U6808B-MFP Atmel, U6808B-MFP Datasheet - Page 2

• Manufacturer Part Number: U6808B-MFP
• Description: IC FAILSAFE W/RELAY DRVR 8-SOIC
• Manufacturer: Atmel

Specifications of U6808B-MFP

• Applications: Automotive
• Current - Supply: 15mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Pin Configuration
Figure 2. Pinning SO8
Pin Description
Fail-safe Functions
Table 1. Table of Fault Conditions
2
RELAY
Pin
OSC
WDI
RIN
Pin
1
2
3
4
5
6
7
8
U6808B
ENABLE
Function
Digital input to
activate the fail-safe
relay
Watchdog trigger
input
Capacitor and
resistor of watchdog
Driver of the fail-safe
relay
Symbol
RESET
RELAY
WDC
GND
WDI
RIN
VS
Open collector
Digital output
Digital output
driver output
Analog input
Digital input
Digital input
Supply
Supply
Type
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). This ensures that a microcontroller system is not
brought into a critical status. A critical status is reached if the system is not able to
switch off the relay and to give a signal to the microcontroller via the ENABLE and
RESET outputs. The following table shows the fault conditions for the pins.
Short to Vs
Relay on
Watchdog reset
Watchdog reset
RELAY
GND
ENABLE
WDC
Function
Fail-safe relay driver
Standard ground
Negative reset signal
External RC for watchdog timer
Negative reset signal
Watchdog trigger signal
Activation of relay driver
5-V supply
1
2
3
4
Short to VBat
Relay on
Watchdog reset
Watchdog reset
8
7
6
5
RIN
WDI
RESET
VS
Short to GND
Relay off
Watchdog reset
Watchdog reset
Relay on
Logic
No signal: driver off
Low: driver on
No signal
Low: reset
No signal
Low: reset
Pulse sequence
High: driver on
Low: driver off
–
Open Circuit
Relay off
Watchdog reset
Watchdog reset
Relay off
4707A–AUTO–05/03