AMC7836IPAP datasheet(36/91 Pages) TI2

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High Threshold

Low Threshold

Over High Alarm

Below Low Alarm

Hysteresis

AMC7836

SLAS986D – NOVEMBER 2014 – REVISED FEBRUARY 2018

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7.3.2.4.3

ALARMIN Alarm

The AMC7836 device offers the option of using an external interrupt signal, such as the output of a comparator

as an alarm event. The GPIO0/ALARMIN pin is used as the alarm input and must be configured accordingly in

the GPIO configuration register (address 0x12). The pin is active low when configured as an alarm input.

A typical application for ALARMIN pin is to use it as a hardware interrupt that is responsible for forcing one or

more DACs to a CLEAR state. The DAC is loaded with a zero-code input and the output voltage is set according

to the operating output range, however the DAC buffer or active registers do not change (see the Digital-to-

Analog Converters (DACs) section for more details). To enable this functionality the ALARMIN pin must be

enabled as a DAC clear-alarm source in the DAC clear source 1 register (address 0x1B). Additionally the DAC

outputs to be cleared by the ALARMIN pin must be specified in the DAC clear enable registers (address 0x18

through 0x19).

In this application when the ALARMIN pin goes low, all the DACs that are set to clear in response to the

ALARMIN alarm in the DAC-clear enable registers enter a CLEAR state. When the ALARMIN pin goes back high

the DACs are reloaded with the contents of the DAC active registers which allows the DAC outputs to return to

the previous operating point without any additional commands.

7.3.2.4.4

Hysteresis

If a monitored signal is out of range and the alarm is enabled, the corresponding alarm bit is set to 1. However,

the alarm condition is cleared only when the conversion result returns either a value lower than the high

threshold register setting or higher than the low threshold register setting by the number of codes specified in the

hysteresis setting (see Figure 57). The ADC and LT hysteresis registers (address 0xA0 through 0xA4) store the

hysteresis value for the external unipolar inputs and internal temperature sensor programmable alarms. The

hysteresis is a programmable value between 0 LSB to 127 LSB for the unipolar inputs alarms and 0°C to 31°C

for the internal temperature-sensor alarms. The die thermal alarm hysteresis is fixed at 8°C.

Figure 57. Device Hysteresis

7.3.2.4.5

False-Alarm Protection

To prevent false alarms, an alarm event is only registered when the monitored signal is out of range for an N

number of consecutive conversions. If the monitored signal returns to the normal range before N consecutive

conversions, an alarm event is not issued. The false alarm factor, N, for the unipolar input and local temperature

sensor out-of-range alarms can be configured in the false alarm configuration register (address 0x11).

AMC7836IPAP 数据表(PDF) 36 Page - Texas Instruments

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