FSD200 View Datasheet(PDF) - Fairchild Semiconductor

Part Name

Description

View to exact match

FSD200

Green Mode Fairchild Power Switch (FPS™)

Fairchild Semiconductor 

standby mode.

OSC

5uA

4

Vfb

250uA

S

Q

R

GATE

DRIVER

on/off

0.64V

/0.58V

FSD2xx

Burst Operation Block

Figure 12. Circuit for burst operation

Vo

Voset

VFB

0.64V

0.58V

Ids

FSD210, FSD200

Internal

Oscillator

Drain to

Source

voltage

138kHz

Drain to

Source

current

Vds

Waveform

130kHz

134kHz

138kHz

8kHz

Turn-on

Turn-off

point

Figure 14. Frequency Modulation Waveforms

CISPR22Q(PK)

CISPR22A(AV)

Vds

time

Figure 13. Burst mode operation

7. Frequency Modulation : EMI reduction can be accom-

plished by modulating the switching frequency of a SMPS.

Frequency modulation can reduce EMI by spreading the

energy over a wider frequency range. The amount of EMI

reduction is directly related to the level of modulation

(Fmod) and the rate of modulation. As can be seen in Figure

14, the frequency changes from 130kHz to 138kHz in 4mS

for the FSD200/FSD210. Frequency modulation allows the

use of a cost effective inductor instead of an AC input mode

choke to satisfy the requirements of world wide EMI limits.

Frequency(MHz)

Figure 15. FSDH0165 Full Range EMI scan(100kHz, no

Frequency Modulation) with charger set

CISPR22Q(PK)

CISPR22A(AV)

Frequency(MHz)

Figure 16. FSD210 Full Range EMI scan(134kHz, with Fre-

quency Modulation) with charger set

11

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