MC44608 Ver la hoja de datos (PDF) - ON Semiconductor

Número de pieza

componentes Descripción

Fabricante

MC44608

Few External Components Reliable and Flexible SMPS Controller

ON Semiconductor 

MC44608

EQUATION 7

dBM +

ȧȡȢ 1 )

IccS) IG

Istup

1

ǒ ǒ kSńStup ) kSńL

ǓǓ Istup

IccL) Ipin3

ȧȣȤ

EQUATION 8

dBM +

ȡ

ǒ Ǔ ȧȧȥ 1 )

k1

)

IG

Istup

Ȣ

1

ȡ

ȧȧȧkSńStup ) (kSńL

Ȣ

ȣȣ

ǒ Ǔ k2)

1

Ipin3

Istup

)ȧȧȧȧȧȦ

ȤȤ

where: k1 = Iccs/Istup

k2 = IccL/Istup

kS/Stup = (Vstup−UVLO2)/(Vstup−UVLO1)

kS/L = (UVLO1−UVLO2)/(Vstup−UVLO1)

PULSED MODE CURRENT SENSE CLAMPING LEVEL

Equations 9, 10, 11 and 12 allow the calculation of the Rcs value for the desired maximum current peak value during the

SMPS standby mode.

EQUATION 9

Ipkstby +

Vcs–th * (Rcs

RS

Ics)

where: Vcs−th is the CS comparator threshold

Ics is the CS internal current source

RS is the sensing resistor

Rcs is the resistor connected between pin 2 and RS

EQUATION 10

Ipkstby + Vcs–th

ǒ Ǔ 1 * Rcs

Ics

Vcs–th

RS

EQUATION 11

Ipkstby + Vcs–th

1 * (Rcs Ycs–stby )

RS

where: Ycs−stby = Ics/Vcs−th

Taking into account the circuit propagation delay (dtcs) and the Power Switch reaction time (dtps):

EQUATION 12

ƪ Ipkstby + Vcs–th

ƫ 1 * (Rcs Ycs–stby )

RS

) Vin

(dtcs ) dtps)

Lp

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10

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