MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1
Hardware description
Page 9 of 55
2.3
Operating modes
u-blox receivers support different power modes. These modes represent strategies of how to control the
acquisition and tracking engines in order to achieve either the best possible performance or good performance
with reduced power consumption.
2.3.1
Continuous Mode
During a cold start, a receiver in Continuous Mode continuously deploys the acquisition engine to search for all
satellites. Once the receiver can calculate a position and track a sufficient number of satellites, the acquisition
engine powers off, resulting in significant power savings. The tracking engine continuously tracks acquired
satellites and acquires other available or emerging satellites. Whenever the receiver can no longer calculate a
position or the number of satellites tracked is below the sufficient number, the acquisition engine powers on
again to guarantee a quick reacquisition. Even if the acquisition engine powers off, the tracking engine
continues to acquire satellites.
For best performance, use
continuous mode
.
2.3.2
Power Save Mode
Two Power Save Mode (
PSM
) operations called
ON/OFF
and
Cyclic tracking
are available. These use different
ways to reduce the average current consumption in order to match the needs of the specific application. PSM
operations are set and configured using serial commands. For more information, see the
u-blox 7 Receiver
Description Including Protocol Specification
The system can shut down an optional external LNA using the ANT_ON signal in order to optimize power
consumption, see section 2.7.5.
Using the USB Interface is not recommended with Power Save Mode since the USB standard does not
allow a device to be non-responsive. Thus, it is not possible to have full advantage of Power Save Mode
operations in terms of saving current consumption.
Power Save Mode is not supported in GLONASS mode.
2.4
Configuration
The configuration settings can be modified using UBX protocol configuration messages. The modified settings
remain effective until power-down or reset. If these settings have been stored in BBR (Battery Backed RAM), then
the modified configuration will be retained, as long as the backup battery supply is not interrupted.
Configuration can be saved permanently in SQI flash.
2.5
Connecting power
u-blox 7 positioning modules have up to five power supply pins:
VCC
,
VCC_IO
,
V_BCKP, V_ANT
and
VDD_USB
.
2.5.1
VCC: Main Supply Voltage
The
VCC
pin provides the main supply voltage. During operation, the current drawn by the module can vary by
some orders of magnitude, especially if enabling low-power operation modes. For this reason, it is important
that the supply circuitry be able to support the peak power (see datasheet for specification) for a short time.
Some u-blox 7 modules integrate a DC/DC converter. This allows reduced power consumption, especially when
using a main supply voltage above 2.5 V.
When switching from backup mode to normal operation or at start-up, u-blox 7 modules must charge
the internal capacitors in the core domain. In certain situations, this can result in a significant current
draw. For low power applications using Power Save and backup modes it is important that the power
supply or low ESR capacitors at the module input can deliver this current/charge.
