AMY-6M - Hardware Integration Manual
UBX-17021971 – R07
Design-in
Page 11 of 57
2.1.2
Power management configuration
Depending on the application, the power supply schematic will differ. Some examples are shown in the
following sections:
Supply voltage nominal 3.3 V (2.5–3.6V)
see section 2.1.5
Supply voltage nominal 1.8 V (1.75–2.0V)
see section 2.1.6
Direct supply of core voltages (1.75–2.0V for RF part, 1.4–3.6V for digital part) see section 2.1.7
Dual power supply using 3.0V and 1.4V (VDD_3V 3.0 V, V_DCDC 1.4 V)
see section 2.1.8
Use of external DCDC converter 1.8V (1.75–2.0V)
see section 2.1.9
2.1.3
System power consumption
This chapter is targeted at the design and dimensioning of the system power supply. In order to analyze the
power consumption and supply currents for various scenarios, Table 1 lists the respective supply currents at the
minimum supply voltages which are 1.4V for the baseband part and 1.8V for the RF part. Table 1 further shows
the power consumption if the RF section needs to be supplied with 2.5V
BB 1.4 V / RF 1.8 V
BB 1.4 V / RF 2.5 V
Continuous
Acquisition
Continuous
Acquisition Continuous
Acquisition
mA
mA
mW
mW
mW
mW
RF-IC
20
20
36
36
50
50
BB-IC
17
27
24
38
24
38
Total
37
47
60
74
74
88
Table 1: Raw Current and Power Consumption (ECO Mode, moderate signal levels)
Table 2 and Table 3 compare the approximate power consumption for the different scenarios and different
system supply voltages. Table 2 shows the continuous power consumption when the system has acquired all
satellites and is running in steady state. Table 3 shows the peak power consumption during signal acquisition.
These two cases allow assessing the dimensioning of peak power and continuous power capabilities of the
power supply circuit. The green and red highlighting illustrates the best and the worst solution in terms of power
consumption.
The following 2 scenarios are being compared:
1.
Using linear regulators (LDO) only. For supply voltages up to 3.6 V the built-in LDOs of u-blox 6 can be
used. For higher supply voltages, an additional external LDO is needed. There is no effect on power
consumption or efficiency regardless whether external or built-in LDOs are being used.
2.
Using an additional external single output voltage DC/DC converter to generate the intermediate system
supply voltage of 1.8V which then is further regulated by the individual LDOs of base-band and RF-IC.
The maximum system supply voltage is only limited by the external DC/DC converter being used.
For the DC/DC converter, an efficiency of 80% has been assumed in calculating the power values shown in
Table 2 and Table 3. If power-efficiency at high system supply voltages is key for the application, use of an ultra-
high efficiency external DC/DC converter such as Linear Technology’s LTC3410 (2.0 × 2.0 mm
2
SC70 package) is
recommended.
Supply Voltage V
LDO [mW]
Single 1.8V DCDC Converter [mW]
1.8
67
83
2.5
93
83
3
111
83
3.3
122
83
4.2
155
83
5
185
83
Table 2: Continuous Tracking Power Consumption (ECO Mode)
