SP7606

12/17/07 rev: A

SP7600

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Output capacitor selection

For best performance a combination of both

electrolytic and ceramic capacitors should be

used. For both DCM and CCM mode the

required ESR is approximately given by

For CCM mode of operation the output

capacitor ripple is approximately:

The minimum output capacitance required in

CCM and DCM mode is approximated by

Where D= duty cycle for different modes of

operation

fsw=switching frequency

Error Amplifier

The SP7606 has built in internal Type 2

compensation.

-

+

RZ

CZ

CP

Vref

R1

Comp

Vout

Type II compensation

The values for

Rz is 200K

Cz is 150pF

CP is 2pF

R1 is chosen for proper gain.

Bode plot of type two compensation

The internal pole and zero location for the

SP7606 internal compensation is

Zero Location= 5.3KHz

Pole Location=398KHz

Modulator Gain CCM (feed forward)

The SP7606 has also built in a feed forward

topology to allows the boost regulator to have

the same modulator gain throughout its full

input voltage range swing when running in

CCM. The modulator gain is for the SP7606 is

Modulator Gain DCM (feed forward)

The SP7606 has also built in a feed forward

topology to allow the boost regulator to have

the same modulator gain throughout its full

input voltage range swing when running in

DCM. The modulator gain is for the SP7606 is

Where M=

D= Duty Cycle in DCM

Boost regulator output filter DCM

When a boost regulator is running in

discontinuous conduction mode the output

Gain (dB)

Frequency (Hz)