AN92584 Datasheet, PDF (16/42 Pages) Ramtron International Corporation – Designing for Low Power and Estimating Battery Life for BLE Applications

Designing for Low Power and Estimating Battery Life for BLE Applications
Table 6. Connection Settings
GAP role
Connection interval
Slave latency
IMO clock
WCO clock accuracy
Remote device sleep clock
accuracy
Peripheral
100 ms
0
16 MHz
0-20 ppm
0-20 ppm
Transmit power
0 dBm
The default clock settings used in the project are shown in Table 7.
Table 7. Clock Settings
IMO
ECO
Direct_Sel
DBL_Sel
PLL_Sel
SYSCLK Divider
WCO
WCO Power Mode
LFCLK
Enabled
Enabled
IMO (16 MHz)
1
Enabled
Low Power
WCO (32 kHz)
After you build and program the project into the kit, you can measure the current and capture the current profile for
analysis. You can also modify these configuration parameters and choose the optimum parameters for your design.
3.3 Average Current Measurement
The example projects can be used to measure the average current consumption and observe the current profile.
The instantaneous current consumed by the device is not a steady value but varies depending on the state of the
chip that dynamically changes with the power-mode transitions. Therefore, it is practically impossible to measure
each individual instantaneous current with a handheld multimeter because the duration of these current bursts is very
small. Therefore, you should use a multimeter that provides the option to set the “aperture” of the measurement. The
aperture is the period “T” during which the multimeter measures the instantaneous currents, integrates them, and
then displays the average current for the period “T”. For accurate measurements, the aperture of the multimeter must
be set to be the same as the advertising or the connection interval.
To measure the current, follow this procedure:
1. Build the chosen example project provided with this application note and program the binary into the BLE
Pioneer Kit.
2. Connect a multimeter across jumper J15 of the BLE Pioneer Kit. A multimeter such as the Keysight 34410A
digital multimeter should be used.
3. Set the aperture for the measurement based on the advertising interval or connection interval. If the exact
aperture is not available, then set it to an integral multiple of the advertising or connection interval.
4. Measure the current. The current measured is the average current over one interval.
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Document No. 001-92584 Rev. *A
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