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: IPS-1820D, Io=20A，R341=10mΩ
Vpin12=Io×R341×A=20×0.01×28.01=5.602V
10V
10k
10k4.99kVR301
6.2
R305
R305R304VR301
6.2Vref
36.15V
20k
72.3k
10
20k
20k52.3k
VrefVout
Vpin13Vpin12
VR303R322R321
R321
10VAR341Io
28.01
3.57k
100k
R342
R326
A
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