參數(shù)資料
型號： MAX1776
廠商： Maxim Integrated Products, Inc.
英文描述： 32-Bit Digital Signal Controller with ROM 100-BGA MICROSTAR -40 to 85
中文描述： 24V、600mA內(nèi)置開關(guān)、100%占空比、降壓型轉(zhuǎn)換器
文件頁數(shù)： 11/13頁
文件大?。?/td> 740K
代理商： MAX1776
Inductor series resistance affects both efficiency and
dropout voltage (see
Input-Output (Dropout) Voltage
).
High series resistance limits the maximum current avail-
able at lower input voltages, and increases the dropout
voltage. For optimum performance, select an inductor
with the lowest possible DC resistance that fits in the
allotted dimensions. Some recommended component
manufacturers are listed in Table 2.
Maximum Output Current
The MAX1776 converter
’
s output current determines
the regulator
’
s switching frequency. When the convert-
er approaches continuous mode, the output voltage
falls out of regulation. For the typical application, the
maximum output current is approximately:
I
LOAD(MAX)
= 1/2 I
LX (PEAK)(MIN)
For low-input voltages, the maximum on-time may be
reached and the load current is limited by:
I
LOAD
= 1/2 (V
IN
- V
OUT
)
10μs / L
Output Capacitor
Choose the output capacitor to service the maximum
load current with acceptable voltage ripple. The output
ripple has two components: variations in the charge
stored in the output capacitor with each LX pulse, and
the voltage drop across the capacitor
’
s equivalent
series resistance (ESR) caused by the current into and
out of the capacitor:
V
RIPPLE
V
RIPPLE(ESR)
+ V
RIPPLE(C)
The output voltage ripple as a consequence of the ESR
and output capacitance is:
where I
PEAK
is the peak inductor current (see
Inductor
Selection
). The worst-case ripple occurs at no-load.
These equations are suitable for initial capacitor selec-
tion, but final values should be set by testing a proto-
type or evaluation circuit. As a general rule, a smaller
amount of charge delivered in each pulse results in
less output ripple. Since the amount of charge deliv-
ered in each oscillator pulse is determined by the
inductor value and input voltage, the voltage ripple
increases with larger inductance, and as the input volt-
age decreases. See Table 3 for recommended capaci-
tor values and Table 2 for recommended component
manufacturers.
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit
’
s switching.
The input capacitor must meet the ripple-current
requirement (I
RMS
) imposed by the switching current
defined by the following equation:
For most applications, nontantalum chemistries (ceram-
ic, aluminum, polymer, or OS-CON) are preferred due to
their robustness to high inrush currents typical of sys-
tems with low-impedance battery inputs. Alternatively,
connect two (or more) smaller value low-ESR capacitors
in parallel to reduce cost. Choose an input capacitor
that exhibits less than +10
°
C temperature rise at the
RMS input current for optimal circuit longevity.
I
I
V
V
V
RMS
LOAD OUTPUT
IN
IN
OUTPUT
=
×
4
3
1
V
V
L
I
I
V
2
V
V
V
RIPPLE(ESR)
PEAK
-
×
RIPPLE(C)
PEAK
C
OUTPUT
OUT
OUTPUT
IN
OUTPUT
IN
-
=
=
×
(
)
ESR I
2
M
24V, 600mA Internal Switch, 100% Duty Cycle,
Step-Down Converter
______________________________________________________________________________________
11
Table 2. Component Suppliers
SUPPLIER
WEBSITE
DIODES
Central Semiconductor
Fairchild
General Semiconductor
International Rectifier
www.centralsemi.com
www.fairchildsemi.com
www.gensemi.com
www.irf.com
Nihon
www.niec.co.jp/engver2/
niec.co.jp_eg.htm
On Semi
www.onsemi.com
Vishay-Siliconix
www.vishay.com/brands/siliconix/
main.html
www.zetex.com
Zetex
CAPACITORS
AVX
Kemet
Nichicon
Sanyo
Taiyo Yuden
INDUCTORS
Coilcraft
Coiltronics
Pulse Engineering
Sumida USA
Toko
www.avxcorp.com
www.kemet.com
www.nichicon-us.com
www.sanyo.com
www.t-yuden.com
www.coilcraft.com
www.cooperet.com
www.pulseeng.com
www.sumida.com
www.tokoam.com
相關(guān)PDF資料
PDF描述
MAX1776EUA 24V, 600mA Internal Switch, 100% Duty Cycle, Step-Down Converter
MAX1777EEI 32-Bit Digital Signal Controller with ROM 100-BGA MICROSTAR -40 to 125
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1776EUA 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
MAX1776EUA+ 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 24V 600mA 100% Duty Cycle Step-Down 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
MAX1776EUA+ 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR ((NW))
MAX1776EUA+ 制造商:Maxim Integrated Products 功能描述:CONVERTER STEP DOWN 24V 0.6A SMD 制造商:Maxim Integrated Products 功能描述:CONVERTER, STEP DOWN, 24V 0.6A, SMD
MAX1776EUA+T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 24V 600mA 100% Duty Cycle Step-Down 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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