Part A
MMBTA92LT1G
onsemi
- Lifecycle
- Active
- Stock
- 6650 PCS
- Package
- SOT-23-3
- Series
- Transistores - Bipolares (BJT) - Single
Replacement verdict
Compatible functional replacement candidate
The MMBTA42 and MMBTA92LT1G are both high-voltage NPN bipolar junction transistors in SOT-23 surface-mount packages, sharing identical pinout and complementary electrical characteristics. While their voltage and current ratings differ, the MMBTA92LT1G can serve as a functional substitute for the MMBTA42 in many low-current, high-voltage switching and amplification applications, provided the circuit's voltage and current requirements fall within the MMBTA92LT1G's specified limits. Designers should verify thermal and breakdown voltage margins before committing to a drop-in replacement.
Transistor Type and Polarity
High match
Package Type
High match
Collector-Emitter Voltage Rating
Validation required
Collector Current Rating
Validation required
Parts at a glance
Part B
MMBTA42
STMicroeletrônica
- Lifecycle
- Active
- Stock
- 6056 PCS
- Package
- SOT-23-3
- Series
- Transistores - Bipolares (BJT) - Single
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | MMBTA42 | MMBTA92LT1G | Why it matters |
|---|---|---|---|
| Transistor Type | NPN | PNP | Complementary polarity determines circuit orientation and cannot be substituted without redesigning the surrounding bias network. |
| Collector-Emitter Voltage (Vceo) | 300 V | 300 V | Maximum voltage the device can block; both match, so voltage headroom is equivalent. |
| Collector Current (Ic) | 500 mA | 500 mA | Continuous current rating defines load-driving capability; identical ratings allow similar load handling. |
| DC Current Gain (hFE) | 40 (min) at 10 mA | 25 (min) at 10 mA | Gain affects base drive requirements; lower hFE needs more base current for the same collector current. |
| Transition Frequency (fT) | 50 MHz (min) | 50 MHz (min) | Determines high-frequency switching capability; matching values indicate similar speed performance. |
| Collector-Emitter Saturation Voltage (Vce(sat)) | 0.5 V max at 20 mA | 0.5 V max at 20 mA | Lower saturation voltage reduces conduction losses in switching applications; equal values mean comparable efficiency. |
| Power Dissipation (Pd) | 350 mW | 300 mW | Thermal limit for the package; lower Pd restricts maximum continuous power handling. |
| Package / Case | SOT-23 | SOT-23 | Footprint compatibility is essential for drop-in replacement on existing PCB layouts. |
| Operating Junction Temperature (Tj) | 150 °C | 150 °C | Maximum junction temperature defines thermal design limits; identical ratings allow equivalent thermal margins. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | MMBTA92LT1G | MMBTA42 |
|---|---|---|
| Part Status | Active | Obsolete |
| Transistor Type | PNP | NPN |
| Current - Collector(Ic)(Max) | 500 mA | 100 mA |
| Voltage - Collector Emitter Breakdown(Max) | 300 V | 300 V |
| Vce Saturation(Max) @ Ib Ic | 500mV @ 2mA, 20mA | 200mV @ 2mA, 20mA |
| Current - Collector Cutoff(Max) | 250nA (ICBO) | 250nA (ICBO) |
| DC Current Gain(h FE)(Min) @ Ic Vce | 25 @ 30mA, 10V | 60 @ 1mA, 10V |
| Power - Max | 300 mW | 350 mW |
| Frequency - Transition | 50MHz | 50MHz |
| Operating Temperature | -55°C ~ 150°C (TJ) | -65°C ~ 150°C (TJ) |
| Mounting Type | Surface Mount | Surface Mount |
| Series | - | SOT-23 |
Frequently asked questions
What are the main differences between the MMBTA42 and MMBTA92LT1G transistors?
The MMBTA42 is an NPN high-voltage transistor rated for 300 V VCEO, while the MMBTA92LT1G is a PNP high-voltage transistor rated for 300 V VCEO. The primary differences are polarity (NPN vs PNP), package type (SOT-23 for MMBTA42 vs SOT-23 for MMBTA92LT1G), and manufacturer-specific specifications. The MMBTA42 is typically used in NPN high-voltage switching and amplification, whereas the MMBTA92LT1G is used in PNP complementary circuits.
Can the MMBTA42 and MMBTA92LT1G be used as complementary pairs?
Yes, they can be used as complementary NPN/PNP pairs in high-voltage applications because both have a 300 V VCEO rating and similar current and power ratings. However, designers must verify that key parameters such as hFE, VCE(sat), and switching characteristics meet the requirements of the specific circuit, as these parameters may differ between the two devices.
What is the collector-emitter voltage rating for both devices?
Both the MMBTA42 and MMBTA92LT1G have a collector-emitter voltage (VCEO) rating of 300 V. This makes them suitable for high-voltage switching and amplification applications where standard low-voltage transistors cannot be used.
What is the continuous collector current rating for the MMBTA42 and MMBTA92LT1G?
The MMBTA42 has a continuous collector current (IC) rating of 500 mA. The MMBTA92LT1G also has a continuous collector current rating of 500 mA. Both devices are therefore suitable for low-to-moderate current high-voltage applications.
What package types are used for the MMBTA42 and MMBTA92LT1G?
The MMBTA42 is typically offered in the SOT-23 surface-mount package. The MMBTA92LT1G is also offered in the SOT-23 package. Both packages are thermally and electrically similar, but designers should confirm the exact package drawing and thermal resistance from the respective manufacturer datasheets.
Are the MMBTA42 and MMBTA92LT1G interchangeable in a circuit?
No, they are not directly interchangeable because the MMBTA42 is an NPN transistor and the MMBTA92LT1G is a PNP transistor. Substituting one for the other would reverse the polarity requirements and likely cause the circuit to malfunction. They can only be used together as complementary devices in push-pull or complementary output stages.
What are the typical applications for the MMBTA42 and MMBTA92LT1G?
Typical applications for both devices include high-voltage switching, telephony, lighting, and amplification circuits. The MMBTA42 (NPN) is often used as a high-voltage driver or switch, while the MMBTA92LT1G (PNP) is used in complementary high-voltage circuits, such as push-pull amplifiers and high-side switching configurations.
Do the MMBTA42 and MMBTA92LT1G have the same power dissipation rating?
Both devices typically have a total power dissipation (PD) rating of 350 mW when mounted on a suitable PCB. However, the actual power dissipation depends on the thermal resistance of the board and the ambient temperature. Designers should refer to the specific manufacturer datasheet for derating curves and thermal resistance values.