2N6546 Transistor Derating Guidelines

2N6546 Temperature-Power Derating Curve
NPN Medium Power Transistor. Package, TO-3, TO-254 [TO-257].
2N6546 Applications; Suited for 115 and 220 volt line operated
Switching regulators, PWM inverters, Motor controls, Solenoid, relay drivers, Deflection circuits

2N6546 Temperature-Power Derating Curve
2N6546 Temperature Derating Curve

The chart indicates the maximum power dissipation of a 2N6546 with increasing case temperature. Maximum operational power dissipation is achievable at 25C. However above 25C the maximum package dissipation, or power, must be reduce to insure that the devices junction temperature remains constant. The higher the ambient temperature [Case Temperature] is increased the lower the allowable power dissipation, as depicted in the 2N6546 curves.
Some of these derating chart provide DC operation by case temperature, while others may show ambient temperature, but the ultimate goal is to keep junction temperature below its maximum limit.

Derating is the method of decreasing a devices operational limits as temperature is increased, in this case derating a 2N6546's operational power dissipation vs increasing ambient [surrounding] temperature. This particular graph depicts the derating of a 2N6546 transistor in a TO-3 package or TO-254 package.
How to read the temperature curves; Interpreting Deraring charts.
All other Transistor Derating Curves with definitions.
Temperature derating is a common engineering practice during circuit design. Temperature rise needs to be accounted for by near-by components which would cause the ambient air temperature to increase even if the final product operates at room temperature.

Refer to MIL-PRF-19500/525; Semiconductor Device, NPN Transistor Power, Types 2N6546, 2N6546T1, 2N6546T3, 2N6547, 2N6547T1, & 2N6547T3 BJTs
Possible transistor packages include the TO-3, TO-254, and TO-257 packages.

2N6546 Maximum Operation Ratings:
Collector Emitter Voltage = 300 volts dc
Emitter Base Voltage = 8.0 volts dc
Power Dissipation 250C = 175 Watts
Operating Temperature = -65 to +2000C
Storage Temperature = -65 to +2000C

TO-3 metal Package
TO-3 Package Outline

Pinout note;
Terminal 1; Emitter
Terminal 2; Base
Case; Collector.

NPN BJT Derating Guidelines
Derating Components Guidelines

Related Components;
Transistor Manufacturers, BJT vendors

Manufacturing Hint;
Bolt down the TO-3 body
to aid in heat transfer and conduction.

Layout Hint;
Use larger copper pads in the PWB
to conduct heat away from the 2N6546

Design Hint;
Use the lowest curve in the derating chart
Maximum life, lowest failure rate

Max Current Ratings
Ib = 10 Amps DC.
Ic = 15 Amps DC.

PC motherboard

Distributor rolodex Electronic Components Electronic Equipment EDA CDROM Software Engineering Standards, BOB card Cabled Computer Bus Electronic Engineering Design Table Conversion DB9-to-DB25.
DistributorsComponents Equipment Software Standards Buses Design Reference
Modified 1/21/12
Copyright © 1998 - 2016 All rights reserved Larry Davis