component
BC858ALT1G
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
markdownBC858ALT1G
onsemi · Bipolar (BJT) · SOT-23
BC858ALT1G 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 | passive | Base terminal of the PNP transistor; the datasheet gives no pin-specific limit, and the device maximum emitter-base voltage is VEBO −5.0 V. |
| 2 | EMITTER | passive | Emitter terminal of the PNP transistor; the datasheet gives no pin-specific limit, and the device maximum continuous collector current is IC −100 mA. |
| 3 | COLLECTOR | passive | Collector terminal of the PNP transistor; for the BC858 type the datasheet gives VCEO −30 V and VCBO −30 V as maximum ratings. |
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 Voltage (BC858) | VCEO | -30 | V | 1 | |||
| Collector-Base Voltage (BC858) | VCBO | -30 | V | 1 | |||
| Emitter-Base Voltage | VEBO | -5 | V | 1 | |||
| Collector Current - Continuous | IC | -100 | mAdc | 1 | |||
| Collector Current - Peak | IC | -200 | mAdc | 1 | |||
| Total Device Dissipation (FR-5 board) | PD | 225 | mW | FR-5 board (Note 1), TA = 25°C | 1 | ||
| Total Device Dissipation (alumina substrate) | PD | 300 | mW | Alumina substrate (Note 2), TA = 25°C | 1 | ||
| Thermal Resistance, Junction-to-Ambient (FR-5 board) | RJA | 556 | °C/W | FR-5 board | 1 | ||
| Thermal Resistance, Junction-to-Ambient (alumina substrate) | RJA | 417 | °C/W | Alumina substrate | 1 | ||
| Junction and Storage Temperature | TJ, Tstg | -55 | 150 | °C | 1 | ||
| Collector-Emitter Breakdown Voltage (BC858) | V(BR)CEO | -30 | V | IC = −10 mA | 2 | ||
| Collector-Base Breakdown Voltage (BC858) | V(BR)CBO | -30 | V | IC = −10 A | 2 | ||
| Emitter-Base Breakdown Voltage (BC858) | V(BR)EBO | -5 | V | IE = −1.0 A | 2 | ||
| Collector Cutoff Current | ICBO | -15 | nA | VCB = −30 V | 2 | ||
| Collector Cutoff Current | ICBO | -4 | A | 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 (BC858 Series) | NF | 10 | dB | IC = −0.2 mA, VCE = −5.0 Vdc, RS = 2.0 k, f = 1.0 kHz, BW = 200 Hz | 2 | ||
| Junction-to-Case Thermal Resistance | RJC | 83.3 | °C/W | ZJC(t) = r(t) RJC (Figure 14 note) | 5 | ||
| Junction-to-Ambient Thermal Resistance | RJA | 200 | °C/W | ZJA(t) = r(t) RJA (Figure 14 note) | 5 |
CAD (KiCad official)
- Symbol:
BC858ALT1G - Footprint:
Package_TO_SOT_SMD:SOT-23 - 3D model: SOT-23 (KiCad packages3D, STEP)
- 3D model files:
bc858alt1g-etched.step/bc858alt1g-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);bc858alt1g.step/bc858alt1g.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: onsemi datasheet (7 pp, sha256
5b3358db41b73faa, retrieved 2026-10-17, 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).