參數(shù)資料
型號(hào)： RT8800AGQV
廠商： Richtek Technology Corporation
英文描述： General Purpose 3-Phase PWM Controller for High-Density Power Supply
中文描述： 通用三相PWM控制器，用于高密度電源
文件頁(yè)數(shù)： 11/21頁(yè)
文件大小： 493K
代理商： RT8800AGQV
RT8800A
11
DS8800A-04 August 2007
www.richtek.com
All brand name or trademark belong to their owner respectively
Figure 2
COMP
V
CORE
SSE_Internal
SS_Internal
Cross-over
V
RAMP_Valley
Time-Sharing DCR Current Sensing
RT8800A adopts an innovative time-sharing DCR current
sensing technique to sense the phase currents for phase
current balance (phase thermal balance), over current
protection and load line regulation as shown in Figure 3.
The current sensing amplifier GM samples and holds
voltages V
X
across the current sensing capacitor C
X
by
turns in a switching cycle. According to the Basic Circuit
Theory, if
LX
LX
I
X
X
X
LX
X
R
V
then
C
R
R
L
×
=
×
=
Consequently, the sensing current I
X
is proportional to
inductor current I
LX
and is expressed as
The sensed current I
X
is used for current balance, over
current protection, and droop tuning as described as
followed. Since all phases share one common GM, GM
offset and linearity variation effect are eliminated in
practical applications. As sub-milli-ohmgrade inductors are
widely used in modern motherboards, slight mismatch of
GM amplifiers offset and linearity results in considerable
current shift between phases. The time sharing DCR current
sensing technical is extremely important to guarantee
phase current balance at mass production.
COMM
LX
LX
R
X
R
I
I
×
=
Figure 3
Figure 4 and 5 show the linearity of GM amplifier and its
test circuit respectively. A voltage source is applied to
ISPx while other ISPx pins are short to V
OUT
. The voltage
V
ADJ
across resistor R
ADJ
is measured. It is observed from
Figu
re 5 shows that
all ISPx share the same
transconductance linearity and voltage offset.
Figure 4. The Linearity of GMx
V
OUT
T1
T3
T2
I
X
S/H CKT
+
-
L
X
R
LX
R
COMM
I
LX
+
R
X
C
X
+ V
X
-
GM
0
10
20
30
40
50
60
70
0
20
40
60
80
100
V
C
(mV)
X
I
A
GM1
GM2
GM3
相關(guān)PDF資料
PDF描述
RT8800APQV General Purpose 3-Phase PWM Controller for High-Density Power Supply
RT8800BGS General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800 General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800BGQV General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800BPQV General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
RT8800APQV 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:General Purpose 3-Phase PWM Controller for High-Density Power Supply
RT8800B 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800BGQV 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800BGS 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
RT8800BPQV 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:General Purpose 2/3-Phase PWM Controller for High-Density Power Supply
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