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參數(shù)資料
| 型號： | LTC1772BIS6#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | LEAD FREE, PLASTIC, MO-193, SOT-23, 6 PIN |
| 文件頁數(shù)： | 2/16頁 |
| 文件大小： | 223K |
| 代理商： | LTC1772BIS6#PBF |
LTC1772B
10
1772bfa
APPLICATIONS INFORMATION
size or height requirements in the design. Due to the high
operating frequency of the LTC1772B, ceramic capacitors
can also be used for CIN. Always consult the manufacturer
if there is any question.
The selection of COUT is driven by the required effective
series resistance (ESR). Typically, once the ESR require-
ment is satised, the capacitance is adequate for ltering.
The output ripple (ΔVOUT) is approximated by:
VOUT IRIPPLE ESR+
1
4fCOUT
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 ΔIL increases with input voltage.
Manufacturers such as Nichicon, United Chemicon and
Sanyo should be considered for high performance through-
hole capacitors. The OS-CON semiconductor dielectric
capacitor available from Sanyo has the lowest ESR (size)
product of any aluminum electrolytic at a somewhat higher
price. Once the ESR requirement for COUT has been met,
the RMS current rating generally far exceeds the IRIPPLE(P-P)
requirement.
Low Supply Operation
Although the LTC1772B can function down to approxi-
mately 2.0V, the maximum allowable output current is
reduced when VIN decreases below 3V. Figure 4 shows
the amount of change as the supply is reduced down to
2V. Also shown in Figure 4 is the effect of VIN on VREF as
VIN goes below 2.3V.
Setting Output Voltage
The regulated output voltage is determined by:
VOUT = 0.8 1+
R2
R1
For most applications, an 80k resistor is suggested for
R1. To prevent stray pickup, locate resistors R1 and R2
close to LTC1772B.
Efciency Considerations
The efciency of a switching regulator is equal to the output
power divided by the input power times 100%. It is often
useful to analyze individual losses to determine what is
limiting the efciency and which change would produce
the most improvement. Efciency can be expressed as:
Efciency = 100% – (η1 + η2 + η3 + ...)
where η1, η2, etc. are the individual losses as a percent-
age of input power.
Although all dissipative elements in the circuit produce
losses, four main sources usually account for most of
the losses in LTC1772B circuits: 1) LTC1772B DC bias
INPUT VOLTAGE (V)
2.0
NORMALIZED
VOLTAGE
(%)
105
100
95
90
85
80
75
2.2
2.4
2.6
2.8
1772 F03
3.0
VREF
VITH
Figure 4. Line Regulation of VREF and VITH
Figure 5. Setting Output Voltage
3
VFB
VOUT
LTC1772B
R1
1772 F04
R2
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1772CS6 | 制造商:Linear Technology 功能描述:Swithed-Mode Power Supply Controller, Current Mode Type, 3 Pin, Plastic, TO-236 |
| LTC1772CS6#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.5V to 9.8V Input 6-Pin TSOT-23 制造商:Linear Technology 功能描述:BUCK 2.8 - 20V 5A 1.23-18V 6SOT23 制造商:Linear Technology 功能描述:BUCK, 2.8 - 20V, 5A, 1.23-18V, 6SOT23 |
| LTC1772CS6#TR | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 RoHS:否 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(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) |
| LTC1772CS6#TRM | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 RoHS:否 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(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) |
| LTC1772CS6#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 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(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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