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| 型号： | LTC1872ES6#TR |
| 厂商： | Linear Technology |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM SOT23-6 |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 650kHz |
| 电源电压： | 2.5 V ~ 9.8 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | SOT-23-6 |
| 包装： | 带卷 (TR) |
| 其它名称： | LTC1872CS6#TR LTC1872CS6TR LTC1872CS6TR-ND LTC1872ES6TR |
LTC1872
APPLICATIO N S I N FOR M ATIO N
Inductor Selection
When selecting the inductor, keep in mind that inductor
saturation current has to be greater than the current limit
set by the current sense resistor. Also, keep in mind that
the DC resistance of the inductor will affect the efficiency.
Off the shelf inductors are available from Murata, Coilcraft,
Toko, Panasonic, Coiltronics and many other suppliers.
Power MOSFET Selection
The main selection criteria for the power MOSFET are the
threshold voltage V GS(TH) , the “on” resistance R DS(ON) ,
reverse transfer capacitance C RSS and total gate charge.
Since the LTC1872 is designed for operation down to low
input voltages, a logic level threshold MOSFET (R DS(ON)
guaranteed at V GS = 2.5V) is required for applications that
work close to this voltage. When these MOSFETs are used,
make sure that the input supply to the LTC1872 is less than
the absolute maximum V GS rating, typically 8V.
The required minimum R DS(ON) of the MOSFET is gov-
erned by its allowable power dissipation given by:
It is important to adequately specify the diode peak current
and average power dissipation so as not to exceed the
diode ratings.
Schottky diodes are recommended for low forward drop
and fast switching times. Remember to keep lead length
short and observe proper grounding (see Board Layout
Checklist) to avoid ringing and increased dissipation.
C IN and C OUT Selection
To prevent large input voltage ripple, a low ESR input
capacitor sized for the maximum RMS current must be
used. The maximum RMS capacitor current for a boost
converter is approximately equal to:
C IN Required I RMS ≈ ( 0 . 3 ) I RIPPLE
where I RIPPLE is as defined in the Inductor Value Calcula-
tion section.
Note that capacitor manufacturer’s ripple current ratings
are often based on 2000 hours of life. This makes it
advisable to further derate the capacitor, or to choose a
( ) I IN ( 1 + δ p )
R DS ( ON ) ?
DC
P P
2
capacitor rated at a higher temperature than required.
Several capacitors may be paralleled to meet the size or
height requirements in the design. Due to the high operat-
ing frequency of the LTC1872, ceramic capacitors can also
? V OUT ≈ ? I O ? OUT D + RIPPLE ? ?
whereP P istheallowablepowerdissipationandδpisthe
temperature dependency of R DS(ON) . (1 + δ p) is generally
given for a MOSFET in the form of a normalized R DS(ON) vs
temperature curve, but δ p = 0.005/ ° C can be used as an
approximation for low voltage MOSFETs. DC is the maxi-
mum operating duty cycle of the LTC1872.
Output Diode Selection
Under normal load conditions, the average current con-
ducted by the diode in a boost converter is equal to the
be used for C IN . Always consult the manufacturer if there
is any question.
The selection of C OUT is driven by the required effective
series resistance (ESR). Typically, once the ESR require-
ment is satisfied, the capacitance is adequate for filtering.
The output ripple ( ? V OUT ) is approximated by:
? V + V I ?
? V IN 2 ?
?
? ESR + ? 2 π fC
?
? ? 2
OUT ? ?
output load current:
I D ( avg ) = I OUT
?
? 2 1
?
?
2 ?
? ?
?
1
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1872ES6TRMPBF | 制造商:Linear Technology 功能描述:DC-DC Controller Step-Up 2.5-9.8V TSOT23 |
| LTC1873EG | 功能描述:IC REG CTRLR BUCK PWM VM 28-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1873EG#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1873EG#TR | 功能描述:IC REG CTRLR BUCK PWM VM 28-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1873EG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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