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參數(shù)資料
| 型號： | NCP5322A |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | TWO-PHASE BUCK CONTROLLER WITH INTEGRATED GATE DRIVERS AND 5-BIT DAC |
| 中文描述： | 兩相降壓控制器，它集成柵極驅(qū)動器和5位DAC |
| 文件頁數(shù)： | 14/32頁 |
| 文件大?。?/td> | 1091K |
| 代理商： | NCP5322A |
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NCP5322A
http://onsemi.com
14
Figure 12. Enhanced V
2
Control Employing Lossless Inductive Current Sensing and Internal Ramp
+
CSA
SWNODE
Ln
R
CSn
RLn
CSn
COn
CS
REF
+
V
OUT
(V
CORE
)
“
Fast
–
Feedback
”
Connection
+
PWM
COMP
To F/F
Reset
Channel
Start
–
Up
Offset
+
E.A.
DAC
Out
V
FB
COMP
Internal Ramp
+
n = 1 or 2
C
CSn
–
+
Inductive Current Sensing
For lossless sensing, current can be sensed across the
inductor as shown in Figure 12. In the diagram, L is the
output inductance and R
L
is the inherent inductor resistance.
To compensate the current sense signal, the values of R
CSn
and C
CSn
are chosen so that L/R
L
= R
CSn
C
CSn
. If this
criteria is met, the current sense signal will be the same shape
as the inductor current and the voltage signal at CSn will
represent the instantaneous value of inductor current. Also,
the circuit can be analyzed as if a sense resistor of value R
L
was used as a sense resistor (R
S
).
When choosing or designing inductors for use with
inductive sensing, tolerances and temperature effects should
be considered. Cores with a low permeability material or a
large gap will usually have minimal inductance change with
temperature and load. Copper magnet wire has a
temperature coefficient of 0.39% per
°
C. The increase in
winding resistance at higher temperatures should be
considered when setting the I
LIM
threshold. If a more
accurate current sense is required than inductive sensing can
provide, current can be sensed through a resistor as shown
in Figure 10.
Current Sharing Accuracy
Printed circuit board (PCB) traces that carry inductor
current can be used as part of the current sense resistance
depending on where the current sense signal is picked off.
For accurate current sharing, the current sense inputs should
sense the current at relatively the same point for each phase
and the connection to the CS
REF
pin should be made so that
no phase is favored. In some cases, especially with inductive
sensing, resistance of the PCB can be useful for increasing
the current sense resistance. The total current sense
resistance used for calculations must include any PCB trace
resistance between the CSn input and the CS
REF
input that
carries inductor current.
Current Sense Amplifier (CSA) input mismatch and the
value of the current sense component will determine the
accuracy of the current sharing between phases. The worst
case Current Sense Amplifier input mismatch is
±
5.0 mV
and will typically be within 3.0 mV. The difference in peak
currents between phases will be the CSA input mismatch
divided by the current sense resistance. If all current sense
components are of equal resistance a 3.0 mV mismatch with
a 2.0 m
sense resistance will produce a 1.5 A difference in
current between phases.
External Ramp Size and Current Sensing
The internal ramp allows flexibility of current sense time
constant. Typically, the current sense R
CSn
C
CSn
time
constant (n = 1 or 2) should be equal to or slower than the
inductor
’
s time constant. If RC is chosen to be smaller
(faster) than L/R
L
, the AC or transient portion of the current
sensing signal will be scaled larger than the DC portion. This
will provide a larger steady state ramp, but circuit
performance will be affected and must be evaluated
carefully. The current signal will overshoot during transients
and settle at the rate determined by R
CSn
C
CSn
. It will
eventually settle to the correct DC level, but the error will
decay with the time constant of R
CSn
C
CSn
. If this error is
excessive it will effect transient response, adaptive
positioning and current limit. During a positive current
transient, the COMP pin will be required to undershoot in
response to the current signal in order to maintain the output
voltage. Similarly, the V
DRP
signal will overshoot which
will produce too much transient droop in the output voltage.
Single phase overcurrent will trip earlier than it would if
compensated correctly and hiccup mode current limit will
have a lower threshold for fast rise step loads than for slowly
rising output currents.
The waveforms in Figure 13 show a simulation of the
current sense signal and the actual inductor current during a
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| NCP5322ADW | TWO-PHASE BUCK CONTROLLER WITH INTEGRATED GATE DRIVERS AND 5-BIT DAC |
| NCP5322ADWR2 | STATIC PROTECTION RoHS Compliant: Yes |
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| NCP5332ADWR2 | Two-Phase Buck Controller with Integrated Gate Drivers and 5-Bit DAC |
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| NCP5322A/D | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Two-Phase Buck Controller with integrated Gate Drivers and 5-Bit DAC |
| NCP5322A_07 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Two−Phase Buck Controller with Integrated Gate Drivers and 5−Bit DAC |
| NCP5322ADW | 功能描述:DC/DC 開關(guān)控制器 2 Phase Buck w/Gate 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 |
| NCP5322ADWG | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Two−Phase Buck Controller with Integrated Gate Drivers and 5−Bit DAC |
| NCP5322ADWR2 | 功能描述:DC/DC 開關(guān)控制器 2 Phase Buck w/Gate 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 |
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