U6808BMFPG3 Atmel, U6808BMFPG3 Datasheet

Page 1

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 ...

Page 2

Pin Configuration Figure 2-1. Pinning SO8 Table 2-1. Pin Description Pin Symbol Type Open collector 1 RELAY driver output 2 GND Supply 3 ENABLE Digital output 4 WDC Analog input 5 RESET Digital output 6 WDI Digital input 7 ...

Page 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). This ensures that a microcontroller system is not brought into a critical status. ...

Page 4

Description of the Watchdog Figure 5-1. 5.1 Abstract 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 ...

Page 5

RESET Input During power-on and under/overvoltage detection a reset signal is fed to this pin. It resets the watchdog timer and sets the initial state. 5.6 WD-OK Output After the up/down counter is incremented to status 3 (see the ...

Page 6

Watchdog Window Calculation 5.9.1 Example with Recommended Values C = 3.3 nF (should be preferably 10%, NPO) osc (may be 5%, R osc 5.9.2 RC Oscillator t ( WDC f (Hz) = 1/(t ...

Page 7

Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated ...

Page 8

Electrical Characteristics (Continued 5V –40 to +125°C, reference pin is GND amb Parameters Digital Output RESET with Internal Pull-up Voltage high Voltage low Zener clamping voltage Reset debounce time Reset delay time Digital ...

Page 9

Electrical Characteristics (Continued 5V –40 to +125°C, reference pin is GND amb Parameters Nominal frequency for WDI Nominal frequency for WDC Minimum pulse duration for a securely WDI input pulse detection Frequency range ...

Page 10

Timing Diagrams Figure 9-1. Watchdog in Too-fast Condition Normal operation 5 V WDI Batt RELAY ENABLE 0 V Figure 9-2. Watchdog in Too-slow Condition Normal operation 5 V WDI ...

Page 11

Figure 9-3. Overvoltage Condition > 5 Batt RELAY ENABLE RESET 0 V Reset debounce time Figure 9-4. Undervoltage Condition 5 V < 4.5 V ...

Page 12

Figure 9-5. Application Circuit U6808B 100 0.01 F U6808B Relay C V Batt osc osc 3.3 nF 4707B–AUTO–10/05 ...

Page 13

Ordering Information Extended Type Number U6808B-MFPY U6808B-MFPG3Y 11. Package Information Package SO8 Dimensions in mm 12. Revision History Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this ...

Page 14

... Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI- TIONS OF SALE LOCATED ON ATMEL’S WEB SITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ...