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參數(shù)資料
| 型號： | LTC3780EUH |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DIODE SCHOTTKY SINGLE 25V 200mW 0.4V-vf 200mA-IFM 10mA-IF 0.5uA-IR SOD-323 3K/REEL |
| 中文描述： | 3 A SWITCHING CONTROLLER, 440 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封裝： | 5 X 5 MM, PLASTIC, MO-220WHHD, QFN-32 |
| 文件頁數(shù)： | 13/28頁 |
| 文件大?。?/td> | 421K |
| 代理商： | LTC3780EUH |
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13
LTC3780
3780f
The duty cycle of Switch C decreases until the minimum
duty cycle of the converter in Buck mode reaches
D
MIN_BOOST
, given by:
D
MIN_BOOST
= (D
BUCK-BOOST
) 100%
where D
BUCK-BOOST
is the duty cycle of the Buck-Boost
switch range:
D
BUCK-BOOST
= (200ns f) 100%
and f is the operating frequency in Hz.
Figure 5 shows typical boost mode waveforms. If V
IN
approaches V
OUT
, the Buck-Boost region is reached.
When the FCB pin voltage is lower than 0.8V, the control-
ler behaves as a continuous, PWM current mode syn-
chronous switching regulator. In Boost mode, Switch A is
always on. Switch C and Synchronous Switch D are
alternately turned on to maintain the output voltage
inde
pendent of direction of inductor current. Every ten
cycles, Switch A is forced off for about 300ns to allow C
A
to recharge. In Buck mode, Synchronous Switch D is
always on. Switch A and Synchronous Switch B are
alternately turned on to maintain the output voltage inde-
pendent of direction of inductor current. Every ten cycles,
Synchronous Switch D is forced off for about 300ns to
allow C
B
to recharge. This is the least efficient operating
mode at light load, but may be desirable in certain appli-
cations. In this mode, the output can source or sink
current. The sunk current will be forced back into the main
power supply potentially boosting the input supply to
dangerous voltage levels—BEWARE!
When the FCB pin voltage is below V
INTVCC
– 1V, but
greater than 0.8V, the controller enters Burst Mode opera-
tion in Boost operation or enters Skip-Cycle mode in Buck
operation. During Boost operation, Burst Mode operation
sets a minimum output current level before inhibiting the
switch C and turns off Synchronous Switch D when the
inductor current goes negative. This combination of re-
quirements will, at low currents, force the I
TH
pin below a
voltage threshold that will temporarily inhibit turn-on of
power switches C and D until the output voltage drops.
There is 100mV of hysteresis in the burst comparator tied
to the I
TH
pin. This hysteresis produces output signals to
the MOSFETs C and D that turn them on for several cycles,
followed by a variable “sleep” interval depending upon the
load current. The maximum output voltage ripple is limited
to 3% of the nominal DC output voltage as determined by
a resistive feedback divider. During buck operation, Skip-
Cycle mode sets a minimum positive inductor current
level. When inductor current is lower than this level,
Synchronous Switch B is kept off. In every cycle, the body
OPERATIOU
SWITCH A
CLOCK
SWITCH B
SWITCH C
SWITCH D
I
0V
2.4V
3780 F05
Figure 5. Boost Mode (V
IN
< V
OUT
)
LOW CURRENT OPERATION
The FCB pin is a multifunction pin providing two functions:
1) to provide regulation for a secondary winding by
temporarily forcing continuous PWM operation in Buck
mode and 2) to select among three modes for both buck
and boost operations by accepting a logic input. Figure 6
shows the different modes.
FCB PIN
0V to 0.75V
0.85V to 5V
>5.3V
BUCK MODE
Force Continuous Mode
Skip-Cycle Mode
DCM with Constant Freq
BOOST MODE
Force Continuous Mode
Burst Mode Operation
DCM with Constant Freq
Figure 6. Different Operating Modes
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3780EUH#PBF | 功能描述:IC REG CTRLR BST PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3780EUH#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC3780EUH#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP T/R |
| LTC3780EUH#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 32-QFN 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:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 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:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3780EUHPBF | 制造商:Linear Technology 功能描述:DC-DC Controller Step-Up/Down 36V QFN32 |
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