DC1280A - Demo Manual

DEMO CIRCUIT 1280
LT3471EDD
QUICK START
GUIDE
LT3471EDD
Dual 1.3A, 1.2MHz Boost/Inverter in 3mmx3mm
DFN
DESCRIPTION
Demonstration circuit 1280A is a dual output converter featuring the LT3471EDD in Boost and Inverter configurations. Both converters are powered
from the same 4.5V to 10V input source. The
Boost converter puts out 12V at 300mA and the
Inverter -12V at 200mA. The demo circuit demonstrates small size and low component count.
The LT3471 operates with inputs as high as 16V
but in this demo board the input is limited by the
magnitude of the Boost output. In a Boost converter the input needs to be less than the output.
The DC1280A is designed so that the Inverting
converter can easily be configured as a Boost. Instructions are included in the schematic.
Both circuits are designed to demonstrate the soft
start feature, advantages of the 1.2MHz switching
frequency and the internal 42V/1.3A switches.
Both outputs on this demo board can be modified
for higher voltages. These circuits are intended for
space-conscious applications such as digital cameras, cellular phones, palmtop computers PC
cards, miniature disk drives, xDSL power supplies,
flash memory products, local 5V or 12V supplies
and LCD displays.
Design files for this circuit board are available.
Call the LTC factory.
L, LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are
registered trademarks of Linear Technology Corporation. Adaptive Power, C-Load,
DirectSense, Easy Drive, FilterCAD, Hot Swap, LinearView, µModule, Micropower
SwitcherCAD, Multimode Dimming, No Latency , No Latency Delta-Sigma, No
RSENSE, Operational Filter, PanelProtect, PowerPath, PowerSOT, SmartStart,
SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT, UltraFast and VLDO are
trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products.
PERFORMANCE SUMMARY FOR BOOST CONVERTER
SYMBOL
VIN
VOUT
PARAMETER
Input Supply Range
Output Voltage Range
RIPPLE
EFFICIENCY
CONDITIONS
VIN = 4.5V, ILOAD = 300mA
VIN = 4.5V, ILOAD = 300mA
VIN = 4.5V, ILOAD = 300mA
Specifications are at TA = 25°C
MIN
4.5
11.64
PERFORMANCE SUMMARY FOR INVERTING REGULATOR
TYP
12
40
84
MAX
10
12.36
UNITS
V
V
mV
%
Specifications are at
TA = 25°C
SYMBOL
VIN
VOUT
RIPPLE
EFFICIENCY
PARAMETER
Input Supply Range
Output Voltage Range
CONDITIONS
VIN = 4.5V, ILOAD = 200mA
VIN = 4.5V, ILOAD = 200mA
VIN = 4.5V, ILOAD = 200mA
MIN
4.5
-11.64
TYP
-12
10
74
MAX
12
-12.36
UNITS
V
V
mV
%
QUICK START PROCEDURE
Demonstration circuit 1280 is easy to set up to
evaluate the performance of the LT3471EDD. Re-
fer to Figure 1 for proper measurement equipment
setup and follow the procedure below:
1
LT3471EDD
NOTE. When 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 ON
JP2 ON
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.
5. Once the proper output voltages are established, adjust the loads within the operating
range and observe the output voltage regulation, ripple voltages, efficiency and other parameters.
2. With power off, connect the input power supply
(4.5V to 10V) to Vin and GND.
3. Turn on the power at the input.
Figure 1. Proper Measurement Equipment Setup for DC1280A
2
LT3471EDD
GND
VIN
Figure 2. Measuring Input or output Ripple
Boost Conv e rte r Efficie ncy
90%
85%
Efficiency (%)
80%
75%
Vin = 4.5V
70%
65%
60%
0
20
40
60
80
100 120 140 160 180 200 220 240 260 280 300
Load Cur re nt (m A)
Figure 3. Boost Converter Efficiency at 4.5Vin
3
LT3471EDD
Inverting Regulator Efficiency
80%
75%
Efficiency (%)
70%
65%
Vin = 4.5V
60%
55%
50%
0
20
40
60
80
100
120
Load Curr e nt (m A)
140
160
Figure 4. Inverting Regulator Efficiency at 4.5Vin
4
180
200
LT3471EDD
5
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