U6808B

Features Digital Self-supervising Watchdog with Hysteresis One 250-mA Output Driver for Relay Enable Output Open Collector 8 mA Over/Undervoltage Detection ENABLE and RELAY Outputs Protected Against Standard Transients and 40V Load Dump ESD Protection According to MIL-STD-883 D Test Method 3015.7 – Human Body Model: ±2 kV (100 pF, 1.5 kΩ) – Machine Model: ±200 V (200 pF, 0Ω) Special Fail-safe IC U6808B 1. Description The U6808B is designed to support the fail-safe function of a safety critical system (e.g., ABS). It includes a relay driver, a watchdog controlled by an external R/C-network and a reset circuit initiated by an over and undervoltage condition of the 5-V supply providing a low-level reset signal. Figure 1-1. Block Diagram VS VS Bandgap reference 2.44 V Power-on reset www.DataSheet4U.com + - RESET Reset debounce Reset delay + RELAY Under/ overvoltage detection ENABLE RIN + + - Internal oscillator Watchdog RC oscillator Current limitation WDI GND WDC Rev. 4707B–AUTO–10/05 2. Pin Configuration Figure 2-1. Pinning SO8 RELAY 1 8 VS GND 2 7 RIN ENABLE 3 6 WDI WDC 4 5 RESET Table 2-1. Pin 1 2 3 4 5 6 7 8 Pin Description Symbol RELAY GND ENABLE WDC RESET WDI RIN VS Type Open collector driver output Supply Digital output Analog input Digital output Digital input Digital input Supply Function Fail-safe relay driver Standard ground Negative reset signal External RC for watchdog timer Negative reset signal Watchdog trigger signal Ac...