PCF84C443 查看數據表（PDF） - Philips Electronics

零件编号

产品描述 (功能)

生产厂家

PCF84C443

8-bit microcontrollers with OSD and VST

Philips Electronics 

Philips Semiconductors

8-bit microcontrollers with OSD and VST

Product specification

84C44X; 84C64X; 84C84X

7 RESET

The RESET pin (active LOW input) is used to initialize the

microcontroller to a defined state. The Reset configuration

is shown in Fig.5.

andbook, halfpage

RESET

VDD

R ≤ 100 kΩ

C

MCD174 VSS

Fig.4 External components for RESET pin.

7.1 Power-on-reset

The Power-on-reset circuit monitors the voltage level of

VDD. If VDD remains below the internal reference voltage

level Vref (typically 1.3 V), the oscillator is inhibited.

When VDD rises above Vref, the oscillator is released and

the internal reset is active for a period of td (typically

50 µs).

Considering the VDD rise time, the following measures for

a correct Power-on-reset can be taken:

• If the VDD rises above the minimum operation voltage

before time period td is exceeded, no external

components are necessary (see Fig.6).

• If VDD has a slow rise time, such that after the time

period (tVref + td) has elapsed the supply voltage is still

below the minimum operation voltage (Vmin),

external components are required (see Figs 4 and 7).

To guarantee a correct reset operation, ensure that the

time constant RC ≥ 8 × tVDD.

A definite Power-on-reset can be realized by applying an

(external) RESET signal during power-on.

handbook, full pagewidth

oscillator

inhibit

VDD

Vref

POWER-ON-RESET

RESET

internal

reset

MLA651

VSS

Fig.5 Reset configuration.

1996 Nov 29

8

Share Link: