Application Notes
Output Over Voltage Protection:
Trim:
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.
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
3.3 (100+∆%)
(100+2∆%)
RTRIM-UP
=
–
5.11kΩ
{
}
1.225∆%
∆%
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.
3.3V Trim-up
1000
100
10
Control Options:
As the behavior of the circuit is determined by
firmware in the microcontroller, specific customer
requirements such as
0
2
3
4
5
6
7
8
9
10
1
• non-latching thermal protection
Increase in Output Voltage (%)
• 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.
Trim-down
100
RTRIM-DOWN
=
– 2
5.11kΩ
{∆% }
Please consult Galaxy Power for your special needs.
Remote Sense:
Trim-down
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.
1000
100
Safety:
An external input fuse must always be used to meet
these safety requirements.
External Output Trimming
10
0
2
3
4
5
6
7
8
9
10
1
Decrease in Output Voltage (%)
+Sense
Trim
Up
10KΩ
Trimpot
Trim
Trim
Down
–Sense
GAQW3V330 – 4
WWW.GALAXYPWR.COM
Part No. 02-GAQ-02 Rev. 3.0 – 041405
Galaxy Power Inc. 155 Flanders Road Westborough, MA 01581 Telephone: 508-870-9775 Fax: 508-870-9796 e-mail: info@galaxypwr.com
GALAXY [ GALAXY POWER, INC. ]
