ZSSC3123AI2R datasheet(39/62 Pages) RENESAS

39 / 62 page

ZSSC3123 Datasheet

Nov 19, 2021

Page 39

Figure 24. Alarm Output Flow Chart

10.8.3 Alarm Output Configuration

The user can select the output driver configuration for each alarm using the Output Configuration bit in the Alarm_High_Cfg and Alarm_Low_Cfg

registers in EEPROM word Cust_Config (see Table 32 for bit assignments). For applications, such as interfacing with a microcontroller or

controlling an external device (as seen in section 14.3), select the full push-pull driver for the alarm output type. For an application that directly

drives a load connected to VDD, as demonstrated in section 14.2, the typical selection is the open-drain output type.

An advantage of making an alarm output open drain is that in a system with multiple devices, the alarm outputs of each ZSSC3123 can be

connected together with a single pull-up resistance so that one can detect an alarm on any device with a single wire.

10.8.4 Alarm Polarity

For both alarm pins, the polarity of the alarm output is selected using the Alarm Polarity bit in the Alarm_High_Cfg and Alarm_Low_Cfg registers

in EEPROM word Cust_Config (see Table 32 for bit assignments). As shown in the example in section 14.3, the alarms can be used to drive a

high voltage humidity control system. Since the humidifier or dehumidifier relays must be on when the alarms are on, the alarm polarity bits are

set to 0 (active high). In the example given in section 14.2, an alarm is used to turn on an LED in an open drain configuration. In order for the

LED to be on when the alarm is on, the output must be low, so the alarm polarity bit is set to 1 (active low).

Another feature of the polarity bits is the ability to create two high alarms or two low alarms. For example, with applications requiring two high

alarms, flip the polarity bit of the Alarm_Low pin, and it will act as a high alarm. However, in this case, the effect of the alarm low registers is

also changed: the Alarm_Low_On register would act like the Alarm_High_Off register and the Alarm_Low_Off register would act like the

Alarm_High_On register. The same can be done to achieve two low alarms: the Alarm_High pin would have the polarity bit flipped, and the two

Alarm_High registers would have opposite meanings.

HIGH ALARM PIN

Yes

Measurement >

Alarm_High_On?

Alarm = On

Measurement ≤

Alarm_High_Off?

Alarm = Off

Yes

LOW ALARM PIN

Yes

Measurement <

Alarm_Low_On?

Alarm = On

Measurement ≥

Alarm_Low_Off?

Alarm = Off

Yes

ZSSC3123AI2R Datasheet(PDF) 39 Page - Renesas Technology Corp

ZSSC3123AI2R Datasheet(HTML) 39 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

Datasheet Download

Link URL