QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 849
750MA, 1.2MHZ SYNCHRONOUS BOOST CONVERTER
LTC3499EDD
DESCRIPTION
Demonstration circuit 849 is a 750mA, 1.2MHz Syn-
chronous Boost Converter with Reverse Battery Pro-
tection featuring the LTC®3499EDD. The demo board
demonstrates a DC/DC boost converter, with a
750mA switch current limit, providing a 3.3V output
at 250mA from a two cell input voltage, or a 5V out-
put at 170mA from either a two cell or a Li-ion bat-
tery.
The LTC3499EDD offers integrated reverse bat-
tery protection up to -6V for both the part and the
load, drawing typically less than 1uA of current.
The input voltage of this supply can also be increased
higher than the output, but thermal limitations reduce
the output current that can be delivered. See
Vin>Vout Operation
section on the datasheet. The
Table 1. Performance Summary (T
A
= 25°C) 3.3V Output
PARAMETERS
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT
Output Voltage V
OUT
Typical Output Ripple V
OUT
Typical efficiency
V
IN
= 1.8V, I
OUT
=0mA to 250mA
V
IN
= 3.0V, I
OUT
=0mA to 500mA
V
IN
= 1.8V, I
OUT
= 250mA
V
IN
=2.4V , I
OUT
= 160mA
CONDITION
VALUE
1.8V
3V
3.3V ±3%
3.3V ±3%
20mV
P–P
90%
circuit also demonstrates the advantages of output
disconnect and inrush current limiting. Small circuit
size and low component count make the
LTC3499EDD suitable for use in many space-
conscious applications such as Medical Equipment,
Digital Cameras, MP3 Players, and other Portable De-
vices. Other integrated features include peak current
limit, soft-start, antiringing control and thermal shut-
down.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
Table 2. Performance Summary (T
A
= 25°C) 5V Output
PARAMETERS
Minimum Input Voltage
Maximum Input Voltage
Output Voltage V
OUT
Output Voltage V
OUT
Output Voltage V
OUT
Typical Output Ripple V
OUT
Typical efficiency
V
IN
= 1.8V, I
OUT
=0mA to 170mA
V
IN
= 2.7V, I
OUT
=0mA to 270mA
V
IN
= 4.2V, I
OUT
=0mA to 480mA
V
IN
= 2.7V, I
OUT
= 270mA
V
IN
=2.7V , I
OUT
= 160mA
CONDITION
VALUE
1.8V
4.2V
5V ±3%
5V ±3%
5V ±3%
22mV
P–P
88%
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 849
750MA, 1.2MHZ SYNCHRONOUS BOOST CONVERTER
QUICK START PROCEDURE
Demonstration circuit 849 is easy to set up to evalu-
ate the performance of the LTC3499EDD. 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 out-
put 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.
NOTE:
When
2.
3.
4.
With power off, connect the input power supply to
VIN and GND.
Turn on the power at the input.
Check for the proper output voltages.
there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
NOTE:
Once
NOTE:
If
Place jumpers in the following positions:
JP1 Run.
JP2 3.3V or 5V (depending on output desired)
the proper output voltages are estab-
lished, 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
2
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