1
dc1988af
DEMO MANUAL DC1988A
Description
LTM8058
Isolated μModule DC/DC Converter
with LDO Post Regulator
Demonstration circuit 1988A is a 2kV AC (3kVDC) isolated
flyback μModule
®
DC/DC converter with LDO post regulator
featuring the
LTM
®
8058
. The demo circuit is designed for
a 6V flyback output and a 5V post regulator output from
a 4.5V to 30V input. The current capability of the 6V fly-
back output varies with input voltage from about 100mA
at 4.5V
IN
to about 320mA at 30V
IN
. Figure 1 shows the
typical maximum output current on V
OUT1
when V
OUT2
is
not loaded. V
OUT2
is the LDO post regulator from V
OUT1
.
The current capability of V
OUT2
is limited by either the cur-
rent capability of V
OUT1
minus V
OUT1
loading or the 300mA
current limit on the LDO post regulator itself. R1 provides
the necessary minimum load current to keep the V
OUT1
in regulation throughout the entire input voltage range.
Please see the typical performance characteristic curves
L
, LT, LTC, LTM, µModule, 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
BoarD photo
in the LTM8058 data sheet to determine the minimum load
current for other input/output configurations.
The two-stage converter provides an isolated flyback output
as well as a low noise LDO output. Figure 2 shows the
output noise spectrum on V
OUT1
and Figure 3 shows the
output noise spectrum on V
OUT2
.
The LTM8058 data sheet gives a complete description
of the device, operation and application information. The
data sheet must be read in conjunction with this quick
start guide for demo circuit 1988A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1988A
Specifications are at T
A
= 25°C
PARAMETER
CONDITIONS
VALUE
Minimum Input Voltage
4.5V
Maximum Input Voltage
30V
Output Voltage V
OUT1
V
IN
= 7V to 30V
6V ±5%
Output Voltage V
OUT2
V
IN
= 7V to 30V
5.0V ±3%
Voltage Ripple V
OUT1
V
IN
= 12V, I
OUT2
= 0mA, I
OUT2
= 100mA
10mV
Voltage Ripple V
OUT2
V
IN
= 12V, I
OUT2
= 0mA, I
OUT2
= 100mA
5mV