QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 518
SLIC POSITIVE INPUT TO NEGATIVE OUTPUT DC/DC CONVERTER
4
MONITORING MOSFET CURRENT
1. To monitor the MOSFET current through
resistor RS1, connect a 50
Ω
coaxial cable
across RS1 with the shield connected to the
ground connection of RS1.
2. Connect the center conductor of the coaxial
cable to the RS1 terminal that is connected
to the source of MOSFET Q1. Use a 50
Ω
surface mount resistor in series with the
center conductor.
3. Set the scope input to 50
Ω
and connect the
coaxial cable to the scope.
4. Set the scope to 5mV/division or less. The
current scale with 15m
Ω
for RS1 and
5mV/div will be .66A/div (50
Ω
resistor at the
input of coaxial cable forms a 2:1 divider
with the 50
Ω
input impedance of scope).
