參數(shù)資料
型號(hào)： LT3511EMS#TRPBF
廠(chǎng)商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 0.43 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
封裝： LEAD FREE, PLASTIC, MSOP-12/16
文件頁(yè)數(shù)： 6/26頁(yè)
文件大?。?/td> 298K
代理商： LT3511EMS#TRPBF
LT3511
14
3511fb
APPLICATION DESIGN CONSIDERATIONS
Iterative Design Process
The LT3511 uses a unique sampling scheme to regulate
theisolatedoutputvoltage.Theuseofthisisolatedscheme
requires a simple iterative process to choose feedback
resistors and temperature compensation. Feedback re-
sistor values and temperature compensation resistance
is heavily dependent on the application, transformer and
output diode chosen.
Once resistor values are fixed after iteration, the values
will produce consistent output voltages with the chosen
transformer and output diode. Remember, the turns ratio
of the transformer must be guaranteed within ±1%. The
transformer vendors mentioned in this data sheet can
build transformers to this specification.
Selecting RFB and RREF Resistor Values
The following section provides an equation for setting
RFB and RREF values. The equation should only serve
as a guide. Follow the procedure outlined in the Design
Procedure to set accurate values for RFB, RREF and RTC
using the iterative design procedure.
Rearrangement of the expression for VOUTintheTempera-
ture Compensation section, developed in the Operations
section, yields the following expression for RFB:
RFB =
RREF NPS VOUT + VF
(
)+ VTC
VBG
where:
VOUT = Output voltage
VF = Switching diode forward voltage
NPS = Effective primary-to-secondary turns ratio
VTC = 0.55V
This equation assumes:
RTC =
RFB
NPS
The equation assumes the temperature coefficients of
the diode and VTC are equal, which is a good first order
approximation.
Strictly speaking, the above equation defines RFBnotasan
absolute value, but as a ratio of RREF. So the next question
is, what is the proper value for RREF? The answer is that
RREFshouldbeapproximately10k.TheLT3511istrimmed
and specified using this value of RREF. If the impedance of
RREF varies considerably from 10k, additional errors will
result. However, a variation in RREF of several percent is
acceptable. This yields a bit of freedom in selecting stan-
dard 1% resistor values to yield nominal RFB/RREF ratios.
Undervoltage Lockout (UVLO)
A resistive divider from VIN to the EN/UVLO pin imple-
ments undervoltage lockout (UVLO). Figure 7 shows this
configuration. The EN/UVLO pin threshold is set at 1.21V.
In addition, the EN/UVLO pin draws 2.6μA when the volt-
age at the pin is below 1.21V. This current provides user
programmable hysteresis based on the value of R1. The
effective UVLO thresholds are:
VIN(UVLO,RISING) =
1.2V R1+R2
(
)
R2
+ 2.6A R1
VIN(UVLO,FALLING) =
1.2V R1+R2
(
)
R2
Figure 7 also shows the implementation of external shut-
down control while still using the UVLO function. The
NMOS grounds the EN/UVLO pin when turned on, and
puts the LT3511 in shutdown with quiescent current draw
of less than 1μA.
LT3511
EN/UVLO
GND
R2
R1
VIN
3511 F07
RUN/STOP
CONTROL
(OPTIONAL)
Figure 7. Undervoltage Lockout (UVLO)
applicaTions inForMaTion
相關(guān)PDF資料
PDF描述
LT3511MPMS#PBF 0.43 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
LT3511HMS#PBF 0.43 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
LT3512EMS#PBF 0.8 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
LT3512HMS#TRPBF 0.8 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
LT3512MPMS#PBF 0.8 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT3511HMS#PBF 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP 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:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱(chēng):AS1323-BTTT-30CT
LT3511HMS#TRPBF 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP 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:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱(chēng):AS1323-BTTT-30CT
LT3511IMS#PBF 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP 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)
LT3511IMS#TRPBF 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP 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)
LT3511MPMS#PBF 功能描述:IC REG FLYBK ISO ADJ .24A 16MSOP 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:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱(chēng):AS1323-BTTT-30CT
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