Power input

Applicable receivers:  BD990 | BD992 | BD992-INS

The unit, excluding the antenna, operates at 3.3 V +5%/-3%. The 3.3 V should be able to supply 2.0 A of worst-case surge current. The typical power consumption based on band usage is:

• L1/L2 GPS + GLONASS = 2.0 W

• L1/L2/L5 GPS + GLONASS + BeiDou + Galileo = 2.5 W

Worst case full-load power consumption including the antenna is 5.0 W. (Note: Worst case was tested with all features, including RF bands, LEDs, enabled, at +85 °C). There are multiple power rails in the system. Voltage rails 1.2 V, 1 V, 1.8 V, 2.35 V, 5.7 V, or 7.6 V (antenna outputs) are provided by switching supplies. 3.1 V, 3.0 V, and 1.95 V use LDOs to achieve low-noise voltage rails.

Power protection

The 3.3 V input is monitored by an LTC2912 for over- and under-voltage conditions. (Basically, a window comparator). If the voltage exceeds 3.64 V or is under 3.01 V, the IC turns off the gate of a MOSET to disconnect the input voltage to the system. Limited protection above 3.64 V is offered by a varistor, which has a clamping voltage of 5.5 V.

Evaluation board power supply circuit