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参数资料
| 型号： | LTC3852EUDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 19/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR DOUBLER PWM 24-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 810kHz |
| 占空比： | 99% |
| 电源电压： | 2.7 V ~ 38 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 是 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3852
APPLICATIONS INFORMATION
V MASTER
V OUT
and the BOOST pin follows. With the topside MOSFET on,
TO
TRACK/SS
PIN
R3
R4
TO
V FB
PIN
R3
R4
the boost voltage is above the input supply:
V BOOST = V IN + V INTVCC
3852 F05a
(5a) Coincident Tracking Setup
The value of the boost capacitor C B needs to be 100 times
that of the total input capacitance of the topside MOSFET.
The reverse breakdown of the external Schottky diode
must be greater than V IN(MAX) .
V MASTER
R1
R3
V OUT
Undervoltage Lockout
TO
TRACK/SS
PIN
R2
TO
V FB
PIN
R4
The LTC3852 has two functions that help protect the
controller in case of undervoltage conditions. A precision
3852 F05b
(5b) Ratiometric Tracking Setup
Figure 5. Setup for Coincident and Ratiometric Tracking
UVLO comparator constantly monitors the INTV CC voltage
to ensure that an adequate gate-drive voltage is present. It
locks out switching action when INTV CC falls below 3.25V.
To prevent oscillation when there is a disturbance on the
INTV CC , the UVLO comparator has 400mV of precision
hysteresis.
I
I
Another way to detect an undervoltage condition is to
TRACK/SS
0.8V
V FB
D1
D2
3852 F06
D3
+
–
EA
monitor the V IN supply. Because the RUN pin has a precision
turn-on reference of 1.25V, one can use a resistor divider
to V IN to turn on the IC when V IN is high enough.
C IN Selection
? V IN
?
? I O(MAX) OUT ?
V IN ? V OUT
?
Figure 6. Equivalent Input Circuit of Error Ampli?er
Although this error is minimized by the exponential I-V
characteristic of the diode, it does impose a ?nite amount
of output voltage deviation. Furthermore, when the master
supply’s output experiences dynamic excursion (under
load transient, for example), the slave channel output will
be affected as well. For better output regulation, use the
coincident tracking mode instead of ratiometric.
Topside MOSFET Driver Supply (C B , D B )
An external bootstrap capacitor C B connected to the
BOOST pin supplies the gate drive voltage for the topside
MOSFET. Capacitor C B in the Functional Diagram is charged
though external diode D B from INTV CC when the SW pin
is low. When the topside MOSFET is to be turned on, the
driver places the C B voltage across the gate source of the
MOSFET. This enhances the MOSFET and turns on the
In continuous mode, the source current of the top N-channel
MOSFET is a square wave of duty cycle V OUT /V IN . To
prevent large voltage transients, a low ESR input capacitor
sized for the maximum RMS current must be used. The
maximum RMS capacitor current is given by:
1/ 2
V
?
I RMS – 1
This formula has a maximum at V IN = 2V OUT , where I RMS =
I O(MAX) /2. This simple worst-case condition is commonly
used for design because even signi?cant deviations do not
offer much relief. Note that capacitor manufacturers’ ripple
current ratings are often based on only 2000 hours of life.
This makes it advisable to further derate the capacitor or
to choose a capacitor rated at a higher temperature than
required. Several capacitors may also be paralleled to meet
size or height requirements in the design. Always consult
the manufacturer if there is any question.
topside switch. The switch node voltage, SW, rises to V IN
3852f
19
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| LTC3852IUDD#PBF | 功能描述:IC REG CTRLR DOUBLER PWM 24-QFN 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) |
| LTC3852IUDD#TRPBF | 功能描述:IC REG CTRLR DOUBLER PWM 24-QFN 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) |
| LTC3853EUJ#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® 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 |
| LTC3853EUJ#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® 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 |
| LTC3853EUJPBF | 制造商:Linear Technology 功能描述:DC-DC Controller Triple Buck 24V QFN40 |
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