MLX16305 Datasheet, PDF (13/29 Pages) Melexis Microelectronic Systems – Interlock switch sensor interface IC

MLX16305
Interlock switch sensor interface IC
9. Voltage Mode (VM)
To go into Voltage Mode (VM) VI_CTRL is set low. In this mode the resulting voltage on the SENSE pin
(V_SENSE) is copied onto the MEAS_OUT pin. For normal operating conditions (Vref>Vsense) it can be
calculated back as:
• for 3V < V_SENSE < 8.25V
- V_{MEASOUT min} = [V_SENSE * (1 - Meas_Verr1)] / 2 - V_{MEASOUT_VOFFSET}
- V_{MEASOUT max} = [V_SENSE * (1 + Meas_Verr1)] / 2 + V_{MEASOUT_VOFFSET}
• for V_SENSE < 3V the accuracy is reduced to Meas_Verr2.
This condition can occur
- with a short to GND
- or for detecting shorts to an external voltage below 3V. This case can be diagnosed by
selecting a pin without supplying it with the regulated voltage. Any voltage that is
measured has to be due to an external source that is connected to that pin.
• for V_SENSE > V_REF (short to supply)
- V_{MEASOUT max} < V_REF + 0.5V
This condition can be diagnosed with the SENSE pin in high impedant state (weak pull down is
active), as well as in the state with the channel is supplied with the regulated voltage.
Remark
• When a SENSE pin is measured in Voltage Mode (VM) without being supplied by the voltage
regulator, then an internal pull down keeps the voltage on that SENSE pin low, unless it is
overruled by a short to supply.
o If no short to VBAT is forced then:
V_MEASOUT < V_{MEAS_DIS}
3901016305
Rev. 005
Page 13 of 29
Data Sheet
Oct/06