QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1242A
600MA SYNCHRONOUS BOOST DC/DC CONVERTER AND 100MA LDO REGULATOR
1
LTC3537
DESCRIPTION
Demonstration circuit 1242A includes a high ef-
ficiency synchronous boost converter, a low
dropout linear regulator and a low battery de-
tector. With a light load, the boost converter can
startup with an input voltage as low as 680mV
and once started, the input can go as low as
500mV while maintaining a regulated output
voltage. With a 50mA load, the linear regulator
features a dropout voltage of less than 100mV.
Separate input terminals are provided for the
boost and linear regulator, and a jumper that
allows the linear regulator to be powered from
any one of three different sources.
Terminals and jumpers for shutting down or se-
quencing each regulators output separately and
individual Power-Good outputs are included.
Jumpers are also provided for selecting a total
of six output voltages, three low battery volt-
ages and a jumper to select BURST or PWM
operation. The 3X3 mm QFN thermally en-
hanced package with a 2.2MHz switching fre-
quency combined with the LDO regulator pro-
vide a very tiny multi output solution. The
LTC3537 boost converter also features output
disconnect and the input voltage can be greater
or less than the output voltage.
This demonstration circuit allows the user to
quickly evaluate the LTC3537 performance.
Jumpers make selecting different output volt-
ages and low battery thresholds simple while
terminals on the board allow easy hookup to
input supplies and output loads.
Design files for this circuit board are available.
Call the LTC factory.
LTC and Burst Mode are trademarks of Linear Technol-
ogy Corporation
Table 1. Typical Specifications (25°C)
Conditions
Limits
Input Voltage Range V
IN
0.68V to 5.5V
Boost 1.8V V
OUT
V
IN
= 1V, I
OUT
= 100mA
1.8V ± 3.5%
Boost 3.3V V
OUT
V
IN
= 1.5V, I
OUT
= 200mA
3.3V ± 3.5%
Boost 5V V
OUT
V
IN
= 1.5V, I
OUT
= 200mA
5.0V ± 3.5%
Output Ripple Voltage (burst mode)
V
IN
= 1.5V, V
OUT
= 3.3V I
OUT
= 15mA
30mV p-p
Output Ripple Voltage (fixed frequency)
V
IN
= 1.5V, V
OUT
= 3.3V I
OUT
= 200mA 10mV p-p
Boost Efficiency
V
IN
= 1.8V, V
OUT
= 3.3V I
OUT
= 100mA 88%
LDO Regulator 1.5V V
OUT
V
IN
= 5V, I
OUT
= 50mA
1.5V ± 2.5%
LDO Regulator 3.0V V
OUT
V
IN
= 5V, I
OUT
= 50mA
3.0V ± 2.5%
LDO Regulator 3.3V V
OUT
V
IN
= 5V, I
OUT
= 50mA
3.3V ± 2.5%
LDO Regulator Drop Out Voltage
V
OUT
= 3.3V, I
OUT
= 50mA,
V
OUT
drops 10%
100mV
Low Battery Threshold Voltage (dropping) 0.8V
800mV ± 5%
Low Battery Threshold Voltage (dropping) 1.7V
1.7V ± 5%
Low Battery Threshold Voltage (dropping) 3.0V
3V ± 5%
