Technical Reference Note

Output Voltage Adjustment (cont'd)

ThetrimequationforthebasicconfigurationshowninFigure5is:

Rtrim(kΩ)=

1.675

Vout - 0.8375

WhereVoutisthedesiredoutputvoltage,RtrimistheresistancerequiredbetweenTrimand

-Trim.

ThetrimequationfortheexternalvoltageconfigurationshownFigure6is:

Rtrim2(kΩ)=

Rtrim1 (1.2 - 2Vt)

Rtrim1 (Vout - 0.8375) - 1.675

WhereVoutisthedesiredoutputvoltage,Rtrim1andRtrim2aretheresistorsinFigure6

andVtistheappliedexternalvoltage.

ThetrimequationforthepotentiometerconfigurationsshowninFigure7is:

Vout=

0.8375

(Rtrim2 + Rpot)Rtrim1

X (2Rtrim2 + 2Rpot + Rtrim1Rtrim2 + Rtrim1Rpot + 2Rtrim1)

WhereVoutisthedesiredoutputvoltage,Rtrim1andRtrim2aretheresistorsinFigure7

andRpotistheresistanceofthepotentiometer.

Undervoltage Lockout

TheSIL/SMT80C2hasbuilt-inundervoltagelockouttoensurereliableoutputpower.Thelockoutprevents

theunitfromoperatingwhentheinputvoltageistoolow.TheUVLOfortheSIL/SMT80C2canbeadjust-

edwiththefollowingequation:

Thetrimequationfortheundervoltagelockoutis:

Ruvlo (kΩ) =

124.8 + Vturn_on

10 Vturn_on - 42.06

Rev. 04.25.11

SIL/SMT80C2

6 of 20

Embedded Power for

Business-Critical Continuity

Application(cont'd)