The Analog Comparator (ACMP) compares two voltages and outputs a digital signal indicating which is larger. It has two analog input terminals, IN+ and IN-, and one digital output OUT.
In order for the ACMP cell to be used in a GreenPAK design, the power up signal (PWR UP) needs to be active (HIGH). It is possible to have each ACMP always on, always off, or switched on dynamically based on a digital signal.
Table 1.
| Parameters | ACMP0 | ACMP1 |
|---|---|---|
| IN+ source | PIN2 | ACMP0 IN+ |
| VDD | ||
| IN- source | 50mV | 50mV |
| … | … | |
| 1200mV | 1200mV | |
| VDD/3 | VDD/3 | |
| VDD/4 | VDD/4 | |
| PIN3 | PIN3 |
Each ACMP has four selectable hysteresis options 0mV, 25mV, 50mV and 200mV.
• 0mV: will disable the input signal hysteresis;
• 25mV: is a +12.5mV and -12.5mV hysteresis;
• 50mV: is a +0mV and -50mV Hysteresis. For Vref=1V, the trigger points will be 1V and 0.95V. Only applies if Vref is internal;
• 200mV: is a +0mV and -200mV hysteresis. For Vref=1V, the trigger points will be 1V and 0.8V. Only applies if Vref is internal;
Enable/Disable a low pass filter, cutoff frequency << 5kHz, to IN+. Not to be confused with the Speed parameter and is much lower than Normal speed.
Positive Analog input source to ACMP.
Negative Analog input source to ACMP. Internal Vref thresholds are optimized near 1000mV.
Any ACMP powered on enables the BandGap internal circuit as well. An analog voltage will appear on Vref (even when the Force BandGap option is set as Disabled).