HMS81032TL datasheet(63/77 Pages) HYNIX

63 / 77 page

HMS81004E/08E/16E/24E/32E

JUNE 2001 Ver 1.00

16. RESET FUNCTION

16.1 EXTERNAL RESET

The RESET pin should be held at low for at least 2machine

cycles with the power supply voltage within the operating

voltage range and must be connected 0.1uF capacitor for

stable system initialization. The RESET pin contains a

Schmitt trigger with an internal pull-up resistor.

16.2 POWER ON RESET

Power On Reset circuit automatically detects the rise of

power voltage (the rising time should be within 50ms) the

power voltage reaches a certain level, RESET terminal is

maintained at “L” Level until a crystal ceramic oscillator

oscillates stably. After power applies and starting of oscil-

lation, this reset state is maintained for about oscillation

cycle of 219 (about 65.5ms : at 4MHz).The execution of

built-in Power On Reset circuit is as follows :

(1) Latch the pulse from Power On Detection Pulse Gener-

ator circuit, and reset Prescaler, B.I.T and B.I.T Overflow

detection circuit.

(2) Once B.I.T Overflow detection circuit is reset. Then,

Prescaler starts to count.

(3) Prescaler output is inputted into B.I.T and PS10 of

Prescaler output is automatically selected. If overflow of

B.I.T is detected, Overflow detection circuit is set.

4) Reset circuit generates maximum period of reset pulse

from Prescaler and B.I.T

Figure 16-1 RESET Pin connection

RESET

GND

0.1uF capacitor

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