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參數(shù)資料
| 型號(hào)： | MAX1937EEI |
| 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 |
| 文件頁數(shù)： | 20/24頁 |
| 文件大?。?/td> | 586K |
| 代理商： | MAX1937EEI |
M
Two-Phase Desktop CPU Core Supply Controllers
with Controlled VID Change
20
______________________________________________________________________________________
V
ILIM
is set from 0.5V to 2V by connecting ILIM to a
resistor-divider from REF to GND. Select resistors R3
and R4 such that the current through the divider is at
least 5μA:
A typical value for R3 is 200k
; then solve for R4 using:
Setting the Voltage Positioning
Voltage positioning dynamically changes the output-
voltage set point in response to the load current. When
the output is loaded, the signals fed back from the cur-
rent-sense inputs adjust the output voltage set point,
thereby decreasing power dissipation. The load-tran-
sient response of this control loop is extremely fast yet
well controlled, so the amount of voltage change can
be accurately confined within the limits stipulated in the
microprocessor power-supply guidelines. To under-
stand the benefits of dynamically adjusting the output
voltage, see the
Voltage Positioning (VPOS)
section.
The amount of output voltage change is adjusted by an
external gain resistor (R
VPOS
). Connect R
VPOS
between
REF and VPOS. The output voltage changes in response
to the load current as follows:
VID
is the programmed output voltage set by
the VID code (Table 1), and the voltage-positioning
transconductance (g
m(VPOS)
) is typically 20μS. R
CS
is
the value of the current-sense resistor connected from
CS_ to PGND. If the on-resistance of the low-side
MOSFETs is used instead of current-sense resistors for
current sensing, then use the maximum on-resistance
of the low-side MOSFETs for R
CS
in the equation
above.
MOSFET Power Dissipation
Power dissipation in the high-side MOSFET is worst at
high duty cycles (maximum output voltage, minimum
input voltage). Two major factors contribute to the high-
side power dissipation, conduction losses, and switch-
ing losses. Conduction losses are because of current
flowing through a resistance, and can be calculated
from:
where R
DS(ON)
is the on-resistance of the high-side
MOSFET and V
IN
is the input voltage. To minimize con-
duction losses, select a MOSFET with a low R
DS(ON)
.
Switching losses are also a major contributor to power
dissipation in the high-side MOSFET. Switching losses
are difficult to precisely calculate and should be mea-
sured in the circuit. To estimate the switching losses,
use the following equation:
where I
PEAK
and I
VALLEY
valley inductor currents, t
FALL
and t
RISE
are the fall and
rise times of the high-side MOSFET, and f
SW
is the
switching frequency (about 250kHz).
The total power dissipated in the high-side MOSFET is
then found from:
P
D(HS)
= P
D(HS)COND
+ P
D(HS)SW
The power dissipation in the low-side MOSFET is high-
est at low duty cycles (high input voltage, low output
voltage), and is mainly because of conduction losses:
Switching losses in the low-side MOSFET are small
because of its voltage being clamped by the body
diode. Switching losses can be estimated from:
where I
LOADMAX/2
is the maximum average inductor
current, t
DT
is the time/cycle that the low-side MOSFET
conducts through its body diode, and V
DF
is the for-
ward voltage drop across the body diode.
The total power dissipation in the low-side MOSFET is:
P
D(LS)
= P
D(LS)COND
+ P
D(LS)SW
IC Power Dissipation
During normal operation, power dissipation in the con-
troller is mostly from the gate drivers. This can be cal-
culated from the following equation:
P
GATE
= 2
V
VLG
f
SW
( Q
GH
+ Q
GL
)
P
I
t
V
f
D LS SW
(
LOADMAX
2
DT
DF
SW
)
×
×
×
P
V
V
I
R
D LS COND
(
)
OUT
IN
LOADMAX
4
DS ON
(
)
=
×
×
1
2
P
I
t
I
t
V
f
D HS SW
(
PEAK
fall
VALLEY
rise
IN
SW
)
(
)
×
+
×
×
2
P
V
I
R
V
D HS COND
(
)
OUT
LOADMAX
×
4
DS ON
(
IN
)
=
×
×
2
V
V
g
R
I
R
OUT
VID
m VPOS
(
VPOS
OUT
CS
=
×
×
×
2
)
R
R
V
V
ILIM
ILIM
4
3
2
=
×
R
R
k
3
4
400
+
≤
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1938 | Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change |
| MAX1938EEI | Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change |
| MAX1939 | Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change |
| MAX1939EEI | Two-Phase Desktop CPU Core Supply Controllers with Controlled VID Change |
| MAX1951 | PLASTIC ENCAPSULATED DEVICES |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1937EEI+ | 功能描述:DC/DC 開關(guān)控制器 2-Phase Desktop CPU Core Supply Ctlr 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 |
| MAX1937EEI+T | 功能描述:DC/DC 開關(guān)控制器 2-Phase Desktop CPU Core Supply Ctlr 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 |
| MAX1937EEI-T | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| MAX1937EEI-TG069 | 制造商:Maxim Integrated Products 功能描述: |
| MAX1938EEI | 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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