Demonstration circuit 1988A is a 2kV AC (3kVDC) isolated
®
flyback μModule
featuring the LTM
DC/DC converter with LDO post regulator
®
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 flyback output varies with input voltage from about 100mA
at 4.5V
typical maximum output current on V
not loaded. V
The current capability of V
rent capability
to about 320mA at 30VIN. Figure 1 shows the
IN
when V
OUT1
is the LDO post regulator from V
OUT2
is limited by either the cur-
OUT2
of V
OUT1
minus V
loading or the 300mA
OUT1
OUT2
OUT1
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
performance summary
PARAMETERCONDITIONSVALUE
Minimum Input Voltage4.5V
Maximum Input Voltage30V
Output Voltage V
Output Voltage V
Voltage Ripple V
Voltage Ripple V
VIN = 7V to 30V6V ±5%
OUT1
OUT2
OUT1
OUT2
Specifications are at TA = 25°C
VIN = 7V to 30V5.0V ±3%
VIN = 12V, I
VIN = 12V, I
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
output noise spectrum on V
The LTM8058 data sheet gives a complete description
is
of the device, operation and application information. The
.
OUT1
OUT2
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
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.
OUT2
OUT2
= 0mA, I
= 0mA, I
= 100mA10mV
OUT2
= 100mA5mV
OUT2
and Figure 3 shows the
.
BoarD photo
dc1988af
1
Page 2
DEMO MANUAL DC1988A
dc1988a F03
Quick start proceDure
Demo circuit 1988A is easy to set up to evaluate the performance of the LTM8058. Refer to Figure 4 for proper
measurement
equipment setup and follow the procedure
below:
NOTE. When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the input or output voltage
ripple by touching the probe tip directly across the V
and GND terminals. See Figure 5 for proper scope
V
OUT
IN
or
probe technique.
1. With power off, connect the input power supply to V
IN
and GND.
2. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed 30V.
3. Check for the proper output voltages. (For V
the voltage between V
OUT1
the voltage between V
OUT2
and V
and V
OUT
OUT
–
. For V
–
.)
OUT1
OUT2
, check
, check
NOTE. 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.
400
350
300
250
200
150
OUTPUT CURRENT (mA)
100
50
0
622 24 26 28 308 10 12181614
4
20
VIN (V)
dc1988a F01
0
–10
–20
–30
–40
–50
–60
INTENSITY (dBm)
–70
–80
–90
0
Figure 2. V
at 100mA and VIN at 12V (V
Figure 3. V
OUT1
0
–10
–20
–30
–40
–50
–60
INTENSITY (dBm)
–70
–80
–90
0
OUT2
FREQUENCY (MHz)
Output Noise Spectrum with I
OUT2
FREQUENCY (MHz)
Output Noise Spectrum with I
at 100mA and VIN at 12V (V
3.5 4 4.5 50.5 12.521.5
3
dc1988a F02
Has No Extra Load)
3.5 4 4.5 50.5 12.521.5
3
Has No Extra Load)
OUT1
OUT1
OUT2
Figure 1. V
Current vs VIN with V
Typical Maximum Output
OUT1
OUT2
Unloaded
2
dc1988af
Page 3
Quick start proceDure
DEMO MANUAL DC1988A
+
–
–
+
LOAD
–
–
LOAD
+
+
–
+
–
+
–
dc1988a F04
Figure 4. DC1988A Proper Equipment Setup
GND
VIN
+
–
–
+
+
Figure 5. Measuring Input or Output Ripple
dc1988af
3
Page 4
DEMO MANUAL DC1988A
parts List
ITEMQTYREFERENCEPART DESCRIPTIONMANUFACTURER/PART NUMBER
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
5
Page 6
DEMO MANUAL DC1988A
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC applica-