ATR2406_14 Datasheet, PDF (22/26 Pages) ATMEL Corporation – Low-IF 2.4-GHz ISM Transceiver

A successful packet exchange needs the following charge
Q = Q1 + Q2 + Q3 + Q4 + Q5 + Q6 + Q7 + Q8 + Q9 + Q10 = 192.47µAs
As the described system is a FHSS system with 5 different channels, the system has to do this up to five times before the
packet is acknowledged by the base station. The average will be 2.5 times. In the case of an interfered environment, some
more retries may be required; therefore, it is assumed the factor will be 3. The power-up time is included only once, as the
cycle will be completed without powering up and down the handheld in order to be as power efficient as possible.
Average current needed for a packet exchange:
155µAs + (37.5µAs × 3) = 267.5µAs
If the device will be used 1000 times a day → 3.1µA
Average current in active mode:
→ System power down current:
Current ATmega88:
Current ATR2406:
Current VREG (+ ShutDown):
1.25µA
1.0µA
2.75µA
Assumed average power-down current is 5µA.
→ Overall power consumption is 8.1µA
It is assumed the system uses a small battery with a capacity of 100mAh. This is 100.000µAh.
→ Battery lifetime will be around: 12345 hours = 514 days = 1.4 years.
The most important factor is to get the power-down current as low as possible!
Example:
Assume a system where the handheld is used just 10 times per day.
→ I_active = 0.031µA
and assuming the power-down current of this device is just 4 µA.
→ I = 0.031µA + 4µA = 4.03µA
→ Battery lifetime will be around 24807 hours = 1033 days = 2.83 years.
→ Power-down current is the main factor influencing the battery lifetime.
22 ATR2406 [DATASHEET]
4779Q–ISM–09/14