Electronic Components Datasheet Search |
|
LM809M3X-3.08 Datasheet(PDF) 6 Page - Texas Instruments |
|
LM809M3X-3.08 Datasheet(HTML) 6 Page - Texas Instruments |
6 / 14 page LM809, LM810 SNVS052D – SEPTEMBER 1999 – REVISED MAY 2013 www.ti.com APPLICATIONS INFORMATION Benefits of Precision Reset Thresholds A microprocessor supply supervisor must provide a reset output within a predictable range of the supply voltage. A common threshold range is between 5% and 10% below the nominal supply voltage. The 4.63V and 3.08V options of the LM809/810 use highly accurate circuitry to ensure that the reset threshold occurs only within this range (for 5V and 3.3V supplies). The other voltage options have the same tight tolerance to ensure a reset signal for other narrow monitor ranges. See Table 1 for examples of how the standard reset thresholds apply to 3V, 3.3V, and 5V nominal supply voltages. Table 1. Reset Thresholds Related to Common Supply Voltages Reset Threshold 3.0V 3.3V 5.0V 4.63 ± 3% 90 - 95% 4.38 ± 3% 85 - 90% 4.00 ± 3% 78 - 82% 3.08 ± 3% 90 - 95% 2.93 ± 3% 86 - 90% 2.63 ± 3% 85 - 90% 77 - 81% 2.45 ± 3% 79 - 84% 72 - 76% Ensuring a Valid Reset Output Down to VCC = 0V When VCC falls below 1V, the LM809 RESET output no longer sinks current. A high-impedance CMOS logic input connected to RESET can therefore drift to undetermined voltages. To prevent this situation, a 100k Ω resistor should be connected from the RESET output to ground, as shown in Figure 9. A 100k Ω pull-up resistor to VCC is also recommended for the LM810, if RESET is required to remain valid for VCC < 1V. Figure 9. RESET Valid to VCC = Ground Circuit Negative-Going VCC Transients The LM809/810 are relatively immune to short negative-going transients or glitches on VCC. Figure 10 shows the maximum pulse width a negative-going VCC transient can have without causing a reset pulse. In general, as the magnitude of the transient increases, going further below the threshold, the maximum allowable pulse width decreases. Typically, for the 4.63V and 4.38V version of the LM809/810, a VCC transient that goes 100mV below the reset threshold and lasts 20µs or less will not cause a reset pulse. A 0.1 µF bypass capacitor mounted as close as possible to the VCC pin will provide additional transient rejection. 6 Submit Documentation Feedback Copyright © 1999–2013, Texas Instruments Incorporated Product Folder Links: LM809 LM810 |
Similar Part No. - LM809M3X-3.08 |
|
Similar Description - LM809M3X-3.08 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |