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FMMT618 Transistor Data

Key transistor data for the FMMT618 transistor including key electrical parameters, pinout, package type and many other key transistor datasheet details.

The FMMT618 is a popular 20V NPN low saturation switching transistor in an SOT23 package. It has a higher operating voltage than the FMMT617.

The FMMT618 is a PNP silicon planar medium power bipolar junction transistor. It is designed for applications that require a combination of high current capability, fast switching speed, and high current gain in a small surface-mount package.

The device is available from a variety of manufacturers as it has been in production for very many years and in many respects it has become an industry standard device.

Key details and performance parameters for the FMMT618 transistor.

FMMT618 transistor datasheet parameters & data
Parameters	Details
Transistor type	NPN low saturation
Package type	SOT23
V_CBO max (V)	20V
V_CEO max (V)	20V
V_EBOmax (V)	7V
V_CEsat (V)	8mV typ, 15mV max @ I 10 mA & VCE = 2V 70mV typ, 150mV max @ I 1 A & IB = 10mA 130mV typ, 200mV max @ I 3 A & IB = 50mA
I_C max (A)	3A
T_J Max °C	-55 - + 150°C
P_TOT W	625mW for given PCB heatsink area
f_T min (MHz)	100 min, 140 typ for IC = 50mA and VCE = 10V
C_OB	23pF typ, 30pF max
h_fe	200 min, 400 typ for IC = 10mA and VCE = 2V 300 min, 450 typ for IC = 200mA and VCE = 2V 200 min, 340 typ for IC = 2A and VCE = 2V 100 min, 150 typ for IC = 6A and VCE = 2V
Similar / equivalents

Outline & pinout:

Explanation of transistor parameters

Parameter	Explanation
V_CBO Max	Maximum collector-base voltage with emitter open circuit .
V_CEO Max	Maximum collector-emitter voltage with base open circuit.
V_EBO Max	Maximum emitter-base voltage with collector open circuit.
V_CEsat (included where applicable)	The voltage drop across the collector-emitter when the transistor is fully saturated (acting as a closed switch).
I_C Max	Maximum collector current.

Parameter	Explanation
T_J	Maximum junction temperature.
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.
f_T Min	Minimum cutoff frequency at which the current gain in a common emitter circuit falls to unity.
C_OB Max	Maximum collector capacitane, normally measured with emitter open circuit.
h_FE	DC current gain for H_FE at I_C. [Note hfe is the small signal gain and although this may be slightly different, the transistor current gain will vary considerably from ne transistor to the next of the same type.]
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.

These are the main transistor parameters that have been included in our list. There are others, but these help quantify the main elements of the performance of the transistor.

Read more about . . . . Transistor Data-sheet Specifications & Parameters.

Please note, that the data given is the best estimate we can give within a tabulated summary of this nature. Parameters also vary between manufacturers. Electronics Notes cannot accept any responsibility for errors, inaccuracies, etc, although we do endevaour to ensure the data is as accurate as possible.

Notes and supplementary information

• Availability & sources

The FMMT618 is available from a number of stockists and electronic component distributors many of which are given in the table below.

FMMT618 Component Distributor, Stock and Pricing

• Notable features

High Current Capability: Despite its small surface-mount SOT23 package, the device is rated for a continuous collector current IC of 3.5A. This high current density allows it to drive significant loads or act as a power switch in small applications.
Low Saturation Voltage: It features a very low collector-emitter saturation voltage VCE(sat), typically less than 120mV at a high current levels. This characteristic ensures minimal power loss when the transistor is operating in the saturation , i.e. fully ON region, improving switching efficiency.
High Current Gain (hFE): The transistor maintains a high current gain over a wide range of collector currents, making it effective for efficient signal amplification and requiring less base current to drive large loads.
High Power Dissipation: The device can dissipate up to 625mW when mounted on a suitable PCB at an ambient temperature of 25°C, which is high for a SOT23 package, facilitating use in demanding power management tasks.
Fast Switching Speed: It exhibits a high transition frequency, fT, enabling fast switching times. This is essential for use in high-frequency switching converters and pulse width modulation (PWM) applications.

• Typical applications summary

Application Category	Typical Use Case	Device Feature Utilised
High-Efficiency Switching	Load switching in battery-powered devices, power management circuits.	Low VCE(sat) minimizes conduction losses, boosting efficiency.
DC-DC Converters	Switching element in Boost (step-up) and Buck} (step-down) regulator topologies.	Fast switching speed and high continuous current handling.
Motor/Solenoid Drivers	Controlling small DC motors, stepper motors, and various solenoids or relays.	High continuous current capacity in a compact SOT23 package.
Linear Amplification	AF (Audio Frequency) power amplification stages and general-purpose medium-power gain circuits.	High hFE maintained over a wide current range provides stable and efficient gain.