參數(shù)資料
型號(hào)： MAX1938EEI
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change
中文描述： SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO28
封裝： 0.150 INCH, 0.025 INCH PITCH, MO-137, QSOP-28
文件頁(yè)數(shù)： 18/24頁(yè)
文件大?。?/td> 586K
代理商： MAX1938EEI
M
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
18
______________________________________________________________________________________
set for Intel VRM 9.0/9.1 and AMD Athlon. The
MAX1939 is set for AMD Athlon Mobile.
VID_ Change Slew Rate (TIME)
The MAX1937/MAX1938/MAX1939 allow the VID_ code
to be changed while the converter is operating (on-the-
fly). The slew rate at which the output voltage is chang-
ing is controlled through TIME. The slew rate is
adjusted externally by connecting a 47k
to 470k
resistor (R
TIME
) from TIME to GND. To set the slew rate,
select the R
TIME
resistor using the following equation:
where SR is the slew rate of the output voltage in V/μs.
The output voltage is stepped up or down in 25mV
steps until it reaches the voltage set by the new VID
code.
Power-Good Output (PWRGD)
PWRGD is an open-drain output that is pulled low when
the output voltage deviates more than 12.5% from its
regulation voltage (set by VID_ inputs). PWRGD is
pulled low in shutdown, input UVLO, and during start-
up. Any fault condition forces PWRGD low until the fault
is cleared, and the IC is reset by cycling power at V
DD
or momentarily toggling EN. For logic-level output volt-
ages, connect an external pullup resistor between
PWRGD and the logic power supply. A 100k
resistor
works well in most applications.
Design Procedure
Output Inductor Selection
For most applications, an inductor value of 0.5μH to
1μH is recommended. The inductance is set by the
desired amount of inductor current ripple (LIR). A larger
inductance value minimizes output ripple current and
increases efficiency, but slows transient response. For
the best compromise of size, cost, and efficiency, a LIR
of 30% to 40% is recommended (LIR = 0.3 to 0.4). The
inductor value is found from:
where f
sw
is the actual switching frequency of a phase.
The selected inductor should have the lowest possible
equivalent DC resistance and a saturation current
greater than the peak inductor current (I
PEAK
). I
PEAK
is
found from:
Output Capacitor Selection
The output capacitor must have low enough ESR to
meet output ripple and load-transient requirements.
Also, the capacitance value must be high enough to
absorb the inductor energy going from a full-load to a
no-load condition without tripping the OVP circuit.
In CPU core power supplies and other applications
where the output is subject to large load transients, the
output capacitor
’
s size typically depends on how much
ESR is needed to prevent the output from dipping too
low under a load transient. Ignoring the sag due to
finite capacitance:
R
ESR
= V
STEP(MAX)
/
I
LOAD(MAX)
The actual capacitance value required relates to the
physical size needed to achieve low ESR, as well as to
the chemistry of the capacitor technology. Thus, the
capacitor is usually selected by ESR and voltage rating
rather than by capacitance value (this is true of OS-
CONs, SP capacitors, POSCAPs, and other electrolytic
capacitors). Generally, ceramic capacitors are not rec-
ommended for bulk output capacitance but make
excellent high-frequency decoupling capacitors.
Once enough capacitance is added to meet the over-
shoot requirement, undershoot at the rising load edge
I
I
LIR
2
PEAK
LOAD MAX
=
×
+
(
)
1
L
V
V
V
V
f
I
LIR
OUT
IN
OUT
IN
SW
LOAD MAX
=
×
(
)
×
×
×
(
)
R
SR
TIME
=
521 ( )
V
OUT
ESR VOLTAGE STEP
(I
STEP
x R
ESR
)
CAPACITIVE SOAR
(dV/dt = I
OUT
/C
OUT
)
RECOVERY
CAPACITIVE SAG
(dV/dt = I
OUT
/C
OUT
)
I
LOAD
Figure 4. Transient Response Regions
相關(guān)PDF資料
PDF描述
MAX1939 Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change
MAX1939EEI Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change
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MAX1951ESA PLASTIC ENCAPSULATED DEVICES
MAX1952 PLASTIC ENCAPSULATED DEVICES
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1938EEI-T 功能描述:DC/DC 開關(guān)控制器 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
MAX1938EEI-TG069 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1938EVKIT 功能描述:電源管理IC開發(fā)工具 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
MAX1939EEI 功能描述:DC/DC 開關(guān)控制器 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
MAX1939EEI-T 功能描述:DC/DC 開關(guān)控制器 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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