AMS AS3933-BTST

The AS3933 is a 3-channel low power ASK receiver that is able to generate a wake-up upon detection of a data signal which uses a LF carrier frequency between 15-150 kHz. The integrated correlator can be used for detection of a programmable 16-bit or 32-bit Manchester wake-up pattern. The device can operate using one, two, or three active channels. The AS3933 provides a digital RSSI value for each active channel, it supports a programmable data rate and Manchester decoding with clock recovery. The AS3933 offers an internal Clock Generator, which is either derived from a crystal oscillator or the internal RC oscillator. The user can decide to use the external clock generator instead. The programmable features of AS3933 enable to optimize its settings for achieving a longer distance while retaining a reliable wake-up generation. The sensitivity level of AS3933 can be adjusted in presence of a strong field or in noisy environments. Antenna tuning is greatly simplified, as the automatic tuning feature ensures perfect matching to the desired carrier frequency. The device is available in 16-pin TSSOP and 16-LD QFN (4x4mm) packages, and DoW (dice on wafer).

The AS3933 is a three-dimensional low power low-frequency wake-up receiver. The AS3933 is capable of detecting the presence of an inductive coupled carrier and can extract the envelope of the ON-OFF-Keying (OOK) modulated carrier. In case the carrier is Manchester coded, the clock can be recovered from the received signal and the data can be correlated with a programmed pattern. If the detected pattern corresponds to the stored one, a wake-up signal (IRQ) is risen up. The pattern correlation can be disabled; in this case the wake-up detection is based only on the frequency detection. The AS3933 is made up of three independent receiving channels, one envelop detector, one data correlator, one Manchester decoder, 19 programmable registers with the main logic and a Clock Generator. The digital logic can be accessed by an SPI. The Clock Generator can be based on a crystal oscillator, or an internal RC-oscillator or an external clock. In case the RC-oscillator is used to improve its accuracy, a calibration can be performed. The internal LC-oscillator can deliver the antenna’s oscillation frequency for each channel and the internal tuning capacitor bank can provide fine tuning. The Internal RC-oscillator can be calibrated either over SPI or using the internal algorithm based on the antenna resonance frequency. AS3933 needs the following external components: • Power supply capacitor - CBAT - 100 nF. • 32.768 kHz crystal with its two pulling capacitors - XTAL and CL - (it is possible to omit these components if the internal RC oscillator is used instead of the crystal oscillator). • One, two, or three LC resonators according to the number of used channels. In case the internal RC-oscillator is used (no crystal oscillator is mounted), the pin XIN has to be connected to the supply, while pin XOUT should stay floating.

• Active RFID tags
• Real-time location systems
• Operator identification
• Access control
• Wireless sensors