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參數(shù)資料
| 型號： | LTC3543EDCB#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | 2 X 3 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-229, DFN-6 |
| 文件頁數(shù)： | 20/20頁 |
| 文件大?。?/td> | 329K |
| 代理商： | LTC3543EDCB#PBF |
LTC3543
9
3543fa
Figure 1a. Output Noise Spectrum of Conventional Buck Switching
Converter (LTC3543 with Spread Spectrum Disabled) Showing
Fundamental and Harmonic Frequencies
FREQUENCY (MHz)
2.0
AMPLITUDE
(dBm) –50
–30
–10
2.8
3543 F01a
–70
–90
–60
–40
–20
–80
–100
–110
2.2
2.4
2.6
3.0
RBW = 3kHz
Unlike conventional buck converters, the LTC3543’s inter-
nal oscillator is designed to produce a clock pulse whose
frequency is randomly varied between 2MHz and 3MHz.
This has the benet of spreading the switching noise over
a range of frequencies, signicantly reducing the peak
noise. Figure 1b shows the output noise spectrum of the
LTC3543 (with spread spectrum operation enabled) with VIN
= 3.6V, VOUT = 1.5V and IOUT = 300mA. Note the signicant
reduction in peak output noise (
20dBm).
Phase-Locked Loop Operation
A phase-locked loop (PLL) is available on the LTC3543
to synchronize the internal oscillator to an external clock
source that is connected to the MODE pin. In this case, an
external capacitor should be connected between the CAP
pin and GND to serve as part of the PLL’s loop lter. The
LTC3543’s phase detector adjusts the voltage on the CAP
pin to align the turn-on of the internal P-channel MOSFET
to the rising edge of the synchronizing signal. Note that
when the MODE pin is not being driven by an external
clock source, the MODE pin must be held to one of the
following voltage potentials: VIN, GND, or VFB.
The typical capture range of the LTC3543 ’s PLL is guar-
anteed over temperature to be 1MHz to 3MHz. In other
words, the LTC3543’s PLL is guaranteed to lock to an
external clock source whose frequency is between 1MHz
and 3MHz.
Selecting the switching frequency is a trade-off between
efciency and component size. Low frequency opera-
tion increases efciency by reducing MOSFET switching
losses, but requires larger inductance and/or capacitance
to maintain low output ripple voltage.
Note that the PLL is inhibited during soft-start and uses
the internal 2.25MHz frequency until regulation is estab-
lished. Also the regulator is in pulse skip mode during
PLL operation.
Short-Circuit Protection
When the output is shorted to ground, the LTC3543 senses
the high inductor current and disallows the main power
FET from turning on. The main FET is held off until the
inductor current decays to a normal level.
Dropout Operation
Depending upon the external feedback resistor ratio, it is
possible for VIN to approach the output voltage level. As
the input supply voltage decreases to a value approaching
the output voltage, the duty cycle increases toward the
maximum on-time. Further reduction of the supply voltage
forces the main switch to remain on for more than one cycle
until it reaches 100% duty cycle. The output voltage will
then be determined by the input voltage minus the voltage
drop across the P-channel MOSFET and the inductor.
Figure 1b. Output Noise Spectrum of the LTC3543 Spread Spectrum
Buck Switching Converter. Note the Reduction in Fundamental and
Harmonic Peak Spectral Amplitude Compared to Figure 1a.
FREQUENCY (MHz)
2.0
AMPLITUDE
(dBm) –50
–30
–10
2.8
3543 F01b
–70
–90
–60
–40
–20
–80
–100
–110
2.2
2.4
2.6
3.0
RBW = 3kHz
OPERATION
相關(guān)PDF資料 |
PDF描述 |
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| LTC3543EDCB#TRM | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3543EDCB | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3544BEUD#TR | 0.8 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC16 |
| LTC3544EUD | 0.8 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC16 |
| LTC3547BEDDB | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3544 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544B | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544BEUD | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544BEUD#PBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN 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:- 標準包裝: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)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC3544BEUD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN 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:- 標準包裝:2,500 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，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
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