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| 型号： | LTC3809EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/24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： | 825kHz |
| 占空比： | 100% |
| 电源电压： | 2.75 V ~ 9.8 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) |
LTC3809
APPLICATIONS INFORMATION
V OUT
is an edge sensitive digital type that provides zero degrees
phase shift between the external and internal oscillators.
LTC3809
R B
C FF
This type of phase detector does not exhibit false lock to
V FB
R A
3809 F03
Figure 3. Settling Output Voltage
For most applications, a 59k resistor is suggested for R A .
In applications where minimizing the quiescent current is
critical, R A should be made bigger to limit the feedback
divider current. If R B then results in very high impedance,
it may be bene?cial to bypass R B with a 50pF to 100pF
capacitor C FF .
Run and Soft-Start Functions
The LTC3809 has a low power shutdown mode which is
controlled by the RUN pin. Pulling the RUN pin below 1.1V
puts the LTC3809 into a low quiescent current shutdown
mode (I Q = 9μA). Releasing the RUN pin, an internal 0.7μA
(at V IN = 4.2V) current source will pull the RUN pin up
to V IN , which enables the controller. The RUN pin can be
harmonics of the external clock.
The output of the phase detector is a pair of complementary
current sources that charge or discharge the external ?lter
network connected to the PLLLPF pin. The relationship
between the voltage on the PLLLPF pin and operating
frequency, when there is a clock signal applied to SYNC/
MODE, is shown in Figure 5 and speci?ed in the electrical
characteristics table. Note that the LTC3809 can only be
synchronized to an external clock whose frequency is within
range of the LTC3809’s internal VCO, which is nominally
200kHz to 1MHz. This is guaranteed, over temperature and
process variations, to be between 250kHz and 750kHz. A
simpli?ed block diagram is shown in Figure 6.
1200
1000
800
600
driven directly from logic as showed in Figure 4.
400
Once the controller is enabled, the start-up of V OUT is
controlled by the internal soft-start, which slowly ramps
200
the positive reference to the error ampli?er from 0V to 0.6V,
allowing V OUT to rise smoothly from 0V to its ?nal value.
The default internal soft-start time is around 1ms.
0
0.2
0.7 1.2 1.7
PLLLPF PIN VOLTAGE (V)
2.2
3809 F05
3.3V OR 5V
Figure 5. Relationship Between Oscillator Frequency
LTC3809
RUN
LTC3809
RUN
and Voltage at the PLLLPF Pin When Synchronizing to
an External Clock
2.4V
Figure 4. RUN Pin Interfacing
3809 F04
R LP
C LP
Phase-Locked Loop and Frequency Synchronization
The LTC3809 has a phase-locked loop (PLL) comprised of
EXTERNAL
OSCILLATOR
SYNC/
MODE
DIGITAL
PHASE/
FREQUENCY
DETECTOR
PLLLPF
OSCILLATOR
an internal voltage-controlled oscillator (VCO) and a phase
detector. This allows the turn-on of the external P-channel
MOSFET to be locked to the rising edge of an external clock
signal applied to the SYNC/MODE pin. The phase detector
3809 F06
Figure 6. Phase-Locked Loop Block Diagram
3809fc
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3809EMSE | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 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) |
| LTC3809EMSE#PBF | 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) |
| LTC3809EMSE#TR | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 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) |
| LTC3809EMSE#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) |
| LTC3809EMSE-1 | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 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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