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參數(shù)資料
| 型號(hào)： | LTC1261LCS8 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Switched Capacitor Regulated Voltage Inverter |
| 中文描述： | 0.02 A SWITCHED CAPACITOR REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.150 INCH, PLASTIC, SO-8 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 182K |
| 代理商： | LTC1261LCS8 |
9
LTC1261L
APPLICATIO
S I
FOR
ATIO
U
3.3
μ
F tantalum capacitor has 1
or 2
of ESR; 100mA
×
2
= 200mV. If the output is within 200mV of the set point
this additional 200mV surge will trip the feedback com-
parator and terminate the charging cycle. The pulse dissi-
pates quickly and the comparator returns to the correct
state, but the RS latch will not allow the charge pump to
respond until the next clock edge. This prevents the charge
pump from going into very high frequency oscillation
under such conditions but it also creates an output error
as the feedback loop regulates based on the top of the
spike, not the average value of the output (Figure 4). The
resulting output voltage behaves as if a resistor of value
C
ESR
×
(I
PK
/I
AVE
)
was placed in series with the output. To
avoid this nasty sequence of events, connect a 0.1
μ
F
ceramic capacitor in parallel with the larger output capaci-
tor. The ceramic capacitor will “eat” the high frequency
spike, preventing it from fooling the feedback loop, while
the larger but slower tantalum or aluminum output capaci-
tor supplies output current to the load between charge
cycles.
W
U
U
approaches half of a clock period (the time the capacitors
have to share charge at full duty cycle) the output current
capability of the LTC1261L starts to diminish. For a 0.1
μ
F
flying capacitor, this gives a maximum total series resis-
tance of:
)
650kHz
=
/0.1
μ
F = 7.7
1
2
)
t
CLK
C
FLY
1
2
)
)
1
Most of this resistance is already provided by the internal
switches in the LTC1261L. More than 1
or 2
of ESR on
the flying capacitors will start to affect the regulation at
maximum load.
RESISTOR SELECTION
Resistor selection is easy with the fixed output voltage
versions of the LTC1261L—no resistors are needed!
Selecting the right resistors for the adjustable parts is only
a little more difficult. A resistor divider should be used to
divide the signal at the output to give 1.23V at the ADJ pin
with respect to V
OUT
(Figure 5). The LTC1261L uses a
positive reference with respect to V
OUT
, not a negative
reference with respect to ground (Figure 1 shows the
reference connection). Be sure to keep this in mind when
connecting the resistors! If the initial output is not what
you expected, try swapping the two resistors.
The LTC1261L can be internally configured for other
fixed output voltages. Contact the Linear Technology
Marketing department for details.
LOW ESR
OUTPUT CAP
CLOCK
V
AVERAGE
V
SET
COMP1
OUTPUT
V
OUT
HIGH ESR
OUTPUT CAP
V
AVERAGE
V
SET
COMP1
OUTPUT
1261L F04
V
OUT
Figure 4. Output Ripple with Low and High ESR Capacitors
Note that ESR in the flying capacitor will not cause the
same condition; in fact, it may actually improve the situa-
tion by cutting the peak current and lowering the ampli-
tude of the spike. However, more flying capacitor ESR is
not necessarily better. As soon as the RC time constant
LTC1261L
GND
R1
4
5
6
1261L F05
V
OUT
= –1.23V
R2
R1 + R2
R2
ADJ
OUT
(
)
Figure 5. External Resistor Connections
相關(guān)PDF資料 |
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| LTC1261LCS8-4 | Switched Capacitor Regulated Voltage Inverter |
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| LTC1262C | 12V, 30mA Flash Memory Programming Supply |
| LTC1262CN8 | 12V, 30mA Flash Memory Programming Supply |
| LTC1262CS8 | 12V, 30mA Flash Memory Programming Supply |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1261LCS8#PBF | 功能描述:IC REG SWITCHD CAP INV ADJ 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC1261LCS8#TR | 功能描述:IC REG SWITCHD CAP INV ADJ 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC1261LCS8#TRPBF | 功能描述:IC REG SWITCHD CAP INV ADJ 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 類型:切換式電容器（充電泵），反相 輸出類型:固定 輸出數(shù):1 輸出電壓:-3V 輸入電壓:2.3 V ~ 5.5 V PWM 型:Burst Mode? 頻率 - 開關(guān):900kHz 電流 - 輸出:100mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 細(xì)型，TSOT-23-6 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:TSOT-23-6 其它名稱:LTC1983ES6-3#TRMTR |
| LTC1261LCS8-4 | 功能描述:IC REG SWITCHD CAP INV -4V 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 類型:切換式電容器（充電泵），反相 輸出類型:固定 輸出數(shù):1 輸出電壓:-3V 輸入電壓:2.3 V ~ 5.5 V PWM 型:Burst Mode? 頻率 - 開關(guān):900kHz 電流 - 輸出:100mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 細(xì)型，TSOT-23-6 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:TSOT-23-6 其它名稱:LTC1983ES6-3#TRMTR |
| LTC1261LCS8-4#PBF | 功能描述:IC REG SWITCHD CAP INV -4V 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 類型:切換式電容器（充電泵），反相 輸出類型:固定 輸出數(shù):1 輸出電壓:-3V 輸入電壓:2.3 V ~ 5.5 V PWM 型:Burst Mode? 頻率 - 開關(guān):900kHz 電流 - 輸出:100mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 細(xì)型，TSOT-23-6 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:TSOT-23-6 其它名稱:LTC1983ES6-3#TRMTR |
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