Automotive PKE Passive Keyless Entry Solution

China produced and sold over 26 million vehicles in 2021 — the automotive era is here. Wireless access technologies (RKE & PKE) are now mainstream, bringing true keyless convenience.

RKE vs PKE

• RKE (Remote Keyless Entry) – Active: user presses button → key fob transmits ASK-modulated 64–128 bit command (preamble + code + rolling code) at 2–20 kHz → vehicle unlocks/locks after BCM validation.

• PKE (Passive Keyless Entry) – Truly passive: vehicle periodically sends 125 kHz LF wake-up → key fob auto-responds on UHF (315/433/868 MHz) when in range → authenticated → doors unlock automatically. No button press needed.

Solution Highlights

• Effective trigger distance: 4–5 meters

• Fully automatic bidirectional communication — zero user action

• SI3933 works at 125 kHz LF + optional UHF (315/433/868 MHz)

• Pin-to-pin compatible with AS3933 — 100 % hardware/software drop-in replacement

Core Chip: SI3933

• 3-channel ultra-low-power ASK receiver (15–150 kHz LF carrier detection)

• Generates wake-up on valid 16/32-bit Manchester-coded pattern (supports double validation)

• Per-channel frequency detection + digital RSSI

• Adjustable sensitivity for longer range & noise immunity

• Internal clock (crystal, RC, or external)

• Manchester decoding with clock recovery + auto antenna tuning

• Data rate programmable

Applications

• Active RFID tags

• High-value asset tracking

• Access control & real-time location systems (RTLS)

• Wireless sensor networks

• Operator identification

• Passive Keyless Entry / Passive Start (PEPS)

True hands-free, secure, and battery-friendly PKE — the standard for tomorrow’s vehicles.