L9966 datasheet(17/122 Pages) STMICROELECTRONICS

17 / 122 page

Symbol

Parameter

Condition

Min Typ Max Unit

3V3_FLTl

3V3_FLT lower threshold

If internal 3V3 < 3V3_FLTl => 3V3_FLT = ‘1’; POR is not

activated

2.75

3.15

UBSW

RST_hi

RST input logic high voltage

1.5

1.7

RST

RST_lo

RST input logic low voltage

1.2

1.4

RST

RST_hys

RST input voltage hyst

200

315

RST

RST_pu

RST pull up to VDD5V

100

140

kΩ

RST

RST_degl_filt RST deglitch filter

-20%

+20%

µs

RST

Overtemperature

OT_FLT set, TRIM_FLT = 0

170

180

190

°C

OT_hys

Overtemperature hysteresis -

°C

OT_de

Overtemperature deglitch

Guaranteed by scan

100

µs

5.8

Polling operation: WAKE and SLEEP modes

SLEEP mode is enabled by sending 3 consecutive specific 32 bits SPI frames. The specific three SPI frames

are intended to avoid any unintentional SLEEP mode activation. Each frame needs a separate chip-select signal.

Once the SPI sequence has been sent, RST pin has to be driven low to enter SLEEP. In case the RST pin is

not driven low, the device stays in NORMAL mode and as soon as a new SPI command is received, the SPI

sequence previously sent to enter SLEEP mode is invalidated.

After the FlexInput has entered SLEEP mode, the ADC, SPI, VRS, pull up and pull down current generators and

sequencer are stopped. VDD5 is no longer necessary (0-5.5 V). In SLEEP mode the current sources are not

enabled, however they keep their configuration. The chip is supplied by UBSW (permanent supply).

The average current consumption in SLEEP / POLLING mode, ISLEEP-POLLING is defined in Table 8. Current

consumption.To save current consumption, current sources are pulsed in SLEEP / POLLING mode.

A pulsed current source is normally switched off, but it will be switched on for the time the chip reads the inputs.

Besides, the main oscillator is stopped and a second one takes over with reduced performances, in order to

guarantee the operation of the POLLING mechanism.

The pulse switch on depends on the configurable polling blanking time PB[1:0] in WAK_CONFIG register. Default

value is 160 µs.

The digital level of all 15 inputs is read (polled) every (m+1)*8 ms, where m is selected in PT[1:0] in

WAK_CONFIG register. WAK_MSK register defines which IOx are selected as WAKE SOURCES.

With respect to the IOx selected in WAK_MSK register, only the channels having CIS[3:0]=”0000”, MODE=”1”,

PullUp/PullDown configuration SEL = “001”(PullUp to battery/HiZ) or SEL = “100”(PullDown/HiZ) will act as WAKE

SOURCES; all the other IO configured through a different SEL selection will be ignored.

During polling, IOx defined as WAKE SOURCES are checked against the value they had before entering SLEEP

mode. These values have been stored in SLEEP_CONFIG register.

The check lasts for a PB time. At the end of PB time, if no WAKE SOURCE has changed its value, the chip goes

back to SLEEP mode. Otherwise, if at least one WAKE SOURCE has changed its value, this starts the verification

that the new status lasts for a longer PT time.

During PT time, the WAKE SOURCES can be as in one of the three below scenarios.

Scenario 1

Once the new status is detected, the WAKE SOURCES return at their PRE_SLEEP value before PB+PT time

elapses.

The IC returns back in SLEEP mode as shown in Figure 8;

IC only moves in INIT once RST pin is released (no wake pin assertion)

L9966

Polling operation: WAKE and SLEEP modes

DS12459 - Rev 10

page 17/122

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