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參數(shù)資料
| 型號： | MIC5159-3.0BM6 |
| 廠商： | MICREL INC |
| 元件分類： | 模擬信號調理 |
| 英文描述： | PROGRAMMABLE CURRENT LIMIT UCAP LDO REGULATOR CONTROLLER |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO6 |
| 封裝： | SOT-23, 6 PIN |
| 文件頁數(shù)： | 7/23頁 |
| 文件大?。?/td> | 400K |
| 代理商： | MIC5159-3.0BM6 |
April 2004
7
M9999-041204
MIC5159
Applications Information
The MIC5159 is a high performance voltage regulator con-
troller. When used with an external P-Channel MOSFET and
a tiny ceramic output capacitor, it forms a wide variety of
simple, inexpensive ultra-low-dropout voltage regulators.
Current Sense Resistor Selection
A current sense resistor placed between the input and the
current sense pin (IS) allows for programmability of the
current limit. This resistor can simply be calculated by:
Micrel
R
50mV
I
OUT
SENSE
=
Where I
OUT
is the maximum output current.
For example, the current sense resistor for a 2.5V
IN
to
1.8V
OUT
, 5A, linear regulator calculates as follows:
50mV
5A
R
SENSE
= 10m
R
SENSE
=
P-Channel MOSFET Selection
The P-Channel MOSFET selected for use with the MIC5159
must satisfy the following requirements:
Input voltage
Gate threshold
Load current
Dropout voltage (input-to-output differential)
Thermal performance
To prevent damage to the P-Channel MOSFET, the maxi-
mum input voltage (V
IN
(max)) must be less than its drain-
source breakdown voltage (BV
DS
). In addition, the minimum
input voltage (V
IN
(min)) must be greater than or equal to the
gate threshold voltage (V
GS
) of the P-Channel MOSFET. For
a given output current and dropout requirement, the ON-
resistance (R
DS(ON)
) of the P-Channel MOSFET must also
be determined. The minimum R
DS(ON)
of the P-Channel
MOSFET is calculated as follows:
(
max)
R
V (
V
I
(
R
DS(ON)
OUT
OUT
SENSE
=
)
min)
Where I
OUT
(max) is the maximum output current and R
SENSE
is the current sense resistor.
For example, the MIC5159-1.8BM6 is used with an external
MOSFET to form a 5A LDO with an input of 2.5V. Either a 2.5V
or 1.8V gate threshold MOSFET can be selected.
The minimum R
DS(ON)
is calculated as:
(
R
DS(ON)
= 130m
R
2.5V 1.8V
5A
10m
DS(ON)
=
)
According to the above calculation, the minimum R
DS(ON)
is
130m
for a 2.5V to 1.8V LDO with 5A of output current. For
this design, the R
DS(ON)
for the FETs should maintain better
than 130m
over the required temperature, current, and
voltage conditions.
Placing two or more P-Channel FETs in parallel can reduce
the total R
DS(ON)
of the regulator. This also aids thermal
dissipation by sharing the current and heat between the
multiple FETs.
Thermal Considerations
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Since the MIC5159 offers no thermal protection, thermal
design requires the following application-specific param-
eters:
Maximum ambient temperature (T
A
)
Output current (I
OUT
)
Output voltage (V
OUT
)
Input voltage (V
IN
)
First, calculate the maximum power dissipation of the
regulator:
P
D
= (V
IN
–
V
OUT
)
×
I
OUT
Ground current can generally be ignored. The amount of
power dissipated by ground current and input voltage is
minimal. Minimum
θ
JA
for the MOSFET can be calculated
using the following formula:
(
θ
JA
A
D
T (
T
P
=
)
max)
Where T
J
(max) is equal to the maximum die temperature of
the P-Channel.
θ
JA
=
θ
JC
+
θ
CS
+
θ
SA
Example
For the same regulator, 2.5V
IN
to 1.8V
OUT
at 5A with an
ambient temperature of 60
°
C:
P
D
= (2.5V
–
1.8V)
×
5A
P
D
= 3.5W
Where V
IN
is the maximum V
IN
and I
OUT
is the maximum
I
OUT
.
The P-Channel MOSFET must be able to dissipate 3.5W.
The minimum
θ
JA
to maintain a maximum T
J
of 150
°
C (max.)
T
J
according to a typical MOSFET data sheet is as follows:
150 C
60 C
3.5W
θ
JA
= 25.71
°
C/W
The heatsink and MOSFET must have a combined thermal
resistance to meet the above criteria.
θ
JA
=
(
)
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MIC5159BM6 | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:RF Micro Devices Inc 功能描述: 制造商:Micrel Inc 功能描述: |
| MIC5159BM6 TR | 功能描述:IC REG CTRLR SGL POS ADJ SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性晶體管驅動器 系列:- 產品培訓模塊:More Information on LDOs 標準包裝:2,500 系列:- 類型:正，固定式 輸出數(shù):2 輸出電壓:2.8V，3.3V 電流 - 電源:12mA 輸入電壓:5 V ~ 22 V 工作溫度:0°C ~ 70°C 封裝/外殼:16-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:16-SOIC 包裝:帶卷 (TR) |
| MIC5159YM6 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:Programmable Current Limit μCap LDO Regulator Controller |
| MIC5159YM6 TR | 功能描述:低壓差控制器 - LDO Progr. Ilim LDO Controller(Lead Free) RoHS:否 制造商:Micrel 最大輸入電壓:5.5 V 輸出電壓:Adjustable 輸出電流:10 mA 負載調節(jié): 輸出類型:Adjustable, Fixed 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-6 |
| MIC5159YM6TR | 制造商:Micrel 功能描述:LDO Regulator 1.235V to 5.5V |
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