Electronic Components Datasheet Search |
|
DS1819 Datasheet(PDF) 2 Page - Dallas Semiconductor |
|
DS1819 Datasheet(HTML) 2 Page - Dallas Semiconductor |
2 / 8 page DS1814/DS1819 2 of 8 The DS1814/DS1819 ‘A’ and ‘C’ perform pushbutton reset control. They debounce the pushbutton input and generate an active reset pulse width of 140ms minimum. The DS1814/9 ‘A’ and ‘B’ versions perform a watchdog function. The watchdog is an internal timer that forces the reset signals to the active state if the strobe input does not change state every 1.12 seconds. The watchdog timer function can be disabled by leaving the watchdog strobe input disconnected. OPERATION Power Monitor The DS1814 detects out-of-tolerance power supply conditions and warns a processor-based system of impending power failure. When VCC falls below a preset level, a comparator outputs the signal RST (or RST). RST (or RST) are excellent control signals for a microprocessor, as processing is stopped at the last possible moment of valid VCC. On power-up, RST (or RST) are kept active for a minimum of 140ms to allow the power supply and processor to stabilize. Pushbutton Reset The DS1814 ‘A’ and ‘C’ provide an input pin for direct connection to a pushbutton reset (see Figure 2). The pushbutton reset input requires an active low signal. Internally, this input is debounced and timed such that a RST (or RST) signal of at least 140ms minimum will be generated. The 140ms delay commences as the pushbutton reset input is released from the low level (see Figure 3). Watchdog Timer The DS1814/DS1819 ‘A’ and ‘B’ versions watchdog timer function forces RST (and RST) signal(s) active when the ST input is not clocked within the 1.12 second watchdog time-out period. Time-out of the watchdog starts when RST (and RST) become(s) inactive. If a transition occurs on the ST input pin prior to time-out, the watchdog timer is reset and begins to time out again. If the watchdog timer is allowed to time out, then the reset output(s) will go active for 140ms. The watchdog can be disabled by floating (or tri-stating) the ST input. The ST input can be derived from many microprocessor outputs. The most typical signals used are the microprocessor data I/O signals and control signals. When the microprocessor functions normally, these signals would as a matter of routine cause the watchdog to be reset prior to time-out. To guarantee that the watchdog timer does not time out, a transition must occur at or less than 1.12 seconds. A typical circuit example is shown in Figure 4. The DS1814/19 watchdog function can be disabled at any time by tri-starting the strobe input. A sample circuit to disable the watchdog is shown in Figure 6. |
Similar Part No. - DS1819 |
|
Similar Description - DS1819 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |