DC877A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 877
BUCK-BOOST REGULATOR
LTC3531
DESCRIPTION
Demonstration circuit 877 is a high efficiency
synchronous Buck-Boost converter using the
LTC3531-3.3. The input range is from 1.8V to 5.5V
making it ideal for single-cell Lithium-Ion, multicell
alkaline or nickel battery applications. This converter
can provide 200mA when the input voltage is above
2.9V.
The DC877 features the LTC3531-3.3 in a tiny 6-pin
ThinSOT package. The converter operates in Burst
Mode, which provides conversion efficiency over a
wide range of load currents. It has minimum
component count and tiny solution size. Other
features include current limiting, thermal shutdown
and output disconnect. In shutdown, the IC itself
draws less than 1uA. The DC877A is ideal for battery
powered, handheld applications such as MP3 players,
handheld computers and PDAs.
Design files for this circuit board are available. Call
the LTC factory.
LTC and ThinSOT are registered trademarks of Linear Technology Corporation
Table 1. Performance Summary ( TA = 25oC )
PARAMETER FOR LED DRIVER
CONDITION
VALUE
Minimum input voltage
1.8V
Maximum input voltage
5.5V
Output voltage VOUT
3.3V +/- 4%
Maximum output current
VIN=1.8V
90mA
Maximum output current
VIN=2.5V
150mA
Maximum output current
VIN=2.9V
200mA
QUICK START PROCEDURE
DC877 is easy to set up for evaluating the
performance of the LTC3531. See Figure 1 for proper
measurement equipment setup and follow the test
procedure outlined below.
1. Place JP1 in the RUN position.
2. Connect a bench supply to the VIN and GND
terminals.
3. Turn on the input power supply and make
sure that the input voltage does not exceed
5.5V.
4. Check for the proper output voltage. If there is
no output, temporarily disconnect the load to
make sure that the load is not set too high.
5. Once the proper output voltage is established,
adjust the load within the operating range and
observe the output voltage regulation, ripple
voltage, efficiency and other parameters. See
Figure 2 for proper scope probe placement for
measuring
input
or
output
ripple.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 877
BUCK-BOOST REGULATOR
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A
+
+
V
_
V
+
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+
A_
+
Load
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Figure 1. Proper Measurement Equipment Setup
Figure 2. Scope Probe Placement for Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 877
BUCK-BOOST REGULATOR
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