SD14-102-R [COOPER]
Switching Regulators; 开关稳压器
| 型号： | SD14-102-R |
| 厂家： | 
COOPER BUSSMANN, INC. |
| 描述： | Switching Regulators |
| 文件： | 总4页 (文件大小：373K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Inductor Selection for Switching Regulators
Introduction/Basic Operation
In switching regulator applications the inductor is used as an energy
storage device. When the semiconductor switch is on the current in the
inductor ramps up and energy is stored. When the switch turns off energy
is released into the load. The amount of energy stored is calculated by the
formula Energy = ½L.I² (Joules), where:
•L is the inductance in Henrys
•I is the peak value of inductor current
The amount by which the current changes during a switching cycle is
known as the ripple current. Ripple current is defined as Vl = L.di/dt:
•V is the voltage across the inductor
l
•di is the ripple current
•dt is the duration for which the voltage is applied
I load
dI
I inductor
0
1
2
V out
ESR
Figure 1:
Buck Inductor
Inductor current is made up of AC and DC components (Figure 1). The AC
component is high frequency and will flow through the output capacitor
because it has a low HF impedance. A ripple voltage is produced due to
the capacitor ‘equivalent series resistance’ (ESR) that will appear at the
output of the switching regulator. This ripple voltage needs to be
sufficiently low as not to effect the operation of the circuit the regulator is
supplying, normally in the order of 10-500mV
.
pk-pk
The following parameters need to be defined or calculated to select an
inductor:
•Maximum input voltage
Selecting the correct ripple current impacts the size of the inductor and
output capacitor. The capacitor needs to have a sufficiently high ripple
current rating or it will overheat and dry out. To achieve a good
compromise between inductor and capacitor size a ripple current value of
10-30% of maximum inductor current should be chosen. The current in
the inductor will be continuous for output currents greater that 5-15% of
full load.
•Output voltage
•Switching frequency
•Maximum ripple current
SD3814
•Duty cycle
Inductor Selection: Buck Converters
Inductor Selection: Boost Converters
Boost
Buck
Inductor
Diode
Inductor
Switch
5V
Output
Voltage
12V
Input
Voltage
Freewheeling
Diode
Output
Cap
12V
Output
Voltage
5V
Input
Voltage
Output
Cap
Switch
Figure 2:
Buck Inductor Example
Figure 3:
Boost Inductor Example
Figure 2 Application Parameters:
•Switching frequency= 250kHz
Figure 3 Application Parameters:
•Switching frequency= 100kHz
•Input voltage range= 12V 10%
•Max ripple current = 220mA
•Output Voltage= 5.0V
•Input voltage range= 4.5-5.5V
•Max ripple current = 100mA
•Output Voltage= 12.0V
Step 1. Calculate the Duty Cycle
Step 1. Calculate the Duty Cycle:
•V = output voltage
•V = output voltage
o
o
•V = Max input voltage
i
•V = Max input voltage
i
•D = 1 - (V / V )
•D = V / V
i
o
o
i
•D = 1 – (5.5/12.0) = 0.542
•D = 5/13.2 = 0.379
Step 2. Calculating the voltage across the inductancce
•V = V (Switch on)
Step 2. Calculate the Voltage Across the Inductance
•V = V -V (Switch on)
1
i
1
i o
•V = 5.5V
1
•V = 13.2 - 5 = 8.2V
1
•V = V – V (Switch off)
•V = -V (Switch off)
1
o
i
1
o
•V = 12 – 5.5 = 6.5V
1
•V = - V = - 5V
1
o
Step 3. Calculating the required inductance
Step 3. Calculate the Required Inductance
•L = V .dt/di
•L = V .dt/di
l
l
•L= (5.5 x 0.542/100 x 103)/0.1
•L = (8.2 x 0.379/250 x 103)/0.22
•L= 298μH
•L = 56μH
Typical Applications Using Inductors for Switching Regulators
Industrial Test Equipment
Media Players
Digital Cameras
Laptop Computers
Backlight Displays
Mobile Phones
SDH3812
Part Number
Rated
OCL
Part
I
I
DCR
DCR
rms
sat
Inductance μH 20% Marking
Amps
Amps
Ω@20°C Ω@20°C
(Typical) (Maximum)
(μH)
1.0
1.5
Designator
SDH3812-1R0-R
SDH3812-1R5-R
SDH3812-2R2-R
SDH3812-3R3-R
SDH3812-4R7-R
SDH3812-100-R
SDH3812-220-R
SDH3812-330-R
SDH3812-470-R
0.89
1.49
2.23
B
D
E
2.07
1.67
1.37
1.14
0.94
0.69
0.50
0.41
0.34
0.25
0.16
3.00
2.30
1.90
1.60
1.25
0.88
0.61
0.49
0.41
0.28
0.19
0.045
0.069
0.104
0.148
0.220
0.398
0.750
1.132
1.583
3.042
7.017
0.054
0.083
0.124
0.177
0.264
0.478
0.900
1.358
1.900
3.650
8.420
2.2
3.3
3.17
F
4.7
4.96
9.67
G
J
L
M
N
Q
S
SDH3812
10.0
22.0
33.0
47.0
22.00
32.90
46.20
97.50
218.50
SDH3812-101-R 100.0
SDH3812-221-R 220.0
Note: For full product information and a listing of all available inductor values, see
http://www.cooperbussmann.com/datasheets/elx, Data Sheet number SDH3812 Series.
