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參數(shù)資料
| 型號： | MAX1624 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power |
| 中文描述： | 高速、同步整流、降壓型控制器，用于CPU電源 |
| 文件頁數(shù)： | 18/24頁 |
| 文件大?。?/td> | 223K |
| 代理商： | MAX1624 |
M
High-S peed S tep-Down Controllers with
S ync hronous Rec tific ation for CPU Power
18
______________________________________________________________________________________
A good compromise between size and loss is a 45%
ripple current to load current ratio (LIR = 0.45), which
corresponds to a peak inductor current 1.23 times
higher than the DC load current.
(
where f is the switching frequency, between 100kHz
and 1MHz; I
OUT
is the maximum DC load current; and
LIR is the ratio of AC to DC inductor current (typically
0.45). The exact inductor value is not critical and can be
adjusted to make trade-offs among size, transient
response, cost, and efficiency. Although lower inductor
values minimize size and cost, they also reduce efficien-
cy due to higher peak currents. In general, higher
inductor values increase efficiency, but at some point
resistive losses due to extra turns of wire exceed the
benefit gained from lower AC current levels. Load-
transient response can be adversely affected by
high inductor values, especially at low (V
IN
- V
OUT
)
differentials.
The peak inductor current at full load is 1.23 x I
OUT
if
the previous equation is used; otherwise, the peak cur-
rent can be calculated using the following equation:
The inductor’s DC resistance is a key parameter for effi-
cient performance, and should be less than the current-
sense resistor value.
Calc ulating the Current-S ense
Resistor V alue
Calculate the current-sense resistor value according to
the worst-case minimum current-limit threshold voltage
(from the Electrical Characteristics) and the peak
inductor current required to service the maximum load.
Use I
PEAK
from the equation in the section Specifying
the Inductor
The high inductance of standard wire-wound resistors
can degrade performance. Low-inductance resistors,
such as surface-mount power metal-strip resistors, are
preferred. The current-sense resistor’s power rating
should be higher than the following:
In high-current applications, connect several resistors
in parallel as necessary, to obtain the desired resis-
tance and power rating.
S elec ting the Output Filter Capac itor
Output filter capacitor values are generally determined
by effective series resistance (ESR) and voltage-rating
requirements, rather than by the actual capacitance
value required for loop stability. Due to the high switch-
ing currents and demanding regulation requirements in
a typical MAX1624/MAX1625 application, use only spe-
cialized low-ESR capacitors intended for switching-
regulator applications, such as AVX TPS, Sprague
595D, Sanyo OS-CON, or Nichicon PL series. Do not
use standard aluminum-electrolytic capacitors, which
can cause high output ripple and instability due to high
ESR. The output voltage ripple is usually dominated by
the filter capacitor’s ESR, and can be approximated as
I
RIPPLE
x R
ESR
. To ensure stability, the capacitor must
meet both minimum capacitance and maximum ESR
values as given in the following equations:
C
V
V
V
V
x R
x f
R
R
OUT
REF
OUT
IN MIN
(
OUT
SENSE
OSC
ESR
SENSE
+
)
>
<
1
R
mV
R
POWER RATING
SENSE
(
)
=
115
2
R
mV
I
SENSE
PEAK
=
85
I
I
V
V
V
f
x L x V
PEAK
OUT
OUT
2
IN MAX
(
OUT
OSC
IN MAX
(
+
)
)
=
(
)
L
V
V
V
V
x f
x I
x LIR
OUT
IN MAX
(
OUT
IN MAX
(
OSC
OUT
)
)
=
)
R3
PLACE VERY CLOSE
TOMAX1625
R2
FB
AGND
V
OUT
LOAD
MAX1625
Figure 7. MAX1625 Adjustable Output Operation
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|---|---|
| MAX1625ESE | High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power |
| MAX1624-MAX1625 | High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power |
| MAX1624EAG | High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power |
| MAX1626ESA | 5V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1624EAG | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1624EAG+ | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1624EAG+T | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1624EAG-T | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| MAX1624EVKIT | 功能描述:DC/DC 開關控制器 Evaluation Kit for the MAX1624 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
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