參數(shù)資料
型號(hào)： LTC3565IMSE#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 2.5 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PDSO10
封裝： LEAD FREE, PLASTIC, MSOP-10
文件頁(yè)數(shù)： 2/22頁(yè)
文件大小： 587K
代理商： LTC3565IMSE#PBF
LTC3565
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operation
The LTC3565 uses a constant frequency, current mode
architecture. The operating frequency is determined by
the value of the RT resistor or can be synchronized to an
external oscillator. To suit a variety of applications, the
selectable MODE pin allows the user to trade-off noise
for efficiency.
The output voltage is set by an external divider returned
to the VFB pin. An error amplifier compares the divided
output voltage with the reference voltage of 0.6V and ad-
justs the peak inductor current accordingly. Overvoltage
and undervoltage comparators will pull the PGOOD output
low if the output voltage is not within ±7% of its regulated
value. A tripping delay of 40s and untripping delay of
105s ensures PGOOD will not glitch due to transient
spikes on VOUT.
Main Control Loop
During normal operation, the top power switch (P-channel
MOSFET) is turned on at the beginning of a clock cycle.
Current flows through this switch into the inductor and
theload,increasinguntilthepeakinductorcurrentreaches
the limit set by the voltage on the ITH pin. Then, the top
switch is turned off, the bottom switch is turned on, and
the energy stored in the inductor forces the current to flow
through the bottom switch and the inductor out into the
load until the next clock cycle.
The peak inductor current is controlled by the voltage
on the ITH pin, which is the output of the error amplifier.
The output is developed by the error amplifier comparing
the feedback voltage, VFB, to the 0.6V reference voltage.
When the load current increases, the output voltage and
VFB decrease slightly. This decrease in VFB causes the er-
ror amplifier to increase the ITH voltage until the average
inductor current matches the new load current.
The main control loop is shut down by grounding the RUN
pin, 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.
Low Current Operation
Three modes are available to control the operation of the
LTC3565 at low currents. All three modes automatically
switch from continuous operation to the selected mode
when the load current is low.
To optimize efficiency, the Burst Mode operation can be
selected. When the load is relatively light, the LTC3565
automaticallyswitchesintoBurstModeoperationinwhich
the PMOS switch operates intermittently based on load
demand. By running cycles periodically, the switching
losses which are dominated by the gate charge losses
of the power MOSFETs are minimized. The main control
loop is interrupted when the output voltage reaches the
desired regulated value. The burst comparator trips when
ITH is below approximately 0.5V, shutting off the switch
and reducing the power. The output capacitor and the in-
ductor supply the power to the load until ITH rises above
approximately 0.5V, turning on the switch and the main
control loop which starts another cycle.
For lower output voltage ripple at low currents, pulse
skipping mode can be used. In this mode, the LTC3565
continues to switch at a constant frequency down to
very low currents, where it will eventually begin skipping
pulses.
Finally, in forced continuous mode, the inductor current
is constantly cycled which creates a fixed output voltage
ripple at all output current levels. This feature is desirable
in telecommunications since the noise is at a constant fre-
quency and is thus easy to filter out. Another advantage of
this mode is that the regulator is capable of both sourcing
current into a load and sinking current from the output.
Dropout Operation
When the input supply voltage decreases toward the
output voltage, the duty cycle increases to 100% which
is the dropout condition. In dropout, the PMOS switch is
turnedoncontinuouslywiththeoutputvoltagebeingequal
to the input voltage minus the voltage drops across the
internal P-channel MOSFET and the inductor.
Low Supply Operation
The LTC3565 incorporates an undervoltage lockout circuit
which shuts down the part when the input voltage drops
below about 1.9V to prevent unstable operation.
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LTC3566EUF#PBF 功能描述:IC USB POWER MANAGER 24-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 電源管理 - 專(zhuān)用 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 應(yīng)用:熱電冷卻器 電流 - 電源:- 電源電壓:3 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:28-SOIC（0.173"，4.40mm 寬）裸露焊盤(pán) 供應(yīng)商設(shè)備封裝:28-TSSOP 裸露焊盤(pán) 包裝:管件 產(chǎn)品目錄頁(yè)面:1410 (CN2011-ZH PDF)
LTC3566EUF#TRPBF 功能描述:IC USB POWER MANAGER 24-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 電源管理 - 專(zhuān)用 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 應(yīng)用:手持/移動(dòng)設(shè)備 電流 - 電源:- 電源電壓:3 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:14-WFDFN 裸露焊盤(pán) 供應(yīng)商設(shè)備封裝:14-LLP-EP（4x4） 包裝:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名稱(chēng):LP3905SD-30DKR
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