SDH3812 Dimensions - mm
Top View
Side View
Bottom View
Recommended Pad Layout
Schematic
1.2 Max.
4.8 Max.
3.65 Typ.
Marking
2.03 +/-0.1
Pin #1 indicator
1.0
2 plcs
1.25 Typ.
2.5
2 plcs
5.0
0.90 Max.
no plating
3.8 +.02/-0.1
3.8 +.02/-0.1
0.415 Min.
SD3814
Part Number
Rated
OCL
Part
I
I
DCR
rms
sat
Inductance μH 15% Marking
Amps
Amps
Ω
(μH)
1.2
Designator
Typical
0.046
0.051
0.077
0.093
0.141
0.311
0.589
0.908
1.322
SD3814-1R2-R
SD3814-1R5-R
SD3814-2R2-R
SD3814-3R3-R
SD3814-4R7-R
SD3814-100-R
SD3814-220-R
SD3814-330-R
SD3814-470-R
1.001
1.286
1.962
2.781
4.276
9.830
21.186
32.151
47.210
C
D
E
1.85
1.76
1.43
1.31
1.06
0.713
0.519
0.418
0.346
2.67
2.35
1.90
1.60
1.29
0.851
0.580
0.471
0.388
1.5
2.2
SD3814
3.3
F
4.7
G
J
L
M
N
10.0
22.0
33.0
47.0
Note: For full product information and a listing of all available inductor values, see
http://www.cooperbussmann.com/datasheets/elx, Data Sheet number SD38 Series.
SD3814 Dimensions - mm
Bottom View
Top View
Side View
Recommended Pad Layout
Schematic
1.0
2 plcs
4.8
Max
Pin #1indicator
1.4
Marking
(see note A)
Max
3.65
Typ
2.5
2 plcs
0.09 Max
no plating
1.25
0.12
4.0typ
5.0
2.03
.02
4.0
Max
4.0
Max
0.415 Min
SD14 & SD25
Part Number
Rated
OCL
Part
I
I
DCR
rms
sat
Inductance
(μH)
1.2
20%
μH
1.23
1.63
3.19
Marking
Amps
Amps
Ω
Typical
0.0344
0.0390
0.0663
0.1363
0.2058
0.3853
0.5852
0.9055
1.68
SD14-1R2-R
SD14-1R5-R
SD14-3R2-R
SD14-6R9-R
SD14-100-R
SD14-220-R
SD14-330-R
SD14-470-R
SD14-101-R
SD14-221-R
SD14-331-R
SD14-471-R
SD14-102-R
SD25-1R2-R
SD25-1R5-R
SD25-2R2-R
SD25-3R3-R
SD25-4R7-R
SD25-100-R
SD25-220-R
SD25-330-R
SD25-470-R
SD25-101-R
SD25-151-R
SD25-221-R
SD25-331-R
SD25-471-R
C
D
G
J
2.7
2.53
1.94
1.35
3.35
2.91
2.08
1.41
1.18
0.793
0.651
0.538
0.373
0.249
0.203
0.171
0.117
3.81
1.5
3.2
6.9
10
22
33
47
6.98
9.93
L
1.1
SD Inductor Series
21.93
32.55
47.57
99.25
222
335.1
471.4
1008
1.15
1.61
2.14
3.43
5.03
10.35
22.81
33.07
47.89
100.79
148.4
222.4
332.2
472.4
N
O
P
S
U
V
W
Z
C
D
E
0.806
0.654
0.525
0.386
0.258
0.206
0.173
0.126
3.33
3.12
2.93
2.64
2.39
1.80
1.34
1.11
0.919
0.670
0.553
0.446
0.359
0.293
Typical SD Series Applications
•Mobile phones
100
220
330
470
1000
1.20
1.50
2.20
3.30
4.70
10.0
22.0
33.0
47.0
100
150
220
330
470
3.77
5.92
8.34
15.8
•Digital cameras
•Industrial test equipment
•Computers
0.0240
0.0274
0.0311
0.0384
0.0467
0.0824
0.1478
0.2149
0.3156
0.5937
0.8723
1.34
•Uninterruptible power supplies
•Televisions
3.23
2.80
2.21
1.83
F
Typical SD Series Uses
•Buck and boost converters
•LED Drivers
G
K
M
N
O
R
S
T
1.27
0.857
0.711
0.592
0.398
0.328
0.268
0.219
0.184
•EL panel drivers
•Backlighting
•Noise filtering chokes
U
V
2.07
3.10
Note: SD10, 12, 18 and 20 not shown. For full product information and a listing of all available inductor
values, see http://www.cooperbussmann.com/datasheets/elx, Data sheet number SD Series
SD14 & SD25 Dimensions - mm
Top View
Schematic
Bottom View
Recommended Pad Layout
Side View
2 Pad Layout
Pin # 1
identifier
4 Pad Layout
1
1
1
2
5.950
5.95
5.2
Max
2.975
1.5 Typ.
Ref.
R2.250
1.0
R2.250
2.975
Part marking
(Note A)
5.950
2.975
2.575
2
5.2
HT
SD14 = 1.45mm Max
SD25 = 2.5mm Max
Max
5.15
The Cooper Bussmann Coiltronics® brand of magnetics specializes in standard and custom solutions, offering the latest in state-of-the-art low-profile high power
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St. Louis, MO 63178
636-394-2877
www.cooperbussmann.com
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