onsemi 2SA1391S

Overview

2SA1391S from SANYO Semiconductor is a PNP epitaxial planar silicon transistor designed for low-noise audio frequency amplification, featuring V_CEO = −50 V, I_C = −200 mA, P_C = 400 mW, f_T = 250 MHz (typ), and noise voltage of 40 mV (ave) at 1 kHz with R_g = 56 kΩ - deployed in high-fidelity preamplifier stages and microphone input buffers.

For engineers reviewing the 2SA1391S datasheet, pinout, applications, or equivalent options, key selection criteria include its low-noise AF performance, PNP polarity with −50 V V_CEO, h_FE rank classification (S: 140–280 at I_C = −1 mA), Cob = 2.7 pF, and TO-92MOD package compatibility with discrete analog signal chains.

Technical Context

The 2SA1391S employs FBET (Flat Base Epitaxial Transistor) process technology to achieve tight h_FE distribution and low 1/f noise, optimized for small-signal linear amplification in the audio band. Its −50 V V_CEO and −60 V V_CBO support operation in negative-rail amplifier topologies with headroom for transient suppression.

Noise performance is characterized under standardized conditions: V_CC = −30 V, I_C = −1 mA, R_g = 56 kΩ, and 1 kHz bandwidth, yielding V_NO(ave) = 40 mV and V_NO(peak) = 280 mV - enabling precise low-level signal gain without degradation in sensitive front-end stages.

Key Specifications

Pinout & Package

2SA1391S is housed in a TO-92MOD plastic package (5.0 × 4.0 × 4.0 mm), lead-free and RoHS-compliant per SANYO specification EN1942B. Pin identification follows JEDEC TO-92 orientation: flat side facing viewer, leads down, left-to-right = Emitter (1), Collector (2), Base (3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise PNP AF amplifier applications.

Compared with 2SA1015BL and BC557C, the 2SA1391S delivers superior noise performance (40 mV vs. ≥60 mV), higher f_T (250 MHz vs. ≤100 MHz), and greater V_CEO margin (−50 V), making it the preferred choice for high-fidelity, wideband, low-noise AF amplification where signal integrity is critical.

Availability

2SA1391S is available at Aetrix Electronics and suitable for microphone preamplifiers, phono stage inputs, tape head recovery circuits, and instrument DI box designs requiring stable component supply with guaranteed long-term obsolescence management.

Supply support for 2SA1391S 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

SANYO Semiconductor was a Japanese semiconductor manufacturer specializing in analog, power, and audio ICs and discrete devices before its acquisition by ON Semiconductor in 2011; known for high-reliability, low-noise bipolar transistors.

The 2SA1391S belongs to SANYO's legacy low-noise AF transistor family, engineered specifically for high-fidelity audio signal amplification in consumer and professional equipment where noise floor and linearity are paramount.

FAQ

What is the h_FE range for the 2SA1391S transistor?

The 2SA1391S is ranked as "S" grade, with DC current gain (h_FE) specified from 140 to 280 at V_CE = −6 V and I_C = −1 mA. This binning ensures consistent biasing in matched-pair configurations and reduces gain variation across production lots - a key requirement for low-drift audio amplifier designs using the 2SA1391S.

Does the 2SA1391S support operation at elevated ambient temperatures?

Yes, the 2SA1391S is rated for junction temperature up to 150°C and storage temperature from −55°C to +150°C. Derating curves in the datasheet confirm usable I_C and h_FE performance up to 120°C ambient, provided PCB copper area and airflow meet SANYO's thermal guidelines - essential for compact 2SA1391S-based amplifier modules in enclosed enclosures.

What is the maximum collector current pulse rating for the 2SA1391S?

The 2SA1391S supports a pulsed collector current (I_CP) of −400 mA under specified test conditions (single pulse, T_a = 25°C). This allows brief overdrive capability in transient-rich audio signals without secondary breakdown, though continuous operation must remain within the −200 mA absolute maximum rating to maintain reliability and noise performance of the 2SA1391S.

How does the 2SA1391S compare to the 2SC3382 NPN counterpart?

The 2SA1391S (PNP) and 2SC3382 (NPN) share identical package, thermal specs, noise test conditions, and FBET process - forming a complementary pair for push-pull or differential amplifier stages. While both achieve 250 MHz f_T and ≤40 mV noise, the 2SA1391S enables negative-rail biasing and level-shifting functions that the 2SC3382 cannot replicate - a functional distinction critical in dual-supply 2SA1391S/2SC3382 amplifier designs.

Is the 2SA1391S RoHS compliant and lead-free?

Yes, the 2SA1391S manufactured under SANYO ordering number EN1942B meets RoHS Directive 2011/65/EU requirements and is lead-free. The TO-92MOD package uses matte tin-plated leads and halogen-free molding compound - verified in SANYO's compliance documentation and confirmed by authorized distributor certifications for the 2SA1391S.