320volt / Zener Power Supply Calculator

Zener Power Supply Calculator


Input voltage Max.: V
Input voltage Min.: V
Output voltage: V
Load current: mA
    Calculated Values:
R1 Resistor Value: Ohm      Watt
D1 Zener Value: Volt       Watt

NOTE: Zener is calculated as the value of using more than 0.1 volts, for example, ultimately resulting to 5v regulated 5v zener 5.1V zener will use the application.


Zener Diode and resistor selection

Choosing a zener diode and resistor:

The zener voltage Vz is the output voltage required
The input voltage Vs must be a few volts greater than Vz
(this is to allow for small fluctuations in Vs due to ripple)
The maximum current Imax is the output current required plus 10%
The zener power Pz is determined by the maximum current: Pz > Vz × Imax
The resistor resistance: R = (Vs – Vz) / Imax
The resistor power rating: P > (Vs – Vz) × Imax

Example: Zener diode regulator output voltage required is 5V, output current required is 60mA.

Vz = 4.7V (nearest value available)
Vs = 8V (it must be a few volts greater than Vz)
Imax = 66mA (output current plus 10%)
Pz > 4.7V × 66mA = 310mW, choose Pz = 400mW
R = (8V – 4.7V) / 66mA = 0.05kohm = 50ohm, choose R = 47ohm

zener reg. info source: http://www.kpsec.freeuk.com/powersup.htm