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| 型號： | LTC3880EUJ-1#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.1 A DUAL SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PQCC40 |
| 封裝： | 6 X 6 MM, LEAD FREE, PLASTIC, WJJD-2, QFN-40 |
| 文件頁數(shù)： | 44/112頁 |
| 文件大?。?/td> | 2182K |
| 代理商： | LTC3880EUJ-1#PBF |
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LTC3880/LTC3880-1
37
3880fa
APPLICATIONS INFORMATION
TheTypicalApplicationonthebackpageisabasicLTC3880
application circuit. The LTC3880 can be configured to use
either DCR (inductor resistance) sensing or low value
resistor sensing. The choice between the two current
sensing schemes is largely a design trade-off between
cost, power consumption and accuracy. DCR sensing
is becoming popular because it saves expensive current
sensing resistors and is more power efficient, especially
in high current applications. The LTC3880 can nominally
account for the temperature dependency of the DCR sens-
ing element. The accuracy of the current reading and cur-
rent limit are typically limited by the accuracy of the DCR
resistor (accounted for in the IOUT_CAL_GAIN parameter
of the LTC3880). Thus current sensing resistors provide
the most accurate current sense and limiting for the ap-
plication. Other external component selection is driven
by the load requirement, and begins with the selection of
RSENSE (if RSENSE is used) and inductor value. Next, the
power MOSFETs are selected. Then the input and output
capacitorsareselected.Finallythecurrentlimitisselected.
All of these components and ranges are required to be
determined prior to calculating the external compensation
components. The current limit range is required because
the two ranges (25mV to 50mV vs 37.5mV to 70mV) have
different EA gains set with bit 7 of the MFR_PWM_MODE_
LTC3880 command. The voltage RANGE bit also modifies
the loop gain and impacts the compensation network set
with bits 5, 6 of MFR_PWM_CONFIG_LTC3880. All other
programmable parameters do not affect the loop gain,
allowing parameters to be modified without impact to the
transient response to load.
CURRENT LIMIT PROGRAMMING
TheLTC3880hastworangesofcurrentlimitprogramming
and a total of eight levels within each range. Refer to the
IOUT_OC_FAULT_LIMITsectionofthePMBuscommands.
Within each range the error amp gain is fixed, resulting in
constant loop gain. The LTC3880 will account for the DCR
oftheinductorandautomaticallyupdatethecurrentlimitas
the inductor temperature changes. The temperature coef-
ficient of the DCR is stored in the MFR_IOUT_TC register.
For the best current limit accuracy, use the 75mV setting.
The 25mV setting will allow for the use of very low DCR
inductors or sense resistors, but at the expense of cur-
rent limit accuracy. Keep in mind this operation is on a
cycle-by-cycle basis and is only a function of the peak in-
ductor current. The average inductor current is monitored
by the ADC converter and can provide a warning if too
much average output current is detected. The overcurrent
fault is detected when the ITH voltage hits the maximum
value. The digital processor within the LTC3880 provides
the ability to either ignore the fault, shut down and latch off
or shut down and retry indefinitely (hiccup). Refer to the
overcurrentportionoftheOperationsectionformoredetail.
ISENSE+ AND ISENSE– PINS
The ISENSE+ and ISENSE– pins are the inputs to the current
comparatorsandtheA/D.Thecommonmodeinputvoltage
range of the current comparators is 0V to 5.5V. Both the
SENSE pins are high impedance inputs with small base
currents typically less than 1A. When the ISENSE pins
ramp up from 0V to 1.4V, the small base currents flow
out of the SENSE pins. When the ISENSE pins are greater
than 1.4V, the base currents flow into the ISENSE pins. The
high impedance inputs to the current comparators allow
accurate DCR sensing. Do not to float these pins during
normal operation.
Filter components mutual to the ISENSE lines should be
placed close to the IC. The positive and negative traces
should be routed differentially and Kelvin connected to
the current sense element, see Figure 17. A non-Kelvin
connection elsewhere can add parasitic inductance and
capacitance to the current sense element, degrading
the information at the sense terminals and making the
programmed current limit unpredictable. In a PolyPhase
system,poorplacementofthesensingelementwillresultin
sub-optimalcurrentsharingbetweenpowerstages.IfDCR
sensing is used (Figure 18a), sense resistor R1 should be
placed close to the switching node to prevent noise from
Figure 17. Optimal Sense Line Placement
COUT
TO SENSE FILTER,
NEXT TO THE CONTROLLER
INDUCTOR OR RSENSE
3880 F17
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相關代理商/技術參數(shù) |
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| LTC3880IUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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® 標準包裝: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 |
| LTC3880IUJ#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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® 標準包裝: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 |
| LTC3880IUJ-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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® 標準包裝: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 |
| LTC3880IUJ-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-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® 標準包裝: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 |
| LTC3883EUH#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL 24V 1MHZ 0.5/5.5V 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, 24V, 1MHZ, 0.5/5.5V, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 1MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:30A, Supply Voltage Min:4.5V, Supply Voltage Max:24V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:1MHz, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Digitally Programmable, Multiphase Step-Down DC/DC Controll |
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