NXP Semiconductors BLT80,115

Overview

BLT80,115 from Philips Semiconductors is an NPN silicon planar epitaxial UHF power transistor in SOT223 SMD package, rated for 900 MHz operation at 7.5 V_CE, delivering 0.8 W output power with ≥6 dB power gain and ≥60% collector efficiency in class-B narrowband mode. It serves as a final-stage RF power amplifier in handheld radios operating in the 900 MHz band.

For engineers reviewing the BLT80,115 datasheet, BLT80,115 pinout, BLT80,115 application, or BLT80,115 equivalent, key selection criteria include its SOT223 thermal performance (R_{th j-s} = 22 K/W), ruggedness under 50:1 VSWR mismatch, and verified RF characteristics at Ts ≤60 °C in common-emitter configuration.

Technical Context

The BLT80,115 operates in class-B narrowband RF amplification with fixed biasing optimized for 900 MHz. Its design incorporates gold metallization for reliability and a dual-emitter-pin SOT223 layout to support low-inductance emitter grounding via copper straps on PTFE-fiberglass PCBs.

Thermal management relies on solder-point temperature (Ts) control - maximum junction temperature is 175 °C, and safe continuous operation requires Ts ≤131 °C for full 2 W dissipation. The device's SOAR curve defines safe operating area under pulsed DC conditions (t_p ≤200 µs, duty δ ≤0.02).

Key Specifications

Pinout & Package

SOT223 plastic surface-mount package with 4 terminals: three leads (1–3) and one large collector tab (pin 4). Mounting requires direct thermal connection of pin 4 to a 35 × 17 mm copper pad on 40 × 40 × 1 mm FR4/PTFE board; emitter leads are grounded via copper straps per Fig.7 layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar UHF power transistor applications.

Compared with BFR92A,115 and MRF581,115, the BLT80,115 uniquely balances handheld-size SOT223 packaging, 0.8 W output, and 50:1 VSWR ruggedness - making it irreplaceable for space-constrained 900 MHz transmitters where thermal and reliability margins are co-constrained.

Availability

BLT80,115 is available at Aetrix Electronics and suitable for 900 MHz handheld radios, ISM-band telemetry links, UHF RFID readers, and low-power repeaters requiring stable component supply across production lifecycles.

Supply support for BLT80,115 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

Philips Semiconductors (now NXP Semiconductors) was a global leader in analog and RF discrete semiconductors, headquartered in Eindhoven, Netherlands.

The BLT80,115 belongs to Philips' UHF power transistor product line, engineered specifically for compact, battery-efficient 900 MHz wireless communication equipment with stringent thermal and ruggedness requirements.

FAQ

What is the maximum safe operating junction temperature for BLT80,115?

The BLT80,115 has a maximum operating junction temperature (T_j) of 175 °C, as defined in the Limiting Values table. Operation must remain within this limit; derating is required above Ts = 131 °C to maintain reliability. Thermal design must ensure R_{th j-s} = 22 K/W is achieved using the specified 35 × 17 mm collector pad on a 40 × 40 × 1 mm PCB. Exceeding T_j risks permanent degradation of the BLT80,115's gold metallization and epitaxial structure.

Does BLT80,115 support class-AB operation, and what is its ruggedness rating?

Yes, the BLT80,115 is explicitly characterized for ruggedness in class-AB operation: it withstands a 50:1 VSWR mismatch at all phase angles when operated at 900 MHz, V_CE = 9 V, P_L = 0.8 W, and Ts ≤60 °C. This capability is confirmed in the Application Information section and makes the BLT80,115 suitable for handheld radios where antenna coupling varies dynamically. No external protection circuitry is needed for this level of mismatch tolerance in the BLT80,115.

What is the recommended PCB layout for optimal thermal performance of BLT80,115?

The BLT80,115 requires mounting on a 40 × 40 × 1 mm PCB with a dedicated 35 × 17 mm copper collector pad connected to pin 4. Emitter leads (pins 1 and 3) must be grounded via copper foil straps to the unetched ground plane on the opposite side, as shown in Fig.7 and Fig.8. Stripline matching networks (L1, L5, L6, L10) use 50 Ω traces on PTFE-fiberglass dielectric (ε_r = 2.2). Deviation from this layout increases R_{th j-s} and degrades BLT80,115's 0.8 W output capability.

Can BLT80,115 be used at frequencies other than 900 MHz?

The BLT80,115 is characterized and optimized for 900 MHz operation, with verified gain (≥6 dB), efficiency (≥60%), and impedance profiles (Z_i, Z_L) shown in Figs 9–11 across 800–1000 MHz. While usable up to ~1 GHz, performance drops outside this band: G_p falls below 6 dB and η_C declines significantly below 850 MHz or above 950 MHz. For designs targeting other bands, the BLT80,115 should be re-characterized - its published specs apply strictly to the 900 MHz condition stated in the Quick Reference Data.

What are the absolute maximum ratings for collector-emitter voltage and collector current in BLT80,115?

The BLT80,115 has an absolute maximum V_CEO of 10 V (open base) and I_C of 250 mA DC. Peak collector current (I_CM) is rated at 750 mA for f > 1 MHz under pulsed conditions (t_p ≤200 µs, δ ≤0.02). These values define hard limits - exceeding them, even momentarily, may cause irreversible damage. The BLT80,115's typical V_(BR)CEO is exactly 10 V, confirming zero margin above the max rating; design must operate conservatively below these thresholds.