Contax SW II - REV 4.01 Manual de usuario descargar pdf (Pagina 17)

R2J20702NP Target Specification

REJ03G1782-0401 Rev.4.01 Page 17 of 27

Jun 17, 2010

Study of Vout Accuracy

The nominal output voltage is calculated as

Vout = VFB  (R1 + R2) / R2 (6)

Here, the typical feedback voltage is 0.6 V.

REG5

TRK-SS

FBCT

Vout

The accuracy of Vout is strongly dependent on the variation of VFB, R1 and R2. VFB has a variation of 1% and

resistance intrinsically has a certain variation. When we take the variation in resistance into account, equation (6) is

extended to produce equation (7).

Vout =

R1 × K1 + R2 × K2

R2 × K2

× VFB

R1 × K1 / K2 + R2

× VFB ……(7)

Here, K1 and K2 are coefficients. Both are 1.00 in the ideal case.

By equation (6), R1 is chosen as

VFB (typical)

Vout (typical)

R1 = − 1 × R2 ……(8)

Substituting this expression for R1 into equation (7) yields the following.

VFB (typical)

Vout (typical)

Vout = VFB × − 1 × + 1 ……(9)

Therefore, variation in Vout is expressed as

VFB (typical)

Vout (typical)

= × − 1 × + 1 − 1 × 100 (%) …… (10)

Vout (typical)

VFB

Vout

Vout (typical)

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Contax SW II - REV 4.01 Manual de usuario Pagina 17