onsemi MPS3638A

Overview

MPS3638A from ON Semiconductor is a PNP silicon switching transistor in TO-92 (CASE 29-11) package, rated for −25 V V_CEO, −500 mA I_C, and 625 mW P_D at T_A = 25°C. It delivers h_FE ≥ 80 at I_C = −1.0 mA and f_T = 150 MHz, supporting fast-switching applications such as relay drivers and low-power logic-level inverters.

For engineers reviewing the MPS3638A datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) ≤ −0.25 V at I_C = −50 mA/I_B = −2.5 mA, guaranteed t_on ≤ 75 ns, and thermal resistance R_JA = 200°C/W - all critical for compact, thermally constrained discrete switching designs.

Technical Context

The MPS3638A operates as a general-purpose PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE spans 80–200 across I_C = −1 mA to −300 mA, with V_BE(sat) ≤ −1.1 V at high drive conditions and C_ibo = 25 pF ensuring stable small-signal behavior up to 100 MHz.

It features defined transient performance: t_d ≤ 20 ns, t_r ≤ 70 ns, t_s ≤ 140 ns, and t_f ≤ 70 ns under V_CC = −10 V, I_C = −300 mA, and I_B1 = I_B2 = −30 mA - confirming suitability for medium-speed digital interface and pulse generation circuits.

Key Specifications

Pinout & Package

Package: TO-92 (CASE 29-11, STYLE 1), plastic through-hole package with 3 leads, JEDEC-compliant outline and Pb-free finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP switching transistor applications.

Compared with MPS3638A, the 2N4403 offers higher voltage and current headroom in the same TO-92 package, while the BC557B trades current capacity for tighter h_FE tolerance and higher gain - making MPS3638A the optimal balance of speed, power handling, and thermal robustness for general-purpose medium-current switching.

Availability

MPS3638A is available at Aetrix Electronics and suitable for relay drivers, logic inverters, LED current sinks, and low-power audio preamplifiers requiring stable component supply across industrial, instrumentation, and consumer electronics programs.

Supply support for MPS3638A 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

ON Semiconductor (now onsemi) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The MPS3638A belongs to ON Semiconductor's legacy general-purpose bipolar transistor family, designed specifically for cost-sensitive, high-reliability discrete switching and amplification in space-constrained through-hole applications.

FAQ

What is the maximum continuous collector current rating for the MPS3638A?

The MPS3638A has a maximum continuous collector current (I_C) rating of −500 mA at T_A = 25°C. This value decreases with rising ambient temperature due to its 5.0 mW/°C derating factor. At 75°C ambient, the usable I_C drops to approximately −375 mA. The MPS3638A must be operated within this thermal envelope to avoid junction overheating and premature failure.

Is the MPS3638A RoHS compliant and lead-free?

Yes, the MPS3638A is available in Pb-free package(s), and all specifications apply identically to both standard and Pb-free versions. ON Semiconductor confirms full RoHS compliance per EU Directive 2011/65/EU, with lead content below 0.1% by weight in homogeneous materials. The MPS3638A meets J-STD-609 Category 1 marking requirements for lead-free identification.

What is the typical DC current gain (h_FE) of the MPS3638A at different collector currents?

The MPS3638A exhibits h_FE = 80 minimum at I_C = −1.0 mA, 100 minimum at I_C = −10 mA, 100 minimum at I_C = −50 mA, and 20 minimum at I_C = −300 mA - all measured at V_CE = −10 V. This wide h_FE variation reflects its intended use as a switching device rather than a precision linear amplifier, and the MPS3638A should be biased accordingly.

Can the MPS3638A be used in high-frequency amplifier circuits?

The MPS3638A has an f_T of 150 MHz and C_ibo = 25 pF, supporting stable small-signal amplification up to ~30 MHz with proper neutralization and layout. However, its noise figure exceeds 10 dB above 10 kHz, and h_FE rolls off rapidly beyond 10 MHz. For RF applications, the MPS3638A is best suited to VHF oscillator buffers or IF stages - not front-end LNA roles - and the MPS3638A must be evaluated with actual matching networks.

What are the absolute maximum ratings for junction temperature and storage temperature of the MPS3638A?

The MPS3638A has an absolute maximum junction and storage temperature range of −55°C to +150°C. Operation outside this range risks permanent parametric shift or catastrophic failure. Thermal design must ensure that under worst-case power dissipation (e.g., 625 mW at T_A = 25°C), the calculated junction temperature - using R_JA = 200°C/W - stays below 150°C. The MPS3638A's reliability is validated across this full range per JESD22-A108.