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| 型号： | MIC2951-03BM |
| 厂商： | Micrel Inc |
| 文件页数： | 11/20页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO 5V/ADJ .15A 8SOIC |
| 标准包装： | 95 |
| 稳压器拓扑结构： | 正，固定式或可调式 |
| 输出电压： | 5V，1.24 V ~ 29 V |
| 输入电压： | 2 V ~ 30 V |
| 电压 - 压降（标准）： | 0.3V @ 150mA |
| 稳压器数量： | 1 |
| 电流 - 输出： | 150mA |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
Micrel, Inc.
Application Information
Automotive Applications
The MIC2950/2951 are ideally suited for automotive
applications for a variety of reasons. They will operate
over a wide range of input voltages, have very low
dropout voltages (40mV at light loads), and very low
quiescent currents. These features are necessary for use
in battery powered systems, such as automobiles. They
are also “bulletproof” devices; with the ability to survive
both reverse battery (negative transients up to 20V below
ground), and load dump (positive transients up to 60V)
conditions. A wide operating temperature range with low
temperature coef ? cients is yet another reason to use
these versatile regulators in automotive designs
External Capacitors
A 1.5μF (or greater) capacitor is required between the
MIC2950/MIC2951 output and ground to prevent
oscillations due to instability. Most types of tantalum or
aluminum elec-trolytics will be adequate; ? lm types will
work, but are costly and therefore not recommended.
Many aluminum electrolytics have electrolytes that freeze
at about –30°C, so solid tantalums are recomm-ended for
operation below –25°C. The important parameters of the
capacitor are an effective series resistance of about 5 ? or
less and a resonant frequency above 500kHz. The value
of this capacitor may be increased without limit.
At lower values of output current, less output capacitance
is required for output stability. The capacitor can be
reduced to 0.5μF for current below 10mA or 0.15μF for
currents below 1 mA. Using the 8-pin versions at voltages
below 5V runs the error ampli ? er at lower gains so that
more output capacitance is needed. For the worst-case
situation of a 150mA load at 1.23V output (Output shorted
to Feedback) a 5μF (or greater) capacitor should be used.
The MIC2950 will remain stable and in regulation with no
load in addition to the internal voltage divider, unlike many
other voltage regulators. This is especially important in
CMOS RAM keep-alive applications. When setting the
output voltage of the MIC2951 version with external
resistors, a minimum load of 1μA is recomm-ended.
MIC2950/2951
Error Detection Comparator Output
A logic low output will be produced by the comparator
whenever the MIC2951 output falls out of regulation by
more than approximately 5%. This ? gure is the
comparator’s built-in offset of about 60mV divided by the
1.235V reference voltage. (Refer to the block diagram on
Page 1). This trip level remains “5% below normal”
regardless of the programmed output voltage of the
MIC2951. For example, the error ? ag trip level is typically
4.75V for a 5V output or 11.4V for a 12V output. The out
of regulation condition may be due either to low input
voltage, current limiting, thermal limiting, or overvolt-age
on input (over ? 40V).
Figure 1 is a timing diagram depicting the /ERROR signal
and the regulated output voltage as the MIC2951 input is
ramped up and down. The /ERROR signal becomes valid
(low) at about 1.3V input. It goes high at about 5V input
(the input voltage at which V OUT = 4.75—for 5.0V
applications). Since the MIC2951’s dropout voltage is
load-dependent (see curve in Typical Performance
Characteristics), the input voltage trip point (about 5V) will
vary with the load current. The output voltage trip point
does not vary with load.
The error comparator has an open-collector output which
requires an external pull-up resistor. Depending on
system requirements, this resistor may be returned to the
output or some other supply voltage. In determining a
value for this resistor, note that while the output is rated to
sink 200μA, this sink current adds to battery drain in a low
battery condition. Suggested values range from 100k to
1M ? . The resistor is not required if this output is unused.
Programming the Output Voltage (MIC2951)
The MIC2951 may be pin-strapped for 5V (or 3.3V or
4.85V) using its internal voltage divider by tying Pin 1
(output) to Pin 2 (sense) and Pin 7 (feedback) to Pin 6 (5V
Tap). Alternatively, it may be programmed for any output
voltage between its 1.235V reference and its 30V
maximum rating. An external pair of resistors is required,
as shown in Figure 2.
The complete equation for the output voltage is:
V OUT = V REF × ? 1 +
R 1 ?
A 0.1μF capacitor should be placed from the MIC2950/
MIC2951 input to ground if there is more than 10 inches
of wire between the input and the AC ? lter capacitor or if a
?
?
? + I FB R 1
R 2 ?
battery is used as the input.
Stray capacitance to the MIC2951 Feedback terminal (pin
7) can cause instability. This may especially be a problem
when using high value external resistors to set the output
voltage. Adding a 100pF capacitor between Output and
Feedback and increasing the output capacitor to at least
3.3μF will remedy this.
where V REF is the nominal 1.235 reference voltage and I FB
is the feedback pin bias current, nominally –20nA. The
minimum recommended load current of 1μA forces an
upper limit of 1.2M ? on the value of R 2 , if the regulator
must work with no load (a condition often found in CMOS
in standby), I FB will produce a 2% typical error in V OUT
which may be eliminated at room temperature by trimming
R 1 . For better accuracy, choosing R 2 = 100k reduces this
error to 0.17% while increasing the resistor program
current to 12μA.
February 2010
11
M9999-021610
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| MIC2951-03BM TR | 功能描述:IC REG LDO 5V/ADJ .15A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:45 系列:- 稳压器拓扑结构:正，固定式 输出电压:5V 输入电压:6 V ~ 30 V 电压 - 压降（标准）:0.47V @ 250mA 稳压器数量:1 电流 - 输出:250mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:TO-220-3 供应商设备封装:TO-220-3 包装:管件 产品目录页面:1289 (CN2011-ZH PDF) 其它名称:*LP2954AIT*LP2954AIT/NOPBLP2954AIT |
| MIC2951-03BMM | 功能描述:IC REG LDO 5V/ADJ .15A 8-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:3,000 系列:- 稳压器拓扑结构:正，固定式 输出电压:3.8V 输入电压:最高 16V 电压 - 压降（标准）:0.3V @ 80mA 稳压器数量:1 电流 - 输出:80mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:带卷 (TR) 其它名称:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC2951-03BMM TR | 功能描述:IC REG LDO 5V/ADJ .15A 8-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:3,000 系列:- 稳压器拓扑结构:正，固定式 输出电压:3.8V 输入电压:最高 16V 电压 - 压降（标准）:0.3V @ 80mA 稳压器数量:1 电流 - 输出:80mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:带卷 (TR) 其它名称:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC2951-03BN | 功能描述:IC REG LDO 5V/ADJ .15A 8DIP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:3,000 系列:- 稳压器拓扑结构:正，固定式 输出电压:3.8V 输入电压:最高 16V 电压 - 压降（标准）:0.3V @ 80mA 稳压器数量:1 电流 - 输出:80mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:带卷 (TR) 其它名称:MIC5203-3.8BM5TRMIC5203-3.8BM5TR-ND |
| MIC2951-03YM | 功能描述:低压差稳压器 - LDO Improved LP2951 Low Drop-out Regulator(Lead Free) RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
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