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參數資料
| 型號： | LTC3833EUDC#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | 3 X 3 MM, LEAD FREE, PLASTIC, QFN-20 |
| 文件頁數： | 7/36頁 |
| 文件大小： | 513K |
| 代理商： | LTC3833EUDC#PBF |
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LTC3833
15
3833f
APPLICATIONS INFORMATION
ripple current does not exceed a specified maximum, the
inductance should be chosen according to:
L
=
VOUT
f
IL(MAX)
1
VOUT
VIN(MAX)
Once the value for L is known, the type of inductor must
be selected. High efficiency converters generally cannot
tolerate the core loss of low cost powdered iron cores,
forcing the use of more expensive ferrite, molypermalloy
or Kool Mμ cores. Ferrite core material saturates hard,
meaning that inductance collapses abruptly when the
peak design current is exceeded. This results in an abrupt
increase in inductor ripple current and consequent output
voltage ripple. Do not allow the core to saturate!
A variety of inductors designed for high current, low volt-
age applications are available from manufacturers such as
Sumida, Panasonic, Coiltronics, Coilcraft, Toko, Vishay,
Pulse and Wurth.
Current Sense Pins and Current Limit Programming
Inductor current is sensed through the SENSE+ and
SENSE– pins and fed into the internal current compara-
tors. The common mode input voltage range of the cur-
rent comparators is –0.5V to 5.5V. Both SENSE pins are
high impedance inputs. When the common mode range
is between –0.5V to 1.1V, there is no input bias current,
and when between 1.4V and 5.5V, there is less than 1μA
of current flowing into the pins. Between 1.1V and 1.4V,
the input bias current will be zero if the common mode
voltage is ramped up from 1.1V and less than 1μA if the
common mode voltage is ramped down from 1.4V. The
high impedance inputs to the current comparator allow
accurate DCR sensing. However, care must be taken not
to float these pins during normal operation.
ThemaximumallowedsensevoltageVSENSE(MAX)between
SENSE+ and SENSE– is set by the voltage applied to the
VRNG pin and is given by:
VSENSE(MAX) = 0.05 VRNG
The current mode control loop does not allow the induc-
tor current valleys to exceed 0.05 VRNG. In practice, one
should allow sufficient margin to account for variations
in the LTC3833 and external component values. Note that
ITH is close to 2.4V when in current limit.
An external resistive divider from INTVCC can be used
to set the voltage on the VRNG pin between 0.6V and 2V,
resulting in maximum sense voltages between 30mV and
100mV. The wide voltage sense range allows for a variety
of applications. The VRNG pin can also be tied to either
SGND or INTVCC to force internal defaults. When VRNG is
tied to SGND, the device operates with a maximum sense
voltage of 30mV. When the VRNG pin is tied to INTVCC, the
device operates with a maximum sense voltage of 50mV.
RSENSE Inductor Current Sensing
A typical RSENSE inductor current sensing scheme is
shown in Figure 3. RSENSEischosenbasedontherequired
maximum output current. Given the maximum current,
IOUT(MAX),maximumsensevoltage,VSENSE(MAX),setbythe
VRNG pin, and maximum inductor ripple current, IL(MAX),
the value of RSENSE can be chosen as:
RSENSE =
VSENSE(MAX)
IOUT(MAX) –
IL(MAX)
2
Conversely, given RSENSE and IOUT(MAX), VSENSE(MAX)
and thus the VRNG voltage could be determined from the
above equation. To assure that the maximum rated output
current can be supplied for different operating conditions
andcomponentvariations,sufficientdesignmarginshould
be built into these calculations.
Figure 3. RSENSE Current Sensing
RF
R
ESL
RSENSE RESISTOR
AND
PARASITIC INDUCTANCE
FILTER COMPONENTS
PLACED NEAR SENSE PINS
RF
SENSE+
LTC3833
SENSE–
CF
3833 F03
VOUT
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC3833IFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數: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) |
| LTC3833IFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數: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) |
| LTC3833IUDC#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數: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) |
| LTC3833IUDC#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數: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) |
| LTC3834EDHC-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,000 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR) |
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