參數(shù)資料
型號(hào)： LTC3805MPMSE-5#PBF
廠(chǎng)商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO10
封裝： LEAD FREE, PLASTIC, MSOP-10
文件頁(yè)數(shù)： 6/20頁(yè)
文件大?。?/td> 254K
代理商： LTC3805MPMSE-5#PBF
LTC3805-5
14
38055fe
APPLICATIONS INFORMATION
Overcurrent Threshold Adjustment
Figure 5 shows the connection of the overcurrent pin, OC,
along with the ISENSE pin and the current sense resistor
RSENSE located in the source circuit of the power NMOS
which is driven by the GATE pin. The internal overcurrent
thresholdontheOCpinissetatVOCT=100mVwhichisthe
sameasthepeakcurrentsensevoltageVI(MAX)=100mVon
the ISENSE pin. The role of the slope compensation adjust-
ment resistor RSLOPE and the slope compensation current
ISLOPEisdiscussedinthepriorsection.Incombinationwith
the overcurrent threshold adjust current IOC = 10A, an
external resistor ROC can be used to lower the overcurrent
trip threshold from 100mV. This section describes how
to pick ROC to achieve the desired performance. In the
discussion that follows be careful to distinguish between
“current limit” where the converter continues to run with
the ISENSE pin limiting current on a cycle-by-cycle basis
while the output voltage falls below the regulation point
and “overcurrent protection” where the OC pin senses an
overcurrent and shuts down the converter for a timeout
period before attempting an automatic restart.
One overcurrent protection strategy is for the converter
to never enter current limit but to maintain output volt-
age regulation up to the point of tripping the overcurrent
protection. Operation at minimum input voltage VIN(MIN)
hits current limiting for the smallest output current and
is the design point for this strategy.
First,foroperationatVIN(MIN),calculatethedutycycleDuty
CycleVIN(MIN)usingtheappropriateformuladependingon
whether the converter is a boost, flyback or SEPIC. Then
use Duty Cycle VIN(MIN) to calculate DVSENSE(VIN(MIN))
using the formula in the prior section. For overcurrent
protection to trip at exactly the point where current limit-
ing would begin set:
ROC(CRIT) =
DVSENSE VIN(MIN)
(
)
10A
To find the actual output current that trips overcurrent
protection, calculate the peak switch current IPK(VIN(MIN))
from:
IPK VIN(MIN)
(
) =
100mV
DVSENSE VIN(MIN)
(
)
RSENSE
Then calculate the converter output current that corre-
sponds to IPK(VIN(MIN)). Again, the calculation depends
both on converter type and the details of converter design
including inductor current ripple. For minimum input volt-
age, ROC(CRIT) produces an overcurrent trip at an output
current just before loss of output voltage regulation and
the onset of current limiting. Note that the output current
that causes an overcurrent trip is higher for higher input
voltages but that an overcurrent trip will always occur
before loss of output voltage regulation. If desired to
meet a specific design target, an increase in ROC above
ROC(CRIT) can be used to reduce the trip threshold and
make the converter trip for a lower output current.
This calculation is based on steady-state operation. De-
pending on design, overcurrent protection can also be
triggered during a start-up transient, particularly if large
outputfiltercapacitorsarebeingchargedasoutputvoltage
rises. If that is a problem, output capacitor charging can
be slowed by using a larger value of SSFLT capacitor. It is
also possible to trip overcurrent protection during a load
step especially if the trip threshold is lowered by making
ROC > ROC(CRIT).
Another overcurrent protection strategy is keep the con-
verter running as current limiting reduces the duty cycle
and the output voltage sags. In this case, the goal is often
keeptheconverterinnormaloperationoveraswidearange
as possible, including current limiting, and to trigger the
Figure 5. Circuit to Decrease Overcurrent Threshold
LTC3805-5
OC
GATE
ISENSE
RSENSE
RSLOPE
IOC = 10A
ISLOPE
GND
38055 F05
ROC
相關(guān)PDF資料
PDF描述
LTC3827IG-1 3 A DUAL SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO28
LTC3827IG-1#TR 3 A DUAL SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO28
LTC3853IUJ#TR 0.15 A DUAL SWITCHING CONTROLLER, 830 kHz SWITCHING FREQ-MAX, PQCC40
LTC3853EUJ#TR 0.15 A DUAL SWITCHING CONTROLLER, 830 kHz SWITCHING FREQ-MAX, PQCC40
LTC3853EUJ 0.15 A DUAL SWITCHING CONTROLLER, 830 kHz SWITCHING FREQ-MAX, PQCC40
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3806EDE 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:否 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3806EDE#PBF 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:是 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3806EDE#TR 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:否 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3806EDE#TRPBF 功能描述:IC REG CTRLR FLYBACK PWM 12-DFN RoHS:是 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3808EDE 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Step Down 2.75V to 9.8V Input 14-Pin DFN EP
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(xiě)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(chǎng)商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*