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参数资料
| 型号： | LTC3543EDCB |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封装： | 2 X 3 MM, 0.75 MM HEIGHT, PLASTIC, MO-229, DFN-6 |
| 文件页数： | 15/16页 |
| 文件大小： | 295K |
| 代理商： | LTC3543EDCB |
LTC3543
8
3543f
OPERATIO
U
of a conventional buck switching converter (LTC3543
with spread spectrum operation disabled) with VIN = 3.6V,
VOUT = 1.5V and IOUT = 300mA.
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 sig-
nicant 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 tradeoff 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.
An important detail to remember is that at low input supply
voltages, the RDS(ON) of the P-channel switch increases
(see Typical Performance Characteristics). Therefore,
the user should calculate the power dissipation when
the LTC3543 is used at 100% duty cycle with low input
voltage (See Thermal Considerations in the Applications
Information section).
Low Supply Operation
The LTC3543 will operate with input supply voltages as
low as 2.5V, but the maximum allowable output current
is reduced at this low voltage. Figure 2 shows the reduc-
tion in the maximum output current as a function of input
voltage for various output voltages.
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
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3543EDCB#PBF | 制造商:Linear Technology 功能描述:REG STEP DOWN 0.6A SMD DFN-6 制造商:Linear Technology 功能描述:REG, STEP DOWN, 0.6A, SMD, DFN-6 |
| LTC3543EDCB#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3543EDCB#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3544 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544B | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
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