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參數(shù)資料
| 型號： | LTC3850EUF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.1 A DUAL SWITCHING CONTROLLER, 860 kHz SWITCHING FREQ-MAX, PQCC28 |
| 封裝： | 4 X 4 MM, PLASTIC, QFN-28 |
| 文件頁數(shù)： | 4/32頁 |
| 文件大小： | 474K |
| 代理商： | LTC3850EUF |
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LTC3850
12
3850f
The Typical Application on the rst page is a basic LTC3850
application circuit. LTC3850 can be congured to use either
DCR (inductor resistance) sensing or low value resistor
sensing. The choice between the two current sensing
schemes is largely a design trade-off between cost, power
consumption, and accuracy. DCR sensing is becoming
popular because it saves expensive current sensing resis-
tors and is more power efcient, especially in high current
applications. However, current sensing resistors provide
the most accurate current limits for the controller. Other
external component selection is driven by the load require-
ment, and begins with the selection of RSENSE (if RSENSE is
used) and inductor value. Next, the power MOSFETs and
Schottky diodes are selected. Finally, input and output
capacitors are selected.
Current Limit Programming
The ILIMpinisatri-levellogicinputwhichsetsthemaximum
current limit of the controller. When ILIM is grounded, the
maximum current limit threshold of the current compara-
tor is programmed to be 30mV. When ILIM is oated, the
maximum current limit threshold is 50mV. When ILIM is
tied to INTVCC, the maximum current limit threshold is
set to 75mV.
APPLICATIONS INFORMATION
SENSE+ and SENSE– Pins
The SENSE+ and SENSE– pins are the inputs to the current
comparators. The common mode input voltage range of
the current comparators is 0V to 5V. Both SENSE pins
are high impedance inputs with small base currents of
less than 1A. When the SENSE pins ramp up from 0V
to 1.4V, the small base currents ow out of the SENSE
pins. When the SENSE pins ramp down from 5V to 1.1V,
the small base currents ow into the SENSE pins. The
high impedance inputs to the current comparators allow
accurate DCR sensing. However, care must be taken not
to oat these pins during normal operation.
Filter components mutual to the sense lines should be
placed close to the LTC3850, and the sense lines should
run close together to a Kelvin connection underneath the
current sense element (shown in Figure 1). Sensing cur-
rent elsewhere can effectively add parasitic inductance
and capacitance to the current sense element, degrading
the information at the sense terminals and making the
programmed current limit unpredictable. If DCR sensing
is used (Figure 2b), sense resistor R1 should be placed
close to the switching node, to prevent noise from coupling
into sensitive small-signal nodes.
Figure 2. Two Different Methods of Sensing Current
VIN
INTVCC
BOOST
TG
SW
BG
PGND
FILTER COMPONENTS
PLACED NEAR SENSE PINS
SENSE+
SENSE–
SGND
LTC3850
VOUT
3850 F02a
Figure 1. Sense Lines Placement with Inductor or Sense Resistor
VIN
INTVCC
BOOST
TG
SW
BG
PGND
*PLACE C1 NEAR SENSE+,
SENSE– PINS
INDUCTOR
DCR
L
SENSE+
SENSE–
SGND
LTC3850
VOUT
3850 F02b
R1
R2
C1*
R1||R2
× C1 =
L
DCR
RSENSE(EQ) = DCR
R2
R1 + R2
COUT
TO SENSE FILTER,
NEXT TO THE CONTROLLER
INDUCTOR OR RSENSE
3850 F01
(2a) Using a Resistor to Sense Current
(2b) Using the Inductor DCR to Sense Current
相關(guān)PDF資料 |
PDF描述 |
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| LTC3850EUF#TR | 0.1 A DUAL SWITCHING CONTROLLER, 860 kHz SWITCHING FREQ-MAX, PQCC28 |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3850EUF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 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 |
| LTC3850EUF#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN CONTROLLER QFN-28 |
| LTC3850EUF#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)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) |
| LTC3850EUFD#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 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 |
| LTC3850EUFD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)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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