For the BD52xxx/53xxx series it's 10k-1MΩ (VDET=2.3-6.0V) and for the BU42xx/43xx it's 50k-1MΩ (VDET=1.5-4.8V). However, this can change depending on board layout, so please perform a thorough evaluation under actual operating conditions.
In applications where the voltage is input using a resistance divider at the supply input pin, a through-current will flow instantaneously when the output logic switches, possibly causing malfunction (i.e. output oscillation). (Through current: Output switches from H to L, resulting in instantaneous current flow from VDD to Ground). Connecting a capacitor to the VDD pin reduces voltage drop, and adding a capacitor to the output pin prevents reset output chattering, making it possible to minimize ouptut oscillation. However, the reaction time may be delayed based on the capacitance. Therefore, we ask that the customer determine the constants after taking into account the set conditions. When inserting resistors (including resistance dividers), the BD52xx series is recommended.
Based on the reference value for Ta=-25 to 125ºC, the theoretical value will be +0.3×106. Therefore, in theory, the value will go from 6.0×106 to 6.3×106. However, please note that these values cannot be guaranteed.
According to the specifications listed in the data sheet, since ICT is the discharge current from the capacitor connected to the CT terminal, VDD will become lower than the detection voltage. For example, in the BD5223 when VDD falls below 2.3V, for power supply voltages greater than 2.3V the capacitor at the CT terminal wil become charged. The discharge current ICT for power supplies at 3.0V will be out of specifications.
Although the situation will change depending on the WD signal, if WD is a pulse type usage is not recommended (since High/Low pulse detection is difficult). If the WD signal is not a pulse type, voltage detection is possible using the configuration in the example above.