Application Notes
Output Over Voltage Protection:
The output voltage is constantly monitored by the
microprocessor with a redundant secondary-side
measurement circuit that both shuts down the duty
cycle and triggers the microprocessor to shut down.
If the output voltage exceeds the over-voltage specifi-
cation, the microprocessor will latch the converter off.
To turn the converter on requires either cycling the
ON/OFF pin or power to the converter. This ad-
vanced feature prevents the converter from damaging
the load if there is a converter failure or application
error. If non-latching is required, consult factory.
Thermal Shutdown:
The printed circuit board temperature is measured
using a semiconductor sensor. If the maximum rated
temperature is exceeded, the converter is latched off.
To re-enable the converter requires cycling the ON/
OFF pin or power to the converter. If non-latching is
required, consult factory.
Control Options:
As the behavior of the circuit is determined by
firmware in the microcontroller, specific customer
requirements such as
• non-latching thermal protection
• custom valid input voltage range
• controlled delay from initiating an ON/OFF signal
for power sequencing
can be accomplished with no change to hardware.
The standard behavior was chosen based on system
design experience but we understand that customers
often have their own requirements.
Please consult Galaxy Power for your special needs.
Remote Sense:
The output voltage is regulated at the point where
the sense pins connect to the power output pins.
Total sense compensation should not exceed 0.4V or
10% of Vout, whichever is greater.
Safety:
An external input fuse must always be used to meet
these safety requirements.
External Output Trimming
+ Sense
Trim:
To trim the output voltage higher, connect the
required trim resistor from the Trim pin to the
+Sense pin. To trim the output voltage lower, con-
nect the required trim resistor from the Trim pin to
the –Sense pin.
Trim-up
R
TRIM-UP
=
{
5(100+∆%)
(100+2∆%)
–
1.225∆%
∆%
5.0V Trim-up
}
5.11kΩ
10000
Trim Resistance (kΩ)
1000
100
0
1
2
3
4
5
6
7
8
9
10
Increase in Output Voltage (%)
Trim-down
R
TRIM-DOWN
=
{
100
∆%
–2
}
5.11kΩ
Trim-down
1000
Trim Resistance (kΩ)
100
10
0
1
2
3
4
5
6
7
8
9
10
Decrease in Output Voltage (%)
Trim
– Sense
GAMW5V020 – 4
WWW.GALAXYPWR.COM
155 Flanders Road
Westborough, MA 01581
Telephone: 508-870-9775
Part No. 02-GAM-01 Rev. 1.0 – 042805
Galaxy Power Inc.
Fax: 508-870-9796
e-mail: info@galaxypwr.com
GALAXY [ GALAXY POWER, INC. ]
