NRF52820-QDAA-R datasheet(110/437 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 36: Comparator overview

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

stopped by triggering the STOP task. The comparator will generate a READY event to indicate when it is

ready for use and the output is correct. The delay between START and READY is tINT_REF,START if an internal

reference is selected, or t COMP,START if an external reference is used. 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 VDDH/5) as VIN+ input, regardless of the

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

operation mode are 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 112). This

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

unwanted events. See Hysteresis example where VIN+ starts below VUP on page 113 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.

4463_156 v1.0

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NRF52820-QDAA-R Datasheet(PDF) 110 Page - Nordic Semiconductor

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