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| 型號(hào)： | SP7655 |
| 英文描述： | Wide Input Voltage Range 8A, 300kHz, Buck Regulator |
| 中文描述： | 寬輸入電壓范圍8A條，300kHz的降壓穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 121K |
| 代理商： | SP7655 |
9
Date: 08/17/04
SP7655 Wide Input Voltage Range 8A, 300kHz, Buck Regulator Copyright 2004 Sipex Corporation
APPLICATIONS INFORMATION
2
)
(
)
(
(max)
)
(
V
IN
IN
S
OUT
IN
OUT
C
MAX
OUT
CIN
ESR
out
IN
F
V
V
V
I
R
I
V
+
=
The capacitor type suitable for the output capac-
itors can also be used for the input capacitors.
However, exercise extra caution when tantalum
capacitors are used. Tantalum capacitors are known
for catastrophic failure when exposed to surge
current, and input capacitors are prone to such
surge current when power supplies are connected
“l(fā)ive” to low impedance power sources. Although
tantalum capacitors have been successfully em-
ployed at the input, it is generally not recom-
mended.
Loop Compensation Design
The open loop gain of the whole system can be
divided into the gain of the error amplifier,
PWM modulator, buck converter output stage,
and feedback resistor divider. In order to cross
over at the desired frequency cut-off (FCO), the
gain of the error amplifier has to compensate for
the attenuation caused by the rest of the loop at
this frequency. The goal of loop compensation
is to manipulate loop frequency response such
that its cross-over gain at 0db, results in a slope
of -20db/dec.
The first step of compensation design is to pick
the loop cross over frequency. High cross over
frequency is desirable for fast transient response,
but often jeopardizes the power supply stability.
Cross over frequency should be higher than the
ESR zero but less than 1/5 of the switching
frequency or 60kHz. The ESR zero is contrib-
uted by the ESR associated with the output
capacitors and can be determined by:
Z(ESR)
=
1
2
π
C
OUT
R
ESR
The next step is to calculate the complex conju-
gate poles contributed by the LC output filter,
P(LC)
=
1
2
π
L C
OUT
When the output capacitors are of a Ceramic
Type, the SP7655 Evaluation Board requires a
Type III compensation circuit to give a phase
boost of 180
°
in order to counteract the effects of
an under damped resonance of the output filter
at the double pole frequency.
SP7655 Voltage Mode Control Loop with Loop Dynamic
Definitions:
R
ESR
= Output Capacitor Equivalent Series Resistance
R
DC
= Output Inductor DC Resistance
R
RAMP_PP
= SP7655 internal RAMP Amplitude Peak to Peak Voltage
Conditions:
(SRz2Cz2+1)(SR1Cz3+1)
(SR
ESR
C
OUT
+ 1)
[S^2LC
OUT
+S(R
ESR
+R
DC
) C
OUT
+1]
V
IN
SR1Cz2(SRz3Cz3+1)(SRz2Cp1+1)
V
RAMP_PP
V
OUT
(Volts)
+
_
V
(Volts)
Notes: R
ESR
= Output Capacitor Equivalent Series Resistance.
R
DC
= Output Inductor DC Resistance.
V
RAMP_PP
= SP6132 Internal RAMP Amplitude Peak to Peak Voltage.
Condition: Cz2 >> Cp1 & R1 >> Rz3
Output Load Resistance >> R
ESR
& R
DC
R
2
V
REF
V
OUT
(R
1
+ R
2
)
or
V
FBK
(Volts)
Type III Voltage Loop
Compensation
G
AMP
(s) Gain Block
PWM Stage
G
PWM
Gain
Block
Output Stage
G
OUT
(s) Gain
Block
Voltage Feedback
G
FBK
Gain Block
C
Z
2 >> Cp1 and R1 >> Rz3
Output Load Resistance >>
R
ESR
and
R
DC
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7655_05 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7655_07 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
| SP7655EB | 功能描述:電源管理IC開(kāi)發(fā)工具 Eval Board for SP7655 Series RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類(lèi)型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SP7655ER | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7655ER/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
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