Transistor Circuits XIV - Electronics – Online Distance ...· First example •If the zener diode
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Transcript of Transistor Circuits XIV - Electronics – Online Distance ...· First example •If the zener diode
Topic 26 The Zener Diode as a Voltage Regulator (Part II)
Equations for circuit analysis
+ ( 2)
= ( 3)
= ( 5)
If the zener diode is disconnected from the source, what is the load voltage?
First example work
Calculate all three currents.
Second example work
= = 15V
= = 19.149mA 10mA =9.149mA
Assuming a tolerance of 5 percent in both resistors, what is the maximum zener current?
To maximize the current, we need to find the lower tolerance for RS and the upper tolerance for RL.
Third example work
5% = 446.5
+ 5% = 1.575k
= = 20.157mA 9.524mA =10.633mA
Suppose the supply voltage can vary from 24 to 40 V. What is the maximum zener current?
Calculate the values at the maximum supply voltage.
Fourth example work
= = 15V
= = 53.191mA 10mA =43.191mA
The zener diode is replaced with a 1N963B diode. What are the load voltage and the zener current?
Data Sheet information
Fifth example work
= = 12V
= = 25.532mA 8mA =17.532mA
Process for solving
Analyzing a Loaded Zener Regulator
Step 1 Calculate the series current (Eq. 1) Apply Ohms Law to RS
Step 2 Calculate the load voltage (Eq. 3) Load voltage equals diode voltage
Step 3 Calculate the load current (Eq. 4) Apply Ohms Law to RL
Step 4 Calculate the zener current (Eq. 5) Apply the current law to the diode
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