User's Manual

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STMicroelectronics Confidential Rev 0.1 9/22
DRAFT
2.2.3 LPS25HB
The LPS25HB is an ultra-compact absolute piezo-resistive pressure sensor. It includes a
monolithic sensing element and an IC interface able to take the information from the
sensing element and to provide a digital signal to the external world.
Thanks to its great accuracy (1 Pa RMS, 24bit ADC resolution), its bandwidth (1 Hz – 25
Hz) and to its very low power consumption (4uA low power mode, 25uA high performance
mode) the integration of this sensor is suitable for height estimation (e.g. VRU Vertical
Reference Unit) and to enhance standard IMU performances with high frequency altitude
reference.
2.3 BLUENRG-MS and BALF-NRG-01D3
The BLUENRG-MS is a very low power Bluetooth low energy (BLE) single-mode network
processor, compliant with Bluetooth specification v4.1. The BLUENRG-MS can act as
master or slave. The entire Bluetooth low energy stack runs on the embedded Cortex M0
core. The non-volatile Flash memory allows on-field stack upgrading. The BLUENRG-MS
allows applications to meet the tight advisable peak current requirements imposed with the
use of standard coin cell batteries. The maximum peak current is only 8.2 mA at 0 dBm of
output power. Ultra low-power sleep modes and very short transition times between
operating modes allow very low average current consumption, resulting in longer battery
life. The BLUENRG-MS offers the option of interfacing with external microcontrollers using
SPI transport layer.
BALF-NRG-01D3 is a 50Ω conjugate match to BLUENRG-MS (QFN32 package) that
integrates balun transformer and harmonics filtering. It features high RF performances with
a very small footprint and a RF BOM reduction. It has been chosen as the best trade-off for
costs, area occupation and high radio performances. The layout has been optimized to
match 4 layers design and a chip antenna.
2.4 Power management
The power management block includes the STNS01, the STLQ015 and the STC3115
2.4.1 STNS01 and STLQ015
The STNS01 is a linear charger for single-cell Li-Ion batteries.
In STEVAL-WESU1 system it is configured as battery charger and as power path selected
between USB power source and battery power source.
The STNS01's battery charger is designed to charge single cell Li-Ion batteries up to 4.2 V
using a CC-CV charging algorithm (see STNS01 datasheet for more details). When a valid
input voltage is detected, the STNS01 starts the charge cycle and the CHG pin switches
from high impedance to low level. The CHG pin is connected to LED2 to monitor the
charger.
The charging status LED (LED 2) can be:
- solid ON: the USB plug is correctly connected and the board is charging;
- solid OFF: the board is not charging (use USB cable reconnection to force re-start);
- blinking (approx. 1Hz): charging failure (e.g. over-temperature, three wires battery not
connected);