- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385553 > MAX858 (Maxim Integrated Products, Inc.) Step-Up DC-DC Converters(可調(diào)節(jié)輸出,高效率,低IQ值,步升DC-DC變換器) PDF資料下載
參數(shù)資料
| 型號： | MAX858 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | DC/DC變換器 |
| 英文描述： | Step-Up DC-DC Converters(可調(diào)節(jié)輸出,高效率,低IQ值,步升DC-DC變換器) |
| 中文描述： | 3.3V/5V或可調(diào)輸出、升壓型DC-DC轉(zhuǎn)換器 |
| 文件頁數(shù)： | 6/12頁 |
| 文件大小： | 152K |
| 代理商： | MAX858 |
M
3.3V /5V or Adjustable-Output,
S tep-Up DC-DC Converters
6
_______________________________________________________________________________________
______________________________________________________________Pin Desc ription
N-Channel Power-MOSFET Drain
8
8
Low-Battery Output. An open-drain N-channel MOSFET sinks current when the voltage at
LBI drops below 1.25V.
4
4
Low-Battery Input. When the voltage on LBI drops below 1.25V, LBO sinks current.
If not used, connect to V
IN
.
5
5
Connect OUT to the regulator output. OUT provides bootstrap power to the IC.
6
6
Power Ground. Must be low impedance; solder directly to ground plane.
7
7
1.25V Reference Voltage Output. Bypass with 0.22μF to GND (0.1μF if there is no external
reference load). Maximum load capability is 250μA source, 20μA sink.
3
3
Feedback Input for adjustable-output operation. Connect to an external resistor voltage
divider between OUT and GND.
2
—
Selects the output voltage; connect to GND for 5V output, and to OUT for 3.3V
output.
—
2
Shutdown Input. When low, the entire circuit is off and V
OUT
= V
IN
- V
D,
where V
D
is the
forward voltage drop of the external Schottky rectifier.
1
1
FUNCTION
PIN
LX
LBO
LBI
OUT
GND
REF
FB
3/––
–———N
NAME
MAX856
MAX858
MAX857
MAX859
_______________Detailed Desc ription
Operating Princ iple
The MAX856–MAX859 combine a switch-mode regula-
tor, N-channel power MOSFET, precision voltage refer-
ence, and power-fail detector in a single monolithic
device. The MOSFET is a “sense-FET” type for best
efficiency, and has a very low gate threshold voltage to
ensure start-up with low battery voltages (0.8V typ).
PFM Control S c heme
A unique minimum-off-time, current-limited pulse-fre-
quency modulation (PFM) control scheme is a key fea-
ture of the MAX856 series (Figure 1). This scheme
combines the high output power and efficiency of a
pulse-width modulation (PWM) device with the ultra-low
quiescent current of a traditional PFM pulse-skipper.
There is no oscillator; at heavy loads, switching is
accomplished through a constant-peak-current limit in
the switch, which allows the inductor current to vary
between this peak limit and some lesser value. At light
loads, switching frequency is governed by a pair of
one-shots, which set a minimum off-time (1μs) and a
maximum on-time (4μs). The switching frequency
depends upon the load and the input voltage, and can
range up to 500kHz.
The peak switch current of the internal MOSFET power
switch is fixed at 500mA ±100mA (MAX856/MAX857)
or 125mA ±25mA (MAX858/MAX859). The switch’s on-
resistance is typically 1
(MAX856/MAX857) or 4
(MAX858/MAX859), resulting in a switch voltage drop
(V
SW
) of about 500mV under high output loads. The
value of V
SW
will decrease with light current loads.
Conventional PWM converters generate constant-fre-
quency switching noise, whereas the unique architec-
ture of the MAX856–MAX859 produces variable-fre-
quency switching noise. However, unlike conventional
pulse-skippers (where noise amplitude varies with input
voltage), noise in the MAX856 series does not exceed
the switch current limit times the filter-capacitor equiva-
lent series resistance (ESR).
V oltage Referenc e
The precision voltage reference is suitable for driving
external loads, such as an analog-to-digital converter.
The voltage-reference output changes less than ±2%
when sourcing up to 250μA and sinking up to 20μA. If
the reference drives an external load, bypass it with
0.22μF to GND. If the reference is unloaded, bypass it
with at least 0.1μF.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX860CSA | DC-to-DC Voltage Converter |
| MAX860CUA | DC-to-DC Voltage Converter |
| MAX861CSA | DC-to-DC Voltage Converter |
| MAX861CUA | DC-to-DC Voltage Converter |
| MAX863EKE | Analog IC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX8581ETB+T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 2.5/1.5MHz Step-Down 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 |
| MAX8582ETB+ | 制造商:Maxim Integrated Products 功能描述: |
| MAX8582ETB+T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 2.5/1.5MHz Step-Down 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 |
| MAX8582EVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX8582 EVAL KIT - Rail/Tube |
| MAX8585EUA | 功能描述:功率驅(qū)動(dòng)器IC RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時(shí)間: 下降時(shí)間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。