User manual

z Description of Circuit Theory

1) +10V Voltage reference circuit：

Start up the circuits of R306 and D302 to ensure the output voltage of OPA U301, PIN 1 is in positive status when power

is on. At this moment, the output voltage of PIN 1 will pass through R307 to maintain the voltage of both ends of

ZENER DIODE ZD301(6.2V) to 6.2V. As OPA has the character of false short circuit, so U301 PIN3=6.2V, refer to the

following formula:

Therefore, the OPA’s output voltage can be changed by adjusting the VR301 as shown in the following formula:

Vref=10V→VR301=1.14kΩ

2) Voltage Adjusting Circuit

The R311, and R313 are voltage feedback attenuating resistors while R312 is to control the output of Reference voltage.

Please refer to the following formula:

If Vref=10V R311=52.3kΩ R313=20kΩ

And the R316, R317, C313, C314, and C315 are compensated circuits for voltage frequency.

3) Current Adjusting Circuit:

The U302 is an Error Amplifier with the gain at:

For example: SPS-1820, Io=20A，R341=10mΩ

Vpin12=Io×R341×A=20×0.01×28.01=5.602V