DC835A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
LTC4441, MOSFET DRIVER
LTC4441
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 can be easily modified to
generate different gate drive output voltages by changing the voltage divider of the internal LDO regulator.
Demonstration circuit DC835 is small and allows the
MOSFET driver LTC4441 to be added to an existing design in order to evaluate the performance. The board has
a ground strip along one side that can be directly soldered 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.
The DC835 has a small circuit footprint. It is a high performance and cost effective solution for driving big
MOSFETs in Telecom, Automotive and Industrial applications.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
QUICK START PROCEDURE
Demonstration circuit DC835 is easy to set up to evaluate the performance of the LTC4441. For proper measurement equipment setup refer to Figure 1 and follow
the procedure below:
NOTE: When
measuring the input or output voltage waveforms, 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.
1.
With power off, connect the input power supply to Vin
and GND.
2.
Turn the input power source on and slowly increase
the input voltage. Be careful not to exceed 24V.
Higher input voltage will cause higher power
dissipation in the LTC4441 LDO regulator. If very big
MOSFETs are used and switching frequency is high
NOTE:
the power dissipation may overheat the part. Please
consult the LTC4441 data sheet for details.
3.
Set the Pulse Generator to 300kHz and turn the pulse
output ON.
4.
Check for the proper output voltage of 6V and waveforms 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.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
LTC4441, MOSFET DRIVER
BEWARE OF MOSFET DRIVER DELAYS
MOSFET driver delays, which are on the order of 30ns,
need careful consideration. Some PWM controllers have
built in leading edge blanking that prevents misstriggering of the current comparator due to leading edge
current spikes. If this blanking period is too short it may
not cover the additional delay caused by the MOSFET
driver. The LTC4441 has a built in programmable blank-
ing circuit that may be used to circumvent the shortcomings of other PWM circuit’s leading edge blanking.
Please refer to the LTC4441 data sheet for more details.
Demo Circuit DC835 has an input filter (R6 and C3) that
is used to prevent ringing on the PWM INPUT line from
causing false pulses at the output. This RC filter also
adds to the delay and needs to be taken into account.
The RC filter can be removed if the PWM input line is
laid out correctly and is relatively short.
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
LTC4441, MOSFET DRIVER
Figure 1. Proper Measurement Equipment Setup
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
LTC4441, MOSFET DRIVER
GND
VIN
Figure 2. Measuring Input or Output Waveforms
Figure 3. Input and Output Waveforms with 10nF load capacitor
4
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 835
LTC4441, MOSFET DRIVER
5
Bill Of Material
Demo Circuit 835A
Linear Technology Corporation
LTC4441EMSE
1/18/2006
Item Qty Reference
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
1
1
0
1
1
1
3
1
1
1
5
1
1
1
Part Description
Manufacture / Part #
C1
Cap., X7R 0.1uF 25V 10%
AVX 08053C104KAT2A
C2
Cap., X5R 10uF 10V 10%
TDK C3216X5R1A106K
C3
Cap., X7R 100pF 25V 10%
AVX 06033C101KAT2A
Q1
(Opt)
R1
Res., Chip 10K 0.1W 5%
AAC CR16-103JM
R2
Res., Chip 330K 0.1W 5%
AAC CR16-334JM
R3
Res., Chip 49.9K 0.06W 1% VISHAY CRCW060349.9K1%
R4,R5,R9
Res., Chip 2.2 0.1W 5%
AAC CR10-2R2JM
R6
Res., Chip 10 OHM 0.1W 5% AAC CR16-100JM
R7
Res., Chip 12.4K 0.1W 1%
AAC CR16-1242FM
R8
Res., Chip 84.5K 0.06W 1% Pansonic ERJ3EKF8452V
Mill Max 2309-1
TP1,TP2,TP3,TP4,TP Testpoint, Turret
U1
I.C., MOSFET Driver
Linear Technology Corp. LTC4441EMSE
FAB, PRINTED CIRCUIT BOADEMO CIRCUIT #835A
STENCIL, 20X20
STENCIL 835A, 20X20
Page 1 - of - 1
Bill Of Material
Demo Circuit 835A
Linear Technology Corporation
LTC4441EMSE
1/18/2006
REQUIRED CIRCUIT COMPONENTS:
1
2
3
4
5
6
7
8
1
1
1
1
3
1
1
1
C2
R1
R2
R3
R4,R5,R9
R7
R8
U1
Cap., X5R 10uF 10V 10%
Res., Chip 10K 0.1W 5%
Res., Chip 330K 0.1W 5%
Res., Chip 49.9K 0.06W 1%
Res., Chip 2.2 0.1W 5%
Res., Chip 12.4K 0.1W 1%
Res., Chip 84.5K 0.06W 1%
I.C., MOSFET Driver
TDK C3216X5R1A106K
AAC CR16-103JM
AAC CR16-334JM
VISHAY CRCW060349.9K1%
AAC CR10-2R2JM
AAC CR16-1242FM
Pansonic ERJ3EKF8452V
Linear Technology Corp. LTC4441EMSE
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS:
1
2
1 C3
1 R6
Cap., X7R 100pF 25V 10%
AVX 06033C101KAT2A
Res., Chip 10 OHM 0.1W 5% AAC CR16-100JM
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