- 您现在的位置：买卖IC网 > PDF目录44991 > LTC3553EUD#PBF (LINEAR TECHNOLOGY CORP) 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 PDF资料下载
参数资料
| 型号： | LTC3553EUD#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 |
| 封装： | 3 X 3 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, QFN-20 |
| 文件页数： | 14/36页 |
| 文件大小： | 518K |
| 代理商： | LTC3553EUD#PBF |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页当前第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页
LTC3553
21
3553fa
buck cycles the power switches enough times to charge
the output capacitor to a voltage slightly higher than
the regulation point. The buck then goes into a reduced
quiescent current sleep mode. In this state, power loss is
minimized while the load current is supplied by the output
capacitor. Whenever the output voltage drops below a
predetermined value, the buck wakes from sleep and cycles
the switches again until the output capacitor voltage is once
again slightly above the regulation point. Sleep time thus
depends on load current, since the load current determines
the discharge rate of the output capacitor.
Standby Mode Buck Operation (STBY Pin High)
There are situations where even the low quiescent current
of Burst Mode operation is not low enough. For instance,
in a static memory keep alive situation, load current may
fall well below 1μA. In this case, the 22μA typical BVIN
quiescent current in Burst Mode operation becomes the
main factor determining battery run time.
Standby mode cuts BVIN quiescent current down to just
1.5μA, greatly extending battery run time in this essen-
tially no-load region of operation. The application circuit
commands the LTC3553 into and out of standby mode
via the STBY pin logic input. Bringing the STBY pin high
places the regulator into standby mode, while bringing it
low returns it to Burst Mode operation. In standby mode,
buck load capability drops to 10mA.
In standby mode, the buck regulator operates hyster-
etically. When the BUCK_FB pin voltage falls below the
internal 0.8V reference, a current source from BVIN to
SW turns on, delivering current through the inductor to
the switching regulator output capacitor and load. When
the FB pin voltage rises above the reference plus a small
hysteresis voltage, that current is shut off. In this way,
output regulation is maintained.
Since the power transfer from BVIN to SW is through a
high impedance current source rather than through a low
impedance MOSFET switch, power loss scales with load
current as in a linear low dropout (LDO) regulator, rather
than as in a switching regulator. For near-zero load condi-
tions where regulator quiescent current is the dominant
power loss, standby mode is ideal. But at any appreciable
load current, Burst Mode operation yields the best overall
conversion efciency.
Shutdown
The buck regulator is shut down and enabled via the
pushbutton interface. In shutdown, it draws only a few
nanoamps of leakage current from the BVIN pin. It also
pulls down on its output with a 10k resistor from its switch
pin to ground.
Dropout Operation
It is possible for the buck regulator’s input voltage to fall
near or below its programmed output voltage (e.g., a bat-
tery voltage of 3.4V with a programmed output voltage of
3.3V). When this happens, the PMOS switch duty cycle
increases to 100%, keeping the switch on continuously.
Known as dropout operation, the output voltage equals the
regulator’s input voltage minus the voltage drops across
the internal P-channel MOSFET and the inductor.
Soft-Start Operation
In normal operating mode, soft-start works by gradually
increasing the maximum allowed peak inductor current
for the buck regulator over a 500μs period. This allows the
output to rise slowly, helping minimize the inrush current
needed to charge up the output capacitor. A soft-start
cycle occurs whenever the buck is enabled.
Soft-start occurs only in normal operation, but not in
standby mode. Standby mode operation is already in-
herently current-limited, since the regulator works by
intermittently turning on a current source from BVIN to
SW. Changing the state of the STBY pin while the regu-
lators are operating doesn’t trigger a new soft-start cycle,
to avoid glitching the outputs.
Inductor Selection
Many different sizes and shapes of inductors are avail-
able from numerous manufacturers. Choosing the right
inductor from such a large selection of devices can be
overwhelming, but following a few basic guidelines will
make the selection process much simpler.
OPERATION
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3554EPD#TRPB | 0.5 A BATTERY CHARGE CONTROLLER, 1295 kHz SWITCHING FREQ-MAX, PQCC20 |
| LTC3560IS6#TRPBF | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3563EDC | 1.75 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3568EDD#TR | 4 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PDSO10 |
| LTC3568IDD | 4 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PDSO10 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3554 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
| LTC3554EPD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
| LTC3554EPD#PBF | 功能描述:IC USB POWER MANAGER 20-UTQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LTC3554EPD#TRPBF | 功能描述:IC USB POWER MANAGER 20-UTQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| LTC3554EPDPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
发布紧急采购，3分钟左右您将得到回复。