Difference between BOR and LPBOR
Ruben Jönssonemail (remove spam text)
I have been studying the datasheets for some of the PIC10/12LF parts. These have both the standard Brown Out Reset (BOR) and also a Low Power BOR (LPBOR). I can't seem to find any difference between these (not even difference in current consumption).
The datasheets are marked as preliminary and no graphs or charts are available. Having both a standard BOR and also an LPBOR seems to indicate that there are some drawbacks using the LPBOR over the BOR. Why would there otherwise be both in the same chip?
I have an idea of using one of these chips for power management for cheap solar PV cells with low capacity NiMh batteries. These work fine when the batteries are somewhat charged but when the batteries are almost completely discharged, the circuit hangs in a mode where more current is drained than can be supplied by the PV cell so the batteries never gets charged and the circuit won't come alive again, no matter how much sunshine there is.
I did a circuit that senses the voltage drop on the batteries in this case that cuts the power to the rest of the circuit for about 90 seconds, giving the PV cells a chance to charge the batteries. When the batteries are charged enough there is a much smaller voltage drop and the rest of the circuit is alowed to draw current. As soon as the battery voltage/capacity is good and the rest of the circuit can start, it runs intermittently alowing the batteries to be continually charged.
The current circuit is made around an OP amp and two diodes as a voltage reference. This could be made much smaller with just one SOT23 PIC10LF320, using the brown out reset circuit to detect the voltage dip (1.8 - 2.10V). I can then also get an external shutdown input, which also simplifies the rest of the circuit.
AB Liros Electronic
200 39 Malmö Sweden
Tel +46 40142078
See also: www.piclist.com/techref/microchip/devices.htm?key=pic
You must be a member of the
piclist mailing list
(not only a www.piclist.com member) to post to the