M51995AFP datasheet(39/43 Pages) RENESAS

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M51995AP/AFP

REJ03D0835-0300 Rev.3.00 Jun 06, 2008

Page 37 of 40

DET Circuit

Figure 41 shows how to use the DET circuit for the voltage detector and error amplifier.

F/B

DET

Detecting

voltage

M51995A

Figure 41 How to use the DET Circuit for the Voltage Detector

For the phase shift compensation, it is recommended to connected the CR network between DET terminal and F/B

terminal.

Figure 42 shows the gain-frequency characteristics between point B and point C shown in figure 41.

Log

GAVDET

(DC Voltage gain)

Figure 42 Gain-Frequency Characteristics between Point B and C shown in Figure 41

The G1,

1 and ω2 are given by following equations;

G1 =

……………………… (12)

R1 / R2

• R3

ω1 =

………………………… (13)

C1 + C2

• C2 • R3

ω2 =

………………… (14)

At the start of the operation, there happen to be no output pulse due to F/B terminal current through C1 and C2, as the

potential of F/B terminal rises sharply just after the start of the operation.

Not to lack the output pulse, is recommended to connect the capacitor C4 as shown by broken line.

Please take notice that the current flows through the R1 and R2 are superposed to ICC(START). Not to superpose, R1 is

connected to CVCC2 as shown in figure 25.

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