1N5819 Forward Drop Sweep

Application

This circuit shows the 1N5819 used as a current-limited forward rectifier path. It is useful when comparing Schottky forward drop against silicon rectifiers or estimating conduction loss in low-voltage supplies.

Design Context

VIN is swept from 0 V to 5 V through R1 into the diode anode, while the cathode returns to ground. R1 limits current so the chart focuses on the diode's forward voltage and current curve instead of creating an uncontrolled short at higher source voltages.

Expected Behavior

At low source voltage, forward current stays near zero. Once the diode begins conducting, Vf rises modestly while If increases through the 1 kOhm resistor. The Schottky model should show a lower forward voltage than a typical silicon rectifier at the same current.

Key Values

• DC sweep: VIN from 0 V to 5 V in 0.05 V steps.
• R1: 1 kOhm current limiter.
• Vf: diode forward voltage at the anode relative to ground.
• If: forward current through the diode branch.

Suggested Experiments

• Change R1 to 330 ohm or 2.2 kOhm and compare the forward-current curve.
• Narrow the sweep around 0 V to 1 V to inspect the Schottky turn-on region.
• Replace the diode with a silicon rectifier model and compare forward voltage at the same current.

Featured Component

The 1N5819 is a Schottky rectifier diode. In this circuit it is forward biased through a current-limiting resistor so the chart highlights its low forward drop and current rise.