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參數(shù)資料
| 型號： | LTC3775EMSE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件頁數(shù)： | 8/34頁 |
| 文件大小： | 534K |
| 代理商： | LTC3775EMSE#TRPBF |
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LTC3775
16
3775fa
response at low load currents, constant frequency opera-
tion, and the ability to maintain regulation when sinking
current. See Figure 8 for a comparison of the efciency
at light loads for each mode.
In pulse-skipping mode, the LTC3775 reverse-current
comparator, IREV, monitors the SW pin for zero crossing
when the bottom gate, BG, is high. It turns off BG if the
inductor current reverses and the SW voltage goes above
GND. To prevent false tripping due to ringing on the SW
node when BG is rst turned on, there is a blanking time
of 200ns similar to the bottom side current limit blanking.
Under certain light load conditions, if the TG on-time is
short, the inductor current may reverse during the IREV
blanking time but the LTC3775 will only turn off BG after
the blanking time.
In applications where a low value inductor is used, the
high di/dt of the inductor ripple current together with the
parasitic series inductance of the bottom MOSFET, QB,
and PCB trace inductance creates an opposing voltage to
the voltage drop across the RDS(ON) of QB. This can cause
IREV to trip early, before the inductor current reverses.
The parasitic series inductance of the PCB trace can be
minimized by connecting the SW pin closer to the drain
of QB.
INTVCC Regulator
The LTC3775 features a P-channel low dropout linear
regulator (LDO) that supplies power to the INTVCC pin from
the VIN supply. INTVCC powers the gate drivers and much
of the LTC3775’s internal circuitry. The LDO regulates the
voltage at the INTVCC pin to 5.2V when VIN is greater than
6.5V. The INTVCC pin must be bypassed to ground with a
low ESR (X5R or better) ceramic capacitor of at least 4.7μF.
Good bypassing is needed to supply the high transient
currents required by the MOSFET gate drivers.
An internal undervoltage lockout (UVLO) monitors the volt-
age on INTVCCtoensurethattheLTC3775hassufcientgate
drive voltage. If the INTVCC voltage falls below the UVLO
threshold of 3.1V, the gate drive outputs remain low.
Thermal Considerations
The LTC3775 is offered in a 3mm × 3mm QFN package
(UD16) that has a thermal resistance RTH(JA) of 68°C/W
and the MSOP (MSE16) package has a thermal resistance
of 40°C/W. Both packages have a lead pitch of 0.5mm.
The regulator can supply up to 50mA of gate drive load cur-
rent. The expected LDO load current can be calculated from
the gate charge requirement of the external MOSFET:
IINTVCC = (fSW) (QG(QT) + QG(QB)) + 3.5mA
where:
3.5mA is the quiescent current of LTC3775
QG(QT) is the total gate charge of the top MOSFET
QG(QB) is the total gate charge of the bottom MOSFET
fSW is the switching frequency
APPLICATIONS INFORMATION
Figure 9. Comparison of Inductor Current Waveforms for Pulse-Skipping Mode and Forced Continuous Mode
PULSE-SKIPPING MODE
FORCED CONTINUOUS
DECREASING
LOAD
CURRENT
0A
3775 F09
相關(guān)PDF資料 |
PDF描述 |
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| LTC3775IMSE#PBF | SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO16 |
| LTC3805MPMSE#PBF | SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO10 |
| LTC3805MPMSE#TR | SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO10 |
| LTC3829IFE#PBF | SWITCHING REGULATOR, PDSO38 |
| LTC3829IFE#TRPBF | SWITCHING REGULATOR, PDSO38 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3775EUD#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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) |
| LTC3775EUD#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN16 |
| LTC3775EUD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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) |
| LTC3775IMSE#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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) |
| LTC3775IMSE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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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