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參數(shù)資料
| 型號(hào)： | LT3640EUFD#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3.4 A DUAL SWITCHING CONTROLLER, 2350 kHz SWITCHING FREQ-MAX, PQCC28 |
| 封裝： | 5 X 4 MM, LEAD FREE, PLASTIC, MO-220, QFN-28 |
| 文件頁數(shù)： | 3/24頁 |
| 文件大小： | 506K |
| 代理商： | LT3640EUFD#TRPBF |
LT3640
3640f
when the VIN2 pin voltage is above 2.3V, the EN2 pin is
pulled high and the FB1 pin voltage is above 1.165V. The
internal top power MOSFET is turned on each cycle at the
beginning of each oscillator cycle, and turned off when
the current flowing through the top MOSFET reaches a
level determined by the voltage at the VC2 node. An error
amplifier measures the output voltage through an external
resistor divider tied to the FB2 pin and servos the VC2
node. The reference of the error amplifier is determined by
the lower of the internal 600mV reference and the voltage
at the SS2 pin.
While the top MOSFET is off, the bottom MOSFET is turned
on in an oscillator cycle until the inductor current starts
to reverse. If the inductor current is higher than the valley
current limit at the beginning of an oscillator cycle, the top
MOSFET will not turn on in this cycle, limiting inductor
current in shorted output fault.
Aninternalregulatorprovidespowertothecontrolcircuitry.
The regulator draws most power from the VIN2 pin and a
small portion of power from the VIN pin when the VIN2 pin
voltage is higher than 3V. If the voltage at VIN2 pin is lower
than 3V, the regulator draws all power from the VIN pin.
The EN/UVLO pin is used to put the LT3640 in shutdown,
reducing the input current to less than 1A. The accurate
1.26V threshold of the EN/UVLO pin provides a program-
mableVINundervoltagelockoutthroughanexternalresistor
divider tied to the EN/UVLO pin. A 2A hysteresis current
on the EN/UVLO pin prevents switching noise from shut-
ting down the LT3640.
The LT3640 has an overvoltage protection feature which
disables switching action in both channels when the VIN
pin voltage goes above 36V. When switching is disabled,
the LT3640 can sustain VIN voltages up to 55V for one
second.
Internal 2A current sources charge the SS1 pin and
the SS2 pin up to about 2V. Soft-start or output voltage
tracking of the two channels can be independently imple-
mented with capacitors from the SS1 pin and the SS2 pin
to ground. Any overvoltage or undervoltage condition on
the VIN pin triggers an internal latch that discharges the
SS1 pin to below 100mV before it is released. If the EN2
pin goes low, the VIN2 voltage falls below 2.2V or the FB1
pin goes below 1.165V, the SS2 pin will be discharged to
below 100mV before it is released.
To optimize efficiency, the LT3640 switches to low ripple
Burst Mode operation in light load situations. Between
switching pulses, control-circuitry current is minimized.
A power good comparator with 40mV of hysteresis trips
when the low voltage channel is enabled and the FB2 pin is
above 550mV. The PGOOD pin is an open-drain output that
is pulled low when both the outputs are in regulation.
Power-On Reset and Watchdog Timer
The LT3640 includes one power-on reset timer for each
buck regulator and one common watchdog timer. Power-
on reset and watchdog timers are both adjustable using
external capacitors. Operation can be best understood by
referring to the Timing Diagram.
The RST1, RST2 and WDO pins are all open-drain outputs
withweakinternalpull-upstoabout2V.The RST1andRST2
pins are pulled low when the LT3640 is enabled and VIN is
above 3.6V. Once the FB1 pin rises above 1.165V, the high
voltage channel reset timer is started and RST1 is released
aftertheresettimeoutperiod.Thelowvoltagechannelreset
timer is started once the FB2 pin rises above 550mV, and
releases RST2 after the reset timeout period.
The watchdog circuit monitors a P’s activity. As soon
as both RST1 and RST2 are released, a delay timer is
started. The watchdog timer is started after the delay timer
times out. The LT3640 implements windowed watchdog
function for higher system reliability. The watchdog timer
detects falling edges on the WDI pin. If the falling edges
are grouped too close together or too far apart, the WDO
pin is pulled down and the reset timer is started. When the
reset timer times out, WDO is released and the watchdog
timer is again started after the delay period.
operaTion
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PDF描述 |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3640IFE | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer |
| LT3640IFE#PBF | 功能描述:IC REG BUCK FIX/ADJ DL 28TSSOP 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:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT3640IFE#TRPBF | 功能描述:IC REG BUCK FIX/ADJ DL 28TSSOP 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:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT3640IFEPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer |
| LT3640IFETRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer |
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