MB91F525FHDPMC datasheet(226/280 Pages) CYPRESS

226 / 280 page

Document Number: 002-04662 Rev. *F

Page 226 of 280

MB91520 Series

■ Scope of Impact

For the affected parts, when the Power-On Reset and Internal Low Voltage Detection are not generated, the MCU may

set invalid package and sub clock option information. Therefore, the MCU may operate with an invalid pin configuration.

■ Workaround

For the affected parts, it is necessary to satisfy at least one of the Power-On Reset requirements for any Power-On event

as given below:

(1) The VCC voltage is less than 200 mV for 50 ms or longer (tOFF)

(2) VCC Power ramp rate is less than 4 mV/µs (dV/dt) until a voltage level for a safe Power-On detection is reached

(3) C-pin voltage is below 60 mV when VCC is turned on again

If the customer system does not satisfy the condition above-mentioned, Cypress will releases new version D, so Cypress

recommends the version D for MB91F52x. The new version prevents the limitation when an external reset signal is

asserted at pin RSTX anytime the supply voltage (VCC) is turned on.

■ Fix Status

Will be fixed in production silicon version D, E

Limitation for Watch mode (power off)

■ Problem Definition

If the below all trigger conditions (1) to (3) are satisfied, the below registers will be initialized after MCU recovers from

watch mode (power off).

■ Trigger Conditions

(1) Using the watch mode (power off)

(2) Interrupt levels that are used as sources for recovering from the watch mode (power off) are

‘16’ to ‘30’, or using

NMIX pin as source for recovering from the watch mode (power off)

(3) The sources for recovering from the watch mode (power off) are generated between PCLK 1 cycle and PMUCLK

3 cycles (*), after CPU state changes to the watch mode (power off)

(*): In case of PCLK = 0.5 MHz and PMUCLK = 32 kHz, it is approx. 2 µs to 100 µs

■ Scope of Impact

If the all trigger conditions (1) to (3) are satisfied, the below registers will be initialized after MCU recovers from watch

mode (power off).

WTCRH, WTCRM, WTCRL

CSELR.SCEN

CMONR.SCRDY

CCRTSELR.CST

CCRTSELR.CSC

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