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参数资料
| 型号： | LTC3853EUJ#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 40-QFN |
| 产品培训模块： | LTC3853 Multiphase Switching Controller |
| 标准包装： | 2,000 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 3 |
| 频率 - 最大： | 830kHz |
| 占空比： | 98% |
| 电源电压： | 4.5 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 ~ 125°C |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3853
APPLICATIONS INFORMATION
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. The capacitor C1 should
be placed close to the IC pins.
The current comparator has a maximum threshold
V SENSE(MAX) determined by the I LIM setting. 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,
D I L . To calculate the sense resistor value, use the equation:
D I L
I (MAX) +
V IN
INTV CC
BOOST
V IN
R SENSE =
V SENSE(MAX)
2
TG
SW
LTC3853
BG
PGND
SENSE +
SENSE –
SGND
R F
C F R F
L1
R S
R SENSE
ESL
Because of possible PCB noise in the current sensing loop,
the AC current sensing ripple of D V SENSE = D 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 D V SENSE voltage is recommended
as a conservative number to start with, either for R SENSE
or DCR sensing applications.
TG
*PLACE C1 NEAR SENSE + ,
R1|| R2 ? C1 =
R SENSE(EQ) = DCR
DCR
R1 + R2
FILTERCOMPONENTS 3853F02a
PLACED NEAR SENSE PINS
(2a) Using a Resistor to Sense Current
V IN V IN
INTV CC
BOOST
INDUCTOR
SW L DCR V OUT
LTC3853
BG
PGND
R1
SENSE +
C1* R2
SENSE –
SGND
L R2
3853 F02b
SENSE – PINS
(2b) Using the Inductor DCR to Sense Current
Figure 2. Two Different Methods of Sensing Current
Low Value Resistors Current Sensing
A typical sensing circuit using a discrete resistor is shown
in Figure 2a. R SENSE is chosen based on the required
output 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
a relatively small error. For today’s highest current density
solutions, however, the value of the sense resistor can be
less than 1m? and the peak sense voltage can be as low
as 20mV. In addition, inductor ripple currents greater than
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 filter placed near the IC was commonly used to reduce
the effects of capacitive and inductive noise coupled in
the sense traces on the PCB. A typical filter consists of
two series 10? resistors connected to a parallel 1000pF
capacitor, resulting in a time constant of 20ns.
This same RC filter, with minor modifications, can be used
to extract the resistive component of the current sense
signal in the presence of parasitic inductance. For example,
Figure 3 illustrates the voltage waveform across a 2m?
sense resistor with a 2010 footprint for the 1.2V/15A
converter operating at 100% load. The waveform is the
superposition of a purely resistive component and a
purely inductive component. It was measured using two
3853fa
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3853IUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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: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 |
| LTC3853IUJ#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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: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 |
| LTC3854EDDB#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Cut Tape Small Footprint, Low Pin Count Synchronous Step-Do |
| LTC3854EDDB#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 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) |
| LTC3854EDDB#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 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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