參數(shù)資料
型號(hào)： MAX8543
廠商： Maxim Integrated Products, Inc.
英文描述： Dual J-K Negative-Edge-Triggered Flip-Flops With Clear And Preset 16-CDIP -55 to 125
中文描述： 降壓型控制器，具有預(yù)偏置啟動(dòng)、無損檢測(cè)、同步整流和OVP
文件頁(yè)數(shù)： 18/27頁(yè)
文件大?。?/td> 399K
代理商： MAX8543
M
S tep-Down Controllers with Prebias S tartup,
Lossless S ensing, S ync hronization, and OV P
18
______________________________________________________________________________________
S witc hing Frequenc y and
S ync hronization
The MAX8543/MAX8544 have an adjustable internal
oscillator that can be set to any frequency from 200kHz
to 1MHz. To set the switching frequency, connect a
resistor from FSYNC to GND. Calculate the resistor
value from the following equation:
The MAX8543/MAX8544 can also be synchronized to an
external clock by connecting the clock signal to FSYNC.
When using an external clock, select R
FSYNC
such that
the free-running frequency is within ±30% of the clock fre-
quency. In addition, the MAX8544 has a synchronization
output (SYNCO) that provides a clock signal that is 180°
out-of-phase with the MAX8544 switching. SYNCO is
used to synchronize a second controller 180° out-of-
phase with the first by connecting SYNCO of the first con-
troller to FSYNC of the second when the first controller
operates in free-running mode. When the first controller is
synchronized to an external clock, the external clock is
inverted to generate SYNCO.
Power-Good S ignal (POK )
POK is an open-drain output on the MAX8544 that moni-
tors the output voltage. When the output is above 91% of
its nominal regulation voltage, POK is high impedance.
When the output drops below 91% of its nominal regula-
tion voltage, POK is pulled low. POK is also pulled low
when the MAX8544 is shut down. To use POK as a logic-
level signal, connect a pullup resistor from POK to the
logic-supply rail.
T hermal-Overload Protec tion
Thermal-overload protection limits total power dissipation
in the MAX8543/MAX8544. When the junction tempera-
ture exceeds T
J
= +160°C, an internal thermal sensor
shuts down the device, allowing the IC to cool. The ther-
mal sensor turns the IC on again after the junction tem-
perature cools by 15°C, resulting in a pulsed output
during continuous thermal-overload conditions.
Design Proc edure
S etting the Output V oltage
To set the output voltage for the MAX8543/MAX8544,
connect FB to the center of an external resistor-divider
from the output to GND (Figure 5). Select R2 between
8k
and 24k
; then calculate R1 with the following
equation:
where V
FB
= 0.8V. R1 and R2 should be placed as
close to the IC as possible.
Induc tor S elec tion
There are several parameters that must be examined
when determining which inductor is to be used: input volt-
age, output voltage, load current, switching frequency,
and LIR. LIR is the ratio of peak-to peak inductor current
ripple to maximum DC load current. A higher LIR value
allows for a smaller inductor, but results in higher losses
and higher output ripple.
R
R
V
V
OUT
FB
1
2
1
=
×
R
f
ns
k
.
ns
FSYNC
S
=
1
2
240
1
14 18
TIME
I
I
VALLEY
I
LOAD
I
PEAK
Figure 4. Inductor-Current Waveform
MAX8543/
MAX8544
R1
R2
LX
FB
Figure 5. Setting the Output Voltage with a Resistor Voltage-
Divider
相關(guān)PDF資料
PDF描述
MAX8544 Dual J-K Negative-Edge-Triggered Flip-Flops With Clear And Preset 20-LCCC -55 to 125
MAX8546EUB PLASTIC ENCAPSULATED DEVICES
MAX8556 3-Line To 8-Line Decoders/Demultiplexers 16-CFP -55 to 125
MAX8556ETE 3-Line To 8-Line Decoders/Demultiplexers 20-LCCC -55 to 125
MAX8557 3-Line To 8-Line Decoders/Demultiplexers 16-CFP -55 to 125
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX8543EEE 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
MAX8543EEE+ 功能描述:電流型 PWM 控制器 Step-Down Controller RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX8543EEE+T 功能描述:電流型 PWM 控制器 Step-Down Controller RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX8543EEE-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
MAX8544EEP 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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