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| 型号： | LX1672-03CPW-TR |
| 厂商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分类： | 稳压器 |
| 英文描述： | 1 A DUAL SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | ROHS COMPLIANT, PLASTIC, TSSOP-28 |
| 文件页数： | 7/20页 |
| 文件大小： | 382K |
| 代理商： | LX1672-03CPW-TR |
PRODUCTION DATA SHEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 15
Copyright
2000
Rev. 1.0, 2005-08-10
WWW
.Microse
m
i
.CO
M
LX1672
Multiple Output LoadSHARE PWM
TM
APPLICATION NOTE
OUTPUT INDUCTOR
The output inductor should be selected to meet the
requirements of the output voltage ripple in steady-state operation
and the inductor current slew-rate during transient. The peak-to-
peak output voltage ripple is:
RIPPLE
I
ESR
V
×
=
where
s
D
L
V
ΔI
OUT
IN
f
×
=
ΔI is the inductor ripple current, L is the output inductor value
and ESR is the Effective Series Resistance of the output
capacitor.
ΔI should typically be in the range of 20% to 40% of the
maximum output current. Higher inductance results in lower
output voltage ripple, allowing slightly higher ESR to satisfy the
transient specification. Higher inductance also slows the inductor
current slew rate in response to the load-current step change, ΔI,
resulting in more output-capacitor voltage droop. When using
electrolytic capacitors, the capacitor voltage droop is usually
negligible, due to the large capacitance
The inductor-current rise and fall times are:
()
OUT
IN
RISE
V
ΔI
L
T
×
=
and
OUT
FALL
V
ΔI
L
T
×
=
The inductance value can be calculated by
s
D
ΔI
V
L
OUT
IN
f
×
=
OUTPUT CAPACITOR
The output capacitor is sized to meet ripple and transient
performance specifications. Effective Series Resistance (ESR) is a
critical parameter. When a step load current occurs, the output
voltage will have a step that equals the product of the ESR and the
current step, ΔI. In an advanced microprocessor power supply, the
output capacitor is usually selected for ESR instead of capacitance
or RMS current capability. A capacitor that satisfies the ESR
requirements usually has a larger capacitance and current capability
than strictly needed. The allowed ESR can be found by:
(
)
EX
RIPPLE
V
ΔI
I
ESR
<
+
×
Where IRIPPLE is the inductor ripple current, ΔI is the maximum
load current step change, and VEX is the allowed output voltage
excursion in the transient.
Electrolytic capacitors can be used for the output capacitor, but
are less stable with age than tantalum capacitors. As they age, their
ESR degrades, reducing the system performance and increasing the
risk of failure. It is recommended that multiple parallel capacitors
be used, so that, as ESR increase with age, overall performance
will still meet the processor’s requirements.
There is frequently strong pressure to use the least expensive
components possible; however, this could lead to degraded long-
term reliability, especially in the case of filter capacitors.
Microsemi’s demonstration boards use the CDE Polymer AL-EL
(ESRE) filter capacitors, which are aluminum electrolytic, and
have demonstrated reliability. The OS-CON series from Sanyo
generally provides the very best performance in terms of long term
ESR stability and general reliability, but at a substantial cost
penalty. The CDE Polymer AL-EL (ESRE) filter series provides
excellent ESR performance at a reasonable cost. Beware of off-
brand, very low-cost filter capacitors, which have been shown to
degrade in both ESR and general electrolytic characteristics over
time.
AA
PP
LL
IICC
AA
TT
IIOO
NN
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相关代理商/技术参数 |
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|---|---|
| LX1672-05CPW | 功能描述:IC REG CTRLR BUCK PWM VM 28TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:LoadSHARE™ 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LX1672-05CPW-TR | 制造商:Microsemi Corporation 功能描述:MOSFET DRVR 0.8V 1A 3-OUT HI/LO SIDE HALF BRDG NON-INV 28TSS - Tape and Reel |
| LX1672-06CLQ | 功能描述:IC REG CTRLR BUCK PWM VM 38MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:LoadSHARE™ 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LX1672-06CLQ-TR | 制造商:Microsemi Corporation 功能描述:MOSFET DRVR 0.8V 1A 3-OUT HI/LO SIDE HALF BRDG NON-INV 38MLP - Tape and Reel |
| LX1673 | 制造商:MICROSEMI 制造商全称:Microsemi Corporation 功能描述:High Frequency PWM Regulator |
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