BETACollector-emitter limit300 V magnitude · absolute
High-voltage NPN transistor
MPSA42 Specifications
Review MPSA42 electrical specifications, operating conditions and package details.
Package view
Key specifications
TO-92 uses E1–B2–C3. SOT-23 uses B1–E2–C3. Check the selected part and mounting conditions before using its limits.
Collector current limit500 mA magnitude · thermal limits apply
TO-92 gain at 10 mA>40 |VCE| = 10 V
Junction limit150 °C · absolute maximum
Package details
MPSA42BK · TO-92
| Property | Details |
|---|---|
| Manufacturer | Diotec Semiconductor |
| Part number | MPSA42BK |
| Package | TO-92 |
| Connections | 3 pins |
| Mounting | Through-hole |
| Lead pitch | 1.27 mm · straight leads |
| Package code | straight |
| Thermal reference | 625 mW with leads held at ambient temperature 2 mm from case; derate. |
Packages and terminal functions
Reviewed Diotec selections
Manufacturer specifications 4 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Through-hole selection | MPSA42BK | Straight-lead TO-92: E1, B2, C3 |
| SMD selection | MMBTA42 | SOT-23: B1, E2, C3 |
| SMD marking | 1D | Manufacturer marking code |
| Polarity | NPN | Magnitudes shown for PNP values |
No specifications match. Try a parameter name or a unit.
Physical pin numbers change between packages; connect by E/B/C function.
TO-92 absolute limits
25°C unless stated
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Collector-emitter / collector-base | 300 / 300 V magnitudes | Base open / emitter open |
| Emitter-base reverse | 6 V magnitude | Collector open |
| DC collector current | 500 mA magnitude | Apply power and junction-temperature limits |
| Power dissipation | 625 mW | Leads held at ambient temperature 2 mm from case |
| Junction temperature | −55 to +150°C | Absolute range |
| Junction-to-ambient | <200 K/W | Manufacturer lead-cooling condition |
No specifications match. Try a parameter name or a unit.
300 V and 500 mA are not a simultaneous operating point.
TO-92 electrical characteristics
25°C · package-specific test points
Manufacturer specifications 7 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Gain at 1 / 10 / 30 mA | >25 / >40 / >40 | |VCE| = 10 V |
| Collector saturation voltage | <0.50 V | |IC| = 20 mA; |IB| = 2 mA |
| Base saturation voltage | <0.90 V | |IC| = 20 mA; |IB| = 2 mA |
| Collector-base leakage | <100 nA | |VCB| = 200 V; emitter open |
| Emitter-base leakage | <100 nA | |VEB| = 6 V; see manufacturer terminal-bias condition |
| Transition frequency | >50 MHz | |VCE| = 20 V; |IC| = 10 mA; f = 100 MHz |
| Collector-base capacitance | <3 pF | |VCB| = 20 V; 1 MHz |
No specifications match. Try a parameter name or a unit.
On-state values use pulsed measurements; typical frequency is not a guaranteed switching rate.
SMD · MMBTA42
Independent manufacturer reference
Manufacturer specifications 10 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| VCEO / VCBO / VEBO | 300 / 300 / 6 V magnitudes | Absolute limits with the specified third terminal open |
| DC collector current | 500 mA magnitude | Apply thermal constraints |
| Power dissipation | 250 mW | PCB with 3 mm² copper at each terminal |
| Gain at 10 mA | 80–200 | |VCE| = 10 V |
| Gain at 1 / 30 mA | >25 / >40 | |VCE| = 10 V |
| VCE(sat) / VBE(sat) | <0.50 / <0.90 V | |IC| = 20 mA; |IB| = 2 mA |
| Transition frequency | >50 MHz | |VCE| = 20 V; |IC| = 10 mA; f = 100 MHz |
| Collector-base capacitance | <3 pF | |VCB| = 20 V; 1 MHz |
| Junction / storage | −55 to +150°C | Absolute ranges |
| Body / full lead span | 2.9 × 1.3 / 2.4 mm nominal | Paired-contact pitch 1.9 mm |
No specifications match. Try a parameter name or a unit.
SMD values belong to the exact listed part; do not substitute the axial thermal rating.
TO-92 mechanical reference
Manufacturer straight-lead drawing
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Body width / height | 4.6 ±0.1 / 4.6 ±0.1 mm | Black flat-front molded body |
| Body depth | 3.6 ±0.1 mm | Flat face 1.1 ±0.2 mm from lead plane |
| Lead pitch | 1.27 ±0.1 mm | Straight-lead option |
| Lead width / thickness | 0.4 +0.15/−0.05 / 0.34 ±0.05 mm | Silver plated stamped contacts |
| Supplied lead length | ≥12.5 mm | Preview shows trimmed leads for readability |
| Authored pad / hole | 1.10 × 1.55 / 0.80 mm | Engineering footprint; review fabrication tolerance |
No specifications match. Try a parameter name or a unit.
The 2.54 mm formed tape option is a different mounting geometry.
5 V LED example
Teaching assumptions, not measured values
Manufacturer specifications 7 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Load / base / bias resistors | 470 Ω / 4.7 kΩ / 100 kΩ | Use separate current limits |
| Assumed drops | LED 2.0 V; |VBE| 0.7 V; |VCE(sat)| 0.2 V | Actual drops vary |
| Collector current | 5.96 mA | (5 − 2 − 0.2) / 470 |
| Net base current | 0.908 mA | (5 − 0.7) / 4700 − 0.7 / 100000 |
| Forced current ratio | Approximately 6.56 | Collector / base current |
| Transistor dissipation | Approximately 1.83 mW | Collector-emitter plus base-emitter terms |
| Inductive loads | Require a revised circuit | Add suitable flyback protection; not pictured here |
No specifications match. Try a parameter name or a unit.
The example is a low-current LED switch; it does not demonstrate the maximum-current rating.
Connections by function
Select a pin for its function, connection guidance and electrical notes.