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| 型号： | MIC29371-5.0BU TR |
| 厂商： | Micrel Inc |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO 5V .75A TO-263-5 |
| 标准包装： | 750 |
| 稳压器拓扑结构： | 正，固定式 |
| 输出电压： | 5V |
| 输入电压： | 最高 26V |
| 电压 - 压降（标准）： | 0.37V @ 750mA |
| 稳压器数量： | 1 |
| 电流 - 输出： | 750mA |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | TO-263-6，D²Pak（5 引线+接片），TO-263BA |
| 供应商设备封装： | TO-263-5 |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC29371-5.0BUTR MIC29371-5.0BUTR-ND |
MIC2937A/29371/29372
Applications Information
External Capacitors
A 10μF (or greater) capacitor is required between the MIC2937A
output and ground to prevent oscillations due to instability. Most
types of tantalum or aluminum electrolytics will be adequate;
?lm types will work, but are costly and therefore not recom-
mended. Many aluminum electrolytics have electrolytes that
freeze at about –30°C, so solid tantalums are recommended
for operation below –25°C. The important parameters of the
capacitor are an effective series resistance of about 5Ω 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. Adjusting the MIC29372 to 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 750mA load at
1.23V output (Output shorted to Adjust) a 22μF (or greater)
capacitor should be used.
The MIC2937A/29371 will remain in regulation with a minimum
load of 5mA. When setting the output voltage of the MIC29372
version with external resistors, the current through these resis-
tors may be included as a portion of the minimum load.
A 0.1μF capacitor should be placed from the input to ground
if there is more than 10 inches of wire between the input and
the AC ?lter capacitor or if a battery is used as the input.
Error Detection Comparator Output (MIC29371)
A logic low output will be produced by the comparator when-
ever the MIC29371 output falls out of regulation by more than
approximately 5%. This ?gure is the comparator ’s built-in
offset of about 75mV divided by the 1.235V reference volt-
age. (Refer to the block diagram on Page 1). This trip level
remains “5% below normal” regardless of the programmed
output voltage of the MIC29371. 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,extremely high input voltage, current limit-
ing, or thermal limiting.
Micrel, Inc.
The error comparator has an NPN open-collector output which
requires an external pull-up resistor. Depending on system
requirements, this resistor may be returned to the 5V output
or some other supply voltage. In determining a value for this
resistor, note that while the output is rated to sink 250μA, this
sink current adds to battery drain in a low battery condition.
Suggested values range from 100k to 1MΩ. The resistor is
not required if this output is unused.
Programming the Output Voltage (MIC29372)
The MIC29372 may programmed for any output voltage be-
tween its 1.235V reference and its 26V maximum rating. An
external pair of resistors is required, as shown in Figure 3.
The complete equation for the output voltage is
V OUT = V REF x { 1 + R 1 /R 2 } – | I FB | R 1
where V REF is the nominal 1.235 reference voltage and I FB is
the Adjust pin bias current, nominally 20nA. The minimum rec-
ommended load current of 1μA forces an upper limit of 1.2MΩ
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. Since the MIC29372 typically
draws 100μA at no load with SHUTDOWN open-circuited,
this is a negligible addition.
Reducing Output Noise
In reference applications it may be advantageous to reduce
the AC noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is relatively inef?cient, as increasing the capaci-
tor from 1μF to 220μF only decreases the noise from 430μV
to 160μV RMS for a 100kHz bandwidth at 5V output. Noise can
be reduced by a factor of four with the adjustable regulators
ERROR NOT *
NOT *
Figure 1 is a timing diagram depicting the ERROR signal
and the regulated output voltage as the MIC29371 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). Since the MIC29371’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 (ap-
proximately 4.75V) does not vary with load.
OUTPUT
VOLTAGE
INPUT 5V
VOLTAGE
4.75V
VALID
1.3V
VALID
* SEE APPLICATIONS INFORMATION
Figure 1. ERROR Output Timing
MIC2937A/29371/29372
8
May 2006
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相关代理商/技术参数 |
参数描述 |
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| MIC29372BT | 功能描述:IC REG LDO ADJ .75A TO220-5 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 |
| MIC29372BU | 功能描述:IC REG LDO ADJ .75A TO263-5 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 |
| MIC29372BU TR | 功能描述:IC REG LDO ADJ .75A TO263-5 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 |
| MIC29372BUTR | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
| MIC29372WT | 功能描述:低压差稳压器 - LDO 750mA LDO Adj + Shutdown(ROHS Compliant) 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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