UCC28951
www.ti.com.cn
ZHCSIQ7A –AUGUST 2018 –REVISED DECEMBER 2021
80
60
40
20
0
180
135
90
45
0
-20
-40
-60
-80
-45
-90
-135
-180
TvdB(f)
&Tv(f)
100
1000
10000
100000
Frequency in Hz
图8-7. Loop Gain and Phase vs Frequency
备注
TI recommends confirming the loop stability of the final design with transient testing and/or a network
analyzer. Adjust the compensation (GC(f)) feedback as necessary.
V ´(1-DTYP
)
IN
LMAG
³
» 2.78mH
DILOUT ´0.5
´ 2´F
SW
a1
(127)
where
• loop gain (TVdB(f))
• loop phase (ΦTV(f))
To limit overshoot during the power up sequence, the UCC28951 has a soft-start function (SS, Pin 5). In this
application the soft-start time is 15 ms (tSS).
t
SS ´ 25mA
V1+ 0.55
CSS
=
» 123nF
(128)
The standard capacitor (CSS) selected for this design is 150 nF.
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Product Folder Links: UCC28951
English Data Sheet: SLUSDB2
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