Voltage Sensing Steps Summary

The DP83TC815-Q1 offers sensors for monitoring voltage at the supply pins. Undervoltage monitoring are always active in the DP83TC815-Q1 by default. If an undervoltage condition is detected, interrupt status flag is set in register 0x0013. These interrupts can also be optionally routed to the INT pin using the same register.

• Step 1: Program register 0x0469 = 0x8324 ; Initial configuration of monitor
• Step 2: Program register 0x046A = 0x0096 and then 0x46A=0x0093; Enables and refreshes monitor
• Step 3: Program register 0x0013 = 0x00C0, Enable over voltage and under voltage interrupts
• Step 4: Configure register 0x0468 with the corresponding setting to select the required sensor.
  Table 7-18 Voltage Sensor Register Selection

  SENSOR	0x0468 REGISTER SETTING
  VDDA	0x0920
  VSLEEP	0x1920
  VDDMAC	0x2920
  VDDIO	0x3920
  VDD1P0	0x5920

• Step 5: Read register 0x047B[14:7] and convert this output code to decimal.
• Step 6: Use the output code in the following equations to get the absolute value of the sensor. Refer to Table 7-19 table for constant values for corresponding sensors.
  • vdda_value = 3.3 + (vdda_output_code – vdda_output_mean_code)*slope_vdda_sensor
  • vsleep_value = 3.3 + (vsleep_output_code – vsleep_output_mean_code)*slope_vsleep_sensor
  • vddmac_value = 3.3 + (vddmac_output_code – vddmac_output_mean_code)*slope_vddmac_sensor
  • vddio_value = 3.3 + (vddio_output_code – vddio_output_mean_code)*slope_vddio_sensor
  • vdd1p0_value = 1.0 + (vdd1_output_code – vdd1_output_mean_code)*slope_vdd1_sensor
    Table 7-19 Voltage Sensors Constant Values

    SENSOR	CONSTANT	VALUE
    VDDA/VSLEEP	vdda_output_mean_code	125.13
    	slope_vdda_sensor	0.00869
    VDDMAC/VDDIO	vddio_output_mean_code	201.62
    	slope_vddio_sensor	0.015387
    VDD1P0	vdd1_output_mean_code	125.17
    	slope_vdd1_sensor	0.00263

Over and Undervoltage Thresholds

There are two over voltage thresholds, over_up_th and over_low_th. When the monitor read value goes above over_up_th, the interrupt is asserted high. After the interrupt is asserted high, the interrupt is asserted low only if the monitor read value goes below over_low_th .

There are two under voltage thresholds, under_up_th and under_low_th. When the monitor read value goes below under_low_th, the interrupt is asserted high. After the interrupt is asserted high, the interrupt is asserted low only if the monitor read value goes above under_up_th