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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)： | 8/13頁 |
| 文件大?。?/td> | 740K |
| 代理商： | MAX1776 |
M
24V, 600mA Internal Switch, 100% Duty Cycle,
Step-Down Converter
8
_______________________________________________________________________________________
Detailed Description
The MAX1776 step-down converter is designed primar-
ily for battery-powered devices and notebook comput-
ers. The unique current-limited control scheme
provides high efficiency over a wide load range.
Operation up to 100% duty cycle allows the lowest pos-
sible dropout voltage, increasing the usable supply
voltage range. Under no load, the MAX1776 draws only
15μA, and in shutdown mode, it draws only 3μA to fur-
ther reduce power consumption and extend battery life.
Additionally, an internal 24V switching MOSFET, inter-
nal current sensing, and a high switching frequency
minimize PC board space and component costs.
Current-Limited Control Architecture
The MAX1776 uses a proprietary current-limited control
scheme with operation to 100% duty cycle. This DC-DC
converter pulses as needed to maintain regulation,
resulting in a variable switching frequency that increas-
es with the load. This eliminates the high supply cur-
rents associated with conventional constant-frequency
pulse-width-modulation (PWM) controllers that switch
the MOSFET unnecessarily.
When the output voltage is too low, the error comparator
sets a flip-flop, which turns on the internal P-channel
MOSFET and begins a switching cycle (Figure 2). As
shown in Figure 3, the inductor current ramps up linear-
ly, storing energy in a magnetic field while charging the
output capacitor and servicing the load. The MOSFET
turns off when the peak current limit is reached, or when
the maximum on-time of 10μs is exceeded and the out-
put voltage is in regulation. If the output is out of regula-
tion and the peak current is never obtained, the
MOSFET remains on, allowing a duty cycle up to 100%.
This feature ensures the lowest possible dropout volt-
age. Once the MOSFET turns off, the flip-flop resets, the
inductor current is pulled through D1, and the current
through the inductor ramps back down, transferring the
stored energy to the output capacitor and load. The
MOSFET remains off until the 0.42μs minimum off-time
expires, and the output voltage drops out of regulation.
Pin Description
PIN
NAME
FUNCTION
1
FB
Dual-Mode Feedback Input. Connect to GND for the preset 5V output. Connect to a resistive divider
between OUT and GND to adjust the output voltage between 1.25V and V
IN
.
Ground
2
GND
3
ILIM
Peak Current Control Input. Connect to IN or GND to set peak current limit. ILIM and ILIM2 together set
the peak current limit. See
Setting Current Limit
.
4
5
LX
IN
Inductor Connection. Connect LX to external inductor and diode as shown in Figure 1.
Input Supply Voltage. Input voltage range is 4.5V to 24V.
6
ILIM2
Peak Current Control Input 2. Connect to IN or GND. ILIM and ILIM2 together set the peak current limit.
See
Setting Current Limit
.
7
SHDN
Shutdown Input. A logic low shuts down the MAX1776 and reduces the supply current to 3
μ
A. LX is high
impedance in shutdown. Connect to IN for normal operation.
8
OUT
Regulated Output Voltage High-Impedance Sense Input. Internally connected to a resistive divider.
Do not connect for output voltages higher than 5.5V. Connect to GND when not used.
Figure 1. Typical Application Circuit
MAX1776
IN
GND
ILIM2
ILIM
LX
OUT
FB
C
IN
: 10
μ
F, 25V CERAMIC
SEE TABLE 3 FOR OTHER COMPONENT VALUES
NOTE:
HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.
OUTPUT
5V
INPUT
4.5V TO 24V
C
IN
D1
L1
C
OUT
SHDN
J1
J2
J3
J4
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| 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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