Linear Technology DC835 Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
DESCRIPTION
Demonstration circuit DC835 is a MOSFET driver circuit
that is designed to facilitate adding a MOSFET driver to
an existing design.
Demonstration circuit DC835 is small and allows the
MOSFET driver LTC4441 to be added to an existing de-
sign in order to evaluate the performance. The board has
a ground strip along one side that can be directly sol-
dered to source pins of an SO-8 or similar MOSFET. This
assures the MOSFET driver will be most effective due to
low connection inductance between it's output and
MOSFET gate pin.
QUICK START PROCEDURE
Demonstration circuit DC835 is easy to set up to evalu-
ate the performance of the LTC4441. For proper meas-
urement equipment setup refer to Figure 1 and follow
the procedure below:
When measuring the input or output voltage wave-
NOTE:
forms, care must be taken to minimize the length of the
oscilloscope probe ground lead. Measure the input or
output voltage waveforms by connecting the probe tip
directly across the PWM INPUT or G1 output and GND
terminals as shown in Figure 2.
With power off, connect the input power supply to Vin
1.
and GND.
Turn the input power source on and slowly increase
2.
the input voltage. Be careful not to exceed 24V.
Higher input voltage will cause higher power
NOTE:
dissipation in the LTC4441 LDO regulator. If very big
MOSFETs are used and switching frequency is high
LTC4441, MOSFET DRIVER
Demonstration circuit DC835 can be easily modified to
generate different gate drive output voltages by chang-
ing the voltage divider of the internal LDO regulator.
The DC835 has a small circuit footprint. It is a high per-
formance and cost effective solution for driving big
MOSFETs in Telecom, Automotive and Industrial applica-
tions.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
the power dissipation may overheat the part. Please
consult the LTC4441 data sheet for details.
Set the Pulse Generator to 300kHz and turn the pulse
3.
output ON.
Check for the proper output voltage of 6V and wave-
4.
forms as shown in Figure 3.
PROGRAMMING GATE OUTPUT VOLTAGE
Changing resistor R8 can program the output voltage at
the OUT pin of the LTC4441. Do not change the value of
resistor R2. The 330kohm value is required for stability
of the internal LDO regulator. For more information,
please refer to the LTC4441 data sheet.
LTC4441
1