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参数资料
| 型号： | MAX1744EUB+T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | High-Voltage, Step-Down DC-DC Controller in µMAX |
| 中文描述： | SWITCHING CONTROLLER, 330 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封装： | MICRO MAX PACKAGE-10 |
| 文件页数： | 2/14页 |
| 文件大小： | 256K |
| 代理商： | MAX1744EUB+T |
MAX1744/MAX1745
High-Voltage, Step-Down DC-DC
Controller in MAX
10
______________________________________________________________________________________
VL Linear Regulator
The MAX1744/MAX1745 contain a 5V low-side linear reg-
ulator (VL) that powers the internal circuit and can supply
up to 1mA to an external load. This allows the
MAX1744/MAX1745 to operate up to 36V input, while
maintaining low quiescent current and high switching fre-
quency. When the input voltage goes below 5.5V, this
regulator goes into dropout and the IN pin quiescent cur-
rent will rise. See the Typical Operating Characteristics.
Bypass VL with a 4.7F or greater capacitor.
VH Linear Regulator
The MAX1744/MAX1745 contain a high-side linear reg-
ulator (VH) that regulates its output to 5V below IN (the
positive supply input voltage). This regulator limits the
external P-channel MOSFET gate swing (EXT), allowing
high input voltage operation without exceeding the
MOSFET gate-source breakdown. Bypass VH with a
4.7F or greater capacitor between IN and VH.
Quiescent Current
The devices’ typical quiescent current is 90A.
However, actual applications draw additional current to
supply MOSFET switching currents, OUT pin current,
external feedback resistors (if used), and both the diode
and capacitor leakage currents. For example, in the cir-
cuit of Figure 1, with IN at 30V and VOUT at 5V, typical
no-load supply current for the entire circuit is 100A.
Shutdown Mode
When SHDN is low, the device enters shutdown mode. In
this mode, the internal circuitry is turned off. EXT is
pulled to IN, turning off the external MOSFET. The shut-
down supply current drops to less than 10A. SHDN is a
logic-level input. Connect SHDN to IN for normal opera-
tion.
Reference
The 1.25V reference is suitable for driving small external
loads. It has a guaranteed 10mV maximum load regula-
tion while sourcing load currents up to 100A. The refer-
ence is turned off during shutdown. Bypass the
reference with 0.1F for normal operation. Place the
bypass capacitor within 0.2in (5mm) of REF, with a direct
trace to GND.
Design Information
Setting the Output Voltage
The MAX1744’s output voltage can be selected to 3.3V
or 5V under logic control by using the 3/5 pin. Connect
the 3/5 pin to GND to ensure a 3.3V output, or connect
the 3/5 pin to VL to ensure a 5V output.
The MAX1745’s output voltage is set using two resis-
tors, R2 and R3 (Figure 5), which form a voltage-divider
between the output and FB. R2 is given by:
R2 = R3 x
V
OUT
REF
1
CIRCUIT OF FIGURE 1, VIN = 18V, VOUT = 3.3V, ILOAD = 100mA
A: MOSFET DRAIN, 10V/div
B: OUT, 50mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 1A/div
A
C
B
10s/div
Figure 3. Discontinuous-Conduction Mode, Light-Load-Current
Waveform
CIRCUIT OF FIGURE 1, VIN = 18V, VOUT = 3.3V, ILOAD = 1.5A
A: MOSFET DRAIN, 10V/div
B: OUT, 50mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 1A/div
A
C
B
10s/div
Figure 4. Continuous-Conduction Mode, Heavy-Load-Current
Waveform
相关PDF资料 |
PDF描述 |
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| MAX1745AUB+T | High-Voltage, Step-Down DC-DC Controller in µMAX |
| MAX1745EUB+T | High-Voltage, Step-Down DC-DC Controller in µMAX |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1744EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1744 MAX1745 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1745AUB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1745AUB+ | 功能描述:DC/DC 开关控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1745AUB+T | 功能描述:DC/DC 开关控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1745AUB-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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