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參數(shù)資料
| 型號： | LTC3806EDE |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Synchronous Flyback DC/DC Controller |
| 中文描述： | 0.05 A SWITCHING CONTROLLER, 290 kHz SWITCHING FREQ-MAX, PDSO12 |
| 封裝： | 4 X 3 MM, PLASTIC, MO-229WGED, DFN-12 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大小： | 241K |
| 代理商： | LTC3806EDE |
12
LTC3806
3806f
APPLICATIOU
Some common secondary turns ratios:
W
U
U
For example, assume we need a regulator that operates
with a nominal 48V input to produce one 3.3V output and
one 5V output. The ideal turns ratio for the 3.3V (master)
output is:
3 3
48
We select a turns ratio of 1/15 or N1 = 0.066…
For the 5V output, the ideal turns ratio is:
5
3 3
.
If we choose:
N2=1
10
and we assume OUT1 is exact, the voltage on slave
output2 is:
N
IDEAL1
0 06875
.
=
=
.
N
N
IDEAL2
1
0 1010
.
=
=
...
V
V
OUT2
3.
1
10
1
15
3 3 1 5
. .
4 95
.
=
=
=
This does not include any other errors, so make sure that
the error in V
OUT2
is only a fraction of what your specifica-
tion allows. When dealing with large numbers of outputs
trial and error is usually required to get reasonable turns
ratios on all outputs while keeping the errors (due to
imperfect turns ratios) low.
For the selected turns ratios, the duty factor for this design
with 48V input would be:
D
V
V
N V
V
48
15
V
V
OUT
+
(
OUT
IN
=
)
=
+
=
1
1
3 3
.
3 3
.
0 508
.
Input Power
The maximum input power is:
P
P
Eff
IN
OUTK
K
N
=∑
=
1
where P
OUTK
is the maximum power supplied by output K
and Eff represents the efficiency of the converter.
Continuing the previous example, assume OUT1 delivers
3.3V at 2A and OUT2 delivers 4.95V at 0.5A. For a
conversion efficiency at maximum output power of 80%:
P
V
A
V
A
W
IN
=
+
0 80
.
=
3 3
.
2
4 95
.
0 5
11 34
.
Transformer Selection
The transformer primary inductance, L
P
, is selected based
on the percentage peak-to-peak ripple current (X) in the
transformer relative to its maximum value. In general, X
should range from 20% to 40% ripple current (i.e., X = 0.2
to 0.4). Higher values of ripple will increase conduction
losses, while lower values will require larger cores.
Ripple current and percentage ripple will be largest at
minimum duty factor D, in other words at the highest input
voltage. L
P
can be calculated from:
L
V
D
f X
P
P
IN MAX
(
MIN
MAX
IN
=
)
2
2
where f is nominally 250kHz.
Continuing the example, allow 40% maximum ripple at a
maximum input voltage of 72V:
D
V
72
15
2
V
V
L
V
Hz
W
H
MIN
P
=
+
=
=
=
μ
3 3
.
3 3
.
0 407
.
72
0 4 11 34
250000
757
2
0 407
.
V
OUT
2.5
3.3
3.3
5.0
1.8
3.3
1.8
2.5
2.5
3.3
5.0
TURNS
3
4
2
3
6
11
5
7
3
4
6
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相關代理商/技術參數(shù) |
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| LTC3806EDE#PBF | 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3806EDE#TR | 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3806EDE#TRPBF | 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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