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onsemi BC557ABU
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- Part No.:
- BC557ABU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
BC557ABU.pdf
- Description:
- TRANS PNP 45V 0.1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:6,299
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Product details
Overview
BC557ABU from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and low-noise amplification, with VCEO = −45 V, hFE = 110–220 (Class A), IC = −100 mA DC, and TO-92-3 (Case 135AN) package. It serves as a complementary pair to BC547/BC548 NPN transistors in dual-rail analog stages and discrete logic inverters.
For engineers reviewing the BC557ABU datasheet, pinout, applications, or equivalent options, key selection criteria include verified VCEO rating, hFE classification consistency, saturation voltage at −10 mA/−0.5 mA drive, thermal resistance (RJA = 250 °C/W), and Pb-free RoHS-compliant packaging per onsemi's Rev. 3 June 2024 specification.
Technical Context
This device operates as a medium-voltage, medium-current PNP bipolar junction transistor with fixed-emitter bias topology. Its −45 V VCEO rating supports rail-to-rail operation in ±15 V analog supplies, while its 150 MHz fT enables audio-frequency amplification up to 20 kHz with stable gain.
The BC557ABU exhibits low base-emitter on-voltage (−600 to −750 mV at IC = −2 mA) and low output capacitance (Cob = 6 pF), making it suitable for high-input-impedance preamplifier stages and fast-switching digital interfaces where charge storage delay must be minimized.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −45 V - Supports operation in dual-supply circuits up to ±22.5 V without breakdown. |
| hFE (Class A) | 110–220 - Ensures predictable current gain in linear amplifier bias networks with minimal spread. |
| IC (DC) | −100 mA - Enables direct drive of LEDs, small relays, or logic-level shifters without external buffering. |
| VCE(sat) | −90 to −300 mV @ IC = −10 mA / IB = −0.5 mA - Minimizes conduction loss in saturated-switch applications. |
| fT | 150 MHz - Provides adequate bandwidth for audio preamps and low-speed signal conditioning. |
| Cob | 6 pF @ VCB = −10 V - Reduces Miller effect in common-emitter configurations above 100 kHz. |
| RJA | 250 °C/W - Requires PCB copper area ≥ 76 mm × 114 mm for full 500 mW dissipation at ambient 25 °C. |
Pinout & Package
BC557ABU uses the TO-92-3 package (Case 135AN), a through-hole plastic encapsulated transistor with 4.825 mm × 4.76 mm footprint and straight leads. Pin identification follows standard JEDEC orientation: viewed with flat side facing user, pins numbered left-to-right as 1–2–3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Collector | Main current sink terminal; connects to negative supply or load return path in PNP switch configurations. |
| 2 | Base | Control input; requires current-limited drive (e.g., 10 kΩ pull-up to −VCC) to ensure reliable turn-on/turn-off. |
| 3 | Emitter | Common reference terminal; tied to most-positive rail in high-side switch or grounded in common-emitter amplifier. |
Key Features
| Feature | Design Value |
|---|---|
| Complementary pairing | Matched hFE range and VCE(sat) with BC547A/BC548A enables balanced push-pull output stages. |
| Low-noise performance | Noise figure ≤10 dB at 1 kHz (IC = −200 µA) supports use in microphone preamp inputs without added op-amp noise. |
| Pb-free & RoHS compliance | Fully halogen-free/BFR-free construction meets IPC-J-STD-020 moisture sensitivity level 1 (MSL-1) requirements. |
| Thermal stability | Junction temperature rating up to +150 °C allows operation in sealed industrial enclosures without forced cooling. |
Applications
| Audio Preamp Stage | Discrete Logic Inverter |
|---|---|
Use Scenario: Low-gain, single-transistor microphone preamplifier in battery-powered voice recorders. IC Role / Device Role / Timing Role: PNP common-emitter amplifier providing 10–15 dB voltage gain with DC-coupled input. Use Value: 6 pF Cob and 10 dB noise figure enable clean signal capture below 100 µV RMS without op-amp overhead. |
Use Scenario: TTL-compatible level-shifting inverter driving 74HC-series inputs from 5 V microcontroller GPIO. IC Role / Device Role / Timing Role: Saturated PNP switch operating in cutoff/saturation with <100 ns propagation delay. Use Value: −300 mV VCE(sat) ensures logic-low output <0.3 V under 4 mA load, meeting 74HC input threshold. |
| High-Side Load Switch | Analog Signal Multiplexer Driver |
Use Scenario: Controlling 12 V solenoid valves in HVAC control panels using 3.3 V MCU outputs. IC Role / Device Role / Timing Role: Emitter-follower configured PNP switch delivering regulated 12 V to load with base driven by resistive divider. Use Value: −45 V VCEO provides 2× safety margin over 12 V rail, preventing avalanche failure during inductive kickback. |
Use Scenario: Driving analog multiplexer channel-enable lines in data acquisition systems with ±15 V supplies. IC Role / Device Role / Timing Role: Discrete current source for CMOS analog switch biasing, ensuring monotonic turn-on across temperature. Use Value: Stable hFE (110–220) and −660 mV typical VBE(on) allow precise 100 µA bias current setting with 1% tolerance resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP general-purpose transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BC557BTA | Same TO-92-3 (135AR) package but Class B hFE = 200–450; higher gain variation; fan-fold packaging. | Preferred in high-gain feedback loops where tighter hFE matching is unnecessary. | Select BC557BTA only when circuit tolerates wider hFE spread and board layout accommodates lead-formed package. |
| MMBT557LT1G | SOT-23 surface-mount package; same VCEO (−45 V), hFE 100–300, but RJA = 300 °C/W; not pin-compatible. | Used in space-constrained PCBs where automated assembly and smaller footprint outweigh thermal derating penalty. | Choose MMBT557LT1G only when redesigning for SMT and accepting 17% lower power dissipation at same ambient. |
Compared with BC557BTA and MMBT557LT1G, the BC557ABU offers the narrowest hFE range (110–220) in through-hole format, enabling repeatable bias point setting in production without individual trimming, while maintaining legacy compatibility with existing TO-92 footprints and hand-soldering workflows.
