參數(shù)資料
型號(hào)： LT3686EDD#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO10
封裝： 3 X 3 MM, LEAD FREE, PLASTIC, MO-229WEED-2, DFN-10
文件頁(yè)數(shù)： 10/28頁(yè)
文件大?。?/td> 509K
代理商： LT3686EDD#PBF
LT3686
18
3686fc
ApplicAtions inForMAtion
below the minimum voltage to sustain boosted operation
(2.2V across the boost capacitor), the output voltage will
fall suddenly to:
VOUT = (VIN–2.2)DCMAX
Figure 9 shows the minimum VIN necessary to sustain
boosted operation during dropout. Once VIN drops below
the sustain voltage, VIN will need to reach the start voltage
again to refresh the boost capacitor. The programmable
undervoltage lockout (UVLO) function can be used to
avoid operating unless VINisgreaterthanthestartvoltage.
Fixed Frequency at Light Load
The LT3686 contains unique active load circuitry to allow
for full frequency switching at very light loads. To enable
the active load, tie the MODE pin to greater than 0.8V.
Typical fixed frequency nonsynchronous buck regulators
skip pulses at light loads. With a fixed input voltage, as
the load current decreases in discontinuous mode, the
regulator is required to switch for shorter periods of time.
When the required on time decreases below the typical
minimum on time, the regulator skips one or more pulses
so the effective average duty cycle is equal to the required
duty cycle. This likelihood of entering pulse-skipping is
exacerbated by the tendency for minimum on time to
increase at very light loads. Pulse-skipping is undesirable
because it causes unpredictable, sub-harmonic output
ripplethatcaninterferewiththeoperationofothersensitive
components such as AM receivers and audio equipment.
The BD active load is designed to combat pulse-skipping
by providing an operational regime between full frequency
discontinuous and pulse-skipping modes.
The maximum VIN before pulse-skipping in discontinu-
ous mode is directly dependent on load current; as the
load decreases, so does the pulse-skipping boundary. An
artificial load on the output helps push the pulse-skipping
boundary higher. The LT3686 achieves this goal by com-
manding the minimum load necessary to keep itself at
full switching frequency, hence the circuitry is called an
active load.
AstheLT3686approachesminimumontimeindiscontinu-
ous mode, its power switch transitions smoothly into a
fixed on time, fixed frequency open loop current source.
Instead of controlling switch current, the internal error
amplifier servos the active load on the output via the BD
pin to maintain output voltage regulation. The impact on
efficiency is mitigated by pulling the minimum current
necessary to keep switching at full frequency. The neces-
sary BD load to maintain output regulation depends on
VIN, inductor size, and load current. As the necessary
BD load increases beyond its 40mA limit, pulse-skipping
mode will resume.
The BD active load circuitry is enabled when MODE tied
high and disabled when MODE is tied low. Even when
activated, the active load will shutdown when BD voltage
exceeds either 5.2V or VIN in an effort to minimize power
dissipationandintelligentlyreacttoexternalconfigurations.
To address the startup concerns delineated in the BOOST
and BD Pin Considerations section, the active load will
assist startup by pulling maximum current (40mA) to
charge the boost capacitor voltage in the absence of an
adequate load. An internal power good circuit will disable
the BD active load when VFB reaches 0.7V. Figure 9 com-
pares plots of minimum input voltage to start and run as
a function of load current. In many cases the discharged
output capacitor will present a load to the switcher which
will allow it to start. The plots show the worst-case situ-
ation where VIN is ramping very slowly.
The active load also activates to hasten the recharge of
boost cap when operating beyond maximum duty cycle.
When not in use, the active load pulls no current.
Figure 10. Regions of Operation (5VOUT, 2MHz)
IOUT (mA)
0
V IN
(V)
5
10
20
25
35
30
40
15
20
40
60
100
120
140
80
3686 F10
CCM
DCM
ACTIVE
LOAD
PULSE-SKIPPING
相關(guān)PDF資料
PDF描述
LT3686IDD#TRPBF 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO10
LT3688IFE#TRPBF SWITCHING REGULATOR, PDSO24
LT3688EUF#PBF SWITCHING REGULATOR, PQCC24
LT3688IFE#PBF SWITCHING REGULATOR, PDSO24
LT3688HFE#PBF SWITCHING REGULATOR, PDSO24
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT3686EDDTRPBF 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:37V/1.2A Step-Down Regulator in 3mm × 3mm DFN
LT3686HDD#PBF 功能描述:IC REG BUCK ADJ 1.2A 10-DFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開(kāi)關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁(yè)面:1032 (CN2011-ZH PDF) 其它名稱(chēng):296-25628-2
LT3686HDD#PBF 制造商:Linear Technology 功能描述:IC PWM STEP-DOWN DC/DC CONVERTER DFN10 制造商:Linear Technology 功能描述:IC, PWM STEP-DOWN DC/DC CONVERTER, DFN10
LT3686HDD#TRPBF 功能描述:IC REG BUCK ADJ 1.2A 10DFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤(pán) 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤(pán)
LT3686IDD 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:37V/1.2A Step-Down Regulator in 3mm × 3mm DFN
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

*
*
*