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參數(shù)資料
| 型號： | MAX1744AUB |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High-Voltage, Step-Down DC-DC Controller in レMAX |
| 中文描述： | SWITCHING CONTROLLER, 330 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | MICRO MAX, MO-187CBA, MICRO SOP10 |
| 文件頁數(shù)： | 10/14頁 |
| 文件大?。?/td> | 256K |
| 代理商： | MAX1744AUB |
M
High-Voltage, Step-Down DC-DC
Controller in μMAX
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 4.7μF 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
4.7μF or greater capacitor between IN and VH.
Quiescent Current
The devices
’
typical quiescent current is 90μA.
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.
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 10μA.
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 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:
R2= R3 x V
V
OUT
REF
1
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
A
C
B
10μs/div
Figure 3. Discontinuous-Conduction Mode, Light-Load-Current
Waveform
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
A
C
B
10μs/div
Figure 4. Continuous-Conduction Mode, Heavy-Load-Current
Waveform
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1744AUB/V+ | 功能描述:DC/DC 開關(guān)控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1744AUB/V+T | 功能描述:DC/DC 開關(guān)控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1744AUB+ | 功能描述:DC/DC 開關(guān)控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1744AUB+T | 功能描述:DC/DC 開關(guān)控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1744AUB-T | 功能描述:DC/DC 開關(guān)控制器 Step-Down DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
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