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参数资料
| 型号： | LTC3809EDD-1#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/24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： | 600kHz |
| 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) |
LTC3809-1
OPERATION
(Refer to Functional Diagram)
In sleep mode, much of the internal circuitry is turned off,
reducing the quiescent current that the LTC3809-1 draws.
The load current is supplied by the output capacitor. As
the output voltage decreases, the EAMP increases the
I TH voltage. When the I TH voltage reaches 0.925V, the
SLEEP signal goes low and the controller resumes normal
operation by turning on the external P-channel MOSFET
on the next cycle of the internal oscillator.
When the controller is enabled for Burst Mode or pulse-
skipping operation, the inductor current is not allowed to
reverse. Hence, the controller operates discontinuously.
The reverse current comparator RICMP senses the
drain-to-source voltage of the bottom external N-channel
MOSFET. This MOSFET is turned off just before the inductor
current reaches zero, preventing it from going negative.
In forced continuous operation, the inductor current is
allowed to reverse at light loads or under large transient
conditions. The peak inductor current is determined by the
high as Burst Mode operation. During start-up or an
undervoltage condition (V FB ≤ 0.54V), the LTC3809-1
operates in pulse-skipping mode (no current reversal
allowed), regardless of the state of the MODE pin.
Short-Circuit and Current Limit Protection
The LTC3809-1 monitors the voltage drop Δ V SC (between
the GND and SW pins) across the external N-channel
MOSFET with the short-circuit current limit comparator.
The allowed voltage is determined by:
Δ V SC(MAX) = A ? 90mV
where A is a constant determined by the state of the IPRG
pin. Floating the IPRG pin selects A = 1; tying IPRG to V IN
selects A = 5/3; tying IPRG to GND selects A = 2/3.
The inductor current limit for short-circuit protection is
determined by Δ V SC(MAX) and the on-resistance of the
external N-channel MOSFET:
voltage on the I TH pin. The P-channel MOSFET is turned
on every cycle (constant frequency) regardless of the I TH
pin voltage. In this mode, the ef?ciency at light loads is
I SC =
Δ V SC(MAX )
R DS ( ON )
lower than in Burst Mode operation. However, continuous
mode has the advantages of lower output ripple and no
noise at audio frequencies.
When the MODE pin is set to the V FB Pin, the LTC3809-1
operates in PWM pulse-skipping mode at light loads. In
this mode, the current comparator ICMP may remain
tripped for several cycles and force the external P-channel
MOSFET to stay off for the same number of cycles. The
inductor current is not allowed to reverse (discontinuous
operation). This mode, like forced continuous operation,
exhibits low output ripple as well as low audible noise
and reduced RF interference as compared to Burst Mode
operation. However, it provides low current ef?ciency
Once the inductor current exceeds I SC , the short current
comparator will shut off the external P-channel MOSFET
until the inductor current drops below I SC .
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 P-channel
MOSFET is turned off and the N-channel MOSFET is turned
on until the overvoltage is cleared.
higher than forced continuous mode, but not nearly as
38091fc
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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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