參數(shù)資料
型號: LTC1871-7
廠商: Linear Technology Corporation
英文描述: Quadruple 2-Input Positive-AND Gate 14-SOIC -40 to 85
中文描述: 2相升壓型DC / DC控制器
文件頁數(shù): 17/36頁
文件大?。?/td> 411K
代理商: LTC1871-7
17
LTC1871
For the bulk C component, which also contributes 1% to
the total ripple:
C
I
V
f
OUT
O MAX
(
0 01
O
)
.
For many designs it is possible to choose a single capaci-
tor type that satisfies both the ESR and bulk C require-
ments for the design. In certain demanding applications,
however, the ripple voltage can be improved significantly
by connecting two or more types of capacitors in parallel.
For example, using a low ESR ceramic capacitor can
minimize the ESR step, while an electrolytic capacitor can
be used to supply the required bulk C.
Once the output capacitor ESR and bulk capacitance have
been determined, the overall ripple voltage waveform
should be verified on a dedicated PC board (see Board
Layout section for more information on component place-
ment). Lab breadboards generally suffer from excessive
series inductance (due to inter-component wiring), and
these parasitics can make the switching waveforms look
significantly worse than they would be on a properly
designed PC board.
The output capacitor in a boost regulator experiences high
RMS ripple currents, as shown in Figure 12. The RMS
output capacitor ripple current is:
I
I
V
V
V
RMS COUT
(
O MAX
(
O
IN MIN
(
IN MIN
(
)
)
)
)
Note that the ripple current ratings from capacitor manu-
facturers are often based on only 2000 hours of life. This
makes it advisable to further derate the capacitor or to
choose a capacitor rated at a higher temperature than
required. Several capacitors may also be placed in parallel
to meet size or height requirements in the design.
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 product of
ESR and size of any aluminum electrolytic, at a somewhat
higher price.
In surface mount applications, multiple capacitors may
have to be placed in parallel in order to meet the ESR or
RMS current handling requirements of the application.
Aluminum electrolytic and dry tantalum capacitors are
both available in surface mount packages. In the case of
tantalum, it is critical that the capacitors have been surge
tested for use in switching power supplies. An excellent
choice is AVX TPS series of surface mount tantalum. Also,
ceramic capacitors are now available with extremely low
ESR, ESL and high ripple current ratings.
Boost Converter: Input Capacitor Selection
The input capacitor of a boost converter is less critical than
the output capacitor, due to the fact that the inductor is in
series with the input and the input current waveform is
APPLICATIU
W
U
U
V
IN
L
D
SW
12a. Circuit Diagram
12b. Inductor and Input Currents
C
OUT
V
OUT
R
L
I
IN
I
L
12c. Switch Current
I
SW
t
ON
12d. Diode and Output Currents
12e. Output Voltage Ripple Waveform
I
O
I
D
V
(AC)
t
OFF
V
ESR
RINGING DUE TO
TOTAL INDUCTANCE
(BOARD + CAP)
V
COUT
Figure 12. Switching Waveforms for a Boost Converter
相關PDF資料
PDF描述
LTC1871EMS Quadruple 2-Input Positive-AND Gate 14-SO -40 to 85
LTC1873EG Quadruple 2-Input Positive-AND Gate 14-TSSOP -40 to 85
LTC1873 Dual 550kHz Synchronous 2-Phase Switching Regulator Controller with 5-Bit VID(550kHz,雙 路,同步2相開關穩(wěn)壓器(帶5位VID))
LTC1874 Dual Constant Frequency Current Mode Step-Down DC/DC Controller(雙路(3.3V,1.8V輸出)恒定頻率,電流模式,步降DC/DC控制器)
LTC1874EGN Quadruple 2-Input Positive-AND Gate 14-VQFN -40 to 85
相關代理商/技術參數(shù)
參數(shù)描述
LTC1871EMS 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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)
LTC1871EMS#PBF 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR
LTC1871EMS#TR 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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)
LTC1871EMS#TRPBF 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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)
LTC1871EMS-1#PBF 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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)