1N4954 Diode Derating Curves

1N4954 Diode Temperature-Current Derating Curve [Axial Lead]
Zener Voltage Regulator Diode.

1N4954 Diode Derating Curve

Use the Graph to determine how much to derate power [wattage] based on ambient operational temperature [leaded devices]. Diode Derating Curves

The above chart details the maximum allowable power dissipation [Watts] at increasing ambient temperature. Maximum operational power dissipation is achievable up to 25⁰C. However above 25⁰C the maximum package dissipation, or current, must be reduce to insure that the devices junction temperature remains constant. The higher the ambient temperature is increased the lower the allowable power dissipation, as depicted in the curves.

Decreasing a devices operational limits as temperature is increased is called derating, in this case derating a 1N4954 operational power dissipation vs increasing ambient temperature [surrounding]. This particular graph depicts the derating of a 1N4954 Zener Diode in a through-hole package.

Refer to MIL-PRF-19500/356K; Semiconductor Device, Diode, Silicon, Voltage, Regulator, Types 1N4954 through 1N4996, 1N5968, 1N5969, and 1N6632 through 1N6637, 1N4954US through 1N4996US, 1N5968US, 1N5969US, and 1N6632US through 1N6637US, and C and D Tolerance suffix Devices, JAN, JANTX, JANTXV, JANS, JANHC, and JANKC, [Axial Leaded]

1N4954 Maximum Ratings:
Maximum Repetitive Reverse Voltage = xx volts
Average Rectified Forward Current = xx mA
Power Dissipation 25⁰C = 5Watts
Operating Temperature = -65⁰C to +175⁰C

This Zener Voltage Regulator series is military qualified to MIL-PRF-19500/356 for high-reliability applications. The case is hermetically sealed voidless hard glass with tungsten slugs with Axial-Lead terminations. For surface mount packages use 1N4954US.
The polarity of all types shall be indicated with a contrasting color band to denote the cathode end.
Refer to MIL-PRF-19500; Semiconductor Devices, General Specification for.
Screening to JANS, JANTX, and JANTXV shall be in accordance with MIL-PRF-19500.

Definition of Terms
Ambient temperature: Ambient temperature is the air temperature measured below a semiconductor device, in an environment of substantially uniform temperature, cooled only by natural air convection, and not materially affected by reflective and radiant surfaces.
Storage temperature: Storage temperature is a temperature at which the device may be stored without any power being applied.
Thermal resistance: Thermal resistance is the temperature rise, per unit power dissipation, of a junction above the temperature of a stated external reference point under conditions of thermal equilibrium.