Electronic Components Datasheet Search |
|
SP705CN-L Datasheet(PDF) 11 Page - Exar Corporation |
|
SP705CN-L Datasheet(HTML) 11 Page - Exar Corporation |
11 / 17 page S SP P7 70 05 5--S SP P7 70 08 8--S SP P8 81 13 3L L L Lo ow w P Po ow we err M Miiccrro op prro occe es ss so orr S Su up pe errv viis so orry y C Ciirrccu uiitts s © 2010 Exar Corporation 11/17 Rev. 2.0.0 MONITORING VOLTAGES OTHER THAN THE UNREGULATED DC INPUT Monitor voltages other than the unregulated DC by connecting a voltage divider to PFI and adjusting the ratio appropriately. If required, add hysteresis by connecting a resistor (with a value approximately 10 times the sum of the two resistors in the potential divider network) between PFI and PFO. A capacitor between PFI and GND will reduce the power-fail circuit's sensitivity to high-frequency noise on the line being monitored. RESET can be used to monitor voltages other than the +5V VCC line. Connect PFO to MR to initiate a RESET pulse when PFI drops below 1.25V. Figure 21 shows the SP705/706/707/708 configured to assert RESET when the +5V supply falls below the RESET threshold, or when the +12V supply falls below approximately 11V. Fig. 21: Monitoring +5V and +12V Power Supplies MONITORING A NEGATIVE VOLTAGE SUPPLY The power-fail comparator can also monitor a negative supply rail, shown in Figure 22. When the negative rail is good (a negative voltage of large magnitude), PFO is LOW. By adding the resistors and transistor as shown, a HIGH PFO triggers RESET. As long as PFO remains HIGH, the SP705-708/813L will keep RESET asserted (where RESET = LOW and RESET = HIGH). Note that this circuit's accuracy depends on the PFI threshold tolerance, the VCC line, and the resistors. Fig. 22: Monitoring a Negative Voltage Supply INTERFACING TO µPS WITH BIDIRECTIONAL RESET PINS µPs with bidirectional RESET pins, such as the Motorola 68HC11 series, can contend with the SP705/706/707/708 RESET output. If, for example, the RESET output is driven HIGH and the µP wants to pull it LOW, indeterminate logic levels may result. To correct this, connect a 4.7KΩ resistor between the RESET output and the µP reset I/O, as shown if Figure 23. Buffer the RESET output to other system components. |
Similar Part No. - SP705CN-L |
|
Similar Description - SP705CN-L |
|
|
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 |