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參數(shù)資料
| 型號(hào)： | SP7650 |
| 英文描述： | Wallmount ULTRX Series Fiberglass Enclosure; NEMA Type:1, 2, 4, 4X, 12, 13; Enclosure Material:Fiberglass; External Height:24.61"; External Width:24.11"; External Depth:12.64"; Enclosure Color:Light Gray |
| 中文描述： | 寬輸入電壓范圍第3A，300kHz的降壓穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 8/12頁(yè) |
| 文件大?。?/td> | 121K |
| 代理商： | SP7650 |
8
Date: 08/24/04
SP7650 Wide Input Voltage Range 3A, 300kHz, Buck Regulator Copyright 2004 Sipex Corporation
Output Capacitor Selection
The required ESR (Equivalent Series Resis-
tance) and capacitance drive the selection of the
type and quantity of the output capacitors. The
ESR must be small enough that both the resis-
tive voltage deviation due to a step change in the
load current and the output ripple voltage do not
exceed the tolerance limits expected on the
output voltage. During an output load transient,
the output capacitor must supply all the addi-
tional current demanded by the load until the
SP7650 adjusts the inductor current to the new
value.
In order to maintain V
OUT
,the capacitance must
be large enough so that the output voltage is
helped up while the inductor current ramps to
the value corresponding to the new load current.
Additionally, the ESR in the output capacitor
causes a step in the output voltage equal to the
current. Because of the fast transient response
and inherent 100%/0% duty cycle capability
provided by the SP7650 when exposed to output
load transient, the output capacitor is typically
chosen for ESR, not for capacitance value.
The output capacitor’s ESR, combined with the
inductor ripple current, is typically the main
contributor to output voltage ripple. The maxi-
mum allowable ESR required to maintain a
specified output voltage ripple can be calculated
by:
R
ESR
≤
V
OUT
I
PK-PK
where:
V
OUT
= Peak to Peak Output Voltage Ripple
I
PK-PK
= Peak to Peak Inductor Ripple Current
The total output ripple is a combination of the
ESR and the output capacitance value and can
be calculated as follows:
V
OUT
=
(
I
PP
(1 – D)
)
2
+ (I
PP
R
ESR
)
2
C
OUT
F
S
F
S
= Switching Frequency
D = Duty Cycle
C
OUT
= Output Capacitance Value
Input Capacitor Selection
The input capacitor should be selected for ripple
current rating, capacitance and voltage rating.
The input capacitor must meet the ripple current
requirement imposed by the switching current.
In continuous conduction mode, the source cur-
rent of the high-side MOSFET is approximately
a square wave of duty cycle V
OUT
/V
IN
. More
accurately the current wave form is trapezoidal,
given a finite turn-on and turn-off, switch tran-
sition slope. Most of this current is supplied by
the input bypass capacitors. The RMS current
handling capability of the input capacitors is
determined at maximum output current and
under the assumption that the peak
to peak inductor ripple current is low, it is given
by:
I
CIN(RMS)
= I
OUT(max)
√
D(1 - D)
The worse case occurs when the duty cycle D is
50% and gives an RMS current value equal to
I
OUT
/2.
Select input capacitors with adequate ripple
current rating to ensure reliable operation.
The power dissipated in the input capacitor is:
)
(
2
)
(
CIN
ESR
rms
CIN
CIN
P
R
I
=
This can become a significant part of power
losses in a converter and hurt the overall energy
transfer efficiency. The input voltage ripple
primarily depends on the input capacitor ESR
and capacitance. Ignoring the inductor ripple
current, the input voltage ripple can be deter-
mined by:
APPLICATIONS INFORMATION
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP7651 | Wide Input Voltage Range 3A, 900kHz, Buck Regulator |
| SP7652 | Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
| SP7652EB | Evaluation Board Manual |
| SP7652EU | Evaluation Board Manual |
| SP7653 | Wide Input Voltage Range, 1.3MHz,Buck Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7650_05 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7650_06 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 300kHz, Buck Regulator |
| SP7650EB | 功能描述:電源管理IC開發(fā)工具 Eval Board for SP7650 Series RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SP7650ER | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SP7650ER/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 300kHz, Buck Regulator |
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