Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

UCC28251 Datasheet(PDF) 38 Page - Texas Instruments

Part No. UCC28251
Description  UCC28251 Advanced PWM Controller With Prebias Operation
Download  55 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  TI [Texas Instruments]
Homepage  http://www.ti.com
Logo 

UCC28251 Datasheet(HTML) 38 Page - Texas Instruments

Zoom Inzoom in Zoom Outzoom out
 38 / 55 page
background image
R
1
2
V
0.7 V
73 V
0.7 V
R
R
866
89.4 k
R1
88.7 k
0.7 V
0.7 V
-
-
=
´
=
´
W =
W Þ
=
W
(
)
(
)
(
)
(
)
r
f
2
r
0.7 V
V
V
0.7 V
73 V
72 V
R
880
R2
866
11 A
V
0.7 V
11 A
73 V
0.7 V
´
-
´
-
£
=
=
W Þ
=
W
m ´
-
m ´
-
HICC
HICC
2.7 A
2.7 A
C
T
0.8 s
1.03 F
C7
1.0 F
2.4 V
0.3 V
2.4 V
0.3 V
m
m
=
´
=
´
=
m
Þ
=
m
-
-
SS
SS
COMP( final)
27 A T
27 A 15ms
C
0.101 F
C8
0.1 F
V
4.0 V
m
´
m
´
=
=
=
m
Þ
=
m
RAMP _ 2
CHARGE
RAMP
sw
CHARGE
RAMP
1
1
R
92.7k
75 V
V
2 ln(
) 470pF 150kHz
2 ln
C
f
75 V
5.523 V
V
V
=
=
=
W
æ
ö
´
´
´
´
´
´
ç
÷
-
-
è
ø
RAMP _ 1
CHARGE
RAMP
sw
CHARGE
RAMP
1
1
R
336.9k
36 V
V
2 ln(
) 470pF 150kHz
2 ln
C
f
36 V
0.750 V
V
V
=
=
=
W
æ
ö
´
´
´
´
´
´
ç
÷
-
-
è
ø
COMP
RAMP
V
1.944 V
V
5.523 V
(D 2)
(0.176 2)
=
=
=
´
´
COMP
V
(SR _ D 0.5) 3.0 V 2
(0.824 0.5) 3.0 V 2
1.944 V
=
-
´
´
=
-
´
´
=
SR _ D
1 D
1 0.176
0.82
=
-
=
-
=
O
IN
n
V
1
4
3.3 V
1
D
0.176
V
2
75 V / 2
2
2
´
´
=
´
=
´
=
UCC28251
SLUSBD8E – FEBRUARY 2013 – REVISED DECEMBER 2014
www.ti.com
(30)
2. Calculate SRA or SRB duty cycle.
(31)
3. Calculate the COMP voltage value in steady state (Equation 23).
(32)
4. Calculate the RAMP peak value (Equation 24).
(33)
5. Arbitrary select CRAMP 470 pF, then C3 = 470 pF.
6. Calculate RRAMP.
(34)
(35)
As different RAMP resistor values are obtained, at this stage, we may take their average value for initial design.
9.2.1.2.4
Step 3-3: Determine Soft-Start Capacitance
Determine soft-start capacitance with soft-start time 15 ms.
(36)
9.2.1.2.5
Step 3-4: Determine Dead-Time Resistance
Assuming the dead time is 150 ns, Select R7 = R8 = 121 k
Ω based on Figure 27 and Figure 28.
9.2.1.2.6
Step 3-5: Determine OCP Hiccup Off-Time Capacitance
Assuming off time is 0.8 s (Equation 14).
(37)
9.2.1.2.7
Step 3-6: Determine Primary-Side OVP Resistance
Assuming OV_OFF = 73 V, OV_ON = 72 V (Equation 15 to Equation 17).
(38)
(39)
38
Submit Documentation Feedback
Copyright © 2013–2014, Texas Instruments Incorporated
Product Folder Links: UCC28251


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn