Power-On-Reset And Brown-Out-Reset; Low Battery Detector; Over Current Protection; Figure 5-1: Lr1121 Por And Brn Functions - Semtech LR1121 User Manual

5.3 Power-On-Reset and Brown-Out-Reset

The LR1121 features both POR and BRN features.
• POR and BRN ensure a proper startup of the circuit, maintaining the internal blocks reset until a safe battery voltage
level is reached, for example at battery insertion.
• The BRN triggers a device reset if the battery voltage goes below the safe operation threshold of 1.7V (typically).
• The POR/BRN detector has a 50mV hysteresis.
• A POR resets the statistics.
Refer to

Figure 5-1: LR1121 POR and BRN Functions

5.4 Low Battery Detector

The Low Battery Detector (LBD) detects when the supply voltage VBAT drops below 1.88V (typ). The LBD indication is given
through an interrupt signal, hence minimizing the host activity in critical supply voltage conditions. The LBD IRQ is
activated though command SetDioIrqParams().

5.5 Over Current Protection

The LR1121 has a built-in Over Current Protection (OCP) block which prevents surge currents when the device is used at its
highest power levels, thus protecting the battery that may power the application. The current clamping values are
trimmable by register access. The OCP threshold should be configured just below the battery requirement but at least 25%
higher than the PA output stage current.
The default OCP values are:
•
60mA for the low power PA (LP PA)
•
150mA for the high power PA (HP PA)
•
50mA for the high frequency PA (HF PA)
LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
for an illustration of the POR and BRN functions.
Figure 5-1: LR1121 POR and BRN Functions
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