- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄382259 > LTC3806EDE (LINEAR TECHNOLOGY CORP) Synchronous Flyback DC/DC Controller PDF資料下載
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)： | 11/20頁 |
| 文件大?。?/td> | 241K |
| 代理商： | LTC3806EDE |
11
LTC3806
3806f
The rising threshold voltage on the RUN pin is equal to the
internal reference voltage of 1.230V. The comparator has
91mV of hysteresis to increase noise immunity.
The turn-on and turn-off input voltage thresholds are
programmed using a resistor divider according to the
following formulas:
V
V
R
R
R
R
V
V
IN OFF
(
IN ON
(
)
)
.
.
=
+
=
+
1 139
1
2
1
2
1
1 230
1
The resistor R1 is typically chosen to be less than 1M.
For
applications where the RUN pin is only to be used as a
logic input, the user should be aware of the 7V Absolute
Maximum Rating for this pin!
The RUN pin can be
connected to the input voltage through an external 1M
resistor, as shown in Figure 3c, for “always on” operation.
Application Circuits
A basic LTC3806 application circuit is shown in Figure 1.
External component selection is driven by the character-
istics of the load and the input supply.
Duty Cycle Considerations
Current and voltage stress on the power switch and
synchronous rectifiers, input and output capacitor RMS
currents and transformer utilization (size vs power) are
impacted by duty factor. Unfortunately duty factor cannot
be adjusted to simultaneously optimize all of these re-
quirements. In general, avoid extreme duty factors since
this severely impacts the current stress on most of the
components. A reasonable target for duty factor is 50% at
nominal input voltage. Using this rule of thumb, calculate
the ideal transformer turns ratio:
N
V
V
D
D
IDEAL
OUT
IN
=
1
1
–
APPLICATIOU
W
U
U
For a 50% duty factor, this reduces to:
N
V
V
IDEAL
OUT
IN
=
1
If N
IDEAL
is integer, use this for your turns ratio. If not, find
a ratio of small integers that comes close to N
IDEAL
. If these
conditions are met, bifilar winding techniques can be used
that will improve coupling coefficient. Cross regulation
will be better and primary-side snubbing may be reduced
or eliminated.
The selected turns ratio doesn’t have to be perfectly equal
to N
IDEAL
because a flyback converter’s output voltage is
not set through transformer action. Instead, the trans-
former stores energy when the primary-side switch turns
on and transfers this energy to the output(s) by flyback
action when the primary-side switch turns off.
Cross regulation may be improved by using a target duty
factor which is less than 50%. This improves cross
regulation because the secondary-side MOSFETs (syn-
chronous rectifiers) will be on a larger percentage of the
time (thereby increasing the average coupling between the
outputs). Duty factor is reduced by proportionately in-
creasing all turns ratios.
Reduced duty factor has the following effect on MOSFET
stresses:
MOSFET
MOSFET
LOCATION
Primary
Secondary
CURRENT STRESS
Increased
Reduced
VOLTAGE STRESS
Reduced
Increased
The duty factor with the selected turns ratio will equal:
V
V
N V
OUT
IN
)
1
D
OUT
+
(
=
1
While the output(s)/input turns ratio are not critical, the
turns ratio
between
outputs are critical and affect the
accuracy of the slave output voltages.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3831 | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| LTC3831EGN | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| LTC3832 | High Power Step-Down Synchronous DC/DC Controllers for Low Voltage Operation |
| LTC3832-1 | High Power Step-Down Synchronous DC/DC Controllers for Low Voltage Operation |
| LTC3832-1ES8 | High Power Step-Down Synchronous DC/DC Controllers for Low Voltage Operation |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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) |
| LTC3808EDE | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Step Down 2.75V to 9.8V Input 14-Pin DFN EP |
| LTC3808EDE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 14-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) |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。