參數(shù)資料
型號(hào)： LTC3833EUDC#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, PQCC20
封裝： 3 X 3 MM, LEAD FREE, PLASTIC, QFN-20
文件頁數(shù)： 16/36頁
文件大?。?/td> 513K
代理商： LTC3833EUDC#PBF
LTC3833
23
3833f
APPLICATIONS INFORMATION
where tON(MIN) is the effective minimum on-time for the
switching regulator. As the equation shows, reducing the
operating frequency will alleviate the minimum duty cycle
constraint.
If the application requires a smaller than minimum duty
cycle, the output voltage will still remain in regulation, but
theswitchingfrequencywilldecreasefromitsprogrammed
valueorlosefrequencysynchronizationifusinganexternal
clock. Depending on the application, this may not be of
critical importance.
For applications that require relatively low on-times,
proper caution has to be taken when choosing the top
power MOSFET. If a high Qg MOSFET is chosen such that
the on-time is not sufficient to fully turn the MOSFET on,
there will be significant losses in efficiency as a result
of larger RDS(ON) resistance and possibly failure of the
MOSFET due to significant heat dissipation.
The minimum off-time is the smallest duration of time
that the top power MOSFET’s gate can be turned off and
then immediately turned back on. This minimum off-time
includes the time to turn on the bottom power MOSFET’s
gate and turn it back off along with the dead time delays
from top MOSFET off to bottom MOSFET on and bottom
MOSFET off to top MOSFET on. The minimum off-time
that the LTC3833 can achieve is 90ns.
The effective minimum off-time of the switching regulator
is defined as the shortest period of time that the SW node
can stay low. This effective minimum off-time can vary
from the LTC3833’s 90ns of minimum off-time. The main
factor impacting the effective minimum off-time is the top
andbottompowerMOSFETs’gatechargingcharacteristics,
including Qg and turn-on/off delays. These characteristics
can either extend or shorten the SW node’s minimum
off-time as compared to the LTC3833’s minimum off-time.
Large size (high Qg) power MOSFETs generally tend to
increase the effective minimum off-time due to longer
gate charging and discharging times. On the other hand,
imbalances in turn-on and turn-off delays could reduce
the effective minimum off-time.
The minimum off-time limit imposes a maximum duty
cycle of:
DMAX = 1 – f tOFF(MIN)
where tOFF(MIN) is the effective minimum off-time of the
switching regulator. Reducing the operating frequency al-
leviatesthemaximumdutycycleconstraint.Ifthemaximum
duty cycle is reached, due to a drooping input voltage for
example, then the output will drop out of regulation. The
minimum input voltage to avoid dropout is:
VIN(MIN) =
VOUT
DMAX
At the onset of dropout, there is a region of VIN about
500mV that generates two discrete off-times, one being
the minimum off-time and the other being an off-time that
is about 40ns to 60ns larger than the minimum off-time.
This secondary off-time is due to the longer delay in trip-
ping the internal current comparator. The two off-times
average out to the required duty cycle to keep the output
in regulation with the output ripple remaining the same.
However, there is higher SW node jitter, especially appar-
ent when synchronized to an external clock. Depending
on the application, this may not be of critical importance.
DEAD-TIME
DELAYS
NEGATIVE
INDUCTOR
CURRENT
IN FCM
DURING BG-TG DEAD TIME,
NEGATIVE INDUCTOR CURRENT
WILL FLOW THROUGH TOP MOSFET’S
BODY DIODE TO PRECHARGE SW NODE
3833 F08
TG-SW
(VGS OF
TOP MOSFET)
BG
(VGS OF
BOTTOM MOSFET)
IL
SW
0
VIN
+–
IL
VIN
L
SW
DURING TG-BG DEAD TIME,
THE RATE OF SW NODE DISCHARGE
WILL DEPEND ON THE CAPACITANCE
ON THE SW NODE AND INDUCTOR
CURRENT MAGNITUDE
L
TOTAL CAPACITANCE
ON THE SW NODE
IL
Figure 8. Light Loading On-Time Extension with Forced
Continuous Mode Operation
相關(guān)PDF資料
PDF描述
LTC3833IFE#PBF SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, PDSO20
LTC3835IGN-1#TR 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PDSO16
LTC3835EDHC-1#TRPBF 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PDSO16
LTC3835IGN-1 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PDSO16
LTC3835IUFD 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PQCC20
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3833IFE#PBF 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP 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)
LTC3833IFE#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP 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)
LTC3833IUDC#PBF 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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)
LTC3833IUDC#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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)
LTC3834EDHC-1#PBF 功能描述:IC REG CTRLR BUCK PWM CM 16-DFN 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:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR)
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*