DESCRIPTION
Demonstration circuit 1028 a highly integrated, 5 out-
put regulator for TFT LCD panels featuring LT
®
3513,
which comes in the 38-pin QFN package. The
DC1028A has an input voltage range from 8 to 30V,
and produce a 5V logic voltage. A lower voltage logic
supply can be generated from this 5V by adding an
external NPN driven by a linear regulator. The other
three regulators provide the three voltages required by
LCDs: a higher power boost regulator to generate
AVDD, a lower power boost to gerneated VON and an
inverting converter to provide VOFF. An internal high
side PNP provides delayed turn on of the VON signal.
The LT3513’s wide input voltage range allows it to
accept a variety of power sources, including automo-
tive batteries, distributed supplies and wall transform-
ers.
All four switchers are synchronized to the internal
2MHz clock, allowing the use of low profile inductors
and ceramic capacitors. They all have soft start to
limit inrush current.
The LT3513 datasheet gives a complete description of
the part, operation and application information. The data-
sheet must be read in conjunction with this quick start
guide for demo circuit 1028A.
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 ( T
A
= 25
o
C )
PARAMETER FOR BUCK REGULATOR CONDITION VALUE
Minimum Input Voltage 8V
Maximum Input Voltage 30V
Output Voltage V
LOGIC
V
IN
=8V to 30V, I
OUT
=0 to 500mA
5V
+/- 4%
Maximum Output Current at V
LOGIC
V
IN
=8V to 30V
500mA
Typical Switching frequency 2MHz
QUICK START PROCEDURE
Demonstration circuit 1028 is easy to set up to evaluate
the performance of the LT3513. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
1. With Power off, connect the input power sup-
ply to Vin and GND. Insert jumper JP1 into the
ON position.
2. Set the input between 8V to 30V. Turn on the
power at the input.
3.
Check for the proper output voltage
. If there is
no output, temporarily disconnect the load to
make sure that the load is not set too high.
4.
Once the proper output voltages are established,
adjust the load within the operating range and
observe the output voltage regulation, ripple
voltage, efficiency and other parameters.
2MHz, High Current 5 Output Switching Regul
tor for TFT-
