DC856A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 856A
500MA, 1.25MHZ SYNCHRONOUS BOOST CONVERTER
LTC3427EDC
DESCRIPTION
Demonstration circuit 856A is a 500mA, 1.25MHz
Synchronous Boost Converter featuring the
LTC®3427EDC. The demo circuit demonstrates a
DC/DC boost converter, with a 500mA switch current
limit, providing 3.3V at 180mA from a 1.8V to 3.6V
input voltage. The input voltage of this supply can go
higher than the output, but thermal limitations reduce
the output current that can be delivered. See
Vin>Vout Operation section on the datasheet. The
circuit demonstrates the advantages of output disconnect and inrush current limiting. Small circuit size
and low component count make the LTC3427 suitable
for use in many space-conscious applications such as
Hand-Held Instruments, Cordless Phones, Wireless
Handsets, GPS Receivers, MP3 players and other
Portable Devices. Other integrated features include
externally programmable burst mode threshold, internal compensation, peak current limit, soft-start,
antiringing control and thermal shutdown. For customers who do not need the output disconnect feature of the LTC3427, an efficiency gain of about 3%
can be achieved by adding a small Schottky diode
between the SW and Vout pins.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a registered trademark of Linear Technology Corporation
Table 1. Performance Summary (TA = 25°C)
PARAMETERS
CONDITION
VALUE
Minimum Input Voltage
1.8V
Maximum Input Voltage
3.6V
Output Voltage VOUT
VIN = 1.8V, IOUT =0mA to 180mA
3.3V ±3%
Output Voltage VOUT
VIN = 3.0V, IOUT =0mA to 180mA
3.3V ±3%
Typical Output Ripple VOUT
VIN = 1.8V, IOUT = 180mA
20mVP–P
Typical efficiency
VIN =3V , IOUT = 180mA
90%
Typical efficiency
VIN =2V , IOUT = 180mA
85%
QUICK START PROCEDURE
Demonstration circuit 856A is easy to set up to evaluate the performance of the LTC3427EDC. Refer to
Figure 1 for proper measurement equipment setup
and follow the procedure below:
measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
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.
1.
Place jumpers in the following positions:
JP1 Run.
NOTE: When
2.
With power off, connect the input power supply to
Vin and Gnd.
3.
Turn on the power at the input.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 856A
500MA, 1.25MHZ SYNCHRONOUS BOOST CONVERTER
NOTE: Make
sure that the input voltage does not ex-
ceed 3.6V.
4.
Check for the proper output voltages.
NOTE: If
there is no output, temporarily disconnect
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.
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 856A
500MA, 1.25MHZ SYNCHRONOUS BOOST CONVERTER
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