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参数资料
| 型号： | LTC3868EUFD-1#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/38页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-QFN |
| 标准包装： | 73 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 850kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 24 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3868-1
APPLICATIONS INFORMATION
The Typical Application on the ?rst page is a basic
LTC3868-1 application circuit. LTC3868-1 can be con?gured
to use either DCR (inductor resistance) sensing or low
value resistor sensing. The choice between the two cur-
rent 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 resistors and is more power ef?cient, 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 requirement, and begins with the selection of
R SENSE (if R SENSE is used) and inductor value. Next, the
programmed current limit unpredictable. If inductor DCR
sensing is used (Figure 5b), resistor R1 should be placed
close to the switching node, to prevent noise from coupling
into sensitive small-signal nodes.
TO SENSE FILTER,
NEXT TO THE CONTROLLER
C OUT
38681 F04
INDUCTOR OR R SENSE
Figure 4. Sense Lines Placement with Inductor or Sense Resistor
power MOSFETs and Schottky diodes are selected. Finally,
input and output capacitors are selected.
SENSE + and SENSE – Pins
The SENSE + and SENSE – pins are the inputs to the cur-
rent comparators. The common mode voltage range on
these pins is 0V to 16V (Absolute Maximum), enabling
the LTC3868-1 to regulate output voltages up to a nominal
14V (allowing margin for tolerances and transients).
V IN
INTV CC
BOOST
TG
SW
LTC3868-1
BG
SENSE +
SENSE –
PLACE CAPACITOR NEAR
SENSE PINS
V IN
V OUT
The SENSE + pin is high impedance over the full common
mode range, drawing at most ±1μA. This high impedance
allows the current comparators to be used in inductor
DCR sensing.
SGND
(5a) Using a Resistor to Sense Current
38681 F05a
The impedance of the SENSE – pin changes depending on
the common mode voltage. When SENSE – is less than
INTV CC – 0.5V, a small current of less than 1μA ?ows out
of the pin. When SENSE – is above INTV CC + 0.5V, a higher
current (~550μA) ?ows into the pin. Between INTV CC – 0.5V
and INTV CC + 0.5V, the current transitions from the smaller
current to the higher current.
V IN
INTV CC
BOOST
TG
SW
LTC3868-1
BG
SENSE +
R1
V IN
INDUCTOR
L DCR
V OUT
Filter components mutual to the sense lines should be
placed close to the LTC3868-1, and the sense lines should
run close together to a Kelvin connection underneath the
current sense element (shown in Figure 4). Sensing cur-
SENSE –
SGND
*PLACE C1 NEAR
SENSE PINS
C1* R2
(R1||R2) ? C1 =
L
DCR
R SENSE(EQ) = DCR
R2
R1 + R2
38681 F05b
rent elsewhere can effectively add parasitic inductance
and capacitance to the current sense element, degrading
the information at the sense terminals and making the
(5b) Using the Inductor DCR to Sense Current
Figure 5. Current Sensing Methods
38681fd
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3868EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3868EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3868IGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3868IGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3868IUFD-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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