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| 型号： | LTC3865EFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/38页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38TSSOP |
| 特色产品： | LTC3865 Dual Synchronous Controllers |
| 标准包装： | 50 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 880kHz |
| 占空比： | 95% |
| 电源电压： | 4.5 V ~ 38 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 ~ 125°C |
| 封装/外壳： | 38-TFSOP （0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3865/LTC3865-1
APPLICATIONS INFORMATION
Filter components mutual to the sense lines should be
placed close to the LTC3865/LTC3865-1, and the sense
V IN
INTV CC
V IN
lines should run close together to a Kelvin connection
underneath the current sense element (shown in Figure 1).
Sensing current elsewhere can effectively add parasitic
inductance and capacitance to the current sense element,
degrading the information at the sense terminals and mak-
ing 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
BOOST
TG
LTC3865 SW
BG
PGND
SENSE +
SENSE –
SGND
C F
R F
R F
SENSE RESISTOR
PLUS PARASITIC
INDUCTANCE
R S ESL
C F ? 2 RF ≤ ESL/R S
POLE-ZERO
CANCELLATION
V OUT
coupling into sensitive small-signal nodes. The capacitor
C1 should be placed close to the IC pins.
FILTER COMPONENTS
PLACED NEAR SENSE PINS
3865 F02a
(2a) Using a Resistor to Sense Current
TO SENSE FILTER,
NEXT TO THE CONTROLLER
V IN
INTV CC
V IN
3865 F01
C OUT
BOOST
INDUCTOR
INDUCTOR OR R SENSE
TG
L
DCR
Figure 1. Sense Lines Placement with Inductor or Sense Resistor
LTC3865
SW
V OUT
BG
PGND
Low Value Resistors Current Sensing
SENSE +
R1
A typical sensing circuit using a discrete resistor is shown
in Figure 2a. R SENSE is chosen based on the required
SENSE –
SGND
C1*
R2
output current.
The current comparator has a maximum threshold
*PLACE C1 NEAR SENSE + ,
SENSE – PINS
R1||R2 ? C1 =
L
DCR
R SENSE(EQ) = DCR
R2
R1 + R2
3865 F02b
V SENSE(MAX) determined by the I LIM setting. The input
common mode range of the current comparator is 0V
to 5V. The current comparator threshold sets the peak of
the inductor current, yielding a maximum average output
current I MAX equal to the peak value less half the peak-to-
peak ripple current, Δ I L . To calculate the sense resistor
value, use the equation:
(2b) Using the Inductor DCR to Sense Current
Figure 2. Two Different Methods of Sensing Current
For previous generation current mode controllers, the
maximum sense voltage was high enough (e.g., 75mV for
the LTC1628 / LTC3728 family) that the voltage drop across
the parasitic inductance of the sense resistor represented
I ( MAX ) +
R SENSE =
V SENSE ( MAX )
Δ I L
2
a relatively small error. For today’s highest current density
solutions, however, the value of the sense resistor can be
less than 1mΩ and the peak sense voltage can be as low
as 20mV. In addition, inductor ripple currents greater than
Because of possible PCB noise in the current sensing loop,
the AC current sensing ripple of Δ V SENSE = Δ I L ? R SENSE
also needs to be checked in the design to get a good
signal-to-noise ratio. In general, for a reasonably good
PCB layout, a 15mV Δ V SENSE voltage is recommended
as a conservative number to start with, either for R SENSE
or DCR sensing applications.
50% with operation up to 1MHz are becoming more com-
mon. Under these conditions the voltage drop across the
sense resistor’s parasitic inductance is no longer negligible.
A typical sensing circuit using a discrete resistor is shown
in Figure 2a. In previous generations of controllers, a small
RC ?lter placed near the IC was commonly used to reduce
the effects of capacitive and inductive noise coupled in
3865fb
15
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相关代理商/技术参数 |
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| LTC3865EUH#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 |
| LTC3865EUH#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) |
| LTC3865EUH-1#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 |
| LTC3865EUH-1#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) |
| LTC3865IFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP 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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