Predicting Battery Depletion Risks during over the Air Profile Reselection under Severe Antenna Mismatch
Severe antenna detuning elevates power amplifier current and airtime during profile reselection, driving battery voltage below shutdown limits.
Undervoltage Lockout
Meaning
An internal electronic protection circuit disables a power converter or integrated circuit when the input voltage falls below a predetermined safe operating threshold. Integrating an undervoltage lockout prevents unpredictable behavior and potential component damage during system startup or battery depletion. The system automatically resumes normal operations once the supply voltage rises back above the turn-on threshold, ensuring reliable start-up performance.
Startup Sequence
Power supplies often experience slow voltage rise times during initial power-up. By utilizing an undervoltage lockout, the chip remains disabled until the input rail has fully stabilized to its nominal value. This delay ensures the internal digital logic circuits initialize in a known state and prevents erratic output behaviors.
Threshold Definition
Designers must configure the turn-on and turn-off voltage limits using resistor dividers on the circuit board. The undervoltage lockout circuit employs hysteresis to prevent the device from rapidly cycling on and off when the supply voltage is near the threshold. This hysteretic band prevents noise on the power rail from causing false trigger events.
Circuit Protection
Low voltage conditions can cause power switches to operate in their linear region, leading to rapid overheating. Implementing an undervoltage lockout protects the power transistors from this high-dissipation state. This safeguard prevents catastrophic board failures when the battery is slowly depleted.