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參數(shù)資料
| 型號： | LTC1143LCS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | SWITCHING CONTROLLER, 400 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SO-16 |
| 文件頁數(shù)： | 11/20頁 |
| 文件大小： | 372K |
| 代理商： | LTC1143LCS |
11
LTC1143/LTC1143L
LTC1143L-ADJ
APPLICATIO
S I
FOR
ATIO
U
but
δ
= 0.005/
°
C can be used as an approximation for low
voltage MOSFETs.
When selecting the P-channel power MOSFET for each
section, consideration should be given to using a dual MOSFET
with the other half used for the second regulator. Assuming
both sections are operating at similar currents, the required
R
DS(ON)
will be half the value of a single MOSFET to stay within
the package dissipation limit. Remember that worst-case
MOSFET dissipation occurs at minimum V
IN
.
W
U
U
RMS current must be used. The maximum RMS capacitor
current is given by:
C
I
V
V
V
V
IN
MAX
OUT
IN
OUT
IN
Required I
RMS
≈
(
)
[
]
1 2
/
This formula has a maximum at V
IN
= 2V
OUT
, where I
RMS
= I
OUT
/2. This simple worst-case condition is commonly
used for design because even significant deviations do not
offer much relief. Note that capacitor manufacturer’s
ripple current ratings 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
paralleled to meet size or height requirements in the
design. Always consult the manufacturer if there is any
question. An additional 0.1
μ
F to 1
μ
F ceramic capacitor is
also required on each V
IN
line (Pins 5, 13) for high
frequency decoupling.
The selection of C
OUT
is driven by the required (ESR). The
ESR of C
OUT
must be less than twice the value of R
SENSE
for proper operation of the LTC1143 series:
C
OUT
Required ESR < 2R
SENSE
Optimum efficiency is obtained by making the ESR equal
to R
SENSE
. As the ESR is increased up to 2R
SENSE
the
efficiency degrades by less than 1%. If the ESR is greater
than 2R
SENSE
, the voltage ripple on the output capacitor
will prematurely trigger Burst Mode operation, resulting in
disruption of continuous mode and an efficiency hit which
can be several percent.
Manufacturers such as Nichicon and United Chemicon
should be considered for high performance capacitors.
The OS-CON semiconductor dielectric capacitor available
from Sanyo has the lowest ESR size/ratio of any aluminum
electrolytic at a somewhat higher price. Once the ESR
requirement for C
OUT
has been met, the RMS current
rating generally far exceeds the I
RIPPLE(P-P)
requirement.
In surface mount applications multiple capacitors may
have to be parallel to meet the capacitance, ESR or RMS
current handling requirements of the application.
Output Diode Selection (D1, D2)
The Schottky diodes D1 and D2 shown in Figure 1 conduct
during the off-time. It is important to adequately specify
the diode peak current and average power dissipation to
not exceed the diode ratings.
The most stressful condition for the output diode is under
short circuit (V
OUT
= 0V). Under this condition the diode
must safely handle I
SC(PK)
at close to 100% duty cycle.
Under normal load conditions the average current con-
ducted by the diode is:
(
I
V
V
V
V
I
DIODE
IN
OUT
D
IN
LOAD
=
+
)(
)
Remember to keep lead lengths short and observe proper
grounding (see Board Layout Checklist) to avoid ringing
and increased dissipation.
The forward voltage drop allowable in the diode is calcu-
lated from the maximum short-circuit current as:
V
P
I
F
D
SC PK
≈
)
where P
D
is the allowable power dissipation and will be
determined by efficiency and/or thermal requirements
(see Efficiency Considerations).
C
IN
and C
OUT
Selection
In continuous mode, the source current of the P-channel
MOSFET is a square wave of duty cycle V
OUT
/V
IN
. To
prevent large voltage transients, a low effective series
resistance (ESR) input capacitor sized for the maximum
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| LTC1143LCS#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 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:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1143LCS#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 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:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1143LCS#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 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:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1143LCS-ADJ | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)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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