參數(shù)資料
型號(hào)： LTC1261
廠商： Linear Technology Corporation
英文描述： Switched Capacitor Regulated Voltage Inverter(開(kāi)關(guān)電容穩(wěn)壓電壓反相器)
中文描述： 開(kāi)關(guān)電容穩(wěn)壓逆變器（開(kāi)關(guān)電容穩(wěn)壓電壓反相器）
文件頁(yè)數(shù)： 10/16頁(yè)
文件大?。?/td> 265K
代理商： LTC1261
10
LTC1261
Most of this resistance is already provided by the internal
switches in the LTC1261 (especially in tripler mode). 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 versions of
the LTC1261—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 1.24V at the ADJ pin with
respect to V
OUT
(Figure 6). The LTC1261 uses a positive
reference with respect to V
OUT
, not a negative reference
with respect to ground (Figure 2 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.
APPLICATIO
S I
N
FOR
ATIO
U
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 5). 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
LOW ESR
OUTPUT CAP
CLOCK
V
AVERAGE
V
SET
COMP1
OUTPUT
V
OUT
HIGH ESR
OUTPUT CAP
V
AVERAGE
V
SET
COMP1
OUTPUT
LTC1261 F05
V
OUT
Note that ESR in the flying capacitors 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
approaches half of a clock period (the time the capacitors
have to share charge at full duty cycle) the output current
capability of the LTC1261 will begin to diminish. For 0.1
μ
F
flying capacitors, this gives a maximum total series resis-
tance of:
)
550kHz
=
/ 0.1
μ
F = 9.1
1
2
)
t
CLK
C
FLY
1
2
)
)
1
Figure 5. Output Ripple with Low and High ESR Capacitors
Figure 6. External Resistor Connections
LTC1261
GND
R1
6 (4*)
10 (5*)
11 (6*)
*LTC1261CS8
LTC1261 F06
V
OUT
= –1.24V
R2
R1 + R2
R2
ADJ
OUT
(
)
The 14-pin adjustable parts include a built-in resistor
string which can provide an assortment of output voltages
by using different pin-strapping options at the R0, R1, and
R
ADJ
pins (Table 2). The internal resistors are roughly
124k, 226k, 100k, and 50k (see Figure 2) giving output
options of –3.5V, –4V, –4.5V, and –5V. The resistors are
carefully matched to provide accurate divider ratios, but
the absolute values can vary substantially from part to
part. It is not a good idea to create a divider using an
external resistor and one of the internal resistors unless
the output voltage accuracy is not critical.
相關(guān)PDF資料
PDF描述
LTC1262 Regulated 12V, 30mA output DC/DC converter.(12V穩(wěn)壓, 30mA輸出DC/DC變換器)
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LTC1264CSW High Speed, Quad Universal Filter Building Block
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1261CS 功能描述:IC REG SWITCHED CAP INV 14SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤(pán) 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤(pán)
LTC1261CS#PBF 功能描述:IC REG SWITCHED CAP INV 14SOIC RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:MIC23xxx HyperLight Load™ Regulators 標(biāo)準(zhǔn)包裝:5,000 系列:HyperLight Load® 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.8V 輸入電壓:2.7 V ~ 5.5 V PWM 型:混合物 頻率 - 開(kāi)關(guān):4MHz 電流 - 輸出:2A 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤(pán)，8-MLF? 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-MLF?（2x2） 產(chǎn)品目錄頁(yè)面:1094 (CN2011-ZH PDF) 其它名稱(chēng):576-3303-2
LTC1261CS#TR 功能描述:IC REG SWITCHED CAP INV 14SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)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(kāi)關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無(wú) 工作溫度:-40°C ~ 85°C 安裝類(lèi)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
LTC1261CS#TRPBF 功能描述:IC REG SWITCHED CAP INV 14SOIC RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)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(kāi)關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無(wú) 工作溫度:-40°C ~ 85°C 安裝類(lèi)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
LTC1261CS8 功能描述:IC REG SWITCHD CAP INV ADJ 8SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:升壓（升壓） 輸出類(lèi)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(kāi)關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無(wú) 工作溫度:-40°C ~ 85°C 安裝類(lèi)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
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