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參數(shù)資料
| 型號： | NCP5306 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Three−Phase VRM 9.0 Buck Controller |
| 文件頁數(shù)： | 16/24頁 |
| 文件大?。?/td> | 879K |
| 代理商： | NCP5306 |
NCP5306
http://onsemi.com
16
Table 1. Fault Protection Logic
Fault Modes
Stop Switching
SS Pin Characteristics
Reset Method
Undervoltage Lockout
Yes
5.0
μ
A
SS < 0.3 V
VID
11111
Yes
5.0
μ
A
Change VID Code
Phase Over Current
(0.31 V Limit)
No
Not Affected
Automatic
The latest VRM and processor specifications require a
power supply to turn its output off in the event of a 11111
VID code. When the DAC sees such a code, the GATE pins
stop switching and go low. This condition is described in
Table 1.
Design Procedure
1. Output Capacitor Selection
The output capacitors filter the current from the output
inductor and provide a low impedance for transient load
current changes. Typically, microprocessor applications
require both bulk (electrolytic, tantalum) and low
impedance, high frequency (ceramic) types of capacitors.
The bulk capacitors provide “hold up” during transient
loading. The low impedance capacitors reduce steady
state
ripple and bypass the bulk capacitance when the output
current changes very quickly. The microprocessor
manufacturers usually specify a minimum number of
ceramic capacitors. The designer must determine the
number of bulk capacitors.
Choose the number of bulk output capacitors to meet the
peak transient requirements. The formula below can be used
to provide a starting point for the minimum number of bulk
capacitors (N
OUT,MIN
):
NOUT,MIN
ESR per capacitor
IO,MAX
VO,MAX
(1)
In reality, both the ESR and ESL of the bulk capacitors
determine the voltage change during a load transient
according to:
VO,MAX
Unfortunately, capacitor manufacturers do not specify the
ESL of their components and the inductance added by the
PCB traces is highly dependent on the layout and routing.
Therefore, it is necessary to start a design with slightly more
than the minimum number of bulk capacitors and perform
transient testing or careful modeling/simulation to
determine the final number of bulk capacitors.
( IO,MAX
t)
ESL
IO,MAX
ESR
(2)
2. Output Inductor Selection
The output inductor may be the most critical component
in the converter because it will directly effect the choice of
other components and dictate both the steady
state and
transient performance of the converter. When selecting an
inductor, the designer must consider factors such as DC
current, peak current, output voltage ripple, core material,
magnetic saturation, temperature, physical size and cost
(usually the primary concern).
In general, the output inductance value should be
electrically and physically as small as possible to provide the
best transient response at minimum cost. If a large
inductance value is used, the converter will not respond
quickly to rapid changes in the load current. On the other
hand, too low an inductance value will result in very large
ripple currents in the power components (MOSFETs,
capacitors, etc.) resulting in increased dissipation and lower
converter efficiency. Increased ripple currents force the
designer to use higher rated MOSFETs, oversize the thermal
solution, and use more, higher rated input and output
capacitors, adversely affecting converter cost.
One method of calculating an output inductor value is to
size the inductor to produce a specified maximum ripple
current in the inductor. Lower ripple currents will result in
less core and MOSFET losses and higher converter
efficiency. Equation 3 may be used to calculate the
minimum inductor value to produce a given maximum
ripple current (
α
) per phase. The inductor value calculated
by this equation is a minimum because values less than this
will produce more ripple current than desired. Conversely,
higher inductor values will result in less than the selected
maximum ripple current.
LoMIN
(VIN
(
VOUT)
D
IO,MAX
fSW)
(3)
α
is the ripple current as a percentage of the maximum
output current
per phase
(
α
= 0.15 for
±
15%,
α
= 0.25 for
±
25%, etc.). If the minimum inductor value is used, the
inductor current will swing
±
α
% about its value at the
center. Therefore, for a three
phase converter, the inductor
must be designed or selected such that it will not saturate
with a peak current of (1 +
α
)
I
O,MAX
/3.
The maximum inductor value is limited by the transient
response of the converter. If the converter is to have a fast
transient response, the inductor should be made as small as
possible. If the inductor is too large its current will change
too slowly, the output voltage will droop excessively, more
bulk capacitors will be required and the converter cost will
be increased. For a given inductor value, it is useful to
determine the times required to increase or decrease the
current.
For increasing current:
tINC
Lo
IO(VIN
VOUT)
(3.1)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| NCP5306DW | Three−Phase VRM 9.0 Buck Controller |
| NCP5306DWR2 | Three−Phase VRM 9.0 Buck Controller |
| NCP5314FTR2G | Two/Three/Four−Phase Buck CPU Controller |
| NCP5318 | Two/Three/Four−Phase Buck CPU Controller |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP5306/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Three Phase VRM 9.0 Buck Controller |
| NCP5306DW | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| NCP5306DWR2 | 功能描述:IC CTRLR BUCK 3PH VRM 9.0 24SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| NCP5314 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Two/Three/Four-Phase Buck CPU Controller |
| NCP5314/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Two/Three/Four-Phase Buck CPU Controller |
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