U6813B 데이터 시트보기 (PDF) - Atmel Corporation

부품명

상세내역

일치하는 목록

U6813B

Fail-safe IC with High-side and Relay Driver

Atmel Corporation 

3. Fail-safe Functions

A fail-safe IC has to maintain its monitoring function even if there is a fault condition at one of the

pins (e.g., short circuit), ensuring that a microcontroller system does not reach a “critical status”.

A critical status means, for example, if the system is not able to switch off the relay or disable the

power MOSFET, or if the system is not able to provide a signal to the microcontroller via

ENABLE- and RESET-outputs in the case of a fault condition. The U6813B is designed to han-

dle those fault conditions according to Table 3-1 for a maximum of system safety.

Table 3-1. Truth Table

VCC

3.3V

WDI

RELI

ok

ok

ok

H

ok

ok

ok

L(1)

ok

ok

ok

x

ok

ok

ok

x

ok

ok

wrong

x

x

wrong

x

x

wrong

x

x

x

Notes: 1. default state at open input

2. P-EN disable: low

3. N-EN disable: high

FETI

x

x

H

L (1)

x

x

x

RELO

on

off

x

x

off

off

off

FETO

x

x

on

off

off

off

off

4. Watchdog Description

Figure 4-1. Watchdog Block Diagram

N-RES

H

H

H

H

H

L

L

P-RES

L

L

L

L

L

H

H

P-EN(2)

H

H

H

H

L

L

L

N-EN(3)

L

L

L

L

H

H

H

WDC

Binary counter

Dual MUX

WDI

RESET

OSCERR

Slope

detector

Up/down

counter

RS-FF

WD-OK

The microcontroller is monitored by a digital window watchdog which accepts an incoming trig-

ger signal of a constant frequency for correct operation. The frequency of the trigger signal can

be varied in a broad range as the watchdog’s time window is determined by external R/C com-

ponents. The following description refers to the watchdog timing diagram with tolerances (see

Figure 4-2 on page 5).

4 U6813B

4543B–AUTO–10/05

Share Link: