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參數(shù)資料
| 型號： | MAX1797 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 數(shù)字信號處理 |
| 英文描述： | Replaced by TMS320C6722B : Digital Signal Processor 144-QFP |
| 中文描述： | 低電流、升壓型DC-DC轉換器，可真正關斷 |
| 文件頁數(shù)： | 10/13頁 |
| 文件大?。?/td> | 397K |
| 代理商： | MAX1797 |
M
pate this energy, minimizing the ringing at LX.
Damping LX ringing does not reduce V
OUT
ripple, but
does reduce EMI (Figures 3, 4, and 5).
Setting the Output Voltage
V
OUT
can be set to 3.3V or 5.0V by connecting the FB
pin to GND (5V) or OUT (3.3V). To adjust the output
voltage, connect a resistive voltage-divider from OUT to
FB to GND (Figure 6). Choose a value less than 250k
for R2.
Use the following equation to calculate R1:
R1 = R2 [(V
OUT
/ V
FB
) - 1]
where V
FB
= +1.245V, and V
OUT
may range from +2V
to +5.5V.
Low-Battery Detection
The MAX1795/MAX1796/MAX1797 each contain an on-
chip comparator for low-battery detection. If the voltage
at LBI is above 0.85V, LBO (an open-drain output)
sinks current to GND. If the voltage at LBI is below
0.85V, LBO goes high impedance. The LBI/LBO func-
tion remains active even when the part is in shutdown.
Connect a resistive voltage-divider to LBI from BATT to
GND. The low-battery monitor threshold is set by two
resistors, R3 and R4 (Figure 6). Since the LBI bias cur-
rent is typically 2nA, large resistor values (R4 up to
250k
) can be used to minimize loading of the input
supply.
Calculate R3 using the following equation:
R3 = R4[(V
TRIP
/ 0.85V) - 1]
Low Supply Current, Step-Up DC-DC Converters
with True-Shutdown
10
______________________________________________________________________________________
Figure 3. Simplified Diagram of Inductor Damping Switch
MAX1795
MAX1796
MAX1797
DAMPING
SWITCH
BATT
R1
200
LX
OUT
22
μ
H
V
IN
47
μ
F
V
OUT
2
μ
s/div
V
LX
1V/div
Figure 4. LX Ringing for Conventional Step-Up Converter
(without Damping Switch)
2
μ
s/div
V
LX
1V/div
Figure 5. LX Waveform with Damping Switch
Figure 6. Setting an Adjustable Output
GND
LBI
LBO
BATT
R3
R4
FB
LX
OUT
SHDN
MAX1795
MAX1796
MAX1797
47
μ
F
1M
OUTPUT
2V TO 5.5V
LOW-BATTERY
OUTPUT
R1
R2
47
μ
F
V
IN
相關PDF資料 |
PDF描述 |
|---|---|
| MAX1795EUA | Low Supply Current, Step-Up DC-DC Converters with True-Shutdown |
| MAX1796EUA | Low Supply Current, Step-Up DC-DC Converters with True-Shutdown |
| MAX1797EUA | Low Supply Current, Step-Up DC-DC Converters with True-Shutdown |
| MAX1798 | Replaced by TMS320C6722B : Digital Signal Processor 144-QFP |
| MAX1798A | CDMA Cellular/PCS System Power Supplies |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1797EUA | 功能描述:直流/直流開關轉換器 Low-Supply Current Step-Up DC/DC Conv 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 |
| MAX1797EUA+ | 功能描述:直流/直流開關轉換器 Low-Supply Current Step-Up DC/DC Conv 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 |
| MAX1797EUA+ | 制造商:Maxim Integrated Products 功能描述:IC STEP-UP DC/DC CONVERTER MAX-8 |
| MAX1797EUA+T | 功能描述:直流/直流開關轉換器 Low-Supply Current Step-Up DC/DC Conv 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 |
| MAX1797EUA-T | 功能描述:直流/直流開關轉換器 Low-Supply Current Step-Up DC/DC Conv 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 |
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