Teardown Tuesday: GPS Navigator

May 24, 2016 by Alex Udanis

Want to see what's inside a GPS unit?

Want to see what's inside a GPS unit?

Garmin Nuvi GPS Navigator 


GPS Navigators were extremely popular as an improvement over printed directions, like Mapquest. Today, smartphone and in-car navigation systems are slowly replacing them. In this Teardown Tuesday, we are going to find out how a Garmin GPS Navigator finds its way!


Opening it Up!

The GPS Navigator with the Screen Removed 


Opening this GPS Navigator up is pretty straight forward. A plastic bezel was removed with a plastic pry bar and a few Torx screws were taken out. The screen was easily unplugged from a connector to reveal the electronics inside! Without removing any of the components, a large battery, speaker, and circuit board are visible.



The Garmin branded STmicroelectroncics ARM processor 


Powering this GPS navigator is a custom marked IC manufactured for Garmin by STmicroelectronics. STmicroelectronics announced in 2008 that their Cartesio line of System-on-Chip processors will be used in upcoming Garmin GPS Navigators. The Cartesio SOC is an application processor with embedded GPS in a single package.



The SanDisk eMMC Memory IC 


A complete map of every roadway in the United States can take up a lot of data. To store all of this data, a SanDisk memory IC is used in this navigator. A SanDisk INAND SDiN2C1-2G eMMC IC is used for this. This iNAND IC contains both the flash memory and controller into a BGA package. To interface the eMMC memory to the STmicroelectronics SOC, a Ti SN74AVCA406L memory card interface is used. This interface IC provides logic level switching and ESD protection. This IC is located to the bottom right of the iNAND IC. 



The Speaker in the GPS Navigator 


In order to communicate with the user, the GPS navigator uses a rear-facing 4-ohm speaker. The speaker connects to the circuit board with a pair of spring connectors. 


The Ti Amplifier 


To drive the speaker, the GPS navigator uses a TI PCM1774 amplifier. The PCM1774 is more than just a normal amplifier; it contains a headphone amplifier, line amplifier, line input, boost amplifier, analog mixing, and sound effects.


GPS Receiver

This GPS navigator has three main components, a GPS front end, an RF Down-Converter, and an antenna.


The GPS Receiver Antenna 


The first component in the GPS system is an antenna! This is a surface mount antenna that is mounted to a right angle with respect to the circuit board. To the right of the antenna is an impedance tuned microstrip is visible.


A Block Diagram of the GPS Front-End 


An Infineon BGM781N11 GPS Front-End Module is used in this GPS navigator. The front end acts as a filter and an amplifier to then pass the signal to the other components of the GPS system.


The Infineon GPS Front End IC 


Located after the front end module is an STMicroelectronics STA5620C. This IC is able to down-convert the GPS L1 signal from 1575.42 MHz to 4.092 MHz. This IC is able to communicate with the baseband chip and the ARM SOC over an SPI interface. The chip is housed in a QFN-32 package.


The STMicroelectronics STA5620C  


Most GPS navigators can run when they aren't powered by an automobile. To achieve this, the navigator contains a single cell lithium battery.  


The 1250mAh Lithium Battery in the GPS Navigator 


The battery used is a 1250mAh cell that is manufactured by Sony. The battery is mounted using aa strong adhesive. The battery pack contains an outer shrink wrap covering, the Sony Lithium Cell, and a protection circuit. The protection circuits in these battery packs often protect against over discharge and against short circuits. Below is the protection circuitry that is attached to the battery cell. 


The Protection Circuity on the Battery Pack 


Thanks for looking at this week's Teardown Tuesday!   

Stop by next Tuesday for another teardown. We're always looking for new things to teardown, so if you have any suggestions or would like to contribute an item for a future Teardown Tuesday, click here for my email address.



As an extra bonus in this Teardown Tuesday, here are the insides of the 12v power supply for this GPS navigator! This power supply uses a switch mode power supply with a buck topology. 


The Top of the Switching Power Supply


The Bottom of the Switching Power Supply


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