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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(yè)數(shù)： | 10/14頁(yè) |
| 文件大小： | 204K |
| 代理商： | MAX618EEE |
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M
28V, PWM, S tep-Up DC-DC Converter
10
______________________________________________________________________________________
Maximum Output Current
The MAX618’s 2.2A LX current limit determines the
output power that can be supplied for most applica-
tions. In some cases, particularly when the input volt-
age is low, output power is sometimes restricted by
package dissipation limits. The MAX618 is protected
by a thermal shutdown circuit that turns off the switch
when the die temperature exceeds +150°C. When the
device cools by 10°C, the switch is enabled again.
Table 3 details output current with a variety of input and
output voltages. Each listing in Table 3 is either the limit
set by an LX current limit or by package dissipation at
+85°C ambient, whichever is lower. The values in Table
3 assume a 40m
inductor resistance.
Capac itor S elec tion
Input Capacitors
The input bypass capacitor, C
IND
, reduces the input
ripple created by the boost configuration. High-imped-
ance sources require high C
IND
values. However, 68μF
is generally adequate for input currents up to 2A. Low
ESR capacitors are recommended because they will
decrease the ripple created on the input and improve
efficiency. Capacitors with ESR below 0.3
are gener-
ally appropriate.
In addition to the input bypass capacitor, bypass IN
with a 1μF ceramic capacitor placed as close to the IN
and GND pins as possible. Bypass VL with a 4.7μF
ceramic capacitor placed as close to the VL and GND
pins as possible.
Output Capacitor
Use Table 4 to find the minimum output capacitance
necessary to ensure stable operation. In addition,
choose an output capacitor with low ESR to reduce the
output ripple. The dominant component of output ripple
is the product of the peak-to-peak inductor ripple cur-
rent and the ESR of the output capacitor. ESR below
50m
generates acceptable levels of output ripple for
most applications.
Integrator Capacitor
The compensation capacitor (C
COMP
) sets the domi-
nant pole in the MAX618’s transfer function. The proper
compensation capacitance depends upon output
capacitance. Table 5 shows the capacitance value
needed for the output capacitances specified in Table
4. However, if a different output capacitor is used (e.g.,
a standard value), then recalculate the value of capaci-
tance needed for the integrator capacitor with the fol-
lowing formula:
Pole Compensation Capacitor
The pole capacitor (C
P
) cancels the unwanted zero
introduced by C
OUT
’s ESR, and thereby ensures stabil-
ity in PWM operation. The exact value of the pole
capacitor is not critical, but it should be near the value
calculated by the following equation:
where R
ESR
is C
OUT
’s ESR.
Layout Considerations
Proper PC board layout is essential due to high current
levels and fast switching waveforms that radiate noise.
Use the MAX618 evaluation kit or equivalent PC layout
to perform initial prototyping. Breadboards, wire-wrap,
and proto-boards are not recommended when proto-
typing switching regulators.
It is important to connect the GND pin, the input
bypass capacitor ground lead, and the output filter
capacitor ground lead to a single point to minimize
ground noise and improve regulation. Also, minimize
lead lengths to reduce stray capacitance, trace resis-
tance, and radiated noise, with preference given to the
feedback circuit, the ground circuit, and LX. Place the
feedback resistors as close to the FB pin as possible.
Place a 1μF input bypass capacitor as close as possi-
ble to IN and GND.
Refer to the MAX618 evaluation kit for an example of
proper board layout.
C
R
C
R1 R2
(R2
R2)
P
ESR
OUT
=
+
C
C
Table
(
C
4
C
Table
COMP
COMP
OUT
OUT
=
)
(
)
5
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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(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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(kāi)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(kāi)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(kāi)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(kāi)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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