MLX16305 Datasheet, PDF (15/29 Pages) Melexis Microelectronic Systems – Interlock switch sensor interface IC

MLX16305
Interlock switch sensor interface IC
10.3. How to do an offset current measurement
In Current Mode (VI_CTRL is set high HIGH),
Set ENABLE = LOW.
This will set MUX_SUP[0:2] = 000
which will disable the Voltage regulator, such that no Isense current is mirrored into RREF.
Remarks:
• Possible Shorts on the SENSE channels have no influence on the offset measurement.
• Since ENABLE is low, the latch is transparent. Therefore make sure MUX_SENSE ≠ 000b or 111b in
order to avoid the Z or the Overtemp condition (MuxSenseLatched ≠ 000b or 111b)
• Offset may drift over longer periods of time and important temperature variations. Before every
measurement sequence the Offset measurement should be repeated.
• In case multiple Rref values are used for the different sense inputs – for instance to set different
sensitivity levels), then the offset voltage (V_{MEASOUT_IOFFSET} ) has to be measured for each Rref
individually. Any change to Rref implies a new offset measurement.
• In case multiple MLX16305 devices are used in parallel, the offset should be measured and stored for
every device.
• An OPEN WIRE condition has Isense = 0mA, and as a result only Ioffset will contribute to the voltage
over Rref. Therefore
Vmeasout_enabled [Open Wire] = V_{MEASOUT_IOFFSET}
3901016305
Rev. 005
Page 15 of 29
Data Sheet
Oct/06