Supply Voltage
- Thread starter Electlen
- Start date
Hi,
The LF is an ultra-low power derivative (maybe just selected from the normal production line) and, as you say, is rated only up to about 3 volts. Since the PICaxe 08M2 is rated for use up to around 5 volts, I think we can assume that it employs the 12F1840 chip (i.e. the "grey" table cells in the data sheet).
Cheers, Alan.
The LF is an ultra-low power derivative (maybe just selected from the normal production line) and, as you say, is rated only up to about 3 volts. Since the PICaxe 08M2 is rated for use up to around 5 volts, I think we can assume that it employs the 12F1840 chip (i.e. the "grey" table cells in the data sheet).
Cheers, Alan.
RevEd say that the 08M2+ is a custom chip. From the data sheet cited, it would seem to be based on the PIC12(L)F1840. You can believe that the 18M2+ is good for a maximum voltage of 5.25V and anything else that relates to the base chip can be found in the datasheet - Happy reading.
Most people tend only to refer to the data sheet for more esoteric features when the standard facilities don't quite do the job in hand. They are considered to be advanced features and are best read about after having got your chops around manuals #1, #2 and #3.
Most people tend only to refer to the data sheet for more esoteric features when the standard facilities don't quite do the job in hand. They are considered to be advanced features and are best read about after having got your chops around manuals #1, #2 and #3.
PICAXE chips are based around standard "industrial" parts rather than the "extended" parts, so "F" sections of the datasheet will apply rather than "LF" sections.
In most cases the specs will be the same though operating temperature range is different and lower operating voltage can vary.
In most cases the specs will be the same though operating temperature range is different and lower operating voltage can vary.
Thanks for your replies, I thought this would be an easy question to have answered. The background is the design of PICAXE circuits for use with radio control receivers and servos. Traditionally receivers have been rated for 4.8 - 6.0V and hence the usual trick of a diode in series with the supply to the PICAXE chip has been sufficient.
However in recent years, particulary with 2.4GHz systems, receivers have been introduced rated at 4.8 - 8.4V with some 'hi-end' systems rated at 3.5 - 9.6V. This complicates the interface of the PICAXE circuit.
For a 'universal' solution the answer may be to use a programmable low drop out (LDO) voltage regulator such as the TI LP2951. This is a 8pin DIL chip which, with an output voltage set at 4.0V, would cater for 4.5v - 30V up to about 50mA. It is rated up to 100mA but the lower the load current the better the input - output differential. This adds cost to the design but may prove to be necessary.
A slightly simpler solution would be to use a TI LP2950-33 which is a fixed voltage version of the LP2951 with an output of 3.3V. In this case a transistor interface would be required for the rx input and possibly transistors on the outputs depending on the design requirements.
I would welcome any other suggestions.
Regards
Len
However in recent years, particulary with 2.4GHz systems, receivers have been introduced rated at 4.8 - 8.4V with some 'hi-end' systems rated at 3.5 - 9.6V. This complicates the interface of the PICAXE circuit.
For a 'universal' solution the answer may be to use a programmable low drop out (LDO) voltage regulator such as the TI LP2951. This is a 8pin DIL chip which, with an output voltage set at 4.0V, would cater for 4.5v - 30V up to about 50mA. It is rated up to 100mA but the lower the load current the better the input - output differential. This adds cost to the design but may prove to be necessary.
A slightly simpler solution would be to use a TI LP2950-33 which is a fixed voltage version of the LP2951 with an output of 3.3V. In this case a transistor interface would be required for the rx input and possibly transistors on the outputs depending on the design requirements.
I would welcome any other suggestions.
Regards
Len