QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 559
SYNCHRONOUS BOOST CONVERTER WITH OUTPUT DISCONNECT
LTC3429
DESCRIPTION
Demonstration circuit 559 is a high efficiency synchro-
nous boost DC/DC converter with output disconnect,
inrush current limiting and soft-start functions featuring
the LTC3429. The board is capable of supplying 90mA
from a single AA cell input or 250mA from a 2-cell input
with a 3.3V output. The input range is from 1V to 3.3V.
DC559 version A uses the LTC3429; version B uses the
LTC3429B. The LTC3429 shifts automatically to power
saving Burst Mode operation at light loads; whereas the
LTC3429B operates at a fixed frequency for all loads with
minimum output voltage ripple.
A switching frequency of 500KHz allows up to 95% effi-
ciency with a tiny solution footprint. Typical applications
include MP3 players, GPS receivers, digital cameras,
PDAs, LCD bias supplies and wireless handsets.
Design files for this circuit board are available. Call
the LTC factory.
Table 1. Performance Summary
PARAMETER
Maximum Load Current, Min
Maximum Load Current, Min
Switching Frequency, Typ
Efficiency, Typ
Output Ripple, Typ
Vout = 3.3V, Vin = 2.8V, Iout = 100mA
Vout = 3.3V, V
IN
= 1.5V, I
OUT
= 100mA (20MHz BW)
CONDITION
Vout = 3.3V, Vin = 1.0V
Vout = 3.3V, Vin = 2.0V
VALUE
90mA
250mA
500KHz
95%
20mV
P–P
QUICK START PROCEDURE
Demonstration circuit 559 is easy to set up to evaluate
the performance of the LTC3429. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
measuring the input or output voltage rip-
ple, 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.
NOTE:
When
1.
Place the jumper in the following position:
JP1
On
With power off, connect the input power supply to Vin
and GND. Connect the load to Vout and GND. Set ini-
tial load = 0A (no load).
Turn on the power at the input.
NOTE:
Make
2.
3.
sure that the input voltage does not ex-
ceed 4.4V.
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 559
SYNCHRONOUS BOOST CONVERTER WITH OUTPUT DISCONNECT
NOTE:
If
4.
5.
Check for the output voltage. Vout should be
3.3V±0.1V.
Once the proper output voltage is established, adjust
the load within the operating range and observe the
output voltage regulation, ripple voltage, efficiency
and other parameters.
there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
The available output current depends on the input
voltage.
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
VIN
GND
2
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