L99DZ120TR datasheet(64/161 Pages) STMICROELECTRONICS

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Application information

L99DZ120

64/161

DS11567 Rev 5

4.4.1

Wake up input

The WU input can be configured as wake-up source. The wake-up input is sensitive to any

level transition (positive and negative edge) and can be configured for static or cyclic

monitoring of the input voltage level.

For static contact monitoring, a filter time of tWU_STAT is implemented. The filter is started

when the input voltage passes the specified threshold VWU_THP or VWU_THN.

Cyclic contact monitoring allows periodical activation of the wake-up input to read the status

of the external contact. The periodical activation can be configured to Timer 1 or Timer 2.

The input signal is filtered with a filter time of tWU_CYC after a delay (80% of the configured

Timer on-time). A Wake-up will be processed if the status has changed versus the previous

cycle. The buffered output OUT_HS can be used to supply the external contacts with the

timer setting according to the cyclic monitoring of the wake-up input.

In standby modes, the input WU is configurable with an internal pull-up or pull-down current

source according to the setup of the external contact. In Active mode the inputs have an

internal pull down resistor (RWU_act) and the input status can be read by SPI. Static sense

should be configured before the read operation is started in order to reflect the actual input

level.

4.5

Functional overview (truth table)

Table 45. Wake-up events description

Wake up source

Description

LIN bus activity

Always enabled

Level change of WU

Can be configured or disabled by SPI

IV1 >Icmp_ris

Device remains in V1_standby mode but watchdog is enabled (If

ICMP = 0). No interrupt is generated.

Timer Interrupt / Wake up

of µC by TIMER

Programmable by SPI:

– V1_standby mode: device wakes up after programmable timer

expiration. NINT and RxDL/NINT interrupt signals are generated

– Vbat_standby mode: device wakes up after programmable timer

expiration, V1 regulator is turned on and NReset signal is generated

SPI Access

Always active (except in VBAT_STANDBY mode)

Wake up event: CSN is low and first rising edge on CLK

Table 46. Status of different functions/features vs operating modes

Function

Comments

Operating modes

Active mode

V1-standby static

mode (cyclic sense)

Vbat-standby static

mode (cyclic sense)

Voltage regulator V1

VOUT = 5 V

On(1)

Off

Voltage regulator V2

VOUT = 5 V

On/ Off(2)

On(2) / Off

Reset generator

Off

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