NXP Semiconductors BAP51L,315

Overview

BAP51L,315 from NXP Semiconductors (formerly Philips) is a silicon PIN diode optimized for high-frequency RF switching and attenuation up to 3 GHz. It features low diode capacitance (0.17–0.30 pF at 1–5 V reverse bias), low forward resistance (0.9–2.5 Ω at 10–100 mA), and very low series inductance (0.6 nH), housed in a leadless SOD882 package (1.0 × 0.6 × 0.5 mm).

For engineers reviewing the BAP51L,315 datasheet, BAP51L,315 pinout, BAP51L,315 application, or BAP51L,315 equivalent, key selection criteria include RF isolation (13–19 dB at 900–2450 MHz), insertion loss (as low as 0.07 dB at 100 mA/900 MHz), cathode/anode polarity marking, thermal resistance (100 K/W), and compatibility with ultra-compact 50 Ω stripline RF layouts.

Technical Context

The BAP51L,315 operates as a current-controlled RF series switch or shunt attenuator element. Its intrinsic I-layer enables fast carrier lifetime (0.55 µs) and linearized RF resistance versus DC bias - critical for analog RF gain control and T/R switching in sub-3 GHz transceivers.

Designed for zero-bias or low-current forward-bias operation, it delivers stable s-parameter performance across 900 MHz, 1800 MHz, and 2450 MHz bands. The SOD882 package's minimal parasitic inductance and symmetric layout support consistent impedance matching without external tuning in compact front-end modules.

Key Specifications

Pinout & Package

Package: SOD882 - leadless ultra-small plastic package; 2-terminal surface-mount; body dimensions 1.0 × 0.6 × 0.5 mm; cathode indicated by marking bar on top surface.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF PIN diode switching applications.

Compared with SKY13370-374LF and MA4P7472F-1072T, the BAP51L,315 offers the smallest footprint and lowest parasitic inductance for space-constrained 2.4 GHz consumer devices, while trading off absolute isolation and voltage rating for superior integration density and broadband matching.

Availability

BAP51L,315 is available at Aetrix Electronics and suitable for Wi-Fi antenna switching, Bluetooth T/R front ends, GSM/EDGE power amplifier output routing, and ISM-band programmable attenuators requiring stable component supply and consistent RF performance across production lots.

Supply support for BAP51L,315 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

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with heritage in Philips' RF component innovation.

The BAP51L,315 belongs to NXP's legacy RF PIN diode portfolio designed specifically for miniaturized, high-frequency front-end switching in wireless consumer electronics - emphasizing ultra-low parasitics, repeatable s-parameters, and SMD manufacturability.

FAQ

What is the maximum RF frequency supported by the BAP51L,315?

The BAP51L,315 is characterized and specified for operation up to 3 GHz, with measured isolation and insertion loss data provided at 900 MHz, 1800 MHz, and 2450 MHz. Its low series inductance (0.6 nH) and controlled capacitance ensure usable RF performance through the upper edge of the 2.4 GHz ISM band and into UMTS/LTE Band 1, though design margin should be verified per application.

How is polarity identified on the BAP51L,315 package?

The BAP51L,315 uses a marking bar on the top surface of the SOD882 package to indicate the cathode terminal (Pin 1). This aligns with the standard SOD882 outline and must be oriented correctly during placement to ensure proper forward/reverse biasing in RF switch circuits - incorrect orientation results in degraded isolation and potential damage under reverse bias.

What is the thermal resistance of the BAP51L,315, and how does it affect power handling?

The BAP51L,315 has a junction-to-solder-point thermal resistance (Rth(j-sp)) of 100 K/W. At its maximum rated forward current of 100 mA and typical forward voltage of 0.95 V, power dissipation reaches ~95 mW - resulting in ~9.5 °C junction-to-solder temperature rise. This enables reliable operation in thermally constrained RF modules without active cooling.

Can the BAP51L,315 be used in zero-bias RF switch configurations?

Yes, the BAP51L,315 is qualified for zero-bias operation, delivering 13–19 dB isolation across 900–2450 MHz with no DC current applied. Its low capacitance (0.17–0.30 pF) and absence of leakage-dependent turn-on make it suitable for passive RF switches where control circuitry must be minimized - such as in battery-powered IoT sensors using the BAP51L,315 for antenna diversity.

What is the forward voltage specification for the BAP51L,315 at 50 mA?

The BAP51L,315 has a typical forward voltage of 0.95 V and a maximum of 1.1 V at 50 mA forward current and Tj = 25 °C. This low VF enables efficient biasing from low-voltage rails (e.g., 1.8 V or 3.3 V) with minimal power loss, supporting compact, low-heat RF switch designs that use the BAP51L,315 as a core switching element.