Startup Timing

7.3 Startup Timing

When power is turned on, or a reset is initiated, a power-on delay circuit is im- plemented with a 17-bit counter to guarantee that the power supply has reached a certain level, and the oscillator is stable. The delay introduced by this counter is:

24MHz System clock: (217 − 1) S (1/24) S 10−6 = 0.005461s

1MHz System clock: (217 − 1) S 10−6 = 0.131071s

7.3.1Normal-Mode Power-On Reset Timing

EA is sampled during power-on reset for code security purposes. PSEN and ALE are internally pulled up during reset for serial and parallel flash program- ming mode detection.

After the reset sequence, PSEN and ALE signals are driven by the CPU, and the internal pull up resistors are removed for saving power.

7.3.2Flash Programming Mode Power-On Reset Timing

EA is ignored for serial and parallel flash programming operations.

Figure 7−5. Reset Timing

Figure 7−6. Parallel Flash Programming Power-On Timing (EA is ignored)

System Timing

7-9

 

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Texas Instruments MSC1210 Startup Timing, Normal-Mode Power-On Reset Timing, Flash Programming Mode Power-On Reset Timing