Use an LM317 as 0 to 3V adjustable regulator
Most engineers know that they can use an inexpensive, three-terminal adjustable regulator, such as Fairchild Semiconductor’s LM317, as an adjustable regulator to only some necessary value of voltage, such as 36 or 3V. This value cannot be less than 1.25V without employing other approaches, however. The devices’ inner reference voltage is 1.25V, and their output voltage accordingly cannot be less than this value without potential bias (Reference 1). One way to solve this problem is to use a reference-voltage source based on two diodes (Reference 2). Although this approach is suitable for a 1.2 to 15V or higher-voltage regulator, it is not appropriate for an extra-low-voltage fixed- or adjustable-voltage regulator. The two 1N4001 diodes it employs do not provide the needed potential bias of 1.2V, and they have additional temperature instability of approximately 2.5 mV/K (Reference 3). Hence, additional temperature drifting of the output voltage is approximately 100 mV; it is more than 6% for a 1.5V output voltage and 10% for a 1V output voltage if you adjust the temperature to 20°C—a typical indoor situation. You can solve these problems by using a Fairchild Semiconductor LM185 or an Analog Devices AD589 adjustable-voltage-reference IC. These devices are expensive, however, and, in this case, they require not only additional zero adjustment but also matching. These adjustments at their reference voltages are 1.215 to 1.255V and 1.2 to 1.25V for the LM185 and AD589, respectively. Note that the reference voltage of the LM317 is 1.2 to 1.3V.
Figure 1 This circuit is an inexpensive approach using a simple 0 to 3V adjustable regulator.
Figure 1 shows an inexpensive approach using a simple 0 to 3V adjustable regulator. You implement the necessary potential bias using a simple temperature-stabilized constant-current source (Reference 4). You calculate this current source using the following equation: I=(VF–VEBO)/(R5+R6), where VF is D1’s forward voltage of approximately 2V and VEBO is Q1’s emitter-base voltage of approximately 0.68V. The current is approximately 1.32/(R5+R6). The constant-current source creates a bias voltage of approximately –1.25V on resistor R3. You implement the zero adjustment using resistor R6, which can change the current of the constant-current source. Resistor R5 protects transistor Q1. You can use D1 as a light indicator. You can adjust the output voltage using resistor R2. Calculate the output voltage as follows: VOUT=VREF(1+R2/R1)–VR3, where VREF is the reference voltage of IC1 and VR3 is some compensative voltage of resistor R3. You should establish this voltage to equal the reference voltage for its compensation. In this case, VOUT=VREF(R2/R1). With R2 having a value of 1.2 kΩ,this circuit found use as the equivalent of a typical battery with an output voltage of 1.56V for development projects.
Use an LM317 as 0 to 3V adjustable regulator的更多相关文章
- STM32-正弦波可调(50HZ~20KHZ可调、峰峰值0~3.3V可调)
1.原理: 通过定时器每隔一段时间触发一次DAC转换,然后通过DMA发送正玄波码表值给DAC. 当需要改变频率HZ时,只需要修改定时器频率即可(最高只能达到20KHz) 当需要改变正玄波的正峰峰值/负 ...
- 一个5.0/3.3V双向通讯的电路
来自群友 西江月-梧州 的分享 硬件程工-深圳福永(79993868) 17:06:33 当3.3V高时二极管阳极为3.3V,阴极接了10K上拉为5V,二极管的压降为反向,此时二极管不导通. 硬件程工 ...
- 1V升3V芯片,1V升3.3V芯片,大电流的,低功耗
一般来说,1V的电压实在很低了,即使是干电池的话,再1V时,也是基本属于没电状态了.还有一种是干电池输出电流大时,也会把干电池的电压从1.5V拉低到1V左右. 更多的是客户对于1V时要能升到3V或者3 ...
- Current-sense monitor and MOSFET boost output current
A previous Design Idea describes a programmable current source that used a three-terminal National S ...
