Maxim Integrated Secure Microcontroller - Manual (Page 80)

Secure Microcontroller User’s Guide
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Figure 9-3. Dummy Bus Access Timing
9.9 Self-Destruct Input
The self-destruct input (SDI) is an active-high input pin designed to be used with external tamper-
detection circuitry. The SDI feature operates in both powered (V
CC
> 4.5V) and battery-backed (V
CC
<
4.5V) modes. To guard against accidental activation, the pin is debounced, with accept and rejection
criteria as shown in the DC electrical characteristics (refer to data sheet). Once activated, the SDI pin
instantaneously clears the security lock, initiating the sequence of events described in the
Security Lock
section. In addition, the microprocessor erases its external memory by:
1) Removing power from the V
CCO
pin
2) Removing power from all bytewide bus control signals (
CEx, R/W, etc.)
3) Grounding address and data lines to remove excess charge that could help retain data.