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參數(shù)資料
| 型號： | MIC39500 |
| 廠商： | Micrel Semiconductor,Inc. |
| 英文描述： | 5A Low-Voltage Low-Dropout Regulator(輸出電流5A 低電壓低壓差穩(wěn)壓器) |
| 中文描述： | 第5A低電壓低壓差穩(wěn)壓器（輸出電流5A條低電壓低壓差穩(wěn)壓器） |
| 文件頁數(shù)： | 8/11頁 |
| 文件大小： | 96K |
| 代理商： | MIC39500 |
MIC39500/39501
Applications Information
The MIC39500/1 is a high-performance low-dropout voltage
regulator suitable for moderate to high-current voltage regu-
lator applications. Its 400mV dropout voltage at full load
makes it especially valuable in battery-powered systems and
as a high-efficiency noise filter in post-regulator applications.
Unlike older NPN-pass transistor designs, where the mini-
mum dropout voltage is limited by the base-to-emitter voltage
drop and collector-to-emitter saturation voltage, dropout per-
formance of the PNP output of these devices is limited only
by the low V
CE
saturation voltage.
A trade-off for the low dropout voltage is a varying base drive
requirement. Micrel
’
s Super
β
eta PNP
process reduces
this drive requirement to only 2% to 5% of the load current.
The MIC39500/1 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload conditions is
constant. Thermal shutdown disables the device when the
die temperature exceeds the maximum safe operating tem-
perature. Transient protection allows device (and load) sur-
vival even when the input voltage spikes above and below
nominal. The output structure of these regulators allows
voltages in excess of the desired output voltage to be applied
without reverse current flow.
Micrel
MIC39500/39501
8
February 2001
MIC39500-x.x
IN
OUT
GND
C
IN
C
OUT
V
IN
V
OUT
Figure 1. Capacitor Requirements
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires four application-specific param-
eters:
Maximum ambient temperature (T
A
)
Output Current (I
OUT
)
Output Voltage (V
OUT
)
Input Voltage (V
IN
)
Ground Current (I
GND
)
Calculate the power dissipation of the regulator from these
numbers and the device parameters from this datasheet,
where the ground current is taken from data sheet.
P
D
= (V
IN
–
V
OUT
)
×
I
OUT
+ V
IN
×
I
GND
The heat sink thermal resistance is determined by:
θ
θ
θ
SA
J(max)
T
A
D
JC
CS
T
P
=
+
(
)
where:
T
J (max)
≤
125
°
C and
θ
CS
is between 0
°
and 2
°
C/W.
The heat sink may be significantly reduced in applications
where the minimum input voltage is known and is large
compared with the dropout voltage. Use a series input
resistor to drop excessive voltage and distribute the heat
between this resistor and the regulator. The low-dropout
properties of Micrel Super
β
eta PNP regulators allow signifi-
cant reductions in regulator power dissipation and the asso-
ciated heat sink without compromising performance. When
this technique is employed, a capacitor of at least 1
μ
F is
needed directly between the input and regulator ground.
Refer to Application Note 9for further details and examples
on thermal design and heat sink specification.
Output capacitor
The MIC39500/1 requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
MIC39500/1 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor
to maintain stability. When the output capacitor is 47
μ
F or
greater, the output capacitor should have less than 1
of
ESR. This will improve transient response as well as promote
stability. Ultra-low-ESR capacitors, such as ceramic chip
capacitors may promote instability. These very low ESR
levels may cause an oscillation and/or underdamped tran-
sient response. When larger capacitors are used, the ESR
requirement approaches zero. A 100
μ
F ceramic capacitor
can be used on the output while maintaining stability. A low-
ESR 47
μ
F solid tantalum capacitor works extremely well and
provides good transient response and stability over tempera-
ture. Aluminum electrolytics can also be used, as long as the
ESR of the capacitor is < 1
.
The value of the output capacitor can be increased without
limit. Higher capacitance values help to improve transient
response and ripple rejection and reduce output noise.
Input capacitor
An input capacitor of 1
μ
F or greater is recommended when
the device is more than 4 inches away from the bulk ac supply
capacitance, or when the supply is a battery. Small surface-
mount ceramic chip capacitors can be used for bypassing.
Larger values will help to improve ripple rejection by bypass-
ing the input to the regulator, further improving the integrity of
the output voltage.
Transient Response and 3.3V to 2.5V or 2.5V to 1.8V
Conversion
The MIC39500/1 has excellent transient response to varia-
tions in input voltage and load current. The device has been
designed to respond quickly to load current variations and
input voltage variations. Large output capacitors are not
required to obtain this performance. A standard 47
μ
F output
capacitor, preferably tantalum, is all that is required. Larger
values improve performance even further.
By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based de-
signs. When converting from 3.3V to 2.5V, or 2.5V to 1.8V,
the NPN-based regulators are already operating in dropout,
with typical dropout requirements of 1.2V or greater. To
convert down to 2.5V without operating in dropout, NPN-
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC39500_05 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:5A ??Cap Low-Voltage Low-Dropout Regulator |
| MIC39500-1.8BT | 功能描述:IC REG LDO 1.8V 5A TO220-3 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:3.8V 輸入電壓:最高 16V 電壓 - 壓降（標(biāo)準(zhǔn)）:0.3V @ 80mA 穩(wěn)壓器數(shù)量:1 電流 - 輸出:80mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:帶卷 (TR) 其它名稱:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC39500-1.8BU | 功能描述:IC REG LDO 1.8V 5A TO-263 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:3.8V 輸入電壓:最高 16V 電壓 - 壓降（標(biāo)準(zhǔn)）:0.3V @ 80mA 穩(wěn)壓器數(shù)量:1 電流 - 輸出:80mA 電流 - 限制（最小）:- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:帶卷 (TR) 其它名稱:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC39500-1.8BU TR | 功能描述:IC REG LDO 1.8V 5A TO-263 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:3.8V 輸入電壓:最高 16V 電壓 - 壓降（標(biāo)準(zhǔn)）:0.3V @ 80mA 穩(wěn)壓器數(shù)量:1 電流 - 輸出:80mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:帶卷 (TR) 其它名稱:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC39500-1.8WT | 功能描述:低壓差穩(wěn)壓器 - LDO 5.0A 1.0% Fixed Voltage LDO(ROHS Compliant) RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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