DC647A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647
1.2MHZ, SOT-23 DC/DC CONVERTER
LT3467
DESCRIPTION
Demonstration circuit 647 is a 1.2MHZ, SOT-23
DC/DC Converter featuring the LT®3467. The demo
board demonstrates two separate DC/DC converters
for different application needs. The Boost Circuit is
designed to convert a 5V input to 12V output at
300mA maximum load. The SEPIC Circuit generates
a constant 12V/300mA output with 10V~16V variable
input. Both circuits are designed to demonstrate the
soft start feature, advantages of the 1.2MHz switching
frequency, the internal 42V/1.1A switch, wide input
voltage range and small circuit size. These circuits
are intended for space-conscious applications such
Table 1.
as digital cameras, cellular phones, palmtop
computers and LCD displays. The 1.2MHz switching
frequency, 1.1A integrated switch, small circuit size,
and low component count makes the LT3467 suitable
for use in many other applications, such as PC cards,
miniature disk drives, xDSL power supplies, flash
memory products and local 5V or 12V supplies.
Design files for this circuit board are available.
Call the LTC factory.
LT is a registered trademark of Linear Technology Corporation
Performance Summary (TA = 25°C)
PARAMETERS FOR BOOST CONVERTER
CONDITION
VALUE
Input Voltage
Output Voltage VOUT
5V
VIN = 5V, IOUT = 0A to 300mA
Maximum Output Current
12V ±2%
300mA
Typical Output Ripple VOUT
VIN = 5, IOUT = 300mA
55mVP–P
Typical efficiency
VIN = 5, IOUT = 300mA
86%
PARAMETERS FOR SEPIC CONVERTER
CONDITION
VALUE
Minimum Input Voltage
10V
Maximum Input Voltage
16V
Output Voltage VOUT
VIN = 10V to 16V, IOUT = 0A to 300mA
Maximum Output Current
12V ±2%
300mA
Typical Output Ripple VOUT
VIN = 10V, IOUT = 300mA
50mVP–P
Typical efficiency
VIN = 10V to 16V, IOUT = 300mA
80%
QUICK START PROCEDURE
Demonstration circuit 647 is easy to set up to
evaluate the performance of the LT3467. Refer to
Figure 1 for proper measurement equipment setup
and follow the procedure below:
on the oscilloscope probe. Measure the input or
output voltage ripple by touching the probe tip
directly across the VIN or VOUT and GND terminals.
See Figure 2 for proper scope probe technique.
NOTE: When measuring the input or output voltage
NOTE: Steps 1-4 are for Boost Converter only.
ripple, care must be taken to avoid a long ground lead
1. Place jumper in the following positions:
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647
1.2MHZ, SOT-23 DC/DC CONVERTER
On
JP1
2. With power off, connect the input power supply to
VIN and GND.
3. Turn on the power at the input.
JP2
On
6. With power off, connect the input power supply to
VIN and GND.
7. Turn on the power at the input.
NOTE: Make sure that the input voltage does not
NOTE: Make sure that the input voltage is set
exceed 5V.
between 10V and 16V.
4. Check for the proper output voltages.
8. Check for the proper output voltages.
NOTE: If there is no output, temporarily disconnect
NOTE: If there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
the load to make sure that the load is not set too
high.
NOTE: Once
the proper output voltages are
established, adjust the loads within the operating
range and observe the output voltage regulation,
ripple voltage, efficiency and other parameters
directly across the VIN or VOUT and GND terminals.
See Figure 2 for proper scope probe technique.
9. Once the proper output voltages are established,
adjust the loads within the operating range and
observe the output voltage regulation, ripple
voltage, efficiency and other parameters.
NOTE: Steps 5-9 are for Sepic converter only.
5. Place jumper in the following positions:
Figure 1. Proper Measurement Equipment setup
Figure 2. Measurement Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647
1.2MHZ, SOT-23 DC/DC CONVERTER
3
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