參數(shù)資料
型號(hào)： LTC3865EFE#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： DUAL SWITCHING CONTROLLER, 880 kHz SWITCHING FREQ-MAX, PDSO38
封裝： 4.40 MM, LEAD FREE, PLASTIC, TSSOP-38
文件頁(yè)數(shù)： 16/38頁(yè)
文件大?。?/td> 400K
代理商： LTC3865EFE#PBF
LTC3865/LTC3865-1
23
3865fb
APPLICATIONS INFORMATION
maximum RMS current of one channel must be used. The
maximum RMS capacitor current is given by:
C
quired I
I
V
VV
V
IN
RMS
MAX
IN
OUT
IN
OUT
Re
–
≈
()(
)
12
/
This formula has a maximum at VIN = 2VOUT, where
IRMS = IOUT/2. This simple worst-case condition is com-
monly used for design because even signicant deviations
do not offer much relief. Note that capacitor manufacturers’
ripple current ratings are often based on only 2000 hours
of life. This makes it advisable to further derate the capaci-
tor, or to choose a capacitor rated at a higher temperature
than required. Several capacitors may be paralleled to meet
size or height requirements in the design. Due to the high
operating frequency of the LTC3865, ceramic capacitors
can also be used for CIN. Always consult the manufacturer
if there is any question.
The benet of the LTC3865/LTC3865-1 2-phase operation
can be calculated by using the equation above for the higher
power controller and then calculating the loss that would
have resulted if both controller channels switched on at
the same time. The total RMS power lost is lower when
both controllers are operating due to the reduced overlap of
current pulses required through the input capacitor’s ESR.
This is why the input capacitor’s requirement calculated
above for the worst-case controller is adequate for the dual
controller design. Also, the input protection fuse resistance,
battery resistance, and PC board trace resistance losses
are also reduced due to the reduced peak currents in a
2-phase system. The overall benet of a multiphase design
will only be fully realized when the source impedance of the
power supply/battery is included in the efciency testing.
The sources of the top MOSFETs should be placed within
1cm of each other and share a common CIN(s). Separating
the sources and CIN may produce undesirable voltage and
current resonances at VIN.
A small (0.1μF to 1μF) bypass capacitor between the chip VIN
pin and ground, placed close to the LTC3865/LTC3865-1,
is also suggested. A 2.2Ω to 10Ω resistor placed between
CIN (C1) and the VIN pin provides further isolation between
the two channels.
The selection of COUT is driven by the effective series
resistance (ESR). Typically, once the ESR requirement
is satised, the capacitance is adequate for ltering. The
output ripple (
ΔVOUT) is approximated by:
Δ≈
+
V
I
ESR
fC
OUT
RIPPLE
OUT
1
8
where f is the operating frequency, COUT is the output
capacitance and IRIPPLE is the ripple current in the induc-
tor. The output ripple is highest at maximum input voltage
since IRIPPLE increases with input voltage.
Setting Output Voltage
The LTC3865/LTC3865-1 output voltages are each set
by the voltages at VID pins. Each of the VID pins can be
oated, or INTVCC or grounded, depending on what preset
voltages are needed at the output (Table 1).
If the desired output voltage is not one of the preset
values, select 0.6V and use 1% resistors to divide VOUT,
as shown in Figure 9. The regulated output voltage is
determined by:
VV
R
OUT
B
A
=+
06
1
.
To improve the frequency response, a feed-forward ca-
pacitor, CFF, may be used. Great care should be taken to
route the VOSENSE line away from noise sources, such as
the inductor or the SW line.
VOSENSE
VOUT
RB
RA
CFF
1/2 LTC3865
3865 F09
Figure 9. Setting Output Voltage
相關(guān)PDF資料
PDF描述
LTC3865IFE#TRPBF DUAL SWITCHING CONTROLLER, 880 kHz SWITCHING FREQ-MAX, PDSO38
LTC3865EUH-1#PBF DUAL SWITCHING CONTROLLER, 880 kHz SWITCHING FREQ-MAX, PQCC32
LTC3865IUH#TRPBF DUAL SWITCHING CONTROLLER, 880 kHz SWITCHING FREQ-MAX, PQCC32
LTC3869IUFD#TRPBF SWITCHING CONTROLLER, PQCC28
LTC3869IUFD#PBF SWITCHING CONTROLLER, PQCC28
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3865EUH#PBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤(pán) 包裝:Digi-Reel® 產(chǎn)品目錄頁(yè)面:1303 (CN2011-ZH PDF) 其它名稱(chēng):LM3754SQDKR
LTC3865EUH#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3865EUH-1#PBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤(pán) 包裝:Digi-Reel® 產(chǎn)品目錄頁(yè)面:1303 (CN2011-ZH PDF) 其它名稱(chēng):LM3754SQDKR
LTC3865EUH-1#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
LTC3865IFE#PBF 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 類(lèi)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(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
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