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參數(shù)資料
| 型號(hào)： | LTC3780 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | DIODE SCHOTTKY DUAL ISOLATED 25V 150mW 0.33V-vf 200mA-IFM 2mA-IF 0.5uA-IR SOT-563 3K/REEL |
| 中文描述： | 高效率，同步，四開關(guān)降壓升壓控制器 |
| 文件頁數(shù)： | 21/28頁 |
| 文件大?。?/td> | 421K |
| 代理商： | LTC3780 |
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21
LTC3780
3780f
The Standby Mode (STBYMD) Pin Function
The Standby mode (STBYMD) pin provides several choices
for start-up and standby operational modes. If the pin is
pulled to ground, the SS pin is internally pulled to ground,
preventing start-up and thereby providing a single control
pin for turning off the controller. If the pin is left open or
decoupled with a capacitor to ground, the SS pin is
internally provided with a starting current, permitting
external control for turning on the controller. If the pin is
connected to a voltage greater than 1.25V, the internal
regulator (INTV
CC
) will be on even when the controller is
shut down (RUN pin voltage < 1.5V). In this mode, the
onboard 6V linear regulator can provide power to keep-
alive functions such as a keyboard controller.
FCB Pin Regulates Secondary Winding in Buck Mode
In Buck mode, the FCB pin can be used to regulate a
secondary winding or as a logic level input. Continuous
operation is forced when the FCB pin drops below 0.8V.
During continuous mode, current flows continuously in
the transformer primary. The secondary winding(s) draw
current only when Switch B and Switch D are on in Buck
mode. When primary load currents are low and/or the
V
IN
/V
OUT
ratio is low, the Synchronous Switch B may not
be on for a sufficient amount of time to transfer power
from the output capacitor to the secondary load. Forced
continuous operation will support secondary windings if
there is sufficient synchronous switch duty factor. Thus,
the FCB input pin removes the requirement that power
must be drawn from the auxiliary windings. With the loop
in continuous mode, the auxiliary outputs may nominally
be loaded without regard to the primary output load.
The secondary output voltage V
SEC
is normally set as
shown in Figure 10 by turns ratio N of the transformer:
V
SEC
≈
(N + 1) V
OUT
However, if the controller goes into Burst Mode operation
and halts switching due to a light primary load current,
then V
SEC
will drop. An external resistive divider from V
SEC
to the FCB pin sets a minimum voltage V
SEC(MIN)
:
V
R
R
SEC MIN
(
)
0.
≈
+
1
6
5
If the V
SEC
drops below this level, the FCB voltage forces
temporary continuous switching operation until V
SEC
is
again above its minimum.
In order to prevent erratic operation if no external connec-
tions are made to FCB pin, the FCB pin has a 0.18
μ
A
internal current source pulling the pin high. Include this
current when choosing resistor values R5 and R6.
Fault Conditions: Current Limit and Current Foldback
The maximum inductor current is inherently limited in a
current mode controller by the maximum sense voltage. In
Boost mode, maximum sense voltage and the sense
resistance determines the maximum allowed inductor
peak current, which is:
I
mV
R
L MAXBOOST
(
,
SENSE
)
=
160
APPLICATIU
W
U
U
A
SW2
TG2
BG2
SW1
TG1
C
OUT
R6
R5
BG1
R
SENSE
3780 F10
LTC3780
FCB
SGND
V
IN
V
SEC
T1
1:N
V
OUT
B
D
C
Figure 10. Secondary Output Loop
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PDF描述 |
|---|---|
| LTC3780IG | High Efficiency, Synchronous, 4-Switch Buck-Boost Controller |
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| LTC3780EG | DIODE SCHOTTKY SINGLE 25V 200mW 0.4V-vf 200mA-IFM 10mA-IF 0.5uA-IR SOD-123 3K/REEL |
| LTC3780EUH | DIODE SCHOTTKY SINGLE 25V 200mW 0.4V-vf 200mA-IFM 10mA-IF 0.5uA-IR SOD-323 3K/REEL |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3780EG | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 24-Pin SSOP |
| LTC3780EG#PBF | 功能描述:IC REG CTRLR BST PWM CM 24-SSOP 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(biāo)準(zhǔn)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 |
| LTC3780EG#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 24-Pin SSOP T/R |
| LTC3780EG#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 24-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)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 |
| LTC3780EGPBF | 制造商:Linear Technology 功能描述:4-Switch Buck-Boost Controller SSOP24 |
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