NPN triode is a triode composed of two N-type semiconductors with a P-type semiconductor sandwiched between them. It is one of the most important devices in electronic circuits. Its main functions are current amplification and switching, which can turn a weak electric signal into a signal with a certain intensity. In this issue, Hottech recommends a widely used NPN triode MMBT3904 product, which can be used in electric toothbrushes, LEDs, batteries and intelligent audio products.

Hottech this triode product has strong current amplification ability and switching ability. It can bear the maximum collector-base voltage of 60V, the maximum collector-emitter voltage of 40V, the voltage bearing capacity of 6V, the minimum amplification factor of 100 and the maximum amplification factor of 300, and can be used to amplify weak signals. The maximum current at the collector pin of this product is 0.2A, and this transistor cannot be used to connect a load that consumes more than 0.2. This transistor has high frequency response capability and can be used in high frequency switching applications. At the same time, it has the characteristics of low noise, low static power consumption and low dynamic power consumption, and is very energy-saving and environmentally friendly, and is suitable for low-power scenarios such as the Internet of Things.

This MMBT3904 product adopts miniaturized SOT-23 package and surface mount package. It has the characteristics of small size, light weight, easy manufacture and installation, good thermal performance, high reliability and relatively low internal resistance. It is widely used in household electronic products, such as TV sets, audio equipment, intelligent electric toothbrushes and other products, as well as electronic remote control toys, wireless routers, smart light bulbs, LED systems, radios, smart plug, and intelligence.

Take a customer's intelligent electric toothbrush application as an example, which uses SOT-23 encapsulated triode MMBT3904 to amplify the signal in the driving circuit of the toothbrush motherboard.

In digital circuit applications, MMBT3904 is usually used as a switch to control the flow and disconnection of current. In the voltage conversion circuit, MMBT3904 can be used to convert low voltage to high voltage. In the field of temperature control, transistor MMBT3904 can be used in temperature sensor circuit to adjust and control the temperature of equipment. MMBT3904 transistor can also be used to build a constant current source, which is applied in LED driving circuit and battery charging management circuit.