# 1N4954 Diode Derating Curves

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

1N4954 Zener 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. Take note that the chart does call out a specific lead length.

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-19500/356; 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 [many devices covered]
Average Rectified Forward Current = xx mA [many devices covered]
Power Dissipation 250C = 5 Watts
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 void-less 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.

Note that this particular specification sheet calls out an axial leaded package, but the package is not given a JEDEC designation [DO-number]. In fact commercial data sheets do not call out a JEDEC number. However the body length is provided as varying between 0.13 to 0.3 inches. The measurement LU is just the portion of the terminal that is un-controlled [0.50 inches]. The lead length may be as long as 1.30 inches; however, recall that the power chart calls out a particular length.

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. There is no storage temperature offered in this particular specification sheet.
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.

### Surface Mount 1N4954 Zener Diode

1N4954US Zener Diode Temperature-Current Derating Curve [Surface Mount]
Zener Voltage Regulator Diode.

1N4954US Surface Mount Diode Derating Curve

Use the Graph to determine how much to derate power [wattage] based on the temperature of the 1N4954 End Cap. Diode Derating Curves

The above chart details the maximum allowable power dissipation [Watts] at increasing end-cap temperature. The end-cap is the metal surfaces at either end of the component, and are used to solder the device to the printed circuit board. 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.

Nominal Zener Voltage [Vz] = 3.3V to 390V [490 volts max], these number are for the entire series, not one particular device.

1N4954US Maximum Ratings:
Maximum Repetitive Reverse Voltage = xx volts
Average Rectified Forward Current = xx mA
Power Dissipation 250C = 5 Watts
Operating Temperature = -650C to +1750C

Related Zener Diodes
1N5968 Curves

Diode Definitions
Diode Terms
Zener Diode Terms

Covered Diodes
1N4954, 1N4955, 1N4956, 1N4957, 1N4958, 1N4959
1N4960, 1N4961, 1N4962, 1N4963, 1N4964
1N4965, 1N4966, 1N4967, 1N4968, 1N4969
1N4970, 1N4971, 1N4972, 1N4973, 1N4974
1N4975, 1N4976, 1N4977, 1N4978, 1N4979
1N4980, 1N4981, 1N4982, 1N4983, 1N4984
1N4985, 1N4986, 1N4987, 1N4988, 1N4989
1N4990, 1N4991, 1N4992, 1N4993, 1N4994
1N4995, 1N4996
1N6632, 1N6633, 1N6634, 1N6635, 1N6636, 1N6637

1N4954 SMD Package

Engineering topic:
Qualified Military Diode and reliability,
for the Axial leaded part shown.

Modified 1/21/12