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參數(shù)資料
| 型號： | SP6120BCY |
| 英文描述： | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| 中文描述： | 低電壓，AnyFETTM，同步，降壓控制器適合2A至10A條，高性能，DC - DC電源轉(zhuǎn)換器 |
| 文件頁數(shù)： | 18/22頁 |
| 文件大小： | 304K |
| 代理商： | SP6120BCY |
18
Date: 5/25/04
SP6120B Low Voltage, AnyFET
TM
, Synchronous, Buck Controller Copyright 2004 Sipex Corporation
Current Sense
The SP6120B allows sensing current using the
inductor, PCB trace or current-sense resistor.
Inductor-sense utilizes the voltage drop across
the ESR of the inductor, while PCB trace and
current-sense resistor introduce additional re-
sistance in series with the inductor. The resis-
tance of the sense element determines the
overcurrent protection threshold as follows,
I
LIM
= 43mV
R
SEN
R
SEN
= current-sense resistance which can be
implemented as ESR of the inductor, trace or
discrete resistor.
The maximum power dissipation on the current-
sense element is:
I
P
=
For the inductor-sense scheme shown in the
application circuit, R
S
and C
S
are used to repli-
cate the signal across the ESR of the inductor. R
S
and C
S
can be looked at as a low pass filter
whose output represents the DC differential
voltage between the switch node and the output.
At steady state, this voltage happens to be the
output current times the ESR of the inductor. In
addition, if the following relationship is satisfied,
L = R
S
C
S
ESR
the output of the RsCs filter represents the exact
voltage across the ESR, including the ripple.
Since the SP6120B’s hiccup overcurrent pro-
tection scheme is intended to safeguard sus-
tained overload conditions, the DC portion of
the current signal is more of interest. Therefore,
designing the R
S
C
S
time constant higher than L/
ESR provides reliable current sense against any
premature triggering due to noise or any tran-
sient conditions. Pick Rs between 10k and 100k,
and Cs can be determined by:
SEN
OUT
SEN
R
2
(max)
C
S
= 2
L
1
ESR R
S
Here the time constant of R
S
C
S
is twice the value
of L/ESR.
In some applications, it may be desirable to
extend the current sense capability of a given
R
SEN
element (usually the inductor ESR) be-
In Figure 18, R1 and C1 provides a zero f
Z1
which needs to be placed at or below f
P(LC)
. If f
Z1
is made equal to f
P(LC)
for convenience, the
value of C1 can be calculated as
C
1
=
1
2
π
f
P(LC)
R
1
The optional C2 generates a pole f
P1
with R1 to
cut down high frequency noise for reliable op-
eration. This pole should be placed one decade
higher than the crossover frequency to avoid
erosion of phase margin. Therefore, the value of
the C2 can be derived from
C
2
=
1
20
π
f
CO
R
1
Figure 19 illustrates the overall loop frequency
response and frequency of each pole and zero.
To fine-tune the compensation, it is necessary to
physically measure the frequency response us-
ing a network analyzer.
Gain
-20db/dec
-40db/dec
-20db/dec
-20db/dec
-20db/dec
Error Amplifier
Loop
f
f
f
Z1
f
P(LC)
f
Z(ESR)
f
CO
f
P1
Figure 19. Frequency response of a stable system and its
error amplifier.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP6120BEY | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120CY | Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120HVEY | High Voltage, Synchronous ,Buck Controller Ideal for 2A to 20A, High Performance, DC-DC Power Converters |
| SP6120HVCY | CAPACITOR, F/TERM 6800PF 50V X8R 0805CAPACITOR, F/TERM 6800PF 50V X8R 0805; CAPACITANCE:6.8NF; VOLTAGE RATING, DC:50V; CAPACITOR DIELECTRIC TYPE:CERAMIC MULTI-LAYER; SERIES:08055F; TOLERANCE, :10%; TOLERANCE, -:10%; TEMP, OP. RoHS Compliant: Yes |
| SP6120EY | Low Voltage, AnyFETTM, Synchronous,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6120BCY/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120BCY-L | 功能描述:DC/DC 開關(guān)控制器 Low Voltage, AnyFET Synchronous, Cntrllr 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 |
| SP6120BCY-L/TR | 功能描述:DC/DC 開關(guān)控制器 Low Voltage, AnyFET Synchronous, Cntrllr 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 |
| SP6120BEY | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
| SP6120BEY/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, AnyFETTM, Synchronous ,Buck Controller Ideal for 2A to 10A, High Performance, DC-DC Power Converters |
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