode range extends to within ~1.5V of either rail, and output swing maintains ≥2V headroom at 100mA load - verified in Figures 6-13 and 6-14 for TO-220/KTT packages.

What thermal considerations apply to the BUF634F in TO-220 and TO-263 packages?

The BUF634F in KC (TO-220) has RθJC = 0.7°C/W and RθJA = 32.1°C/W with proper heatsinking; KTT (TO-263) has RθJC = 2.4°C/W and RθJA = 41.8°C/W. Maximum power dissipation drops from ~2.5W at 25°C ambient to ~0.8W at 85°C ambient (Figure 6-15). Thermal shutdown activates at 175°C junction temperature, providing robust protection during transient overloads.

Is the BUF634F pin-compatible with the BUF634A?

Yes, the BUF634F and BUF634A share identical pinouts, package footprints (KC and KTT), and electrical interface - including VIN, VO, V+, V–, and BW pin assignments and functions. They are drop-in replacements for each other in TO-220 and TO-263 layouts, though BUF634A offers enhanced AC performance (3750V/µs slew rate, 210MHz max bandwidth) and slightly lower voltage noise.