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參數(shù)資料
| 型號： | LT3581EMSE#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, PDSO16 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件頁數(shù)： | 2/36頁 |
| 文件大?。?/td> | 498K |
| 代理商： | LT3581EMSE#PBF |
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LT3581
0
3581f
operaTion
OPERATION – OVERVIEW
TheLT3581usesaconstant-frequency,currentmodecon-
trol scheme to provide excellent line and load regulation.
Thepart’sundervoltagelockout(UVLO)function,together
with soft-start and frequency foldback, offers a controlled
means of starting up. Fault features are incorporated in the
LT3581 to aid in the detection of output shorts, over-volt-
age, and overtemperature conditions. Refer to the Block
Diagram (Figure 1) and the State Diagram (Figure 2) for
the following description of the part’s operation.
OPERATION – START-UP
Several functions are provided to enable a very clean
start-up for the LT3581:
Precise Turn-On Voltage
The SHDN pin is compared to an internal voltage reference
to give a precise turn on voltage level. Taking the SHDN pin
above1.33V(typical)enablesthepart.Takingthe SHDNpin
below 300mV shuts down the chip, resulting in extremely
lowquiescentcurrent.TheSHDNpinhas30mVofhysteresis
to protect against glitches and slow ramping.
Undervoltage Lockout (UVLO)
The SHDN pin can also be used to create a configurable
UVLO.TheUVLOfunctionsetstheturnon/offoftheLT3581
at a desired input voltage (VINUVLO). Figure 3 shows how a
resistor divider (or single resistor) from VIN to the SHDN
pin can be used to set VINUVLO. RUVLO2 is optional. It may
be left out, in which case set it to infinite in the equation
below. For increased accuracy, set RUVLO2 ≤ 10k. Pick
RUVLO1 as follows:
R
V
R
UVLO
INUVLO
UVLO
1
2
1 33
11 6
=
+
– .
.
. AA
RUVLO2
(OPTIONAL)
1.33V
RUVLO1
3581 F03
VIN
ACTIVE/
LOCKOUT
GND
11.6A
AT 1.33V
–
+
SHDN
Figure 3. Configurable UVLO
The LT3581 also has internal UVLO circuitry that disables
the chip when VIN < 2.3V (typical).
Soft-Start of Switch Current
The soft-start circuitry provides for a gradual ramp-up
of the switch current (refer to Commanded Current Limit
vs SS Voltage in Typical Performance Characteristics).
When the part is brought out of shutdown, the external
SS capacitor is first discharged which resets the states
of the logic circuits in the chip. Then an integrated 250k
resistor pulls the SS pin to ~1.8V. The ramp rate of the SS
pin voltage is set by this 250k resistor and the external
capacitor connected to this pin. Once SS gets to 1.8V, the
CLKOUT pin is enabled, and an internal regulator pulls
the pin up quickly to ~2.1V. Typical values for the external
soft-start capacitor range from 100nF to 1μF.
Soft-Start of External PMOS (if used)
The soft-start circuitry also gradually ramps up the GATE
pin pull-down current which allows an external PMOS to
slowlyturnon(M1inBlockDiagram).TheGATEpincurrent
increases linearly with the SS voltage, with a maximum
current of 933A when the SS voltage gets above 500mV.
Note that if the GATE pin voltage is less than 2V for SS
voltages exceeding 500mV, then the GATE pin impedance
to ground is 2kΩ. The soft turn on of the external PMOS
helps limit inrush current at start-up, making hot-plugs
of LT3581s feasible and safe.
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| LT3581EMSE#TRPBF | SWITCHING REGULATOR, PDSO16 |
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| LT3581IMSE#TRPBF | SWITCHING REGULATOR, PDSO16 |
| LT3581IMSE#PBF | SWITCHING REGULATOR, PDSO16 |
| LT3581IDE#PBF | SWITCHING REGULATOR, PDSO14 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT3581EMSE-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:3.3A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3581HDE#PBF | 制造商:Linear Technology 功能描述:IC REG MULTI CONFIG ADJ 14DFN |
| LT3581HDE#TRPBF | 制造商:Linear Technology 功能描述:IC REG MULTI CONFIG ADJ 14DFN |
| LT3581IDE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 14DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(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:- 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) 供應商設備封裝:10-MSOP 裸露焊盤 |
| LT3581IDE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 14DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(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:- 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) 供應商設備封裝:10-MSOP 裸露焊盤 |
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