TPS22949 Power Supply Protection Solution for Fingerprint Sensors

Over-Current Protection of a Dual Power Rail Fingerprint Sensor Available at Digi-Key

TPS22949 Power Supply Protection Solution for Fingerprint SensorsTexas Instruments' fingerprint authentication sensors are increasingly used in multiple applications to provide the convenience and security advantages that biometrics offers to consumers and businesses. One of the key challenges sensor manufacturers face is exposing the sensor to applications where the device can be shorted. This can occur if excessive pressure is placed on the sensor or if liquid is accidentally spilled on the device. A short circuit results in high current through the sensor, which can burn a finger and damage the motherboard or baseband in the equipment.

One solution to overcome this problem is to use a current limited switch. The switch monitors the supply current of the sensor and limits the output current if an over-current is detected. The sensor is very sensitive to noise, thus the designer will often generate a lower regulated voltage (1.8V) with low noise performance to supply the sensor supply rail.

The TPS22949 provides a single device solution to customers integrating a 100mA low voltage (1.62V to 4.5V) current limiter with ultra-fast current limit response, automatic shut-off and auto-restart and an integrated high performance low-dropout (LDO) regulator. The output of the current limiter is internally connected to an RF LDO, which offers good AC performance with very low ground current, good power-supply rejection ratio (PSRR), low noise, fast start-up, and excellent line and load transient response.


Features Applications
  • Integrated Current Limiter
    • Input Voltage Range: 1.62V to 4.5V
    • Low ON-Resistance
      • rON = 300-mΩ at VIN = 4.5V
      • rON = 350-mΩ at VIN = 3.3V
      • rON = 400-mΩ at VIN = 2.5V
      • rON = 600-mΩ at VIN = 1.8V
    • Integrated 100-mA Minimum Current Limit
    • Under-Voltage Lockout
    • Fast-Current Limit Response Time
    • Integrated Fault Blanking and Auto Restart
  • Integrated Low-Noise RF LDO
    • Input Voltage Range: 1.62V to 4.5V
    • Low Noise: 50µVrms (10Hz to 100kHz)
    • 80-dB VIN PSRR (10Hz to 10kHz)
    • Fast Start-Up Time: 130 µs
    • Low Dropout 100 mV at Iload =100 mA
    • Integrated Output Discharge
    • Stable With 2.2-µF Output Capacitor
  • 1.8-V Compatible Control Input Threshold
  • ESD Performance Tested Per JESD 22
    • 3500-V Human-Body Model (A114-B, Class II)
    • 1000-V Charged-Device Model (C101)
  • Tiny 8-Terminal YZP Package (1.9mm × 0.9mm, 0.5mm Pitch, 0.5mm Height) and SON-8 (DRG 3.0mm × 3.0mm)
  • Fingerprint Module Protection
  • Portable Consumer Electronics
  • Smartphone
  • Notebooks
  • Control Access Systems

TPS22949 Power Supply

ImageManufacturer Part NumberDescriptionSwitch TypeNumber of OutputsAvailable QuantityView Details
TPS22949YZPR datasheet linkIC LOAD SWITCH LN RF LDO 8DSBGATPS22949YZPRIC LOAD SWITCH LN RF LDO 8DSBGAGeneral Purpose21322 - Immediate
TPS22949YZPR product page link
Published: 2009-06-15