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參數(shù)資料
| 型號(hào)： | LTC3803ES6-3 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING CONTROLLER, 330 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | 1 MM HEIGHT, PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件頁(yè)數(shù)： | 2/16頁(yè) |
| 文件大?。?/td> | 165K |
| 代理商： | LTC3803ES6-3 |
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10
LTC3803-3
38033fa
APPLICATIO S I FOR ATIO
WU
UU
Many LTC3803-3 application circuits can be derived from
the topology shown in Figure 2.
The LTC3803-3 itself imposes no limits on allowed power
output, input voltage VIN or desired regulated output volt-
age VOUT; these are all determined by the ratings on the
external power components. The key factors are: Q1’s
maximum drain-source voltage (BVDSS), on-resistance
(RDS(ON)) and maximum drain current, T1’s saturation flux
level and winding insulation breakdown voltages, CIN and
COUT’s maximum working voltage, ESR, and maximum
ripple current ratings, and D1 and RSENSE’s power ratings.
VCC
ITH/RUN
LTC3803-3
GND
NGATE
SENSE
VFB
5
R3
6
4
1
2
3
D1
D2
COUT
CIN
LSEC
LPRI
LBIAS
CVCC
CC
VOUT
38033 F02
RSENSE
RSL
R1
RSTART
R2
Q1
T1
VIN
Figure 2. Typical LTC3803-3 Application Circuit
TRANSFORMER DESIGN CONSIDERATIONS
Transformer specification and design is perhaps the most
critical part of applying the LTC3803-3 successfully. In
addition to the usual list of caveats dealing with high fre-
quency power transformer design, the following should
prove useful.
Turns Ratios
Due to the use of the external feedback resistor divider
ratio to set output voltage, the user has relative freedom in
selecting transformer turns ratio to suit a given applica-
tion. Simple ratios of small integers, e.g., 1:1, 2:1, 3:2, etc.
can be employed which yield more freedom in setting total
turns and mutual inductance. Simple integer turns ratios
also facilitate the use of “off-the-shelf” configurable trans-
formers such as the Coiltronics VERSA-PAC
TM series in
applications with high input to output voltage ratios. For
example, if a 6-winding VERSA-PAC is used with three
windings in series on the primary and three windings in
parallel on the secondary, a 3:1 turns ratio will be achieved.
Turns ratio can be chosen on the basis of desired duty
cycle. However, remember that the input supply voltage
plus the secondary-to-primary referred version of the
flyback pulse (including leakage spike) must not exceed
the allowed external MOSFET breakdown rating.
Leakage Inductance
Transformer leakage inductance (on either the primary or
secondary) causes a voltage spike to occur after the
output switch (Q1) turn-off. This is increasingly promi-
nent at higher load currents, where more stored energy
must be dissipated. In some cases a “snubber” circuit will
be required to avoid overvoltage breakdown at the
MOSFET’s drain node. Application Note 19 is a good
reference on snubber design.
A bifilar or similar winding technique is a good way to
minimize troublesome leakage inductances. However,
remember that this will limit the primary-to-secondary
breakdown voltage, so bifilar winding is not always
practical.
SELECTING FEEDBACK RESISTOR DIVIDER VALUES
The regulated output voltage is determined by the resistor
divider across VOUT (R1 and R2 in Figure 2). The ratio of R2
to R1 needed to produce a desired VOUT can be calculated:
R
VV
V
R
OUT
2
08
1
=
–.
.
Choose resistance values for R1 and R2 to be as large as
possible in order to minimize any efficiency loss due to the
static current drawn from VOUT, but just small enough so
that when VOUT is in regulation, the error caused by the
nonzero input current to the VFB pin is less than 1%. A
good rule of thumb is to choose R1 to be 80k or less.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3803ES6-3#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Flyback 6-Pin TSOT-23 Bulk 制造商:Linear Technology 功能描述:DC/DC CONTRLER FLYBACK 300KH 制造商:Linear Technology 功能描述:DC/DC CONTRLER, FLYBACK, 300KHZ, 6SOT23 |
| LTC3803ES6-3#TRMPBF | 功能描述:IC REG CTRLR FLYBK PWM TSOT23-6 RoHS:是 類別: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 包裝:帶卷 (TR) |
| LTC3803ES6-3#TRPBF | 功能描述:IC REG CTRLR FLYBK PWM TSOT23-6 RoHS:是 類別: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 包裝:帶卷 (TR) |
| LTC3803ES6-5 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Flyback 5V Input 6-Pin TSOT-23 |
| LTC3803ES6-5#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Sync Flyback 5V Input 6-Pin TSOT-23 Bulk |
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