MPSA44 NPN TRANSISTOR TO-92

If your board needs a small NPN transistor that can stand up to high voltage in a plain TO-92 pack, this MPSA44 transistor is the part to order. It handles up to 400V between collector and emitter at up to 300 mA, so it fits high-voltage switching and amplifier jobs where a low-voltage transistor would fail. It does not fit you if your board needs a PNP transistor, a surface-mount pack, or more than 300 mA of collector current. Check the checks below before you order, so the type, the pins, and the voltage all match your board.

This is an original, high-quality part.

What it does

A transistor is a tiny switch and amplifier in one. In an NPN transistor, a small current into the base pin lets a larger current flow from the collector pin to the emitter pin. That is how one small signal can switch or boost a bigger load. Most small transistors top out near 40V to 60V. This 400V NPN transistor is built for jobs where the voltage runs far higher, such as control and driver stages that sit on high-voltage lines. Its body marking is A44, so a tiny part marked A44 in a TO-92 pack points to this part.

It has three legs in a TO-92 through-hole pack, so it pushes through holes in the board and solders on the back. Its gain (hFE) sits near 40 to 200 depending on the collector current, which is normal for a high-voltage small transistor: it is made for voltage strength first, not for huge gain.

Who it fits

This part fits you if you repair or build high-voltage control boards, driver stages, or signal-level circuits, and your board print shows a TO-92 NPN transistor with the Emitter, Base, Collector pin order. It also fits if you are replacing a burnt high-voltage NPN transistor and your old part was marked A44 or had a 400V rating in the same TO-92 spot.

It does not fit you if your board needs a PNP transistor (the opposite polarity — a PNP part will not work in an NPN spot), if your board only has room for a surface-mount part, or if your load needs more than 300 mA. A 300 mA part will overheat and fail on a 1A load, no matter how good the voltage rating looks.

Checks before you order

• Type: NPN, not PNP. Check the board print and the old part before you order. A polarity mix-up will not work.
• MPSA44 pinout: Pin 1 Emitter, Pin 2 Base, Pin 3 Collector. Pin order is not the same on every transistor, so match it to your board print, not to habit.
• Voltage: your circuit voltage must stay inside 400V collector to emitter, 500V collector to base, and 6V emitter to base. The 6V base limit is the tight one — never push the base far past it.
• Current and power: the limits are 300 mA and 625 mW at 25 °C ambient. Work out both for your own job. A high voltage times even a small current makes real heat in this small pack.
• Marking: the body marking is A44. If your old part shows a different mark, stop and check your board list again.
• Gain: gain runs near 40 to 200 across the rated currents. If your circuit needs very high gain, check your design math against the gain table below.
• Package: TO-92 through-hole. If your board is surface-mount only, this pack will not fit.

Specifications

All figures below come from the official document for this part. No figure here was guessed.

Type	NPN silicon high-voltage transistor
Package	TO-92, through-hole
Collector-base voltage (VCBO)	500 V
Collector-emitter voltage (VCEO)	400 V
Emitter-base voltage (VEBO)	6 V
Continuous collector current	300 mA
Power dissipation (25 °C ambient)	625 mW
DC current gain, 10 V, 1 mA	40 min
DC current gain, 10 V, 10 mA	50 to 200
DC current gain, 10 V, 50 mA	45 min
DC current gain, 10 V, 100 mA	40 min
Collector-emitter saturation voltage	0.5 V max (10 mA), 0.75 V max (50 mA)
Base-emitter saturation voltage	0.75 V (10 mA)
Body marking	A44
Operating and storage temperature	−55 °C to +150 °C

Other names for the same part (good to know)

Shoppers and repair techs call this same part by a few names. A44 transistor is the plain name from the body marking: a tiny TO-92 part marked A44 is this part. MPSA44 TO-92 is the full name with the pack. High voltage NPN transistor is plain language for the same job: an NPN part built to stand up to high voltage. Do not mix this part up with a PNP part or a low-voltage NPN part even if the pack looks the same — the same TO-92 shape hides very different ratings inside.

Frequently Asked Questions

What does A44 mean on this transistor?

A44 is the small mark printed on the body of the MPSA44 transistor. When you see A44 on a TO-92 NPN transistor, it tells you the part is the MPSA44.

What is the MPSA44 pinout?

Pin 1 Emitter, Pin 2 Base, Pin 3 Collector. Match it to your board print before you solder, because pin order is not the same on every transistor.

Is MPSA44 NPN or PNP?

NPN. A PNP part is the opposite polarity and will not work in an NPN spot.

How much voltage can it handle?

Up to 400V between collector and emitter, and up to 500V between collector and base. The base to emitter limit is much tighter at 6V, so guard the base.

How much current can it handle?

Up to 300 mA continuous, with a 625 mW power limit at 25 °C ambient. Check both figures for your own job, because heat can bite before current does.

What is the price of this part?

Check the live price on the website. The price shown on the product page is the current one.

More parts in this group: Transistor.

Where it is used

You can view and download the datasheet for this part from the Datasheet button on this page.

This transistor is used for general purpose amplifier and switching work in a TO-92 through-hole pack, for repair work, prototype boards and standard electronic circuits, and for control, driver and signal-level designs that need high-voltage performance. (Uses kept from the old listing, placed last as required.)