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| 型号： | LTC3822EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 8/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 10-DFN |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 850kHz |
| 占空比： | 99% |
| 电源电压： | 2.75 V ~ 4.5 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 ~ 85°C |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
LTC3822
OPERATION
Main Control Loop
(Refer to Functional Diagram)
EAMP compares the feedback signal V FB to the internal
The LTC3822 uses a constant frequency, current mode
architecture. During normal operation, the top external
N-channel power MOSFET is turned on when the clock
sets the RS latch, and is turned off when the current
comparator (ICMP) resets the latch. The peak inductor
current at which ICMP resets the RS latch is determined
by the voltage on the I TH pin, which is driven by the output
of the error ampli?er (EAMP). The V FB pin receives the
output voltage feedback signal from an external resistor
divider. This feedback signal is compared to the internal
0.6V reference voltage by the EAMP. When the load cur-
rent increases, it causes a slight decrease in V FB relative
to the 0.6V reference, which in turn causes the I TH voltage
to increase until the average inductor current matches the
new load current. While the top N-channel MOSFET is off,
the bottom N-channel MOSFET is turned on until either
the inductor current starts to reverse, as indicated by the
current reversal comparator RICMP, or the beginning of
the next cycle.
Shutdown and Soft-Start (RUN Pin)
The LTC3822 is shut down by pulling the RUN pin low. In
shutdown, all controller functions are disabled and the chip
draws only 7.5μA. The TG and BG outputs are held low
(off) in shutdown. Releasing the RUN pin allows an internal
0.7μA current source to pull up the RUN pin to V IN . The
controller is enabled when the RUN pin reaches 1.1V.
The start-up of V OUT is controlled by the LTC3822’s
internal soft-start. During soft-start, the error ampli?er
soft-start ramp (instead of the 0.6V reference), which rises
linearly from 0V to 0.6V in about 650μs. This allows the
output voltage to rise smoothly from 0V to its ?nal value
while maintaining control of the inductor current.
Light Load Operation
LTC3822 operates discontinuously at low load currents.
The reverse current comparator RICMP senses the
drain-to-source voltage of the bottom external N-channel
MOSFET. This MOSFET is turned off when the inductor
current reaches zero. Under certain operating conditions
brief inductor current reversal may cause continuous
switching operation.
Short-Circuit Protection
The LTC3822 monitors V FB to detect a short-circuit on
V OUT . When V FB is near ground, switching frequency is
reduced to prevent the inductor current from running
away. The oscillator frequency will progressively return
to normal when V FB rises above ground. This feature is
disabled during startup.
Output Overvoltage Protection
As further protection, the overvoltage comparator (OVP)
guards against transient overshoots, as well as other more
serious conditions that may overvoltage the output. When
the feedback voltage on the V FB pin has risen 13.33%
above the reference voltage of 0.6V, the external top-side
MOSFET is turned off and the bottom MOSFET is turned
on until the overvoltage is cleared.
3822fa
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相关代理商/技术参数 |
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| LTC3822EGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 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 |
| LTC3822EGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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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| LTC3822EMSE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP 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) |
| LTC3823EGN#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:- 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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