Add current boost to a USB charger
The popular USB interface can charge a portable device while transferring data. But for high-capacity batteries, the 500-mA output current of USB hosts and powered hubs greatly extends the charging time. (Unpowered USB hubs supply no more than 100 mA.) Thus, a system that accepts charging power from an ac adapter as well as the USB port is more convenient. Such a system can charge from a notebook USB port when you're traveling, yet can charge faster via the adapter when you're at home or in the office. An external transistor current source adds dual-input capability to a single-chip lithium-cell charger (Figure 1). The chip, IC1, operates alone when you connect to USB power and allows you to pin-program it for a maximum charging current of either 500 or 100 mA. When you plug in an ac adapter, which the 600-mA components set, the external-transistor current source, Q2 and Q3, turns on and sets IC1's charging current to 500 mA. Because IC1 and Q2 both charge the battery under that condition, the total charging current is 1100 mA.
Q2 and Q3 form a current limiter for the ac adapter. The limiter allows Q2 and R1 to pass the additional 600 mA. When the voltage drop across R1 exceeds that across R2, which R2 and R5 set, Q2 begins to turn off. Q2 cancels VBE, enabling R1 to more accurately set the maximum current. Voltage across R3 sets the reference voltage, and the output current limits when the voltage drop on R1 matches the voltage on R3. Q3should have a beta higher than 200 at 1A, so that IC1's pin can sink enough current to turn on Q3. High beta also minimizes error in the transistor current source. When IC1 changes from current mode to voltage mode at approximately 4.15V, IC1's output turns off the transistor current source. IC1 remains on and finishes off the taper to full charge. It also remains on and continues to function when USB power is gone and only ac power remains.
IC1 also controls the prequalification current, which is the current level necessary to safely recover deeply discharged cells at low battery voltage. The output assumes a high-impedance state during cell prequalification to ensure that the external current source remains off, and that the prequalification current of approximately 50 mA comes only from IC1. When you plug in the ac power, Q1 turns off to prevent back-feeding the USB input. You install Q1 "backward" with the drain connected to USB input side, so that USB power remains connected to the IN pin (IC1 pin 4) via Q1's body diode, even when Q1 is off.
Add current boost to a USB charger的更多相关文章
- Current limiter allows large USB bypass capacitance
The USB (Universal Serial Bus) specification requires a connected USB device to present a load to th ...
- USB port 如何识别不同的Charger类型
基于Qualcom 8960/8921平台 一,软件分析 1. USB charger types & Power supply types USB_INVALID_CHARGER ...
- C++ boost.python折腾笔记
为了让当年研究生时写的图像处理系统重出江湖起到更大的作用,应研究生导师的意见,对原有的c++框架做了python扩展处理,为了避免遗忘,备注如下: 一.boost 编译 下载boost源码,这里使用b ...
- virtual box + win7 + usb + share folder
1.enable virtaulization on BIOS 2.new machine setup, memory, harddisk size 3. 4.install extension pa ...
- imx6 usb otg config 配置
imx6 usb的host和slave配置,配置之后,安装gadget模块,就能够在host和slave之间切换. 参考文档: i.MX 6Dual/6Quad Linux Reference Man ...
- VS2010安装Boost库
source URL: http://stackoverflow.com/questions/2629421/how-to-use-boost-in-visual-studio-2010 While ...
- debian下使用dynamic printk分析usb转串口驱动执行流程
看了一篇文章<debug by printing>,文中提到了多种通过printk来调试驱动的方法,其中最有用的就是"Dynamic debugging". “Dyna ...
- Power OFF and ON USB device in linux (ubuntu)
Power OFF and ON USB device in linux (ubuntu) http://loginroot.com/power-off-and-on-usb-device-in-li ...
- LeetCode.989-数组形式的整数做加法(Add to Array-Form of Integer)
这是悦乐书的第371次更新,第399篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第233题(顺位题号是989).对于非负整数X,X的数组形式是从左到右顺序的数字数组.例 ...
随机推荐
- 21.Merge Two Sorted Lists---《剑指offer》面试17
题目链接:https://leetcode.com/problems/merge-two-sorted-lists/description/ 题目大意: 给出两个升序链表,将它们归并成一个链表,若有重 ...
- 数据结构与算法之KMP 字符串匹配
举例来说,有一个字符串"DSFFKFJD KFJLKFDLJFJ IWWJKJFJIA",我想知道,里面是否包含另一个字符串"JFJI",有的话就返回在原字符串 ...
- PyQt: eg2
#coding:utf-8 from __future__ import division import sys from math import * from PyQt4 import QtCore ...
- C#串口serialPort操作
现在大多数硬件设备均采用串口技术与计算机相连,因此串口的应用程序开发越来越普遍.例如,在计算机没有安装网卡的情况下,将本机上的一些信息数据 传输到另一台计算机上,那么利用串口通信就可以实现.运行本程序 ...
- Denoise Autoencoder简单理解
自编码器通过学习隐含特征来表达原始数据,那什么是denoise autoencoder呢? 关于Autoencoder参考:http://blog.csdn.net/on2way/article/de ...
- [Ext JS 4]后台自动产生图档
前言 [Ext JS 4] 实战之将chart导出为png, jpg 格式的文件 承接上一篇, 我们可以做到在Browser端打开一个Chart,并导出为png或是jpg 等格式的图档. 但实际的需求 ...
- ECMA6
let关键字 用来替代var 的关键字,不能重复定义一个变量 举例: for(var i=0; i<5; i++){ setTimeout(function(){ ...
- WordPress 用户管理插件 WP User Manager
WP User Manager 是一个较新的用户管理插件,可以在前端实现 用户注册.登录.找回密码.修改个人资料.修改密码等功能,如果你在找这方面的插件,WP User Manager 应该是一个不错 ...
- ubuntu sublime text 3 build 3083 license
经验证:sublime text 3 3083可用 ----- BEGIN LICENSE -----Andrew WeberSingle User LicenseEA7E-855605813A03D ...
- c++ getline()
#include <iostream>#include <string> int main (){ std::string name; std::cout << & ...