As there's been a bit of discussion in the Oshsonsoft Forum (which is where I first heard of the UC1609C), I thought I'd keep any potential interested members updated on my progress.
I choose the UC1609C because it's a 3.3V device, and I want to power the product from a single 18650 Li-Ion cell - the conventional Hitachi based text LCD's only work at 5V, otherwise I'd have used those - and this also gives me three lines of good sized text, instead of two, plus pretty graphics capabilities.
Firstly, I'm using the PIC 18F27K42, running at 64MHz, with SPI running at 32MHz, to provide the fastest possible screen updating, and I'm using a RAM buffer to assemble the screen display, then copying it to the screen in one go.
As with many of my work projects power consumption is critical, with extended battery life essential, so it will spend almost all of it's time in sleep, and I power down the UC1609C using an I/O pin, and the same for the MCP6022 opamp buffer I use to read the battery voltage, while drawing almost no current due to a 1meg resistor in the potential divider. I use a 470K for the bottom part of the divider (so about 6V FSD), and the FVR 2.048V reference using the 12 bit A2D (another nice feature of the K42). I've used the second half of the opamp for another A2D input, this time using a 1meg and 100K (about 22V FSD), with the possibility of monitoring the incoming charging voltage? (but basically because it was there).
So while in sleep, the device draws 50-60uA (bearing in mind it's waking every second, and running an RTTC), and with the display and opamp powered up (and the PIC running fully) it draws between 16-18mA, the opamp on it's own only takes 0.8mA, and is a nice low voltage rail-to-rail device.
I might be able to prune a little off the 50-60uA, but I've never found it to get any where near the MicroChip claimed figures - and in the industry, anything below 100uA is considered perfectly acceptable - and 60uA gives a theoretical life of about 5 years with a 2600mA/Hr battery. Recharging only once a year or more should be easily achieved.
I choose the UC1609C because it's a 3.3V device, and I want to power the product from a single 18650 Li-Ion cell - the conventional Hitachi based text LCD's only work at 5V, otherwise I'd have used those - and this also gives me three lines of good sized text, instead of two, plus pretty graphics capabilities.
Firstly, I'm using the PIC 18F27K42, running at 64MHz, with SPI running at 32MHz, to provide the fastest possible screen updating, and I'm using a RAM buffer to assemble the screen display, then copying it to the screen in one go.
As with many of my work projects power consumption is critical, with extended battery life essential, so it will spend almost all of it's time in sleep, and I power down the UC1609C using an I/O pin, and the same for the MCP6022 opamp buffer I use to read the battery voltage, while drawing almost no current due to a 1meg resistor in the potential divider. I use a 470K for the bottom part of the divider (so about 6V FSD), and the FVR 2.048V reference using the 12 bit A2D (another nice feature of the K42). I've used the second half of the opamp for another A2D input, this time using a 1meg and 100K (about 22V FSD), with the possibility of monitoring the incoming charging voltage? (but basically because it was there).
So while in sleep, the device draws 50-60uA (bearing in mind it's waking every second, and running an RTTC), and with the display and opamp powered up (and the PIC running fully) it draws between 16-18mA, the opamp on it's own only takes 0.8mA, and is a nice low voltage rail-to-rail device.
I might be able to prune a little off the 50-60uA, but I've never found it to get any where near the MicroChip claimed figures - and in the industry, anything below 100uA is considered perfectly acceptable - and 60uA gives a theoretical life of about 5 years with a 2600mA/Hr battery. Recharging only once a year or more should be easily achieved.
