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參數(shù)資料
| 型號： | MIC5252-3.0BMLTR |
| 廠商： | MICREL INC |
| 元件分類： | 固定正電壓單路輸出LDO穩(wěn)壓器 |
| 英文描述： | 3 V FIXED POSITIVE LDO REGULATOR, 0.25 V DROPOUT, PDSO6 |
| 封裝： | 2 X 2 MM, MLF-6 |
| 文件頁數(shù)： | 8/9頁 |
| 文件大?。?/td> | 642K |
| 代理商： | MIC5252-3.0BMLTR |
MIC5252
Applications Information
Enable/Shutdown
The MIC5252 comes with an active-high enable pin that al-
lows the regulator to be disabled. Forcing the enable pin low
disables the regulator and sends it into a “zero” off-mode-cur-
rent state. In this state, current consumed by the regulator
goes nearly to zero. Forcing the enable pin high enables
the output voltage. This part is CMOS and the enable pin
cannot be left floating; a floating enable pin may cause an
indeterminate state on the output.
Input Capacitor
The MIC5252 is a high performance, high bandwidth device.
Therefore, it requires a well-bypassed input supply for opti-
mal performance. A 1
μ
F capacitor is required from the input
to ground to provide stability. Low-ESR ceramic capacitors
provide optimal performance at a minimum of space. Addi-
tional high-frequency capacitors, such as small valued NPO
dielectric type capacitors, help filter out high frequency noise
and are good practice in any RF based circuit.
Output Capacitor
The MIC5252 requires an output capacitor for stability. The
design requires 1
μ
F or greater on the output to maintain stabil-
ity. The design is optimized for use with low-ESR ceramic chip
capacitors. High ESR capacitors may cause high frequency
oscillation. The maximum recommended ESR is 300m
.
The output capacitor can be increased, but performance has
been optimized for a 1
μ
F ceramic output capacitor and does
not improve significantly with larger capacitance.
X7R/X5R dielectric-type ceramic capacitors are recom-
mended because of their temperature performance. X7R-type
capacitors change capacitance by 15% over their operating
temperature range and are the most stable type of ceramic
capacitors. Z5U and Y5V dielectric capacitors change value
by as much as 50% and 60%, respectively, over their operat-
ing temperature ranges. To use a ceramic chip capacitor with
Y5V dielectric, the value must be much higher than an X7R
ceramic capacitor to ensure the same minimum capacitance
over the equivalent operating temperature range.
Bypass Capacitor
A capacitor is required from the noise bypass pin to ground
to reduce output voltage noise. The capacitor bypasses
the internal reference. A 0.01
μ
F capacitor is recommended
for applications that require low-noise outputs. The bypass
capacitor can be increased, further reducing noise and im-
proving PSRR. Turn-on time increases slightly with respect
to bypass capacitance. A unique quick-start circuit allows
the MIC5252 to drive a large capacitor on the bypass pin
without significantly slowing turn-on time. Refer to the “Typi-
cal Characteristics” section for performance with different
bypass capacitors.
Active Shutdown
The MIC5252 also features an active shutdown clamp, which
is an N-Channel MOSFET that turns on when the device is
disabled. This allows the output capacitor and load to dis-
charge, de-energizing the load.
Micrel, Inc.
M9999-020305
8
February 2005
No-Load Stability
The MIC5252 will remain stable and in regulation with no
load unlike many other voltage regulators. This is especially
important in CMOS RAM keep-alive applications.
Thermal Considerations
The MIC5252 is designed to provide 150mA of continuous
current in a very small package. Maximum power dissipation
can be calculated based on the output current and the voltage
drop across the part. To determine the maximum power dis-
sipation of the package, use the junction-to-ambient thermal
resistance of the device and the following basic equation:
T (max)
T
JA
T
J
(max) is the maximum junction temperature of the die,
125°C, and T
A
is the ambient operating temperature.
θ
JA
is
layout dependent; Table 1 shows examples of junction-to-
ambient thermal resistance for the MIC5252.
Package
θ
JA
Recommended
Minimum Footprint
SOT-23-5
235°C/W
(M5 or D5)
Table 1. SOT-23-5 Thermal Resistance
P (max)
A
=
θ
θ
JA
1” Square
Copper Clad
185°C/W
θ
JC
145°C/W
The actual power dissipation of the regulator circuit can be
determined using the equation:
P
D
= (V
IN
– V
OUT
) I
OUT
+ V
IN
I
GND
Substituting P
D
(max) for P
D
and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For
example, when operating the MIC5252-2.8BM5 at 50°C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:
125 C
50 C
235 C/W
The junction-to-ambient thermal resistance for the minimum
footprint is 235°C/W, from Table 1. The maximum power dis-
sipation must not be exceeded for proper operation. Using
the output voltage of 2.8V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 100μA over
the load range, the power dissipation contributed by the ground
current is < 1% and can be ignored for this calculation.
315mW = (V
IN
– 2.8V) 150mA
315mW = V
IN
×
150mA – 420mW
735mW = V
IN
×
150mA
V
IN
(max) = 4.9V
Therefore, a 2.8V application at 150mA of output current
can accept a maximum input voltage of 4.9V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
effects on voltage regulators, refer to the “Regulator Ther-
mals” section of Micrel’s Designing with Low-Dropout Voltage
Regulators handbook.
P (max)
=
P
D
(max) = 315mW
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC5252-4.75BM5 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:150MA HIGH PSRR LOW NOISE UCAP CMOS LDO |
| MIC5252-4.75BM5 TR | 功能描述:IC REG LDO 4.75V .15A SOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:12V 輸入電壓:14.5 V ~ 35 V 電壓 - 壓降（標(biāo)準(zhǔn)）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:500mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:TO-205AD，TO-39-3 金屬罐 供應(yīng)商設(shè)備封裝:TO-39 包裝:散裝 其它名稱:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
| MIC5252-4.75BML TR | 功能描述:IC REG LDO 4.75V .15A 6-MLF RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:12V 輸入電壓:14.5 V ~ 35 V 電壓 - 壓降（標(biāo)準(zhǔn)）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:500mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:TO-205AD，TO-39-3 金屬罐 供應(yīng)商設(shè)備封裝:TO-39 包裝:散裝 其它名稱:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
| MIC5252-4.75YM5 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:150mA High PSRR, Low Noise μCap CMOS LDO |
| MIC5252-4.75YM5 TR | 功能描述:低壓差穩(wěn)壓器 - LDO 150mA High-PSRR CAP LDO (Lead Free) 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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