3.1 Analog Monitor (MONx/AMONx) Pin Review
The following list provides analog monitor (MONx/AMONx) pin information:
- Internal or external voltage reference is used by ADC to monitor the external signal. Be sure to have the proper voltage divider to limit the input signal.
Table 1. UCD90xxx Voltage References
||UCD90240, UCD90320 and UCD90320U
||Remaining UCD90xxx Devices
|Internal Voltage Reference
|External Voltage Reference
- When a digital signal is connected to the analog monitor (MONx/AMONx) pin, please check the logic level of the input signal to see whether it is over the voltage reference
- TI recommends having a 10-nF to 100-nF decoupling capacitor close to the analog monitor (MONx/AMONx) pin to remove rail ripple voltage
- For UCD90240,UCD90320 and UCD90320U, TI recommends maintaining at least a 200-Ω resistance between a low-impedance analog input and an AMON pin. For example, when monitoring a rail voltage without a resistor divider, place a 200-Ω resistor in series between the rail output and AMON pin, as shown in Figure 2.
- Ground unused MONx/AMONx pins to save power consumption and decrease EMI.