Battery
http://tclbattery.en.ec21.com/Polymer_Lithium_Ion_Battery_Cell–604293_604294.html https://www.sparkfun.com/products/11316 http://www.powerstream.com/thin-lithium-ion.htm http://www.aliexpress.com/item/Wholesale-Small-Rechargeable-Cylindrical-Lipo-Battery-3-7v-45mAh-60220-100pcs-lot/707397136.html http://www.aliexpress.com/item/Wholesale-3-7V-40mAh-PL031220-Small-Rechargeable-LIPO-Battery-100pcs-lot/707964273.html
This is an interesting battery: http://www.fdk.com/battery/lithium_e/pdf/data_sheet/coin_p_type/CR1.3N_spec-sheet.pdf.
But it’s too high.
With this battery: http://www.digikey.com/product-detail/en/BR-1225/P183-ND/31915the enclosure could be 1/2″ in diameter and all the components could sit on top.
Buzzer
This buzzer claims almost 90dB at 4kHz.http://www.aliexpress.com/item/RUIDA-ELECTRONC-BUZZER-SMD-3V-5x5x2-5mm-PIEZO-TRANSDUCER/754733076.html
Layout
The TI BLE SOC is 6mm square. The new Invensense IMU is 3mm square. We need a 1206 capacitor and space for the antenna. Maybe the total size could be about 1/2″ by 1/4″. How would connection be made for programming? It would need pads and a special fixture to fit into.
Beeper
This beeper only draws 3mA but the rated voltage is 9V (78db) so at 3V I’ll bet it barely squeaks: http://www.aliexpress.com/item/SMD-120025F-09041TJ-SMD-piezo-disc/623852162.html. And it’s really big. I think it’s better to go with a low voltage, electromagnetic beeper (shown in the drawing, 5mm x 5mm) and just give it really short bursts of pulses. With a short pulse duration, short burst, and long duty cycle (perhaps once every three seconds) the power consumption may be acceptable.
Current Consumption
| CC2541 | CC2540 | ||
|
C
o r e c c |
Operating voltage | 2V – 3.6V | 2V – 3.6V |
| Shutdown current | |||
| Idle current | |||
| Max current | |||
| Task 1 current | |||
| Task 2 current | |||
| Task 3 current | |||
| RX mode, standard mode, no peripherals active, low MCU activity | 17.9mA | 19.6mA | |
| RX mode, high-gain mode, no peripherals active, low MCU activity | 20.2mA | 22.1mA | |
| TX mode, –20 dBm output power, no peripherals active, low MCU activity | 16.8mA | ||
| TX mode, –23-dBm output power, no peripherals active, low MCU activity, MCU at 250 kHz | 21.1mA | ||
| TX mode, 0 dBm output power, no peripherals active, low MCU activity | 18.2mA | 27mA | |
| TX mode, –6-dBm output power, no peripherals active, low MCU activity, MCU at 250 kHz | 23.8mA | ||
| TX mode, 4-dBm output power, no peripherals active, low MCU activity, MCU at 250 kHz | 31.6mA | ||
| Power mode 1. Digital regulator on; 16-MHz RCOSC and 32MHz crystal oscillator off; 32.768-kHz XOSC, POR, BOD and sleep timer active; RAM and register retention | 270uA | 235uA | |
| Power mode 2. Digital regulator off; 16-MHz RCOSC and 32MHz crystal oscillator off; 32.768-kHz XOSC, POR, and sleep timer active; RAM and register retention | 1uA | 0.9uA | |
| Power mode 3. Digital regulator off; no clocks; POR active; RAM and register retention | 0.5uA | 0.4uA | |
| Low MCU activity: 32-MHz XOSC running. No radio or peripherals. Limited flash access, no RAM access. | 6.7mA | 6.7mA | |
|
P
e r i p h e r a l |
Timer 1. Timer running, 32-MHz XOSC used | 90uA | 90uA |
| Timer 2. Timer running, 32-MHz XOSC used | 90uA | 90uA | |
| Timer 3. Timer running, 32-MHz XOSC used | 60uA | 60uA | |
| Timer 4. Timer running, 32-MHz XOSC used | 70uA | 70uA | |
| Sleep timer, including 32.753-kHz RCOSC | 0.6uA | 0.6uA | |
| ADC, when converting | 1.2mA | 1.2mA |
Battery Power
As I look at the capacity of these coin cells and the power requirements of the components, I don’t see how it could work for more than a few months. The IMU draws 6.4uA with the accel running at 1Hz and the CPU needs 0.5uA with all clocks off just for RAM retention, and the sleep timer needs 0.6uA with the internal RC oscillator. If the crystal oscillator is running it needs 60uA-90uA. Whatever “BOD” is it takes more than 200uA.
Hopefully the IMU has a deep sleep function to get its power consumption way down.
At least things look good for making AA-battery-operated anchors to put around the house. They could potentially last years with a lithium AA battery (more than 3000 mAh).
This paper has a table that lists the power consumption for various medical devices and how long they typically last using a CR1025, which is the battery I have been considering.
I also attached the paper.
If the battery is 10mm diameter the enclosure has two be at least another 1mm thick so the diameter will be at least 12mm. The height will have to be at least 7mm.