Pisces II Series, Page 4

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Part No. 02-007 Rev. 3.0–061004

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 specification,

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 advanced 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

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, connect the

required trim resistor from the Trim pin to the –Sense

pin. The Trim-down equation applies to all Voltages.

Application Notes

Vo (100+

∆%)

−

(100+

2∆%)

5.11k

Ω

1.225∆%

∆%

{

}

Trim-up

(for 3.3V)

+ Sense

Trim

– Sense

100

– 2

5.11k

Ω

∆%

{

}

Trim-down

Trim-down (%)

Vo (100+

∆%)

−

(100+

2∆%)

5.11k

Ω

0.62∆%

∆%

{

}

Trim-up for 1.5V and above:

Trim-up for less than 1.5V:

Trim-down for all voltages: