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参数资料
| 型号： | MAX1744AUB/V+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 10/15页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 10-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 控制器 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 100% |
| 电源电压： | 4.5 V ~ 36 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
High-Voltage, Step-Down DC-DC
Controllers in μMAX
A
B
A
B
C
C
R2= R3 x ? OUT ? 1 ?
10μs/div
CIRCUIT OF FIGURE 1, V IN = 18V, V OUT = 3.3V, I LOAD = 100mA
A: MOSFET DRAIN, 10V/div
B: OUT, 50mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 1A/div
Figure 3. Discontinuous-Conduction Mode, Light-Load-Current
Waveform
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 4.7μF or greater capacitor.
VH Linear Regulator
The MAX1744/MAX1745 contain a high-side linear regu-
lator (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
4.7μF or greater capacitor between IN and VH. Fast line
transients may drive the voltage on VH negative. The
clamp diode (D2) prevents damage to the IC during
such a condition. A Schottky diode with a minimum 40V
reverse rating such as the Nihon EP05Q04 is sufficient
for most applications.
Quiescent Current
The devices ’ typical quiescent current is 90 μA.
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 V OUT at 5V, typical
no-load supply current for the entire circuit is 100μA.
10 μ s/div
CIRCUIT OF FIGURE 1, V IN = 18V, V OUT = 3.3V, I LOAD = 1.5A
A: MOSFET DRAIN, 10V/div
B: OUT, 50mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 1A/div
Figure 4. Continuous-Conduction Mode, Heavy-Load-Current
Waveform
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 shutdown
supply current drops to less than 10μA. SHDN is a logic-
level input. Connect SHDN to IN for normal operation.
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 100μA. The refer-
ence is turned off during shutdown. Bypass the
reference with 0.1μF 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 V L 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:
? V ?
? V REF ?
where V REF = 1.25V. Since the input bias current at FB
has a maximum value of 50nA, large values (10k Ω to
200k Ω ) can be used for R3 with no significant accuracy
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1744EUB | 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 |
| MAX1744EUB/V+ | 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 |
| MAX1744EUB/V+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 |
| MAX1744EUB+ | 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 |
| MAX1744EUB+ | 制造商:Maxim Integrated Products 功能描述:CONTROLLER STEP DOWN DC-DC 1744 制造商:Maxim Integrated Products 功能描述:CONTROLLER, STEP DOWN, DC-DC, 1744 |
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