參數(shù)資料
型號： MAX1790
廠商： Maxim Integrated Products, Inc.
元件分類： DC/DC變換器
英文描述： Low-Noise Step-Up DC-DC Converter(低噪聲步升DC-DC轉換器)
中文描述： 低噪聲、升壓型DC-DC轉換器
文件頁數(shù)： 7/12頁
文件大?。?/td> 405K
代理商： MAX1790
M
Low-Noise Step-Up DC-DC Converter
_______________________________________________________________________________________
7
Output Current Capability
The output current capability of the MAX1790 is a func-
tion of current limit, input voltage, operating frequency,
and inductor value. Because of the slope compensation
used to stabilize the feedback loop, the duty cycle
affects the current limit. The output current capability is
governed by the following equation:
I
OUT(MAX)
= [I
LIM
·
(1.26 - 0.4
·
Duty) -
0.5
·
Duty
·
V
IN
/ (f
OSC
·
L)]
·
η
·
V
IN
/ V
OUT
where:
I
LIM
= current limit specified at 65% (see
Electrical
Characteristics
)
Duty = duty cycle = (V
OUT
- V
IN
+ V
DIODE
) /
(V
OUT
- I
LIM
·
R
ON
+ V
DIODE
)
V
DIODE
= catch diode forward voltage at I
LIM
η
=conversion efficiency, 85% nominal
Soft-Start
The MAX1790 can be programmed for soft-start upon
power-up with an external capacitor. When the shutdown
pin is taken high, the soft-start capacitor (C
SS
) is immedi-
ately charged to 0.5V. Then the capacitor is charged at a
constant current of 4μA (typ). During this time, the SS
voltage directly controls the peak inductor current, allow-
ing 0A at V
SS
= 0.5V to the full current limit at V
SS
= 1.5V.
The maximum load current is available after the soft-start
cycle is completed. When the shutdown pin is taken low,
the soft-start capacitor is discharged to ground.
Frequency Selection
The MAX1790
’
s frequency can be user selected to
operate at either 640kHz or 1.2MHz. Tie FREQ to GND
for 640kHz operation. For a 1.2MHz switching frequen-
cy, tie FREQ to IN. This allows the use of small, mini-
mum-height external components while maintaining low
output noise. FREQ has an internal pull-down, allowing
the user the option of leaving FREQ unconnected for
640kHz operation.
Shutdown
The MAX1790 shuts down to reduce the supply current
to 0.1μA when
SHDN
is low. In this mode, the internal
reference, error amplifier, comparators, and biasing cir-
cuitry turn off while the N-channel MOSFET is turned
off. The boost converter
’
s output is connected to IN via
the external inductor and catch diode.
Applications Information
Boost DC-DC converters using the MAX1790 can be
designed by performing simple calculations for a first
iteration. All designs should be prototyped and tested
prior to production. Table 1 provides a list of compo-
nents for a range of standard applications. Table 2 lists
component suppliers.
GND
LX
IN
FREQ
FB
COMP
4
μ
A
5
μ
A
N
ERROR
COMPARATOR
ERROR
AMPLIFIER
ENABLE
COMPARATOR
SS
CLOCK
ENABLE
BIAS
SHDN
MAX1790
Σ
CURRENT
SENSE
CONTROL
AND DRIVER
LOGIC
SOFT-
START
SLOPE
COMPEN-
SATION
OSCILLATOR
∞
1.24V
Figure 2. Functional Diagram
相關PDF資料
PDF描述
MAX1802 Digital Camera Step-Down Power Supply
MAX1802EHJ Digital Camera Step-Down Power Supply
MAX1804 External Four-Input Feedback Integrator for Power Supplies
MAX1804EUB External Four-Input Feedback Integrator for Power Supplies
MAX1809 3A, 1MHz, DDR Memory Termination Supply
相關代理商/技術參數(shù)
參數(shù)描述
MAX1790ESA+ 制造商:Maxim Integrated Products 功能描述:- Rail/Tube
MAX1790EUA 功能描述:直流/直流開關轉換器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率: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 安裝風格:SMD/SMT
MAX1790EUA+ 功能描述:直流/直流開關轉換器 Low-Noise Step-Up RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率: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 安裝風格:SMD/SMT
MAX1790EUA+T 功能描述:直流/直流開關轉換器 Low-Noise Step-Up RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率: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 安裝風格:SMD/SMT
MAX1790EUA+-T 制造商:Maxim Integrated Products 功能描述:CONV DC-DC SGL-OUT STEP UP 8PIN UMAX - Tape and Reel
發(fā)布緊急采購，3分鐘左右您將得到回復。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*