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| Power Management Circuit | ||
| Author yutcxa Views 18 Posted at 2008/8/27 00:48 [View In Forum] | ||
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Hi all,dmisxf dmisxf Here is a practical problem that someone gave me & it turned out to be more difficult than I imagined! :dmisxf dmisxf dmisxf dmisxf In the attached diagram the circuit inside the box has to be designed to satisfy the following requirements:dmisxf dmisxf dmisxf dmisxf The circuit initially (state 1) provides a small supply 5V, 30mA(or less) to output 1 and a supply of 5V, 1A to output 2. It should monitor output 1's current, if the current exceeds a certain value, it should cut-off (buffer) output 2 & direct all power to output 1 (state 2). Also while operating in state 2 it should monitor an input logic, if this input goes low the circuit should go back to state 1.dmisxf dmisxf The circuit has to have minimum power consumption & minimum voltage drop from source to each of the outputs (<100mV), a quick response time is also important.dmisxf dmisxf dmisxf dmisxf I have been thinking of using an OpAmp across a small resistor (0.1 ohm) to detect the current on input 1 with minimum voltage drop & power dissipation- which is not good because at full current of output 1 there will be a drop of 0.1*3= 0.3V in the output voltage which is not acceptable. Also no ideas about connecting & disconnecting output 2! dmisxf dmisxf dmisxf dmisxf I also thought the function might be already implemented in a power management IC, which would be an ideal solution; unfortunately I have no idea what to look for?dmisxf dmisxf dmisxf dmisxf Any help is much appreciated |
| Reply No. | Replier | Total Replies 4 [View All Replies] [New Reply] | Replied at |
| 1 | bubulu | Someone can tell the relevant articles materials or website of digital power management?? Thanks in advance Best regards,jinsin |
2008/8/27 00:48 |
| 2 | ai8957382 | voltage drop from source to each of the outputs (<100mV)?? that's to say, it's difficult to insert a device in the path from source to the output. so it's impossible to detect the output current. where does the ouput current go? if the output current goes to A ,you could detect the output current in A and produce a control signal to control the source. |
2008/8/27 00:48 |
| 3 | ken7976 | Hi What's the matter? You monitor the current with a small resistor. When the current has to increase, you shunt the resistor with a Mos transistor as long as the logical input is not activated! Ok ? A Fishkiller _________________ www.benito-design.fr |
2008/8/27 00:49 |
| 4 | gao51755775 | You can find the answer at this web | 2009/12/16 20:20 |
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