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參數(shù)資料
| 型號(hào)： | LTC3809EMS-1#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING CONTROLLER, 600 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | PLASTIC, MSOP-10 |
| 文件頁(yè)數(shù)： | 2/24頁(yè) |
| 文件大?。?/td> | 318K |
| 代理商： | LTC3809EMS-1#PBF |
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LTC3809-1
38091f
10
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 ITH
voltage. When the ITH voltage reaches 0.925V, the SLEEP
signal goes low and the controller resumes normal opera-
tion 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
voltage on the ITH pin. The P-channel MOSFET is turned on
every cycle (constant frequency) regardless of the ITH pin
voltage. In this mode, the efficiency at light loads is 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 VFB 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 efficiency
higher than forced continuous mode, but not nearly as
high as Burst Mode operation. During start-up or an
undervoltage condition (VFB ≤ 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
VSC (between
the SGND/PGND and SW pins) across the external
N-channel MOSFET with the short-circuit current limit
comparator. The allowed voltage is determined by:
VSC(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 VIN
selects A = 5/3; tying IPRG to GND selects A = 2/3.
The inductor current limit for short-circuit protection is
determined by
VSC(MAX) and the on-resistance of the
external N-channel MOSFET:
I
V
R
SC
SC MAX
DS ON
=
()
Once the inductor current exceeds ISC, the short current
comparator will shut off the external P-channel MOSFET
until the inductor current drops below ISC.
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 VFB pin has risen 13.33%
above the reference voltage of 0.6V, the external P-chan-
nel MOSFET is turned off and the N-channel MOSFET is
turned on until the overvoltage is cleared.
(Refer to Functional Diagram)
OPERATIO
U
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| LTC3809EMSE | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3809EMSE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3809EMSE#TR | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3809EMSE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3809EMSE-1 | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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