onsemi MPS6729

Overview

MPS6729 from onsemi is a PNP silicon bipolar junction transistor designed for general-purpose amplification and switching in low-to-medium power linear and switching applications. It delivers −500 mA continuous collector current, −80 V collector-emitter breakdown voltage, and 1.0 W total device dissipation at TA = 25°C, housed in a TO-92 package. It is commonly used in audio preamplifier stages, relay drivers, and voltage-level translation circuits.

For engineers reviewing the MPS6729 datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, DC current gain (hFE = 80–250 at IC = −50/−250 mA), VCE(sat) ≤ −0.5 V, thermal resistance RJA = 125°C/W, and TO-92 mechanical compatibility with legacy through-hole designs.

Technical Context

The MPS6729 operates as a single PNP BJT with fixed emitter-base and collector-base junctions optimized for DC-coupled amplification and saturated switching. Its hFE exhibits strong temperature dependence-decreasing at TJ = −55°C and increasing at TJ = 125°C-and its safe operating area is bounded by thermal limit (2.5 W at TC = 25°C), second breakdown, and current limit curves.

Electrical behavior is defined under standardized test conditions: VCE = −1.0 Vdc for hFE, IC = −250 mAdc/IB = −10 mAdc for VCE(sat), and VCB = −60 Vdc for ICBO. Small-signal parameters include fT ≈ 20 MHz at IC = −200 mA and Ccb ≤ 30 pF at VCB = −10 Vdc, confirming suitability for audio-frequency and low-speed digital switching.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-10, Style 1), through-hole, Pb-free option available (MPS6729G). Dimensions comply with ON Semiconductor Issue D (05 MAR 2021).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPS6729, MPS6728 serves complementary NPN roles in push-pull pairs, while BC557 offers higher hFE but reduced voltage and power margins-neither is pin-compatible, and both require layout verification for functional equivalence.

Availability

MPS6729 is available at Aetrix Electronics and suitable for audio preamplifiers, relay drivers, and voltage level translators requiring stable component supply and long-term industrial availability.

Supply support for MPS6729 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 specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MPS6729 belongs to onsemi's legacy discrete bipolar transistor family, engineered for reliability in general-purpose linear amplification and switching applications where cost-effective, through-hole PNP performance is required.

FAQ

What is the maximum collector-emitter voltage rating for the MPS6729?

The MPS6729 has a guaranteed minimum collector-emitter breakdown voltage V(BR)CEO of −80 Vdc at IC = −1.0 mAdc and IB = 0. This rating defines the absolute maximum reverse bias the device can withstand in common-emitter configuration without avalanche conduction. Operating above this voltage risks irreversible junction damage, and derating is recommended for reliability in high-temperature environments.

Is the MPS6729 available in a lead-free package?

Yes, the MPS6729G variant is the Pb-free version of the MPS6729, fully compliant with RoHS directives. It shares identical electrical specifications and TO-92 mechanical dimensions with the standard MPS6729, differing only in termination plating. The "G" suffix denotes Pb-free packaging, and the marking may include a microdot or "G" code per ON Semiconductor's generic marking diagram.

What is the DC current gain (hFE) range for the MPS6729 at typical operating conditions?

The MPS6729 exhibits hFE = 80–250 at TA = 25°C, measured with IC = −50 mAdc and VCE = −1.0 Vdc (min/max bounds), and IC = −250 mAdc and VCE = −1.0 Vdc (typical mid-range). This gain spread reflects process variation and must be accounted for in base resistor calculations-designs should function correctly across the full hFE range, not just nominal values.

Can the MPS6729 replace the BC557 in an existing design?

No, the MPS6729 cannot directly replace the BC557 without board-level changes. Although both are TO-92 PNP transistors, they differ in pinout (MPS6729: E-B-C; BC557: E-C-B), VCEO (−80 V vs. −45 V), and power rating (1.0 W vs. 0.5 W). Substitution requires verifying SOA, updating footprint, and recalculating bias networks to avoid overstress or malfunction.

What thermal derating applies to the MPS6729 above 25°C ambient temperature?

The MPS6729 derates linearly at 8.0 mW/°C above TA = 25°C when mounted in free air (RJA = 125°C/W). For example, at TA = 75°C, allowable power dissipation drops to 1.0 W − (50 × 0.008 W) = 0.6 W. This derating ensures junction temperature remains within the −55°C to +150°C operating range; heatsinking or forced airflow extends usable power at elevated ambient temperatures.