DC879A - Demo Manual

DEMO CIRCUIT 879
LTC3525-3.3
AND
LTC3525-5
QUICK
START
GUIDE
DESCRIPTION
LTC3525-3.3 and LTC3525-5
Micropower Synchronous Step-Up
Converter with Output Disconnect
Demonstration circuit 879 is a Micropower Synchronous
Step-Up Converter with Output Disconnect featuring the
LTC3525-3.3 and LTC3525-5. The LTC3525 is a high performance Burst Mode operation only, synchronous boost
converter. The LTC3525 incorporates a feature that
maximizes efficiency by adjusting the peak and valley of
the inductor current as a function of load. The demo
board has two assembly versions: DC879A-A and
DC879A-B. The DC879A-A offers fixed 3.3V output. The
DC879A-B offers fixed 5V output. They offer a compact,
high efficiency solution in single cell or dual cell alkaline
or Li-ion applications. Only three small external components are required.
The LTC3525 datasheet gives a complete description of
the part, operation and application information. The datasheet must be read in conjunction with this quick start
guide for demo circuit 879.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT and
PowerPath are trademarks of Linear Technology Corporation.
PERFORMANCE SUMMARY
Specification s are at TA = 25°C
SYMBOL
VIN
VIN
VOUT
PARAMETER
Input Supply Range
Input Supply Range
Output Voltage Range
VOUT
VOUT
Output Voltage Range
Output Voltage Range
VOUT
IQ
IQ
η
η
Output Voltage Range
Quiescent Current at No Load
Quiescent Current at No Load
Efficiency
Efficiency
CONDITIONS
DC879A-A
DC879A-B
1.8V < VIN < 3.2V, ILOAD < 140mA
(DC879A-A)
1V < VIN < 3.2V, ILOAD < 60mA (DC879A-A)
3V < VIN < 4.5V, ILOAD < 175mA (DC879AB)
1V < VIN < 4.5V, ILOAD < 40mA (DC879A-B)
VIN = 2.4V (DC879A-A)
VIN = 3V (DC879A-B)
VIN = 2.4V, ILOAD = 100mA
VIN = 3V, ILOAD = 175mA
MIN
1
1
3.168
TYP
3.3
MAX
3.2
4.5
3.432
UNITS
V
V
V
3.168
4.8
3.3
5
3.432
5.2
V
V
4.8
5
16
21
83
86
5.2
V
µA
µA
%
%
QUICK START PROCEDURE
Demonstration circuit 879 is easy to set up to evaluate
the performance of the LTC3525-3.3 and LTC3525-5.
Refer to Figure 1 for proper measurement equipment
setup and follow the procedure below:
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. Verify the jumper in the following position:
JP1
ON
1
LTC3525-3.3 AND LTC3525-5
2. With power off, connect the input power supply to Vin
and GND.
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, ad-
3. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed 6V.
4. Check for the proper output voltages. VOUT = 3.3V for
just the loads within the operating range and observe
the output voltage regulation, ripple voltage, efficiency
and other parameters.
DC879A-A and VOUT = 5V for DC879A-B.
Figure 1. Proper Measurement Equipment Setup
GND
VIN
Figure 2. Measuring Input or Output Ripple
2
LTC3525-3.3 AND LTC3525-5
3
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