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TO-92 · 2N3906
ActivePNP General-Purpose BJT
2N3906
onsemi · TO-92 · PNP General-Purpose BJT
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Overview
The 2N3906 is the PNP complement of the 2N3904 and completes the most widely used complementary small-signal pair in electronics. The onsemi TO-92 version is rated -40V collector-emitter, -40V collector-base and -5.0V emitter-base, with -200mA continuous collector current and 625mW dissipation at TA = 25°C, mirroring the NPN part in every practical respect.
DC current gain is 100 to 300 at IC = -10mA and VCE = -1.0V, with a minimum of 30 at -100mA, and the gain-bandwidth product is 250MHz at IC = -10mA and VCE = -20V. Saturation voltage is -0.4V maximum at IC = -50mA with IB = -5mA, and switching times (35ns delay and rise) support switching duty into the megahertz range.
Its natural roles are the high-side half of push-pull and totem-pole output stages, complementary feedback pairs, level shifters that pull toward the positive rail, and P-side switches for loads referenced to ground. Because it is so common, the 2N3906 is second-sourced by onsemi, STMicroelectronics, Diodes Inc and many Asian vendors, and remarked low-gain dies appear regularly in broker stock. Verify hFE at -10mA and VCE(sat) at -50mA/-5mA on incoming inspection. Pinout is emitter-base-collector. Shenzhen stock is deep, MOQ 2,000 pcs on tape or 1,000 pcs bulk.
Key Features
- -40V / -200mA PNP small-signal transistor in TO-92
- hFE 100-300 at IC = -10mA, VCE = -1.0V
- 250MHz fT for fast complementary switching
- Exact PNP complement of the 2N3904
- 625mW dissipation, -55 to +150°C junction
Typical Applications
- Push-pull and totem-pole output stages with 2N3904
- High-side switching of ground-referenced loads
- Level shifting toward the positive rail
- Complementary feedback pair amplifiers
- Current mirrors and active loads
- Inverting and non-inverting small-signal stages
Specifications
- Polarity / Channel Type
- PNP
- Collector-Emitter Voltage (VCEO)
- -40 V
- Collector-Base Voltage (VCBO)
- -40 V
- Emitter-Base Voltage (VEBO)
- -5.0 V
- Continuous Collector Current (IC)
- -200 mA
- DC Current Gain hFE (IC = -10 mA, VCE = -1.0 V)
- 100 to 300
- Gain-Bandwidth Product (fT)
- 250 MHz
- Power Dissipation (PD, TA = 25 °C)
- 625 mW
- Pins
- 3
- RoHS
- Compliant
Procurement Tips
When you qualify a 2N3904 for a push-pull stage, qualify the 2N3906 from the same vendor and lot family so the complementary pair tracks thermally; mismatched vendors give visibly asymmetric crossover distortion in audio stages.
Frequently Asked Questions
2N3906 vs 2N3904 - how do I keep them straight?
They are complementary: 2N3904 is NPN (current flows into the collector), 2N3906 is PNP (current flows out of the collector). Same TO-92 pinout (emitter-base-collector) and similar magnitudes of rating, but all voltages and currents are negative for the 2N3906. Use them as a matched pair in push-pull stages.
2N3906 vs BC557 - can I substitute?
Functionally similar PNP small-signal parts, but pinouts differ: 2N3906 TO-92 is emitter-base-collector while BC557 is commonly collector-base-emitter, and BC557 is rated -45V/-100mA with higher gain bands. Re-check pinout, current rating and gain band before substituting.
How do I use the 2N3906 as a high-side switch?
Connect emitter to the positive rail and the load between collector and ground. Drive the base through a resistor to ground (or an NPN/MCU open-drain) to turn on. Size base current at one tenth of load current for saturation, and add a base-emitter resistor (about 10kΩ) to guarantee turn-off when the drive floats.
Why is the 2N3906 fT lower than the 2N3904?
PNP silicon transistors rely on hole mobility, which is lower than electron mobility, so the PNP member of a complementary pair typically shows 10-20% less transition frequency. 250MHz vs 300MHz is normal and rarely matters below a few megahertz.
Is the 2N3906 counterfeit-prone?
Yes, like all high-volume TO-92 bipolars. Verify hFE at IC = -10mA (genuine reads 100-300), VCE(sat) at -50mA/-5mA, and check marking quality and lead finish. Pulled and remarked parts show high leakage and low gain. We sample-test every reel before dispatch.
What is the MOQ and lead time?
MOQ is 2,000 pcs on tape-and-reel or 1,000 pcs bulk for onsemi 2N3906; 100 pcs loose for prototypes. Shenzhen stock ships in 1-2 days; authorized replenishment is 8-14 weeks.
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