- 常见电子元器件检测方法。——Arvin
电子设备中使用着大量各种类型的电子元器件,设备发生故障大多是由于电子元器件失效或损坏引起的.因此怎么正确检测电子元器件就显得尤其重要,这也是电子维修人员必须掌握的技能.我在电器维修中积累了部分常见电子 ...
- Linux学习 : 裸板调试 之 配置UART
1.UART原理说明 发送数据时,CPU将并行数据写入UART,UART按照一定的格式在一根电线上串行发出:接收数据时,UART检测另一根电线上的信号,串行收集然后放在缓冲区中,CPU即可读取UART ...
- STM32 DAC的配置与使用
本博文转自:http://blog.chinaunix.net/uid-24219701-id-4101802.html STM32 的 DAC 模块(数字/模拟转换模块)是 12 位数字输入,电压输 ...
- 基于DDS的任意波形发生器
实验原理 DDS的原理 DDS(Direct Digital Frequency Synthesizer)直接数字频率合成器,也可叫DDFS. DDS是从相位的概念直接合成所需波形的一种频率合成技术. ...
- jquery点击label触发2次的问题
今天写问卷的时候遇到个label点击的时候,监听的click事件被执行两次:产生这个的原因么...事件冒泡 <div class="questionBox checkBox" ...
随机推荐
- JNDI(Java Naming and Directory Interface,Java命名和目录接口)
JNDI(Java Naming and Directory Interface,Java命名和目录接口)是SUN公司提供的一种标准的Java命名系统接口,JNDI提供统一的客户端API,通过不同的访 ...
- plsql例子
create or replace procedure find_difference(db_link in varchar2) is /* 比对两套环境建表脚本差异,以224环境为主 当前环境,db ...
- LeetCode741. Cherry Pickup
https://leetcode.com/problems/cherry-pickup/description/ In a N x N grid representing a field of che ...
- csu 1767(循环节)
1767: 想打架吗?算我一个!所有人,都过来!(2) Time Limit: 1 Sec Memory Limit: 128 MBSubmit: 99 Solved: 18[Submit][St ...
- 高屋建瓴之WebMail攻与防
0x01:前言 随着互联网的快速发展,我们的生活与互联网的联系愈加的紧密.各种快捷方便的信息化通信工具渐渐取代了传统的通信方式.微博.QQ.MSN.微信.陌陌, …这样的社交软件和平台已经成为了我们生 ...
- JMeter -----设置代理抓取web的HTTPS请求,“您的连接不是私密链接”的处理方案
出现如上截图的问题,已确定将网站的证书.jmeter的证书均安装完成,并未提示报错,但是在配置代理后,刷新网站抓取请求时总是提示如上报错 解决方案: 1.关闭电脑上的所有浏览器 2.打开“终端”运行: ...
- [转]跟我一起写Makefile系列
原作者:陈皓专栏 [空谷幽兰,心如皓月] 跟我一起写 Makefile(一) 跟我一起写 Makefile(二) 跟我一起写 Makefile(三) 跟我一起写 Makefile(四) 跟我一起写 M ...
- LR参数和变量
一.参数: 1. 在LR函数中可以直接使用参数.参数必须在双引号“”中才能应用.大部分情况下,可以直接用参数代替函数中双引号内的数据.如下使用方法: lr_save_string("http ...
- 十四 oracle 视图
一.介绍视图是一张虚拟表,其内容由查询定义,同真实的表一样,视图包含一系列带有名称的列和行数据.但是,视图并不在数据库中以存储的数据值集形式存在.行和列数据来自由定义视图的查询所引用的表,并且在引用视 ...
- Web开发——服务器端应用技术简单比较
在开发动态网站时,离不开服务器端技术,服务器端技术主要有CGI.ASP.PHP.ASP.NET和JSP. 1.CGI CGI(Common Gateway Interface 通用网关接口)是最早用来 ...