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参数资料
| 型号： | LM4120AI2.0MDC |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 基准电压源/电流源 |
| 英文描述： | 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.048 V, UUC |
| 封装： | DIE |
| 文件页数： | 15/16页 |
| 文件大小： | 391K |
| 代理商： | LM4120AI2.0MDC |
Pin Functions
Output (Pin 5): Reference Output.
Input (Pin 4):Positive Supply.
Ground (Pin 2):Negative Supply or Ground Connection.
Enable (Pin 3):Pulled to input for normal operation. Forcing
this pin to ground will turn-off the output.
REF (Pin 1):REF Pin. This pin should be left unconnected.
Application Hints
The standard application circuit for the LM4120 is shown in
Figure 1. It is designed to be stable with ceramic output ca-
pacitors in the range of 0.022F to 0.047F. Note that
0.022F is the minimum required output capacitor. These ca-
pacitors typically have an ESR of about 0.1 to 0.5
. Smaller
ESR can be tolerated, however larger ESR can not. The out-
put capacitor can be increased to improve load transient re-
sponse, up to about 1F. However, values above 0.047F
must be tantalum. With tantalum capacitors, in the 1F
range, a small capacitor between the output and the refer-
ence pin is required. This capacitor will typically be in the
50pF range. Care must be taken when using output capaci-
tors of 1F or larger. These application must be thoroughly
tested over temperature, line and load.
An input capacitor is typically not required. However, a 0.1F
ceramic can be used to help prevent line transients from en-
tering the LM4120. Larger input capacitors should be tanta-
lum or aluminium.
The reference pin is sensitive to noise, and capacitive load-
ing. Therefore, the PCB layout should isolate this pin as
much as possible.
The enable pin is an analog input with very little hysteresis.
About 6A into this pin is required to turn the part on, and it
must be taken close to GND to turn the part off (see spec.
table for thresholds). There is a
minimum slew rate on this
pin of about 0.003V/S to prevent glitches on the output. All
of these conditions can easily be met with ordinary CMOS or
TTL logic. If the shutdown feature is not required, then this
pin can safely be connected directly to the input supply.
Floating this pin is not recommended.
Input Capacitor
Noise on the power-supply input can effect the output noise,
but can be reduced by using an optional bypass capacitor
between the input pin and the ground.
Printed Circuit Board Layout Consideration
The mechanical stress due to PC board mounting can cause
the output voltage to shift from its initial value. References in
SOT packages are generally less prone to assembly stress
than devices in Small Outline (SOIC) package.
To reduce the stress-related output voltage shifts, mount the
reference on the low flex areas of the PC board such as near
to the edge or the corner of the PC board.
DS101047-32
FIGURE 1.
LM4120
www.national.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM4120AI-4.1 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Self-Calibrating 12-Bit Plus Sign Serial I/O A/D Converters with MUX and Sample/Hold |
| LM4120AIM50 | 制造商:Texas Instruments 功能描述: |
| LM4120AIM5-1.8 | 功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
| LM4120AIM5-1.8 | 制造商:Texas Instruments 功能描述:IC SM MICROPOWER REFERENCE 1.8V |
| LM4120AIM5-1.8/NOPB | 功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
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