EVK-M91 - User guide
5 Current measurement
5.1 GNSS current
At start-up, the receiver starts in acquisition state to search for available satellites and to download
GNSS orbital data, i.e., ephemeris and almanac. Once the data has been downloaded, the receiver
enters tracking state. In continuous operation, the receiver typically remains in tracking state once
entering it. The current consumption reduces when the receiver enters the tracking state. The time
required to enter tracking mode can be reduced by downloading aiding data from the AssistNow
™
Online service.
On EVK-M91, the main supply voltage for the u-blox M9 GNSS receiver is 3.0 V. The internal DCDC
converter is enabled to reduce power consumption. To measure the total GNSS supply current with
EVK-M91, follow these steps:
1.
Power up EVK-M91.
2.
Connect a true RMS voltmeter across GNSS I1 (pin 12) and GNSS I2 (pin 13) of the 14-pin
connector.
3.
Read the voltage (and average if necessary) on the voltmeter and convert to current (1 mV
equals 1 mA).
4.
Perform the test with good signals and clear sky view to ensure that the receiver can acquire
the satellite signals.
The total GNSS current includes the internal LNA, SPI flash and TCXO.
5.2 Backup current
To measure the backup current with EVK-M91, follow these steps:
1.
Connect a true RMS voltmeter across BCKP I1 (pin 11) and BCKP I2 (pin 10) of the 14-pin
connector.
2.
Remove power supply (USB cable or other external power supply).
3.
Read the voltage (and average if necessary) on the voltmeter and convert to current (1 mV
equals 10 µA).
UBX-19056858 - R02
5 Current measurement
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