參數(shù)資料
型號(hào)： LTC3823IGN#TRPBF
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 4 A SWITCHING CONTROLLER, PDSO28
封裝： 0.150 INCH, LEAD FREE, PLASTIC, SSOP-28
文件頁(yè)數(shù)： 5/26頁(yè)
文件大?。?/td> 302K
代理商： LTC3823IGN#TRPBF
LTC3823
13
3823fd
When there is no RON resistor connected to the ION pin,
the on-time tON is theoretically innite, which in turn could
damage the converter. To prevent this, the LTC3823 detects
this fault condition and provides a minimum ION current
of 5μA to 10μA.
Changes in the load current magnitude will cause fre-
quency shift. Parasitic resistance in the MOSFET switches
and inductor reduce the effective voltage across the
inductance, resulting in increased duty cycle as the load
current increases. By lengthening the on-time slightly as
current increases, constant frequency operation can be
maintained. This is accomplished with a resistive divider
from the ITH pin to the VON pin and VOUT. The values
required will depend on the parasitic resistances in the
specic application. A good starting point is to feed about
25% of the voltage change at the ITH pin to the VON pin
as shown in Figure 3a. Place capacitance on the VON pin
to lter out the ITH variations at the switching frequency.
The resistor load on ITH reduces the DC gain of the error
amp and degrades load regulation, which can be avoided
by using the PNP emitter follower of Figure 3b.
MOSFET back off. This time is generally about 280ns.
The minimum off-time limit imposes a maximum duty
cycle of tON/(tON + tOFF(MIN)). If the maximum duty cycle
is reached, due to a dropping input voltage for example,
then the output will drop out of regulation. The minimum
input voltage to avoid dropout is:
VV
tt
t
IN MIN
OUT
ON
OFF MIN
ON
()
=
+
A plot of maximum duty cycle vs frequency is shown in
Figure 4.
APPLICATIONS INFORMATION
CVON
0.01μF
RVON2
100k
RVON1
30k
CC
VOUT
RC
(3a)
(3b)
VON
ITH
LTC3823
CVON
0.01μF
RVON2
10k
Q1
2N5087
RVON1
3k
10k
CC
3823 F03
VOUT
INTVCC
RC
VON
ITH
LTC3823
Figure 3. Correcting Frequency Shift with Load Current Changes
Minimum Off-Time and Dropout Operation
The minimum off-time tOFF(MIN) is the smallest amount of
time that the LTC3823 is capable of turning on the bottom
MOSFET, tripping the current comparator and turning the
2.0
1.5
1.0
0.5
0
0.25
0.50
0.75
3823 F04
1.0
DROPOUT
REGION
DUTY CYCLE (VOUT/VIN)
SWITCHING
FREQUENCY
(MHz)
Figure 4. Maximum Switching Frequency vs Duty Cycle
Inductor Selection
Given the desired input and output voltages, the induc-
tor value and operating frequency determine the ripple
current:
ΔI
V
fL
V
L
OUT
IN
=
1
Lower ripple current reduces core losses in the inductor,
ESR losses in the output capacitors and output voltage
ripple. Highest efciency operation is obtained at low
frequency with small ripple current. However, achieving
this requires a large inductor. There is a tradeoff between
component size, efciency and operating frequency.
A reasonable starting point is to choose a ripple current
that is about 40% of IOUT(MAX). The largest ripple current
occurs at the highest VIN. To guarantee that ripple current
相關(guān)PDF資料
PDF描述
LTC3851AEMSE-1#PBF 0.05 A SWITCHING CONTROLLER, 810 kHz SWITCHING FREQ-MAX, PDSO16
LTC3851AIUD-1#TRPBF 0.05 A SWITCHING CONTROLLER, 810 kHz SWITCHING FREQ-MAX, PQCC16
LTC3851AMPMSE-1#PBF 0.05 A SWITCHING CONTROLLER, 810 kHz SWITCHING FREQ-MAX, PDSO16
LTC3856IFE#PBF SWITCHING CONTROLLER, PDSO38
LTC3856EFE#PBF SWITCHING CONTROLLER, PDSO38
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3823IUH#PBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無(wú) 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:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤(pán) 包裝:Digi-Reel® 產(chǎn)品目錄頁(yè)面:1303 (CN2011-ZH PDF) 其它名稱(chēng):LM3754SQDKR
LTC3823IUH#PBF 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN32
LTC3823IUH#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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)
LTC3824EMSE 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 4V to 60V Input 10-Pin MSOP EP
LTC3824EMSE#PBF 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無(wú) 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:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤(pán) 包裝:Digi-Reel® 產(chǎn)品目錄頁(yè)面:1303 (CN2011-ZH PDF) 其它名稱(chēng):LM3754SQDKR
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 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*