Availability
BC557ABU is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic inverters, and high-side load switches requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole sourcing.
Supply support for BC557ABU 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, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The BC557ABU belongs to onsemi's legacy general-purpose bipolar transistor family, engineered for cost-sensitive, high-reliability discrete analog and switching functions in consumer, industrial, and communication equipment.
FAQ
What is the maximum continuous collector current for BC557ABU?
The BC557ABU supports a maximum DC collector current of −100 mA at TA = 25 °C, as specified in the Absolute Maximum Ratings table. Derating applies above 25 °C at 4.0 mW/°C, limiting usable current in high-temperature environments unless heatsinking is added. This rating ensures safe operation in relay drivers and LED switches without secondary protection circuitry.
Is BC557ABU pin-compatible with BC557BTA?
Yes, BC557ABU and BC557BTA share identical TO-92-3 pinout (Collector-Base-Emitter, left-to-right with flat side facing), but differ in hFE classification (A vs. B) and packaging (bulk vs. fan-fold). The BC557ABU uses Case 135AN (straight leads), while BC557BTA uses Case 135AR (lead-formed); mechanical fit requires verification if replacing in existing sockets.
Does BC557ABU meet modern RoHS and REACH requirements?
Yes, BC557ABU is explicitly marked Pb-free, halogen-free, and BFR-free in the onsemi datasheet Rev. 3 (June 2024), and complies fully with EU RoHS Directive 2011/65/EU and REACH SVHC regulations. Certificate of Compliance is available upon request from Aetrix Electronics for audit-ready documentation.
What is the typical noise figure of BC557ABU at audio frequencies?
The BC557ABU has a noise figure of 2–10 dB at 1 kHz with VCE = −5 V and IC = −200 µA, as measured per the Electrical Characteristics table. This makes it suitable for low-level signal amplification in electret microphone bias circuits where op-amp noise would dominate, provided emitter degeneration and proper bypassing are applied.
Can BC557ABU replace BC558 in a circuit designed for −30 V VCEO?
No - BC557ABU has VCEO = −45 V, exceeding BC558's −30 V rating, so it can safely substitute in circuits operating ≤−45 V. However, BC557ABU's higher VCEO does not imply improved speed or gain; hFE and fT remain comparable. Verify base drive strength and thermal margins, as BC557ABU's higher voltage rating may reduce early effect in linear regions.
BC557ABU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 100 mA
- Voltage - Collector Emitter Breakdown (Max):
- 45 V
- Vce Saturation (Max) @ Ib, Ic:
- 650mV @ 5mA, 100mA
- Current - Collector Cutoff (Max):
- 15nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 110 @ 2mA, 5V
- Power - Max:
- 500 mW
- Frequency - Transition:
- 150MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BC557ABU FAQ
1.How can I place an order for BC557ABU through Aetrix?
Please submit a Request for Quotation (RFQ) for BC557ABU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BC557ABU reliable?
The price and inventory of BC557ABU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC557ABU is usually 5 days.
3.What payment methods are accepted for BC557ABU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC557ABU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC557ABU?
BC557ABU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC557ABU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BC557ABU?
For technical support, including BC557ABU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC557ABU requirements.
6.How does Aetrix verify that BC557ABU is sourced from the original manufacturer or authorized distributors?
All BC557ABU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BC557ABU meets industry standards.
7.What is the process for return or replacement of BC557ABU?
All BC557ABU units undergo pre-shipment inspection (PSI). If there is an issue with BC557ABU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BC557ABU part is unused and in its original packaging.
Return procedure for BC557ABU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BC557ABU Tags
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MMBT3906LT1G
onsemi
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MMBT3904-7-F
Diodes Incorporated
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MMBT3904LT1G
onsemi
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MMBT3906-7-F
Diodes Incorporated
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MMBT3904-TP
Micro Commercial Co
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MMBT2222A-7-F
Diodes Incorporated
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BC846BLT1G
onsemi
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BC847B,215
Nexperia USA Inc.
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SMMBT3904LT1G
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MMBT2222A-TP
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MMBTA06LT1G
onsemi
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MMBT2222ALT1G
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