QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 883
LI-ION TO 25V STEP-UP DC-DC CONVERTER
1
LT3473EDD
DESCRIPTION
Demonstration circuit DC883 features the LT
®
3473
micropower step-up DC/DC converters with inte-
grated Schottky diode and output disconnect cir-
cuitry. The output on DC883 is 25V at up to 80mA
from a 3~4.2V input, while automatic Burst Mode op-
eration maintains efficiency at light load. The lithium
ion battery input voltage range, high output voltage,
internal NPN power switch, minimal external compo-
nents and simple design make the LT3473 an excel-
lent solution for OLED and CCD Bias.
The DC883 has a jumper for enabling the output
(JP2). Placing the jumper to “OFF”, disables the DC-
DC converter and jumper to “ON”, enables the DC-DC
converter. There is a jumper (JP1) and a control pin
(CTRL) for varying the output voltage. Placing the
jumper to “VIN” provides 25V output. Placing the
jumper to “CTRL” and changing the voltage at CTRL
pin can change the output voltage. The voltage of the
PGOOD pin is approximately 0V as the output voltage
reaches 90% of final value.
Design files for this circuit board are available. Call
the LTC factory.
LT is a registered trademark of Linear Technology Corporation
Table 1.
Performance Summary ( TA = 25
°°°°
C )
PARAMETER
CONDITION
VALUE
Minimum Input Voltage
3V
Maximum Input Voltage
4.2V
Maximum Output Current
Vin = 3 − 4.2V
80mA
Typical Switching Frequency
1.2MHz
QUICK START PROCEDURE
Demonstration circuit 883 is easy to set up to evalu-
ate the performance of the LT3473. Refer to Figure 1.
for proper measurement equipment setup and follow
the procedure below:
1.
Set the input supply between 3V to 4.2V.
With power off, connect the input power sup-
ply to VIN and GND. Make sure JP2 is set to
“ON” and JP1 is set to “VIN”.
2.
Turn on the power at the input.
3.
The output voltage should measure about 25V
across the “VOUT” terminal to “GND” terminal
and the voltage across the PGOOD pin and
“GND” terminal should measure about 0V.
4.
Test the shutdown function by placing JP2 to
“OFF”. Observe the output voltage is about
0.7V lower than the input voltage.
5.
The output voltage can be controlled by DC
voltage at the CTRL terminal. With JP2 placed
at “ON” and JP1 placed at “CTRL”, observe
the output voltage change with DC voltage
applied to the CTRL terminal. The DC voltage
range recommended is 200mV ~ 1.5V. The
maximum DC voltage is 10V. Refer to the
datasheet for further details.
