component
BC857ALT1G
Public Made by Adomby adom
onsemi Bipolar (BJT), SOT-23. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownBC857ALT1G
onsemi · Bipolar (BJT) · SOT-23
BC857ALT1G from onsemi, in a SOT-23. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | BASE | input | Base terminal of the PNP transistor; the datasheet gives VCE(sat) test conditions at IB = −0.5 mA (IC = −10 mA) and IB = −5.0 mA (IC = −100 mA), and the emitter-base breakdown voltage V(BR)EBO is −5.0 V minimum. |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; the emitter-base voltage is rated VEBO −5.0 V, with the continuous collector current limited to −100 mA and peak to −200 mA. |
| 3 | COLLECTOR | passive | Collector terminal of the BC857 PNP transistor; the collector-emitter voltage is rated VCEO −45 V and collector-base voltage VCBO −50 V. |
Key specifications
| Parameter | Value |
|---|---|
| Manufacturer | onsemi |
| Package | SOT-23 |
| Category | Transistors/Thyristors |
| Pins | 3 |
Electrical characteristics
Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).
| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Collector-Emitter Breakdown Voltage (BC857 series) | V(BR)CEO | -45 | V | IC = -10 mA | 2 | ||
| Collector-Emitter Breakdown Voltage (BC857A) | V(BR)CES | -50 | V | IC = -10 µA, VEB = 0 (as printed: IC = -10 A) | 2 | ||
| Collector-Base Breakdown Voltage (BC857 series) | V(BR)CBO | -50 | V | IC = -10 µA (as printed: IC = -10 A) | 2 | ||
| Emitter-Base Breakdown Voltage (BC857 series) | V(BR)EBO | -5 | V | IE = -1.0 µA (as printed: IE = -1.0 A) | 2 | ||
| Collector Cutoff Current | ICBO | -15 | nA | VCB = -30 V | 2 | ||
| Collector Cutoff Current | ICBO | -4 | µA | VCB = -30 V, TA = 150°C | 2 | ||
| Collector-Emitter Saturation Voltage | VCE(sat) | -0.3 | V | IC = -10 mA, IB = -0.5 mA | 2 | ||
| Collector-Emitter Saturation Voltage | VCE(sat) | -0.65 | V | IC = -100 mA, IB = -5.0 mA | 2 | ||
| Base-Emitter Saturation Voltage | VBE(sat) | -0.7 | V | IC = -10 mA, IB = -0.5 mA | 2 | ||
| Base-Emitter Saturation Voltage | VBE(sat) | -0.9 | V | IC = -100 mA, IB = -5.0 mA | 2 | ||
| Base-Emitter On Voltage | VBE(on) | -0.6 | -0.75 | V | IC = -2.0 mA, VCE = -5.0 V | 2 | |
| Base-Emitter On Voltage | VBE(on) | -0.82 | V | IC = -10 mA, VCE = -5.0 V | 2 | ||
| Current-Gain - Bandwidth Product | fT | 100 | MHz | IC = -10 mA, VCE = -5.0 Vdc, f = 100 MHz | 2 | ||
| Output Capacitance | Cob | 4.5 | pF | VCB = -10 V, f = 1.0 MHz | 2 | ||
| Noise Figure (BC857 series) | NF | 10 | dB | IC = -0.2 mA, VCE = -5.0 Vdc, RS = 2.0 k, f = 1.0 kHz, BW = 200 Hz | 2 | ||
| Collector-Emitter Voltage (BC857 series) | VCEO | -45 | V | Maximum Ratings, TA = 25°C | 1 | ||
| Collector-Base Voltage (BC857 series) | VCBO | -50 | V | Maximum Ratings, TA = 25°C | 1 | ||
| Emitter-Base Voltage | VEBO | -5 | V | Maximum Ratings, TA = 25°C | 1 | ||
| Collector Current - Continuous | IC | -100 | mAdc | Maximum Ratings, TA = 25°C | 1 | ||
| Collector Current - Peak | IC | -200 | mAdc | Maximum Ratings, TA = 25°C | 1 | ||
| Junction and Storage Temperature | TJ, Tstg | -55 | 150 | °C | 1 | ||
| Total Device Dissipation, FR-5 Board | PD | 225 | mW | FR-5 board (Note 1), TA = 25°C | 1 | ||
| Derate above 25°C, FR-5 Board | PD | 1.8 | mW/°C | FR-5 board (Note 1), derate above 25°C | 1 | ||
| Thermal Resistance, Junction-to-Ambient, FR-5 Board | RJA | 556 | °C/W | FR-5 board (Note 1) | 1 | ||
| Total Device Dissipation, Alumina Substrate | PD | 300 | mW | Alumina substrate (Note 2), TA = 25°C | 1 | ||
| Derate above 25°C, Alumina Substrate | PD | 2.4 | mW/°C | Alumina substrate (Note 2), derate above 25°C | 1 | ||
| Thermal Resistance, Junction-to-Ambient, Alumina Substrate | RJA | 417 | °C/W | Alumina substrate (Note 2) | 1 | ||
| Thermal Resistance, Junction-to-Ambient (transient-response note) | RJA | 200 | °C/W | Figure 14 SOA note: RJA = 200°C/W MAX | 5 | ||
| Thermal Resistance, Junction-to-Case (transient-response note) | RJC | 83.3 | °C/W | Figure 14 SOA note: RJC = 83.3°C/W MAX | 5 |
CAD (KiCad official)
- Symbol:
BC857ALT1G - Footprint:
Package_TO_SOT_SMD:SOT-23 - 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files:
bc857alt1g-etched.step/bc857alt1g-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);bc857alt1g.step/bc857alt1g.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: onsemi datasheet (7 pp, sha256
5b3358db41b73faa, retrieved 2026-10-09, tier: lcsc) - Extractor: parts-factory
2.0.0/extract_pins 0.3, primaryclaude-haiku-5-5(text), consensusclaude-sonnet-5-5(agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish. - CAD: KiCad official libraries (CC-BY-SA 4.0).