Power Consumption Measurement Hardware for Portable Platforms
Ruoko, Kalle (2016)
2016
Sähkötekniikan koulutusohjelma
Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2016-06-08
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201605133976
https://urn.fi/URN:NBN:fi:tty-201605133976
Tiivistelmä
When new portable platforms are developed, the platform power consumption is a key point of interest that needs to be simulated and measured. Commercial measurement equipment used in the industry can’t cover multi rail measurements in a small, portable form factor.
This thesis covers the design process of a system called PnP DAQ. It is a small, portable and easy to use multi-channel power consumption measurement system that is partly integrated into the device under test. The architecture of the device consist of a connector, an analog switch, an analog front-end, an 8 channel simultaneous sampling analog-to-digital converter, a microcontroller and a micro SD memory card. The device connects to the device under test via a board-to-board connector. Current on the power rails of the device under test are measured by measuring the voltage drop over shunt resistors integrated on the device under test. These sense voltages are routed to the PnP DAQ board via the connector. An analog switch is used to multiplex 8 sense pairs to 4 pairs to operational amplifier inputs. The differential voltage on these pairs is amplified with a difference amplifier and input to an analog-to-digital converter. The current through a voltage rail can be calculated using this voltage difference. Furthermore, by feeding the voltage on the load side of the measurement resistor to the analog-to-digital converter it is possible to monitor the actual voltage of the rail. The microcontroller reads the measurement data from the analog-to-digital converter and streams it through the UART bus to a host PC via a USB bridge. The microcontroller also logs the measurement data to a micro SD card in the portable use case. Measurement can be triggered in three different manners: via the host PC software, by physical push button or by software running in the device under test.
The PnP DAQ system was characterized, in order to find out its measurement accuracies and other major characteristics. Each manufactured device was individually unit tested to meet the specifications before sending to end users.
The measurement accuracy, which each tested device had to meet for voltage measurement, was ±1 mV against a reference device and between the different channels of the PnP DAQ. The requirement for current measurement accuracy was ±3 mA measured over a 20 mΩ shunt against the reference device and between the different channels of the PnP DAQ.
This thesis covers the design process of a system called PnP DAQ. It is a small, portable and easy to use multi-channel power consumption measurement system that is partly integrated into the device under test. The architecture of the device consist of a connector, an analog switch, an analog front-end, an 8 channel simultaneous sampling analog-to-digital converter, a microcontroller and a micro SD memory card. The device connects to the device under test via a board-to-board connector. Current on the power rails of the device under test are measured by measuring the voltage drop over shunt resistors integrated on the device under test. These sense voltages are routed to the PnP DAQ board via the connector. An analog switch is used to multiplex 8 sense pairs to 4 pairs to operational amplifier inputs. The differential voltage on these pairs is amplified with a difference amplifier and input to an analog-to-digital converter. The current through a voltage rail can be calculated using this voltage difference. Furthermore, by feeding the voltage on the load side of the measurement resistor to the analog-to-digital converter it is possible to monitor the actual voltage of the rail. The microcontroller reads the measurement data from the analog-to-digital converter and streams it through the UART bus to a host PC via a USB bridge. The microcontroller also logs the measurement data to a micro SD card in the portable use case. Measurement can be triggered in three different manners: via the host PC software, by physical push button or by software running in the device under test.
The PnP DAQ system was characterized, in order to find out its measurement accuracies and other major characteristics. Each manufactured device was individually unit tested to meet the specifications before sending to end users.
The measurement accuracy, which each tested device had to meet for voltage measurement, was ±1 mV against a reference device and between the different channels of the PnP DAQ. The requirement for current measurement accuracy was ±3 mA measured over a 20 mΩ shunt against the reference device and between the different channels of the PnP DAQ.