TH8065 datasheet(21/40 Pages) MELEXIS

21 / 40 page

TH8065

Voltage Regulator with LIN Transceiver and Watchdog

TH8065 – Datasheet

Page 21 of 40

3901008065

May 2006

Rev 003

3.8 RESET and Watchdog

The TH8065 contains a combined reset- and watchdog-unit which secures the correct initialization and

generation of the reset signal.

VSUP,

VCC

VRES

RESET

trr

tRes

int.

POR

signal

tWDH

tWDL

WDI

CWD VCWDH

VCWDL

Start-up

ON delay

Watchdog

Power-off

Figure 11 - Reset and Watchdog behaviour

The RESET pin outputs the reset state and the watchdog state of the TH8065. The POR timer will be started

if VSUP is switched on and VCC> POR threshold (4.65V). The Watchdog is inactive. After the time tRes the

RESET output is switched from low to high and the watchdog becomes active. The charging of the watchdog

capacity starts and dependent from the trigger pulse on the WDI input the Reset outputs the status of the

watchdog.

The watchdog is only active if VCC > VRES. If VCC drops below VRES the watchdog will be switched off and the

watchdog capacity will be discharged.

3.8.1. RESET

The RESET unit combines a VCC low voltage detection unit with fixed POR timer This output is switched

from low to high if VSUP is switched on and VCC>VRES (4.65V) after the time tRes .

All conditions which cause a drop of the VCC voltage will be detected from the low voltage reset unit which

generates a reset signal. The TH8065 will be reinitialized if the VCC voltage rises above the low voltage limit.

If the voltage VCC drops below VRES then the RESET output is switched from high to low after the time trr has been

reached. For this reason short breaks of the VCC voltage and uncontrolled reset generations will be inhibited.

The circuitry of the RESET output driver guarantees, that the reset low level during decreasing of the VCC

voltage will be secure kept (see Figure 13).

TH8065 Datasheet(PDF) 21 Page - Melexis Microelectronic Systems

TH8065 Datasheet(HTML) 21 Page - Melexis Microelectronic Systems

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Datasheet Download

Link URL