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參數(shù)資料
| 型號： | LTC3856EFE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, PDSO38 |
| 封裝： | 4.4 MM, LEAD FREE, PLASTIC, TSSOP-38 |
| 文件頁數(shù)： | 6/40頁 |
| 文件大?。?/td> | 2222K |
| 代理商： | LTC3856EFE#TRPBF |
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LTC3856
3856f
operaTion (Refer to Functional Diagram)
operating frequency from 250kHz to 770kHz. There is a
precision10AcurrentflowingoutoftheFREQpinenabling
the user to program the controller’s switching frequency
with a single resistor to SGND. A curve is provided later in
theApplicationsInformationsectionshowingtherelation-
ship between the voltage on the FREQ pin and switching
frequency.
A phase-locked loop (PLL) is available on the LTC3856
to synchronize the internal oscillator to an external clock
source that is connected to the PLLIN pin. The PLL loop
filter network is integrated inside the LTC3856. The
phase-locked loop is capable of locking any frequency
within the range of 250kHz to 770kHz. The frequency
setting resistor should always be present to set the
controller’s initial switching frequency before locking to
the external clock.
Sensing the Output Voltage with a Differential Amplifier
The LTC3856 includes a low offset, unity-gain, high band-
widthdifferentialamplifierforapplicationsthatrequiretrue
remote sensing. Sensing the load across the load capaci-
torsdirectlygreatlybenefitsregulationinhighcurrent,low
voltage applications, where board interconnection losses
can be a significant portion of the total error budget.
TheLTC3856differentialamplifierhasatypicaloutputslew
rate of 2V/s. The amplifier is configured for unity gain,
meaning that the difference between DIFFP and DIFFN is
translated to DIFFOUT, relative to SGND.
Care should be taken to route the DIFFP and DIFFN PCB
traces parallel to each other all the way to the terminals
of the output capacitor or remote sensing points on the
board. In addition, avoid routing these sensitive traces
near any high speed switching nodes in the circuit. Ideally,
the DIFFP and DIFFN traces should be shielded by a low
impedance ground plane to maintain signal integrity.
The maximum output voltage when using the differential
amplifier is INTVCC – 1.4V (typically 3.6V). The differential
amplifier should not be used above this voltage.
Power Good (PGOOD Pin)
ThePGOODpinisconnectedtoanopendrainofaninternal
N-channel MOSFET. The MOSFET turns on and pulls the
PGOOD pin low when either VFB pin voltage is not within
±10% of the 0.6V reference voltage. The PGOOD pin is
also pulled low when the RUN pin is below 1.22V or when
the LTC3856 is in the soft-start or tracking phase. When
the VFB pin voltage is within the ±10% regulation window,
the MOSFET is turned off and the pin is allowed to be
pulled up by an external resistor to a source of up to 6V.
The PGOOD pin will flag power good immediately when
VFB is within the regulation window. However, there is an
internal 20s power-bad mask when VFB goes out of the
regulation window.
Output Overvoltage Protection
An overvoltage comparator, OV, guards against transient
overshoots (>10%) as well as other more serious condi-
tions that may overvoltage the output. In such cases, the
topMOSFETisturnedoffandthebottomMOSFETisturned
on until the overvoltage condition is cleared.
Undervoltage Lockout
The LTC3856 has two functions that help protect the
controller in case of undervoltage conditions. A precision
UVLO comparator constantly monitors the INTVCCvoltage
to ensure that an adequate gate-drive voltage is present. It
locks out the switching action when INTVCC is below 3.2V.
To prevent oscillation when there is a disturbance on the
INTVCC, the UVLO comparator has 600mV of precision
hysteresis.
Another way to detect an undervoltage condition is
to monitor the VIN supply. Because the RUN pin has
a precision turn-on reference of 1.22V, one can use a
resistor divider to VIN to turn on the IC when VIN is high
enough. An extra 4.5A of current flows out of the RUN
pin once the RUN pin voltage passes 1.22V. The RUN
comparator itself has about 80mV of hysteresis. One
can program additional hysteresis for the RUN com-
parator by adjusting the values of the resistive divider.
For accurate VIN undervoltage detection, VIN needs to
be higher than 4.5V.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3856EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32WFQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3856EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3856IFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TFSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3856IFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3856IUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32WFQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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