Texas Instruments LM8365 User Manual Download Page 9 | Manualshive

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Texas Instruments LM8365 User Manual Download Page 9

Fast RST Response to Falling VIN

6

Fast RST Response to Falling VIN

In an application, it is beneficial to have flexibility in time delay for exiting reset state, but when entering
reset state we need extremely fast response. For example, if we have a microprocessor running code, it is
crucial that this device does not operate below its specified operating voltage. This could potentially lead
to disastrous results.

shows the reaction time of the RESET output when VIN falls below the

RESET threshold.

Figure 6. RST Output Low Response

9

SNVU493 – October 2015

Applications

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Copyright © 2015, Texas Instruments Incorporated

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Summary of Contents for LM8365

Page 1: ...LM8365EVM User Guide User s Guide Literature Number SNVU493 October 2015 ...

Page 2: ...nal and electrical characteristics consult the LM8365 datasheet SNVS233 The EVM contains one LM8365 Micropower Undervoltage Supervisor See Table 1 Table 1 Device and Package Configurations REF DES IC PACKAGE U1 LM8365BALMF27 NOPB SOT 23 1 Features INPUT Voltage Range 1 V to 6 V Extremely Low Quiescent Current 0 65 µA at VIN 2 87 V Threshold Voltage of 2 7 V High Accuracy Threshold Voltage 2 5 Acti...

Page 3: ... off and connected with proper polarity to the VIN TP1 and GND TP4 connectors The input voltage range for the EVM is 1 V to 6 V The RST TP2 pin can be used to monitor the RESET output of the LM8365 in response to various input voltages The DLY TP3 terminal provides a means for observation of the capacitor charging discharging behavior Furthermore the LM8365EVM allows for programming of the RESET o...

Page 4: ... programmed output delay As shown in Figure 1 the RST voltage follows VIN as long as the VIN voltage is above the RESET threshold When VIN falls below this threshold the RESET pin outputs low When VIN rises above the threshold the RST voltage is pulled back up to VIN corresponding to the RESET pin outputting high The LM8365 provides proper voltage supervision in critical situations like undervolta...

Page 5: ...ET pin outputs high only when VIN rises above the RESET threshold plus a certain amount of hysteresis Figure 2 shows the observed hysteresis which can eliminate erratic reset responses in certain situations for example when the input voltage is hovering very close to the threshold voltage Figure 2 RST Response to Threshold VIN 5 SNVU493 October 2015 Applications Submit Documentation Feedback Copyr...

Page 6: ...ettle to a stable voltage before the microprocessor begins running Figure 3 shows this delay which is programmed by populating J2 This corresponds to a CD capacitor of 0 1 µF In an application this provides the user confidence that the microprocessor will exit its reset state when its VCC has stabilized above the minimum operating voltage Figure 3 0 1 µF Capacitor Programmed Delay 6 Applications S...

Page 7: ...o stabilize above the RESET threshold before the supervised device can exit reset state Using the exact same setup as in Section 3 Programmed Delay with 0 1 µF Capacitor we populate J3 instead This corresponds to a CD capacitor of 1 µF Figure 4 1 µF Capacitor Programmed Delay 7 SNVU493 October 2015 Applications Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 8: ... 1 µF Capacitor The behavior of the 1 µF CD capacitor is shown in Figure 5 It should be noted that when the DLY terminal voltage is measured using an oscilloscope probe the CD capacitor may exhibit some leakage current into the oscilloscope probe As a result the RESET pin may output with a slightly longer delay Figure 5 1 µF Capacitor Delay Behavior 8 Applications SNVU493 October 2015 Submit Docum...

Page 9: ...nse For example if we have a microprocessor running code it is crucial that this device does not operate below its specified operating voltage This could potentially lead to disastrous results Figure 6 shows the reaction time of the RESET output when VIN falls below the RESET threshold Figure 6 RST Output Low Response 9 SNVU493 October 2015 Applications Submit Documentation Feedback Copyright 2015...

Page 10: ...t for the LM8365EVM Please note that we have provided an unpopulated footprint for C4 which allows room for an input capacitor Figure 7 Top Layer Layout 10 Board Layout SNVU493 October 2015 Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 11: ...SNVU493 October 2015 Schematic Figure 8 LM8365EVM Schematic 11 SNVU493 October 2015 Schematic Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 12: ...able Labels PCB Label 0 650 H Brady THT 14 423 10 M 0 650 W x 0 200 H 10 000 per x 0 200 W roll 1 R1 RES 470 k 5 0 1 W 0603 603 Vishay Dale CRCW0603470KJNEA 3 SH J3 Shunt 100mil Gold plated Black Shunt 3M 969102 0000 DA 4 TP1 TP2 Terminal Turret TH Double Keystone 1502 2 Keystone 1502 2 TP3 TP4 1 U1 Micropower Undervoltage Sensing MF05A Texas LM8365BALMF27 Circuits with Programmable Output Instrum...

Page 13: ...dervoltage Sensing Circuits with Programmable Output Delay datasheet SNVS233 Revision History DATE REVISION NOTES October 2015 Initial release 13 SNVU493 October 2015 Related Documentation Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 14: ...ring the warranty period to the address designated by TI and that are determined by TI not to conform to such warranty If TI elects to repair or replace such EVM TI shall have a reasonable time to repair such EVM or provide replacements Repaired EVMs shall be warranted for the remainder of the original warranty period Replaced EVMs shall be warranted for a new full ninety 90 day warranty period 3 ...

Page 15: ... by Industry Canada to operate with the antenna types listed in the user guide with the maximum permissible gain and required antenna impedance for each antenna type indicated Antenna types not included in this list having a gain greater than the maximum gain indicated for that type are strictly prohibited for use with this device Concernant les EVMs avec antennes détachables Conformément à la rég...

Page 16: ... connecting any load to the EVM output If there is uncertainty as to the load specification please contact a TI field representative During normal operation even with the inputs and outputs kept within the specified allowable ranges some circuit components may have elevated case temperatures These components include but are not limited to linear regulators switching transistors pass transistors cu...

Page 17: ...F REMOVAL OR REINSTALLATION ANCILLARY COSTS TO THE PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES RETESTING OUTSIDE COMPUTER TIME LABOR COSTS LOSS OF GOODWILL LOSS OF PROFITS LOSS OF SAVINGS LOSS OF USE LOSS OF DATA OR BUSINESS INTERRUPTION NO CLAIM SUIT OR ACTION SHALL BE BROUGHT AGAINST TI MORE THAN ONE YEAR AFTER THE RELATED CAUSE OF ACTION HAS OCCURRED 8 2 Specific Limitations IN NO EVENT SHALL T...

Page 18: ...esponsible for compliance with all legal regulatory and safety related requirements concerning its products and any use of TI components in its applications notwithstanding any applications related information or support that may be provided by TI Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failur...

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