Vicor 4kW MegaPAC AC-DC Switchers - Manual (Page 24)

UG:107 vicorpower.com Applications Engineering: 800 927.9474 Page 24
Setting the bottom limit:
V
R6
= 2.5 V - 10% = 2.25 V
And since I
R5
= I
R6
= 25 mA,
R6 = V
R6
/I
R6
= 2.25 V/25 mA = 90 kW
V
2
= V
1
+ V
R6
= 2.75 V + 2.25 V = 5 V
I
R7
= V
2
/R7 = 5 V/10 kW = 500 mA
I
R8
= I
R7
+ I
R6
= 525 mA
V
R8
= (V
nom
+10%) - V
2
= 13.2 V - 5 V = 8.2 V Given: V
nom
= 12 V
R8 = V
R8
/I
R8
= 8.2 V/525 mA = 15.62 kΩ
Using the previous resistor combination, a 12 V output can be trimmed externally up
to 13.2 V and down to 10.8 V. For further information on external trimming, refer to
Chapter 5 of the Applications Manual or consult the factory for assistance.
CONSULT APPLICATIONS ENGINEERING WHEN TRIMMING OUTPUTS BELOW 5V.