- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383501 > MAX777L (Maxim Integrated Products, Inc.) Triple 3-Input Positive-NAND Gates 14-CDIP -55 to 125 PDF資料下載
參數(shù)資料
| 型號(hào)： | MAX777L |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Triple 3-Input Positive-NAND Gates 14-CDIP -55 to 125 |
| 中文描述： | 低電壓輸入，3V/3.3V/5V /可調(diào)輸出，升壓型DC - DC轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 7/12頁(yè) |
| 文件大?。?/td> | 117K |
| 代理商： | MAX777L |
_______________Detailed Desc ription
Operating Princ iple
The MAX777L/MAX778L/MAX779L combine a switch-
mode regulator with an NPN bipolar switch, current
limit, precision voltage reference, and active rectifier—
all in a single monolithic device. In shutdown mode,
the internal rectifier is completely turned off and dis-
connects the load from the source. Only two external
components are required in addition to the input
bypass capacitor: a 22μH inductor and a 100μF filter
capacitor.
A minimum off-time, current-limited, pulse-frequency-
modulation (PFM) control scheme combines the advan-
tages of pulse width modulation (PWM) (high output
power and efficiency) with those of a traditional PFM
pulse skipper (low quiescent currents).
External conditions (inductor value, load, and input volt-
age) determine the way the converter operates, as follows:
At light loads,
the current through the inductor starts at
zero, rises to a peak value, and drops down to zero in
each cycle (discontinuous-conduction mode). In this
case, the switching frequency is governed by a pair of
one-shots that set a maximum on-time inversely propor-
tional to VIN[t
ON
= 8.8/(V
IN
- 0.25)] and a minimum off-
time (1.3μs for MAX777L/MAX779L and 2.3μs for
MAX778L). With a 22μH inductor, LX’s peak current is
about 400mA and is independent of input voltage.
Efficiency at light loads is improved because of lower
peak currents.
At very light loads
, more energy is stored in the coil
than is required by the load in each cycle. The converter
regulates by skipping entire cycles. Efficiency is typically
65% to 75% in the pulse-skipping mode. Pulse-skipping
waveforms can be irregular, and the output waveform
contains a low-frequency component. Larger, low equiv-
alent series resistance (ESR) filter capacitors can help
reduce the ripple voltage if needed.
M
Low-Voltage Input, 3V /3.3V /5V /
Adjustable Output, S tep-Up DC-DC Converters
_______________________________________________________________________________________
7
MAX778L
DELAY
TIMER
t
OFF
DELAY
TIMER
t
ON
VREF
0.2025V
SHUTDOWN
CONTROL
SHDN
7
ACTIVE RECTIFIER
RECTIFIER
CONTROL
OUT
PGND
AGND
3
SEL 8
4
6
100
μ
F
V
OUT
100
μ
F
V
IN
22
μ
H
R
LIM
SWITCH
DRIVER
LX
ILIM
IN
2
1
1 : N
Figure 1. MAX778L Block Diagram
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX777LCPA | Triple 3-Input Positive-NAND Gates 14-CFP -55 to 125 |
| MAX777LCSA | Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters |
| MAX778L | Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters |
| MAX779L | Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters |
| MAX777LEPA | Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX777LEPA | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX77803EWJ+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX77803EWJ+T | 制造商:Maxim Integrated Products 功能描述:- Tape and Reel |
| MAX77803GEWJ+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX77803GEWJ+T | 制造商:Maxim Integrated Products 功能描述:- Tape and Reel |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。