7.1 Synchronous Mode for Embedded Applications

The Two-Wire serial interface is used for fast and efficient communication with logic and controllers. Synchronous mode is the default after powering up VCC due to the internal and/or external pull-up on RST. For embedded applications using CryptoMemory® in standard plastic packages, RST is not bonded out, and this is the only communication protocol available.

  • Power-up VCC; RST goes high.
  • After VCC is stable, apply five CLK-SCL pulses.
  • CLK-SCL and I/O-SDA may then be driven.
Figure 7-1. Asynchronous Mode
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Asynchronous mode is selected when RST is low on a rising edge of CLK. Once Asynchronous mode has been selected, it is not possible to return to Synchronous mode except by powering the device off and on again.