- 您现在的位置：买卖IC网 > PDF目录69004 > LM234H/NOPB (NATIONAL SEMICONDUCTOR CORP) SPECIALTY ANALOG CIRCUIT, MBCY3 PDF资料下载
参数资料
| 型号： | LM234H/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 模拟信号调理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, MBCY3 |
| 封装： | METAL CAN, TO-46, 3 PIN |
| 文件页数： | 10/14页 |
| 文件大小： | 759K |
| 代理商： | LM234H/NOPB |
Typical Performance Characteristics (Continued)
Turn-On Voltage
Ratio of I
SET to IBIAS
00569729
00569703
Application Hints
The LM134 has been designed for ease of application, but a
general discussion of design features is presented here to
familiarize the designer with device characteristics which
may not be immediately obvious. These include the effects
of slewing, power dissipation, capacitance, noise, and con-
tact resistance.
CALCULATING R
SET
The total current through the LM134 (I
SET) is the sum of the
current going through the SET resistor (I
R) and the LM134’s
bias current (I
BIAS), as shown in Figure 1.
A graph showing the ratio of these two currents is supplied
under Ratio of I
SET to IBIAS in the Typical Performance
Characteristics section. The current flowing through R
SET is
determined by V
R, which is approximately 214V/K (64
mV/298K
214V/K).
Since (for a given set current) I
BIAS is simply a percentage of
I
SET, the equation can be rewritten
where n is the ratio of I
SET to IBIAS as specified in the
Electrical Characteristics Section and shown in the graph.
Since n is typically 18 for 2A
≤ I
SET
≤ 1mA, the equation can
be further simplified to
for most set currents.
SLEW RATE
At slew rates above a given threshold (see curve), the
LM134 may exhibit non-linear current shifts. The slewing
rate at which this occurs is directly proportional to I
SET.At
I
SET = 10A, maximum dV/dt is 0.01V/s; at ISET = 1mA, the
limit is 1V/s. Slew rates above the limit do not harm the
LM134, or cause large currents to flow.
THERMAL EFFECTS
Internal heating can have a significant effect on current
regulation for I
SET greater than 100A. For example, each
1V increase across the LM134 at I
SET = 1 mA will increase
junction temperature by
≈0.4C in still air. Output current
(I
SET) has a temperature coefficient of
≈0.33%/C, so the
change in current due to temperature rise will be (0.4)
(0.33) = 0.132%. This is a 10:1 degradation in regulation
compared to true electrical effects. Thermal effects, there-
fore, must be taken into account when DC regulation is
critical and I
SET exceeds 100A. Heat sinking of the TO-46
package or the TO-92 leads can reduce this effect by more
than 3:1.
SHUNT CAPACITANCE
In certain applications, the 15 pF shunt capacitance of the
LM134 may have to be reduced, either because of loading
problems or because it limits the AC output impedance of the
current source. This can be easily accomplished by buffering
the LM134 with an FET as shown in the applications. This
can reduce capacitance to less than 3 pF and improve
00569727
FIGURE 1. Basic Current Source
LM134/LM234/LM334
www.national.com
5
相关PDF资料 |
PDF描述 |
|---|---|
| LM25085MMY | SWITCHING CONTROLLER, PDSO8 |
| LM25119PSQX | DUAL SWITCHING CONTROLLER, QCC32 |
| LM25119PSQE | DUAL SWITCHING CONTROLLER, QCC32 |
| LM25119PSQ | DUAL SWITCHING CONTROLLER, QCC32 |
| LM2576TV-ADJ | 3 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM234S8 | 制造商:Linear Technology 功能描述: |
| LM234Z | 功能描述:基准电压& 基准电流 3-Term Adjust Currnt 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 |
| LM234Z | 制造商:STMicroelectronics 功能描述:IC - Adjustable Current Source |
| LM234Z-3 | 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 |
| LM234Z-3/NOPB | 功能描述:基准电压& 基准电流 3-TERM ADJ CURRENT SOURCE 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 |
发布紧急采购，3分钟左右您将得到回复。