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參數(shù)資料
| 型號(hào)： | LTC3560IS6#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | 1 MM HEIGHT, LEAD FREE, PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 256K |
| 代理商： | LTC3560IS6#TRPBF |
LTC3560
7
3560fb
OPERATION (Refer to Functional Diagram)
Main Control Loop
The LTC3560 uses a constant frequency, current mode step-
down architecture. Both the main (P-channel MOSFET)
and synchronous (N-channel MOSFET) switches are
internal. During normal operation, the internal top power
MOSFET is turned on each cycle when the oscillator sets
the RS latch, and turned off when the current comparator,
ICOMP, resets the RS latch. The peak inductor current
at which ICOMP resets the RS latch, is controlled by the
output of error amplier EA. The VFB pin, described in
the Pin Functions section, allows EA to receive an output
feedback voltage from an external resistive divider. When
the load current increases, it causes a slight decrease in
the feedback voltage relative to the 0.6V reference, which
in turn, causes the EA amplier’s output voltage to increase
until the average inductor current matches the new load
current. While the top MOSFET is off, the bottom MOSFET
is turned on until either the inductor current starts to
reverse, as indicated by the current reversal comparator
IRCMP, or the beginning of the next clock cycle.
The main control loop is shut down by grounding RUN,
resetting the internal soft-start. Re-enabling the main
control loop by pulling RUN high activates the internal
soft-start, which slowly ramps the output voltage over
approximately 0.9ms until it reaches regulation.
Burst Mode Operation
The LTC3560 is capable of Burst Mode operation in which
the internal power MOSFETs operate intermittently based
on load demand. To enable Burst Mode operation, simply
connect the SYNC/MODE pin to GND. To disable Burst
Mode operation and enable PWM pulse-skipping mode,
connect the SYNC/MODE pin to VIN or drive it with a logic
high (VMODE > 1.5V). In this mode, the efciency is lower
at light loads, but becomes comparable to Burst Mode
operation when the output load exceeds 100mA. The
advantage of pulse-skipping mode is lower output ripple
and less interference to audio circuitry.
When the converter is in Burst Mode operation, the peak
current of the inductor is set to approximately 150mA
regardless of the output load. Each burst event can last
from a few cycles at light loads to almost continuously
cycling with short sleep intervals at moderate loads. In
between these burst events, the power MOSFETs and any
unneeded circuitry are turned off, reducing the quiescent
current to 16μA. In this sleep state, the load current is being
supplied solely from the output capacitor. As the output
voltage droops, the EA amplier’s output rises above the
sleep threshold signaling the BURST comparator to trip
and turn the top MOSFET on. This process repeats at a
rate that is dependent on the load demand.
Frequency Synchronization
When the LTC3560 is clocked by an external source, Burst
Mode operation is disabled; the LTC3560 then operates in
PWM pulse-skipping mode. In this mode, when the output
load is very low, current comparator ICOMP may remain
tripped for several cycles and force the main switch to stay
off for the same number of cycles. Increasing the output
load slightly allows constant frequency PWM operation
to resume. This mode exhibits low output ripple as well
as low audio noise and reduced RF interference while
providing reasonable low current efciency.
Dropout Operation
Astheinputsupplyvoltagedecreasestoavalueapproaching
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.
Another 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 LTC3560 is used at 100% duty cycle with low
input voltage (See Thermal Considerations in the Applica-
tions Information section).
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3561 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3561A | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3561AEDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1A 8DFN 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)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC3561AEDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1A 8DFN 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:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC3561AEDD-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1A, 4MHz, Synchronous Step-Down DC/DC Converter |
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