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.

Activation

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 from the connection matrix.

Parameters

Table 1.

Parameters	ACMP0	ACMP1
IN+ source	PIN10	PIN9
	PGA out	PGA out
	VDD	PIN10
IN- source	50mV	50mV
	…	…
	1200mV	1200mV
	VDD/3	VDD/4
	VDD/4	PIN5
	PIN5	PIN4
	PIN4	PIN5 / 2
	PIN5 / 2	PIN4 / 2
	PIN4 / 2	DAC1 out
	DAC1 out	DAC1 out
	DAC0 out	DAC0 out

Hysteresis:

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;

Low bandwidth:

Enable/Disable a low pass filter, cutoff frequency << 5kHz, to IN+.

Input 100uA current:

Enable/Disable a 100uA constant current source at the IN+ source

IN+ gain:

The IN+ source has a selectable gain stage of 1X, 0,5X, 0.33X and 0.25X before connection to the analog comparator. A gain stage aside from 1X causes the input impedance to decrease dramatically, see Table below.

IN+ source:

Positive Analog input source to ACMP.

IN- source:

Negative Analog input source to ACMP. Internal Vref thresholds are optimized near 1000 mV.