Vout & Short Circuit Output Current: Need Help!

In summary, for the given problem, the open circuit output voltage, Vout, can be calculated using the values of R1, R2, and the manufacturer's specification for the relationship between Vout and the voltage at the ADJ pin. To estimate the short circuit output current, one should refer to the datasheet for the characteristics of the LT1084C regulator and the threshold load current that would trigger the transistor Q1 for overload protection.
  • #1
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Homework Statement


Here is the problem: http://img507.imageshack.us/img507/6488/unled2b.jpg [Broken]

What is the open circuit output voltage, Vout?
Estimate the short circuit output current

Can someone explain to me how to do these.

Homework Equations



Honestly... no idea. I know V=IR and all that but it doesn't seem to help here.

The Attempt at a Solution

 
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  • #2
You'll have to look up the characteristics of the LT1084C regulator to see how it operates. Perhaps download a datasheet.

The transistor Q1 looks like it might be for overload (short circuit?) protection. Its base bias resistors are in the path of the load current (returning back to the bridge rectifier). After some load current threshold it's going to turn on and pull the regulator's Adj pin low, dropping the output voltage. You should probably look into what load current will cause the transistor to turn on and start to pull the output voltage down.
 
  • #3
For OC output voltage Vout, all you need is the values of R1, R2 and the mfr's spec on the relationship between Vout and the voltage at the ADJ pin.

For SC current, I'd look at the spec sheet for that info.
 

1. What is Vout?

Vout refers to the output voltage of a circuit or device. It is the voltage that is produced by the circuit or device and is typically measured in volts (V).

2. How is Vout calculated?

Vout can be calculated using Ohm's Law, which states that Vout = I x R, where Vout is the output voltage, I is the current flowing through the circuit, and R is the resistance of the circuit. Vout can also be calculated using Kirchhoff's Voltage Law, which states that the sum of all voltages in a closed loop must equal zero.

3. What is short circuit output current?

Short circuit output current refers to the maximum amount of current that a device or circuit can supply when a short circuit occurs. This is an important specification to consider when designing circuits, as exceeding the short circuit output current can damage the device or cause other issues.

4. How do I determine the short circuit output current of a circuit?

The short circuit output current can be determined by calculating the maximum current that can flow through the circuit. This can be done by analyzing the components and their specifications, such as the maximum current ratings of resistors and transistors, and the maximum output current of the power supply.

5. What should I do if I need help with Vout and short circuit output current?

If you need help with Vout and short circuit output current, you can consult a knowledgeable colleague or seek assistance from a professional in the field of electronics or circuit design. You can also refer to online resources or textbooks for further information and guidance.

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