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參數(shù)資料
| 型號(hào)： | MAX618EEE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3.3-V ABT Scan Test Devices With 18-Bit Universal Bus Transceivers 68-CFP -55 to 125 |
| 中文描述： | 3 A SWITCHING REGULATOR, 312 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, QSOP-16 |
| 文件頁數(shù)： | 9/14頁 |
| 文件大?。?/td> | 204K |
| 代理商： | MAX618EEE |
S hutdown Mode
In shutdown mode (
SHDN
= 0), the MAX618’s feed-
back and control circuit, reference, and internal biasing
circuitry turn off and reduce the IN supply current to
3μA (10μA max). When in shutdown, a current path
remains from the input to the output through the exter-
nal inductor and diode. Consequently, the output falls
to V
IN
less one diode drop in shutdown.
SHDN
may not exceed VL. For always-on operation,
connect
SHDN
to VL. To add on/off control to the circuit
of Figure 1 or 4, pull
SHDN
to VL with a resistor (10k
to 100k
) and drive
SHDN
with an open-drain logic
gate or switch as shown in Figure 5. Alternatively, the
circuit of Figure 3 allows direct
SHDN
drive by any
logic-level gate powered from the same supply that
powers VL and IN, as shown in Figure 6.
__________________Design Proc edure
The MAX618 operates in a number of DC-DC converter
configurations including step-up, SEPIC, and flyback.
The following design discussion is limited to step-up
converters.
S etting the Output V oltage
Two external resistors (R1 and R2) set the output volt-
age. First, select a value for R2 between 10k
and
200k
. Calculate R1 with:
where V
FB
is 1.5V.
Determining the Induc tor V alue
The MAX618’s high switching frequency allows the use
of a small value inductor. The recommended inductor
value is proportional to the output voltage and is given
by the following:
After solving for the above equation, round down as
necessary to select a standard inductor value.
When selecting an inductor, choose one rated to
250kHz, with a saturation current exceeding the peak
inductor current, and with a DC resistance under
200m
. Ferrite core or equivalent inductors are gener-
ally appropriate (see MAX618 EV kit data sheet).
Calculate the peak inductor current with the following
equation:
Note that the peak inductor current is internally limited
to 2A.
Diode S elec tion
The MAX618’s high switching frequency demands a
high-speed rectifier. Schottky diodes are preferred for
most applications because of their fast recovery time
and low forward voltage. Make sure that the diode’s
peak current rating exceeds the 2A peak switch cur-
rent, and that its breakdown voltage exceeds the out-
put voltage.
I
I
V
V
2 s
V
L
V
V
V
LX(PEAK)
OUT
OUT
IN
IN
OUT
IN
OUT
=
+
(
)
L
V
OUT
=
7 10
5
R
R
V
V
OUT
FB
1
2
1
=
M
28V, PWM, S tep-Up DC-DC Converter
_______________________________________________________________________________________
9
MAX618
VL
100k
ON/OFF
CONTROL
OPEN-DRAIN
LOGIC
SHDN
MAX618
IN
VL
SYSTEM LOGIC
ON/OFF
CONTROL
SHDN
SYSTEM
LOGIC SUPPLY
Figure 5. Adding On/Off Control to Circuit of Figure 1 or 4
Figure 6. Adding On/Off Control to Circuit of Figure 3
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX618EEE/GG8 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| MAX618EEE/GH9 | 制造商:Maxim Integrated Products 功能描述:STEP-UP DC-DC CONVERTER - Rail/Tube |
| MAX618EEE/V+T | 制造商:Maxim Integrated Products 功能描述:28V, PWM, STEP-UP DC-DC CONVERTER - Tape and Reel |
| MAX618EEE+ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 28V PWM Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| MAX618EEE+T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 28V PWM Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
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