S3882P
4. Current Sense Circuit
ER R O R
A MP
2R
Iβ
R
R (V p i n 1 - 2V b e )
Ip e a k =
3R x R s
R
3
C
Rs
5
1
CO MP
CUR R E NT
S ENS E
G ND
IV
CUR R ENT
S E NS E
C O MP A R A T O R
A normal operating conditions occurs when the power supply output is overloaded or if output voltage to 1.0V
Therefore the maximum peak switch current is lpk(max)=1.0V/Rs, and under the normal operating conditions the
peak inductor current controlled by the voltage at pin1.
5. Shutdown Techniques
4.7K
8
V
RE F
1
CO MP
Shutdown of the S3882 can be
accomplished by two methods;
either raise pin3 above 1V or pull
3
4.7K
S HUT
DO W N
T O CUR R E NT
S E NS E R ES I S T O R
5.00
I
SEN SE
S HUT
DO W N
pin1 below a voltage two diodes
drops above ground. Either causes
the output of the PWM method
comparator
to be high (refer to
block diagram). The PWM latch is reset dominant so that the output will remain low until the next clock cycle after
the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally latched shutdown may be
accomplished by adding an SCR which turn off, allowing the SCR to reset.
KSI-L008-000
5
AUK [ AUK CORP ]
