Hi Caludio,
This 21.5mA value were measured at battery positive terminal, and some further detail will hopefully help to understand this issue, I'll try to explain the current "state of the art" in Clonix-41 power management:
The power requirements has been one my major concerns since the begining of this project. As you probably know, Clonix hardware design have suffered several minor mods since it was first released for beta-testing by mid Dec.
Beta units used a series diode(s) in the V+ line.
A first mod substituted the diode(s) for a 47 Omh resistor, actually only one Clonix unit is equiped with such resistor, and it's one of my own units.
All the Clonix's that have been sold or traded "wear" a 100 Ohms resistor, wich means a reasonable compromise between the operative lower limit (about 270 Ohms for a 1.7x HP-41, or 360 Omhs for a 1x machine) for low power requirements, and the system stability.
Whit this in mind, the latest version of the Clonix-41 manual, properly reflects those changes. Alas, it hasn't been published yet due to other mods related with the 6 pages and RAM upgrading. It will hopefully be on-line during this week.
Some technical aspects regarding HP-41 power supply, must be taken into consideration prior to look at "mA" figures.
- The DC/DC convertor IC draws more current from the batteries as the voltage of said batteries decreases. Thus, the batery terminal in not approprite for an accurate power consumption measurement, as Current is rising up while Voltage is falling down.
- The V+ line at I/O port is the real line from wich Conix (or any other module) draws its power from. Measures made at this point are quite more reliable and there is where they've been done for the latest documentation.
The figures at this point are almost independent from battery Voltage, and shows up the following values:
SLEEP: <100µA
STAND-BY: <500µA
ON: 13.5mA
Should you still need to reduce this figures and (as stated above) *only* for 1x machines, resistor values of 220 Ohms are acceptable, lowering the ON state power drain to the 9.5mA mark. Further reduction is possible but by no means advisable... ;-)
Hope this helps.
Diego.