參數(shù)資料
型號： MAX1809EEE
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： 3A, 1MHz, DDR Memory Termination Supply
中文描述： 4.7 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16
封裝： QSOP-16
文件頁數(shù)： 9/17頁
文件大?。?/td> 803K
代理商： MAX1809EEE
M
3A, 1MHz, DDR Memory Termination Supply
_______________________________________________________________________________________
9
Programming the Switching Frequency
and Off-Time and On-Time
The MAX1809 features a programmable PWM-mode
switching frequency, which is set by the input and out-
put voltage and the value of R
TOFF
, connected from
TOFF to GND. R
TOFF
sets the PMOS power switch off-
time in PWM mode. Use the following equation to select
the off-time while sourcing current according to the
desired switching frequency in PWM mode:
where:
t
OFF
= the programmed off-time
V
IN
= the input voltage
V
OUT
= the output voltage
V
PMOS
= the voltage drop across the internal
PMOS power switch
|
I
OUT
R
PMOS
|
V
NMOS
= the voltage drop across the internal
NMOS synchronous-rectifier switch
|
I
OUT
R
NMOS
|
f
SW
= switching frequency
Make sure that t
ON
and t
OFF
are greater than 400ns
when sourcing current. Select R
TOFF
according to the
formula:
R
TOFF
= (t
OFF
- 0.07μs)
(117k
/1.00μs)
Recommended values for R
TOFF
range from 36k
to
430k
for off-times of 0.4μs to 4μs.
When sinking current, the switching frequency increas-
es due to the on-resistances of the internal switches
adding to the voltage across the inductor, reducing the
on-time. Calculate t
ON
when sinking current using the
equation:
Check that t
ON
in the current sinking mode is greater
than 350ns.
Inductor Selection
The key inductor parameters must be specified: inductor
value (L) and peak current (I
PEAK
). The following equa-
tion includes a constant, denoted as LIR, which is the
ratio of peak-to-peak inductor AC current (ripple current)
t
t
V
V
V
V
V
ON
OFF
OUT
NMOS
PMOS
+
IN
OUT
=
t
V
(
V
V
f
V
V
V
OFF
IN
OUT
PMOS
+
SW
IN
PMOS
NMOS
=
(
)
)
Figure 3. Sourcing and Sinking Capabilities of the MAX1809
SYNCHRONOUS BUCK MODE
(SOURCING CURRENT)
V
IN
V
OUT
I
SOURCE
SYNCHRONOUS BOOST MODE
(SINKING CURRENT)
V
IN
V
SOURCE
> V
OUT
I
SINK
Figure 4. Maximum Recommended Operating Frequency vs.
Input Voltage
0
400
200
800
600
1200
1000
1400
2.7
3.1
3.5
4.3
4.7
5.1
5.5
3.9
V
IN
(V)
O
V
OUT
= 2.5V
V
OUT
= 1.25V
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1809EEE+ 功能描述:電壓模式 PWM 控制器 3A 1MHz DDR Memory Termination Supply RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
MAX1809EEE+T 功能描述:電壓模式 PWM 控制器 3A 1MHz DDR Memory Termination Supply RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
MAX1809EEE-T 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 安裝風格:SMD/SMT
MAX1809EGI 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 安裝風格:SMD/SMT
MAX1809EGI+ 制造商:Maxim Integrated Products 功能描述:- Rail/Tube
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