CS5127 View Datasheet(PDF) - Cherry semiconductor
Part Name
Description
MFG CO.
CS5127
Cherry semiconductor
'CS5127' PDF : 24 Pages View PDF
Additional Application Circuits
5V
5V
VOUT
R1
24K
R2
5K
R3
10K
Q2
FMMT2907ACT
R4
10K
OVP OUT
Q1
FMMT2222ACT
R1
6.3K
Q1
Q2
Q3
FMMT2907ACT
R2
1k
FMMT2907ACT
FMMT2907ACT
ENABLE 1
SIGNAL
TO VFFB1
TO COMP1
Q4
FMMT2222ACT
R3
1K
(R1 + R2)(0.65V)
VOVP =
R2
Figure 12: Example external over voltage protection circuit. If VOUT
exceeds VOVP, OVP out goes high. Resistor values shown above pro-
vide a +10% tolerance for a 3.3V output.
5V
VOUT
R1
18K
R2
5K
R3
10K
Q1
FMMT2222ACT
PGOOD OUT
Q2
FMMT2222ACT
Figure 14: An external circuit can be built to provide an enable func-
tion for channel 1. The circuit shown above connects to the VFB1 and
COMP1 pins as indicated. If the ENABLE1 signal is left floating or is
pulled high, channel 1 is enabled. If the ENABLE1 pin is pulled
below 1V, Q1 will conduct, and mirror Q3 pulls VFFB1 up at the same
time as Q2 and Q4 pull COMP1 low. This will force GATE1 to go low
and turn off the switch FET. The circuit above will provide about
1mA of additional drive to the VFFB1 pin components. This additional
current must be sufficient to pull VFFB1 up to about 1V in order to
guarantee GATE1 is held low.
(R1 + R2)(0.65V)
VPGOOD =
R2
Figure 13: Example external Power GOOD circuit. PGOOD(OUT) is low
until VOUT exceeds VPGOOD. VPGOOD is typically chosen to be 10%
below nominal VOUT. Resistor values above provide a -10% tolerance
on VOUT =3.3V.
15
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