DC1450A - Demo Manual

DEMO CIRCUIT 1450A
QUICK START GUIDE
LTC3854EDDB
SMALL FOOTPRINT BUCK CONVERTER
DESCRIPTION
Demonstration circuit 1450A is a small foot print,
high efficiency synchronous buck converter with
4.5V to 26V input range. It can supply 5A maximum
load current at 2.5V output. The demo board features
the LTC®3854EDDB controller. The controller features a 400kHz constant frequency current mode
architecture. With a wide input range and output
range, the LTC3854 is ideal for automotive, telecom,
industrial and distributed DC power systems. This
board has a compact solution size with dual So-8
MOSFETs, small inductor and capacitor footprints.
The package of LTC3854EDDB is a small, low thermal impedance, 12-Lead (3mm x 2mm) plastic DFN.
Table 1.
The RUN/SS pin (JP1) provides both soft-start and
enable features. To shut down the converter, one
simple way is to force the RUN pin below 0.4V (JP1:
OFF).
Design files for this circuit board are available. Call
the LTC factory.
Performance Summary (TA = 25°C)
PARAMETER
CONDITION
Input Voltage Range
VALUE
4.5V to 26V
Output Voltage, VOUT
VIN = 4.5-26V, IOUT = 0A to 5A
2.5V ±2%
Maximum Output Current, IOUT
VIN = 4.5-26V, VOUT = 2.5V
5A
Typical Efficiency
VIN = 15V, VOUT = 2.5V, IOUT = 5A
89.5%
Typical Switching Frequency
400kHz
1
LTC3854EDDB
QUICK START PROCEDURE
Demonstration circuit 1450A is easy to set up to
evaluate the performance of the LTC3854EDDB. Refer
to Figure 1 for the proper measurement equipment
setup and follow the procedure below:
1. With power off, connect the input power supply to Vin (4.5V-26V) and GND (input return).
2. Connect the 2.5V output load between Vout
and GND (Initial load: no load).
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for
the proper output voltages. Vout should be
2.5V+/-2%.
5. Once the proper output voltages are established, adjust the loads within the operating
range and observe the output voltage regulation, ripple voltage and other parameters.
Note: When measuring the output or input voltage
ripple, do not use the long ground lead on the oscilloscope probe. See Figure 2 for the proper scope probe
technique. Short, stiff leads need to be soldered to the
(+) and (-) terminals of an output capacitor. The
probe’s ground ring needs to touch the (-) lead and
the probe tip needs to touch the (+) lead.
2
LTC3854EDDB
Figure 1. Proper Measurement Equipment Setup
+
COUT
VOUT
-
GND
Figure 2. Measuring Output Voltage Ripple
3
LTC3854EDDB
Figure 3. Efficiency vs load current
4
LTC3854EDDB
5
Similar pages