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| 型号： | LTC3838EUHF#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 23/54页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38-QFN |
| 标准包装： | 52 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 2MHz |
| 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-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3838
APPLICATIONS INFORMATION
? 1 + 0.4% ( T L(MAX) – 25 ° C ) ?
?
?
2 ? ?
? ? I OUT(MAX) –
< 10A, set R F to 10Ω and C F to 1000pF. This will provide
a good starting point.
The filter components need to be placed close to the IC.
The positive and negative sense traces need to be routed
as a differential pair and Kelvin (4-wire) connected to the
sense resistor.
DCR Inductor Current Sensing
For applications requiring higher efficiency at high load
currents, the LTC3838 is capable of sensing the voltage
drop across the inductor DCR, as shown in Figure 5. The
DCR of the inductor represents the small amount of DC
winding resistance, which can be less than 1mΩ for today’s
low value, high current inductors.
In a high current application requiring such an inductor,
conduction loss through a sense resistor would cost several
points of efficiency compared to DCR sensing.
The inductor DCR is sensed by connecting an RC filter
across the inductor. This filter typically consists of one or
two resistors (R1 and R2) and one capacitor (C1) as shown
in Figure 5. If the external (R1||R2) ? C1 time constant is
chosen to be exactly equal to the L/DCR time constant, the
voltage drop across the external capacitor is equal to the
voltage drop across the inductor DCR multiplied by R2/
(R1 + R2). Therefore, R2 may be used to scale the voltage
across the sense terminals when the DCR is greater than
INDUCTOR
the target sense resistance. With the ability to program
current limit through the V RNG pin, R2 may be optional. C1
is usually selected in the range of 0.01μF to 0.47μF. This
forces R1||R2 to around 2k to 4k, reducing error that might
have been caused by the SENSE pins’ input bias currents.
Resistor R1 should be placed close to the switching node,
to prevent noise from coupling into sensitive small-signal
nodes. Capacitor C1 should be placed close to the IC pins.
The first step in designing DCR current sensing is to
determine the DCR of the inductor. Where provided, use
the manufacturer’s maximum value, usually given at 25°C.
Increase this value to account for the temperature coef-
ficient of resistance, which is approximately 0.4%/°C. A
conservative value for inductor temperature T L is 100°C.
The DCR of the inductor can also be measured using a good
RLC meter, but the DCR tolerance is not always the same
and varies with temperature; consult the manufacturers’
data sheets for detailed information.
From the DCR value, V SENSE(MAX) is easily calculated as:
V SENSE(MAX) = DCR MAX(25 ° C)
?
? Δ I L ?
?
If V SENSE(MAX) is within the maximum sense voltage (30mV
to 100mV) of the LTC3838 as programmed by the V RNG
pin, then the RC filter only needs R1. If V SENSE(MAX) is
LTC3838
L DCR
L/DCR = (R1||R2) C1
V OUT
C OUT
higher, then R2 may be used to scale down the maximum
sense voltage so that it falls within range.
R1
SENSE +
SENSE –
C1
R2
(OPT)
3838 F05
C1 NEAR SENSE PINS
Figure 5. DCR Current Sensing
3838fa
23
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相关代理商/技术参数 |
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| LTC3838IFE#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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3838IFE#TRPBF | 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3838IUHF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-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) |
| LTC3838IUHF#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-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) |
| LTC3838IUHF-1#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 38QFN 制造商:Linear Technology 功能描述:BUCK DUAL CNTRL 4.5-38V 2MHZ 38QFN 制造商:Linear Technology 功能描述:BUCK, DUAL, CNTRL, 4.5-38V, 2MHZ, 38QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual, Fast, Accurate Step-Down Controller with Differential 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, DUAL, BUCK, ADJ, QFN-38, Primary Input Voltage:38V, No. of Outputs:2, Output Current:25A, No. of Pins:38, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes |
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