參數(shù)資料
型號(hào)： LT3575EFE#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 4.2 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16
封裝： 4.40 MM, LEAD FREE, PLASTIC, TSSOP-16
文件頁(yè)數(shù)： 23/24頁(yè)
文件大?。?/td> 240K
代理商： LT3575EFE#PBF
LT3575
8
3575f
ERROR AMPLIFIER—PSEUDO DC THEORY
In the Block Diagram, the RREF (R4) and RFB (R3) resistors
can be found. They are external resistors used to program
theoutputvoltage.TheLT3575operatesmuchthesameway
as traditional current mode switchers, the major difference
being a different type of error amplier which derives its
feedback information from the yback pulse.
Operation is as follows: when the output switch, Q1,
turns off, its collector voltage rises above the VIN rail. The
amplitude of this yback pulse, i.e., the difference between
it and VIN, is given as:
VFLBK = (VOUT + VF + ISEC ESR) NPS
VF = D1 forward voltage
ISEC = Transformer secondary current
ESR = Total impedance of secondary circuit
NPS = Transformer effective primary-to-secondary
turns ratio
The yback voltage is then converted to a current by
the action of RFB and Q2. Nearly all of this current ows
through resistor RREF to form a ground-referred voltage.
This voltage is fed into the yback error amplier. The
yback error amplier samples this output voltage
information when the secondary side winding current is
zero. The error amplier uses a bandgap voltage, 1.23V,
as the reference voltage.
The relatively high gain in the overall loop will then cause
the voltage at the RREF resistor to be nearly equal to the
bandgap reference voltage VBG. The relationship between
VFLBK and VBG may then be expressed as:
α
V
R
V
R
or
VV
R
FLBK
FB
BG
REF
FLBK
BG
FB
REF
=
,
1
α
α = Ratio of Q1 IC to IE, typically ≈ 0.986
VBG = Internal bandgap reference
In combination with the previous VFLBK expression yields
an expression for VOUT, in terms of the internal reference,
programming resistors, transformer turns ratio and diode
forward voltage drop:
VV
R
RN
VI
ES
OUT
BG
FB
REF
PS
FSEC
=
1
α
(R
R)
Additionally, it includes the effect of nonzero secondary
output impedance (ESR). This term can be assumed to
be zero in boundary control mode. More details will be
discussed in the next section.
Temperature Compensation
The rst term in the VOUT equation does not have a tem-
perature dependence, but the diode forward drop has a
signicant negative temperature coefcient. To compen-
sate for this, a positive temperature coefcient current
source is connected to the RREF pin. The current is set by
a resistor to ground connected to the TC pin. To cancel the
temperature coefcient, the following equation is used:
δ
V
T
R
RN
V
T
or
R
NV
FFB
TC
PS
TC
FB
PS
=
,
1
FF
TC
FB
PS
T
V
T
R
N
/
δ
≈
(
δVF/δT) = Diode’s forward voltage temperature
coefcient
(
δVTC/δT) = 2mV
VTC = 0.55V
The resistor value given by this equation should also be
veried experimentally, and adjusted if necessary to achieve
optimal regulation overtemperature.
The revised output voltage is as follows:
VV
R
RN
V
R
OUT
BG
FB
REF
PS
F
TC
=
1
α
–
(
)
R
N
IESR
FB
PS
SEC
α
APPLICATIONS INFORMATION
相關(guān)PDF資料
PDF描述
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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LT3575IFE#TRPBF 功能描述:IC REG FLYBACK ISO ADJ 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(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:- 類型:升壓（升壓） 輸出類型: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 - 開關(guān):- 電流 - 輸出:100mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型: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:AS1323-BTTT-30CT
LT3579 制造商:LINER 制造商全稱:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection
LT3579-1 制造商:LINER 制造商全稱:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection
LT3579EFE#PBF 功能描述:IC REG MULTI CONFIG SYNC 20TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型: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:296-25628-2
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