NRF52811-QCAA-R7 datasheet(98/444 Pages) NORDIC

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Peripherals

Comparator

core

MODE

VIN-

MUX

VIN+

PSEL

RESULT

Output

0 = BELOW (VIN+ < VIN-)

1 = ABOVE (VIN+ > VIN-)

HYST

Figure 33: Comparator overview

Once enabled (using the ENABLE register), the comparator is started by triggering the START task and

stopped by triggering the STOP task. After a start-up time of tCOMP,START, the comparator will generate a

READY event to indicate that it is ready for use and that its output is correct. When the COMP module is

started, events will be generated every time VIN+ crosses VIN-.

Operation modes

The comparator can be configured to operate in two main operation modes, differential mode and single-

ended mode. See the MODE register for more information. In both operation modes, the comparator can

operate in different speed and power consumption modes (low-power, normal and high-speed). High-

speed mode will consume more power compared to low-power mode, and low-power mode will result in

slower response time compared to high-speed mode.

Use the PSEL register to select any of the AIN0-AIN6 pins (or VDD/2) as VIN+ input, irregardless of the

operation mode selected for the comparator. The source of VIN- depends on which operation mode is

used:

• Differential mode: Derived directly from AIN0 to AIN7

• Single-ended mode: Derived from VREF. VREF can be derived from VDD, AIN0-AIN7 or internal 1.2 V,

1.8 V and 2.4 V references.

The selected analog pins will be acquired by the comparator once it is enabled.

An optional hysteresis on VIN+ and VIN- can be enabled when the module is used in differential mode

through the HYST register. In single-ended mode, VUP and VDOWN thresholds can be set to implement

a hysteresis using the reference ladder (see Comparator in single-ended mode on page 100). This

hysteresis is in the order of magnitude of 30 mV, and shall prevent noise on the signal to create unwanted

events. See Hysteresis example where VIN+ starts below VUP on page 101 for illustration of the effect of

an active hysteresis on a noisy input signal.

An upward crossing will generate an UP event and a downward crossing will generate a DOWN event. The

CROSS event will be generated every time there is a crossing, independent of direction.

The immediate value of the comparator can be sampled to RESULT register by triggering the SAMPLE task.

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