1
dc2049af
DEMO MANUAL DC2049A
DESCRIPTION
LT3999EMSE
Low Noise Isolated
Power Supply
The DC2049A demonstrates how a power supply regulates
two output voltage by using the
LT
®
3999
and low dropout
(LDO) regulators.
The LT3999 is a monolithic push-pull DC/DC driver which
features wide input range and small external passive
components.
The LT3999 has duty circle control for ΔV
IN
compensa-
tion, which allows for a wide input voltage range and low
LDO losses.
The DC2049A employs a push-pull topology that inherently
provides a low-noise solution. The design is well suited
to noise sensitive systems such as medical instruments,
industrial sensing and control, data conversion and wide
band communications. The post regulator LDOs reduce
output noise further. For more details about the LDOs,
please check the LT3065 and LT3090 data sheets.
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
The DC2049A produces an isolated 12V
OUT
and –12V
OUT
at
up to 200mA each from a 10V ~ 15.5V input voltage range.
This board can be modified, by changing the transformer
(and duty cycle), to produce other output voltages.
The DC2049A features a small transformer, small inductors
and capacitors that work at a 1MHz switching frequency.
The LT3999 data sheet gives a complete description of the
part, operation and applications information. The data sheet
must be read in conjunction with this demo manual. The
LT3999EMSE is assembled in a 10-lead plastic MSE pack-
age with a thermally enhanced ground pad. Proper board
layout is essential for maximum thermal performance. See
the data sheet section Layout Consideration Check List.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2049A
Specifications are at T
A
= 25°C
PARAMETERS
MIN
TYP
MAX
UNITS
Input Voltage Range
10.0
15.5
VDC
Output Voltage 1 (VOUT1)
11.64
12.0
12.3
VDC
Output Voltage 2 (VOUT2)
–12.36
–12.0
–11.64
VDC
Output Current 1
0
200
mA
Output Current 2
0
200
mA
Switching Frequency
1.0
MHz
Isolation
1000
VDC
