Contents

AN4450

2/26

DocID025978 Rev 1

Contents

1

Pressure sensor evaluation boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2

Hardware (designing PCB schematics and layout) . . . . . . . . . . . . . . . . 6

2.1

LPS25H device package, interconnect and polarization . . . . . . . . . . . . . . 6

2.1.1

Package drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.2

Pin mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.3

Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2

Pressure sensor PCB layout and soldering recommendations . . . . . . . . . 9

2.2.1

PCB design rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2.2

Stencil design and solder paste application . . . . . . . . . . . . . . . . . . . . . . 10

2.2.3

Process consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.2.4

Manual soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3

Power supply: consumption estimation and optimization . . . . . . . . . 12

3.1

Common rules for low power consumption . . . . . . . . . . . . . . . . . . . . . . . 14

4

Using the device step-by-step, from basic to advanced . . . . . . . . . . . 15

4.1

First time bring-up (I²C example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.2

Quick troubleshooting guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.3

One-shot mode measurement sequence . . . . . . . . . . . . . . . . . . . . . . . . . 16

5

Using FIFO modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1

Effective use of the FIFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1.1

Accessing the FIFO data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1.2

Bypass mode (F_MODE[2..0]="000" in FIFO_CTRL (0x2E)) . . . . . . . . 18

5.1.3

FIFO mode (F_MODE[2..0]="001" in FIFO_CTRL (0x2E)) . . . . . . . . . . 18

5.1.4

Stream mode (F_MODE[2..0]="010" in FIFO_CTRL (0x2E)) . . . . . . . . 18

5.1.5

FIFO mean mode (F_MODE[2..0]="110" in FIFO_CTRL (0x2E)) . . . . . 18

5.1.6

Hardware digital filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5.2

Extra FIFO modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.2.1

Stream to FIFO mode (F_MODE[2..0]="011" in FIFO_CTRL (0x2E)) . . 20

5.2.2

Bypass to Stream mode (F_MODE[2..0]="100" in FIFO_CTRL (0x2E)) 20

5.2.3

Bypass to FIFO mode (F_MODE[2..0]="111" in FIFO_CTRL (0x2E)) . . 21