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參數(shù)資料
| 型號： | SP6122ACU-15 |
| 英文描述： | Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
| 中文描述： | 低電壓，微8，PFET的，降壓控制器適合第1A至5A，占地面積小，DC - DC電源轉換器 |
| 文件頁數(shù)： | 15/19頁 |
| 文件大小： | 174K |
| 代理商： | SP6122ACU-15 |
15
Date: 10/02/04
SP6122 Low Voltage, Micro 8, PFET, Buck Controller Copyright 2004 Sipex Corporation
For the SP6122 example, the schottky
STPS2L25U has V
F
= 0.5V for I
OUT
of 4A,
the power loss in the schottky P
DIODE
=
848mW.
Note that this power dissipation is 2.5 times
greater than the MOSFET. If we assume the
same thermal conductivity as the MOSFET
(according to the data sheets, this is close)
we should get a 40
°
C rise due to the Schottky
diode alone. It is apparent that due to the
proximity of all the components involved
that the board temperature is higher than
ambient and this temperature rise must be
considered when attempting to protect the
power converter.
Features and Protection
PROGRAMMING THE SP6122 OUTPUT
VOLTAGE
For Applications requiring output other than
1.5V, the 1.25V adjustable version is
recommended. The output voltage can be
programmed through a simple voltage
divider shown in Figure 5. The set point for
the output voltage can be determined by
V
OUT
= 1.25 (R1 + R2)
R2
Select R1 and R2 in the range from 1k to
100k.
The 1.5V version of SP6122 has built in
voltage divider that presets the output
voltage. Simply connect the V
OUT
pin to the
power supply output for 1.5V regulation.
Due to the internal voltage divider, the
version of SP6122 sinks 23
μ
A current at
the V
OUT
pin. Consider this error term if a
resistor voltage divider is used.
SOFT START
The SP6122 has a built-in soft start feature
that automatically limits the inrush currents
to reasonable levels for most power sup-
plies. For our 1.9V example, the inrush cur-
rent on start up is:
I
INRUSH
= 470
μ
F * 0.5V/ms * 1.9V/1.25V
= 357mA
This extra current must be factored in when
calculating over current margins.
LOCK-UP AND HICCUP MODES
Basically, when the SP6122 sees an over
current fault, the part can react in two ways.
If the FFLAG is not tied to ENABLE, the part
will put the driver into a low impedance state
to the high rail during a fault. The ENABLE
pin must be manually cycled to remove the
fault. This mode is useful when power sup-
ply sequencing and system fault manage-
ment is complex. If the FFLAG pin is tied to
ENABLE, then a ‘hiccup’ time can be de-
signed by adding a capacitor from ENABLE
to ground. The 4
μ
A ENABLE pin charge
current acts as a timer. The driver will be put
into a low impedance state to the high rail for
a certain amount of time.
T
OFF
= C
ENABLE
* 1.21V/5
μ
A
For C
ENABLE
= 4.7nF, this time equals 1.3ms.
This represents a ‘cool off’ time required for
the power supply to cycle and see if the fault
has been removed. This mode is useful for
short term faults or in single supply systems.
Guidelines for Component Selection:
continued
SP6122
V
OUT
R1
Pin 3
Vb
R2
Va
–
+
Error
1.25V
+
–
R
IN1
Figure 5: Schematic: Output Voltage Divider Resistors
相關PDF資料 |
PDF描述 |
|---|---|
| SP6122CU | Evaluation Board Manual |
| SP6122EB | Evaluation Board Manual |
| SP6122UEB | Evaluation Board Manual |
| SP6122ACU-1.5 | Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
| SP6122 | Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SP6122ACU-15/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
| SP6122ACU-L | 功能描述:DC/DC 開關控制器 Low Voltage, Micro 8 PFET Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| SP6122ACU-L/TR | 功能描述:DC/DC 開關控制器 Low Voltage, Micro 8 PFET Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| SP6122ACU-L-1-5 | 制造商:Exar Corporation 功能描述:BUCK CONTROLLER LOW VOLT PFET 6122 |
| SP6122CU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
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