PNI SENtral MandM - Manual (Page 38)

PNI Sensor Corporation Doc #1020129 revE
SENtral M&M Technical Datasheet Page 37
Appendix III
– Measuring Current Consumption
All SENtral M&M modules, except the White and Blue versions, have two distinct electrical
supply lines. One line is for both the EEPROM and the sensors, and one is for just SENtral. The
pins for these voltages are labeled DVDD and DVDD2, respectively. To measure the current on
these lines, PNI recommends placing a 1 Ω resistor in series with the DVDD pin to measure
combined current consumption for the EEPROM and sensors, and a 100 Ω resistor in series with
the DVDD2 pin to measure current consumption by SENtral.
The SENtral Blue M&M has a single DVDD pin that supplies current for SENtral, the EEPROM
and the sensors. However, the current consumption of only the SENtral Motion Coprocessor can
be measured by modifying the module, as given in the two options listed below.
1. Replace a zero-ohm resistor with a 100Ω resistor and measure voltage across the resistor.
2. Remove the zero-ohm resistor, then solder wires in series with a connected ammeter.
The location of the zero-ohm resistor is given below, and a discussion of the two implementation
methods follows.
Figure A3-1: SENtral Blue M&M Zero-Ohm Resistor Location
Method 1: Replace zero-ohm resistor with 100 Ω resistor.
This method provides flexibility in terms of measuring with either a voltmeter or an
oscilloscope, although it may be slightly difficult to implement as holding the probes
in the proper position can be tricky. As long as the resistor is ≤100 Ω, there is no
need to remove it, as it should not affect performance.