- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄375341 > AOZ1017AI (ALPHA) EZBuck⑩ 3A Simple Regulator PDF資料下載
參數(shù)資料
| 型號： | AOZ1017AI |
| 廠商： | ALPHA |
| 英文描述： | EZBuck⑩ 3A Simple Regulator |
| 中文描述： | EZBuck⑩3A條簡單的穩(wěn)壓 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 612K |
| 代理商： | AOZ1017AI |
AOZ1017
Rev. 1.0 July 2007
www.aosmd.com
Page 10 of 16
When low ESR ceramic capacitor is used as output
capacitor, the impedance of the capacitor at the switching
frequency dominates. Output ripple is mainly caused by
capacitor value and inductor ripple current. The output
ripple voltage calculation can be simplified to:
If the impedance of ESR at switching frequency domi-
nates, the output ripple voltage is mainly decided by
capacitor ESR and inductor ripple current. The output
ripple voltage calculation can be further simplified to:
For lower output ripple voltage across the entire
operating temperature range, an X5R or X7R dielectric
type of ceramic, or other low ESR tantalum capacitor
or aluminum electrolytic capacitor may also be used as
output capacitors.
In a buck converter, output capacitor current is continu-
ous. The RMS current of output capacitor is defined by
the peak to peak inductor ripple current. It can be
calculated by:
I
L
12
Usually, the ripple current rating of the output capacitor
is a smaller issue because of the low current stress.
When the buck inductor is selected to be very small and
inductor ripple current is high, the output capacitor could
be overstressed.
Schottky Diode Selection
The external freewheeling diode supplies the current to
the inductor when the high side PMOS switch is off. To
reduce the losses due to the forward voltage drop and
recovery of diode, a Schottky diode is recommended.
The maximum reverse voltage rating of the chosen
Schottky diode should be greater than the maximum
input voltage, and the current rating should be greater
than the maximum load current.
Loop Compensation
The AOZ1017 employs peak current mode control for
easy use and fast transient response. Peak current mode
control eliminates the double pole effect of the output
L&C filter. It greatly simplifies the compensation loop
design.
With peak current mode control, the buck power stage
can be simplified to be a one-pole and one-zero system
in frequency domain. The pole is dominant pole and can
be calculated by:
The zero is a ESR zero due to output capacitor and its
ESR. It is can be calculated by:
where;
C
O
is the output filter capacitor,
R
L
is load resistor value, and
ESR
CO
is the equivalent series resistance of output capacitor.
The compensation design is actually to shape the con-
verter close loop transfer function to get the desired gain
and phase. Several different types of compensation net-
work can be used for the AOZ1017. For most cases, a
series capacitor and resistor network connected to the
COMP pin sets the pole-zero and is adequate for a stable
high-bandwidth control loop.
In the AOZ1017, FB pin and COMP pin are the inverting
input and the output of internal transconductance error
amplifier. A series R and C compensation network
connected to COMP provides one pole and one zero.
The pole is:
where;
G
EA
is the error amplifier transconductance, which is 200 x 10
-6
A/V,
G
VEA
is the error amplifier voltage gain, which is 500 V/V, and
C
C
is compensation capacitor.
The zero given by the external compensation network,
capacitor C
C
and resistor R
C
, is located at:
To design the compensation circuit, a target crossover
frequency f
C
for close loop must be selected. The system
crossover frequency is where control loop has unity gain.
The crossover frequency is also called the converter
bandwidth. Generally, a higher bandwidth means faster
response to load transient. However, the bandwidth
should not be too high because of system stability
V
O
I
L
1
×
8
f
C
O
×
--------------------------
×
=
V
O
I
L
ESR
CO
×
=
I
CO_RMS
----------
=
f
p
1
1
2
π
C
O
R
L
×
×
-----------------------------------
=
f
Z
1
1
×
2
π
C
O
ESR
CO
×
-------------------------------------------------
=
f
p
2
G
C
C
2
π
G
VEA
×
×
-------------------------------------------
=
f
Z
2
1
2
π
C
C
R
C
×
×
------------------------------------
=
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AOZ1020-EVA | EZBuck⑩ 2A Simple Buck Regulator Evaluation Board Note |
| AOZ1210-EVA | EZBuck⑩ 2A Simple Buck Regulator Evaluation Board Note |
| AOZ1210 | EZBuck⑩ 2A Simple Buck Regulator |
| AOZ1210AI | EZBuck⑩ 2A Simple Buck Regulator |
| AP01C | 1000V,Fast-Recovery Rectifier Diodes(1000V,快速恢復整流二極管) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AOZ1017DI | 制造商:AOSMD 制造商全稱:Alpha & Omega Semiconductors 功能描述:EZBucka?￠ 3A Simple Regulator |
| AOZ1017-EVA | 制造商:AOSMD 制造商全稱:Alpha & Omega Semiconductors 功能描述:EZBuck? 3A Simple Buck Regulator Evaluation Board Note |
| AOZ1018 | 制造商:AOSMD 制造商全稱:Alpha & Omega Semiconductors 功能描述:EZBuck⑩ 2A Simple Regulator |
| AOZ1018AI | 制造商:AOSMD 制造商全稱:Alpha & Omega Semiconductors 功能描述:EZBuck⑩ 2A Simple Regulator |
| AOZ1019 | 制造商:AOSMD 制造商全稱:Alpha & Omega Semiconductors 功能描述:EZBuck⑩ 2A Simple Regulator |
發(fā)布緊急采購，3分鐘左右您將得到回復。