onsemi BC237BZL1G

Overview

BC237BZL1G from onsemi is an NPN silicon small-signal amplifier transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 100 mA, P_D = 350 mW at T_A = 25°C, with h_FE = 200–380 (at I_C = 10 mA, V_CE = 5 V), used in low-noise audio preamplifier stages and general-purpose switching circuits.

For engineers reviewing the BC237BZL1G datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain range, V_CE(sat) ≤ 0.2 V at I_C/I_B = 10, f_T ≥ 150 MHz, C_obo = 4.5 pF, and Pb-free TO-92 packaging compliance.

Technical Context

The BC237BZL1G operates as a linear amplifying device with specified h_FE min/max across collector currents from 2 mA to 100 mA, and exhibits stable f_T = 150 MHz at I_C = 0.5 mA, V_CE = 3 V. Its low noise figure of 4.0 dB (at I_C = 0.2 mA, f = 1 kHz) supports high-fidelity analog signal conditioning.

Thermal resistance R_JA = 357°C/W confirms suitability for ambient-temperature-limited PCB layouts without forced cooling. The device's V_BE(on) = 0.62 V (typ.) and V_CE(sat) = 0.07 V (min.) at I_C/I_B = 10 enable efficient biasing in Class-A amplifier designs.

Key Specifications

Pinout & Package

BC237BZL1G uses the standard TO-92 (Case 29-11, Style 17) plastic package with 3 leads, lead-free (Pb-free) construction, and 2000-unit ammo pack packaging format.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal amplifier applications.

Compared with BC237BZL1G, BC547B trades lower noise for slightly higher gain variability, while 2N3904 offers superior speed and current capability at the cost of reduced voltage safety margin and noisier operation-making BC237BZL1G optimal for precision low-noise linear amplification at 45 V.

Availability

BC237BZL1G is available at Aetrix Electronics and suitable for audio preamplifiers, RF buffer stages, level-shifting interfaces, and current-mirror bias networks requiring stable component supply and Pb-free compliance.

Supply support for BC237BZL1G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, and intelligent edge applications.

The BC237 series belongs to onsemi's legacy small-signal transistor product line, designed specifically for high-fidelity analog amplification, low-noise signal conditioning, and reliable general-purpose switching in cost-sensitive consumer and industrial electronics.

FAQ

What is the maximum collector-emitter voltage rating for BC237BZL1G?

The BC237BZL1G has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc under open-base conditions. This value defines the absolute upper limit for safe operation in common-emitter configurations. Exceeding 45 V risks avalanche breakdown and permanent damage. Derating is recommended above 25°C ambient, and the device must never be operated beyond this rating even transiently. The BC237BZL1G datasheet specifies this as a hard limit-not a typical or recommended operating point.

Is BC237BZL1G RoHS-compliant and lead-free?

Yes, BC237BZL1G is explicitly marked with the "G" suffix indicating Pb-free (lead-free) construction per RoHS Directive 2011/65/EU. It uses matte tin lead finish and complies with JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for TO-92 packages. The "G" designation appears in both the part marking and ordering information, confirming full regulatory compliance for environmentally restricted markets and modern assembly processes.

What is the typical DC current gain (h_FE) of BC237BZL1G at 10 mA collector current?

The BC237BZL1G exhibits a guaranteed minimum h_FE of 200 and a maximum of 380 at I_C = 10 mA, V_CE = 5 V, and T_A = 25°C. This binning (designated "B") ensures tighter gain distribution than the base BC237 grade, reducing design margin requirements in precision bias networks. Typical h_FE falls near 290 under these conditions, supporting predictable quiescent point setting without iterative emitter resistor tuning.

Can BC237BZL1G be used in RF amplifier applications up to what frequency?

The BC237BZL1G has a current-gain bandwidth product (f_T) of 150 MHz, measured at I_C = 0.5 mA, V_CE = 3 V, and f = 100 MHz. In practical small-signal amplifier designs, it delivers usable gain up to approximately 50 MHz with adequate stability margin. Performance degrades above this due to falling h_FE and rising C_obo (4.5 pF); for >100 MHz applications, devices like 2N3904 (f_T = 300 MHz) are more appropriate. Layout parasitics must be minimized to realize stated RF capability.

What are the thermal limitations of BC237BZL1G in a standard PCB layout?

The BC237BZL1G has a junction-to-ambient thermal resistance (R_JA) of 357°C/W under standard test conditions (still air, FR-4 board, no copper pour). At 25°C ambient, its 350 mW power dissipation limit implies a maximum junction temperature of 134°C - within its −55°C to +150°C operating range. To avoid thermal runaway, keep continuous power below 200 mW on typical layouts; use thermal relief pads or local copper pours to reduce R_JA if sustained >250 mW operation is required. Derate linearly above 25°C ambient at 2.8 mW/°C.