ILPS28QSW datasheet(22/52 Pages) STMICROELECTRONICS

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The metal lid is physically connected to pin 7 at component level and pin 7 can be used to connect the metal lid

either to GND or left unconnected (floating) on the PCB of the application. The following table indicates the two

cases of the metal LID connection. It is highly recommended that pin 7 be soldered to the PCB (left unconnected

electrically) or soldered to GND to enhance the solderability of the device.

Table 11. Metal lid and pin 7 connections

Metal lid

Pin 7 connection to PCB(1)

Leave unconnected (floating)

Electrically leave unconnected (floating)

Connect to GND

Electrically connect to GND

1. Pin 7 should be soldered to the PCB to improve the solderability of the device.

Note:

To guarantee proper power-off of the device, it is recommended to maintain the duration of the VDD line to GND

for at least 10 ms.

Figure 16. ILPS28QSW power-off sequence

VDD

Time



VDD rise / fall time : 10 µs ~ 100 ms



VDD must be lower than 0.7 V for at least 10 ms during power-off sequence for correct POR

0.7 V

Min.10 ms

7.1

Analog hub (AH) / Qvar functions

The ILPS28QSW embeds an analog hub sensing functionality that is able to connect an analog input and convert

it to a digital signal as output. In addition, Qvar sensing with external electrodes can be used for user interfaces

like water-leak detection, tap, double tap, long press, and L/R - R/L swipe. Refer to application note AN5755 for

additional details.

The input impedance between AH/QVAR1 (pin 2) and AH/QVAR2 (pin 4) of ILPS28QSW depends on the AVG

and ODR configuration in Table 6. Input impedance of Qvar.

7.2

Power-saving tip for the pressure sensor, disabling the analog hub (AH) / Qvar

feature

The analog hub (AH) / Qvar feature is enabled by default and this feature causes slightly higher power

consumption during operating and power-down modes to support the AH/Qvar functions. Thus, it is

recommended to use the following procedure to save power consumption in case the application doesn't need the

AH/Qvar feature.

How to save power consumption? First of all, AH1/QVAR1 (pin 2) and AH2/QVAR2 (pin 4) must be connected

to GND on the PCB (hardware design). Second, the application must write 00h in the 5Fh register whenever the

application is powered on. Following this procedure, the device operates only in pressure sensor mode, disabling

AH/Qvar to achieve lower power consumption as described in Table 4. Electrical characteristics.

ILPS28QSW

Analog hub (AH) / Qvar functions

DS13905 - Rev 1

page 22/52

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