參數(shù)資料
型號(hào)： SP6122ACU-15
英文描述： Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters
中文描述： 低電壓，微8，PFET的，降壓控制器適合第1A至5A，占地面積小，DC - DC電源轉(zhuǎn)換器
文件頁(yè)數(shù)： 12/19頁(yè)
文件大?。?/td> 174K
代理商： SP6122ACU-15
12
Date: 10/02/04
SP6122 Low Voltage, Micro 8, PFET, Buck Controller Copyright 2004 Sipex Corporation
The copper loss in the inductor can be
calculated from the equation:
P
L(Cu)
= I
L(RMS)2
R
WINDING
I
OUT(max)2
R
WINDING
For the 2.2
μ
H example with 0.012
ESR in
the winding, 4A load and 1.9V output, the
copper loss in the inductor is 190mW.
OUTPUT CAPACITOR SELECTION
The output capacitor is typically selected
based on its ability to maintain the output
within specified tolerance limits during load
transients. During an output load transient,
the output capacitor must supply all the
additional current demanded by the load
until the SP6122 adjusts the inductor cur-
rent to the new value. Therefore the capaci-
tance must be large enough so that the
output voltage is held up while the inductor
current ramps up or down to the value
corresponding to the new load current. For
power converters delivering greater than
1A at less than 1MHz switching frequency,
the output capacitor is typically greater than
100
μ
F. Typically, tantalum and OSCON
capacitors are used to get high output ca-
pacitance in a small space. These capaci-
tors have a high Equivalent Series Resis-
tance (ESR) when compared to ceramic
capacitors and this ESR is both a curse and
a blessing. Unfortunately, the ESR (Equiva-
lent Series Resistance) in the output ca-
pacitor causes a step in the output voltage
equal to the ESR value multiplied by the
change in load current. As a result, in a
power supply using a tantalum, aluminum
electrolytics or OSCON output capacitor,
the value of output capacitance (or number
of output capacitors) is typically chosen to
minimize the output variation due to the
load step imposed on this ESR. However,
the SP6122 takes advantage of the natural
presence of this ESR to control the loop.
Because the inductor ripple current also
flows through this ESR, and output ripple
voltage is created and the waveform is
resembles a miniature current-mode timing
waveform. For a 1.9V output voltage, the
required ripple is a reasonable 38 mV. The
designer must chose all other trade-offs
wisely to maintain this ripple
0.02 * V
OUT
< I
PP
* R
ESR
and
I
LOAD
* R
ESR
<
V
TOL
where:
V
OUT
= DC output voltage
R
ESR
= ESR of the output capacitor
DI
LOAD
= change in current due to load
step
DV
TOL
= tolerable deviation due to load
transient
I
PP
= peak to peak inductor ripple current
Output ripple is due primarily to the output
ripple current and the output capacitor ESR
value as seen in the following equation:
V
OUT
I
PP
R
ESR
For our SP6122 evaluation board example
with ESR = 35m
and I
PP
= 1.32A,
V
OUT
=
46mV. Note that a 4A step creates a 140mV
deviation. If this is unacceptable, ESR and
I
PP
must be reconsidered in order to im-
prove step response and maintain output
ripple.
Recommended capacitors that can be used
effectively in SP6122 applications are: low-
ESR aluminum electrolytic capacitors,
OSCON capacitors that provide a very high
performance/size ratio for electrolytic ca-
pacitors and low-ESR tantalum capacitors.
AVX TPS series and Kemet T510 surface
mount capacitors are popular tantalum ca-
pacitors that work well in SP6122 applica-
tions. POSCAP from Sanyo is a solid elec-
trolytic chip capacitor that has low ESR and
high capacitance. For the same ESR value,
POSCAP has lower profile compared with a
tantalum capacitor.
Guidelines for Component Selection:
continued
相關(guān)PDF資料
PDF描述
SP6122CU Evaluation Board Manual
SP6122EB Evaluation Board Manual
SP6122UEB Evaluation Board Manual
SP6122ACU-1.5 Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters
SP6122 Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SP6122ACU-15/TR 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters
SP6122ACU-L 功能描述:DC/DC 開關(guān)控制器 Low Voltage, Micro 8 PFET Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
SP6122ACU-L/TR 功能描述:DC/DC 開關(guān)控制器 Low Voltage, Micro 8 PFET Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
SP6122ACU-L-1-5 制造商:Exar Corporation 功能描述:BUCK CONTROLLER LOW VOLT PFET 6122
SP6122CU 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual
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