Related Manuals for Texas Instruments TPS3801
Summary of Contents for Texas Instruments TPS3801
- Page 1 TPS3801/09 - Smallest SVS for Monitoring DSPs and Processors Application Report September 1999 Mixed Signal Products SLVA075...
- Page 2 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
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Page 3: Table Of Contents
................. . . TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... - Page 4 ..........11 TPS3801 With a Low Pass Filter at V Terminal .
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Page 5: Introduction
Bernd Kornmeier ABSTRACT This application report describes the TPS3801 and TPS3809 supply voltage supervisor (SVS) families of devices. The report gives a general introduction to reset generators followed by an overview of the technical parameters and the special features of the TPS380x. -
Page 6: Circuit Description
2.2 Supervised Supply Voltages Table 1 gives an overview of the nominal supply voltages, which can be supervised by the TPS3801 and TPS3809. The values in the column of threshold voltage are the negative-going threshold voltages. The differences between positive-going and negative-going threshold voltage is explained in Chapter 3. -
Page 7: Terminals
2.93 V TPS3801I50, TPS3809I50 5.0 V 4.55 V 2.3 Terminals The TPS3801 is available in a 5-pin SOT323 package, the TPS3809 in a 3-pin SOT23 package. More information about the package dimensions are in Chapter 6. TPS3801 TPS3809 V DD... -
Page 8: Basic Timings
TPS3801J25, TPS3809J25 334 kΩ 326 kΩ The TPS3801 has in addition to the TPS3809 a manual reset input. This input has an internal pullup resistor of 30 kΩ to V . Therefore an external resistor is not necessary if the function is not used. -
Page 9: Timing Diagram Of Tps3801
Circuit Description V DD V nom V IT 1.1 V ‘1‘ ‘0‘ RESET ‘1‘ ‘0‘ For V DD < 1.1 V Undefined Behavior of RESET Output Figure 5. Timing Diagram of TPS3801 TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 10: Voltage Supervision At The Vdd Terminal
Voltage Supervision at the V Terminal 3 Voltage Supervision at the V Terminal 3.1 Functional Description The main function of an SVS is to supervise a supply voltage and to trigger a reset signal if necessary. If the supply voltage falls below the negative-going threshold voltage V , the IT–... -
Page 11: Measurement Of A Voltage Drop On The Supply Line
The 1 MΩ resistor and the 39 pF capacitor are to simulate a CMOS load. The 100 nF capacitor at the V pin of the TPS3801 is recommended for all applications. The oscilloscope records the measurement data for the plot. TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 12: Threshold Overdrive Versus Pulsewidth
Voltage Supervision at the V Terminal V DD and RESET V DD and RESET RESET Figure 8. Measurement of the Voltage Drop at V A delay time of 232 ms is measured. This parameter is specified between 120 ms minimum value and 280 ms maximum value with a typical value of 200 ms. This wide range is because of variations in the process. -
Page 13: Breakdown Voltage Versus Pulsewidth At A Tps380Xi50
– Time – µs Figure 9. Breakdown Voltage versus Pulsewidth at a TPS380xI50 V IT = 2.25 V t – Time – µs Figure 10. Breakdown Voltage versus Pulsewidth at a TPS380xJ25 TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 14: Making The Supervisor Circuit Less Sensitive
RESET TPS3801J25 C = 100 nF Figure 11. TPS3801 With a Low Pass Filter at V Terminal Care has to be so taken that the additional resistor does not alter the threshold voltage too much. The threshold voltage is determined by the internal voltage divider, like shown in the block diagram in Chapter 2. -
Page 15: Manual Reset
0.3 V with a duration of at least 100ns is enough to trigger a reset. For shorter signals at manual reset input, the triggering of a reset can not be assured. TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 16: Saving Current While Using The Manual Reset Function
V . Thereby a steady current flow can be avoided. If a reset should be triggered with a low pulse at manual reset, it should be a short pulse. V DD TPS3801 30 kΩ I MR Reset Logic V MR... -
Page 17: Lateral Current In Dependence Of The Voltage At A Cmos Input Stage
Manual Reset 350.0 300.0 250.0 200.0 150.0 100.0 50.0 –50.0 0.00 1.00 2.00 3.00 4.00 5.00 – V Figure 16. Lateral Current in Dependence of the Voltage at a CMOS Input Stage TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 18: Applications
The manual reset input of the TPS3801 allows a remote power control. This input can be connected with an output of a DSP, which turns the power of a subsystem... -
Page 19: System Power Control With The Tps3801
500 mA. For the measurement , a function generator with a limited output current was used to generate the shape of input voltage. Therefore the output current was limited to 1.5 mA with the 3.3 kΩ resistor . TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 20: Keeping A Low Signal At Reset Output For Voltages Below 1.1
Applications Figure 19. Measurements of Switching Power With A TPS2051 5.3 Keeping a Low Signal at Reset Output for Voltages Below 1.1 V The reset output is defined for supply voltages above 1.1 V. Below this voltage, a low level at RESET cannot be assured, because the internal transistors need a certain voltage level to pull down the output to ground. -
Page 21: Supervising A Customer Defined Threshold Voltage
Applications 5.4 Supervising a Customer Defined Threshold Voltage Both families, TPS3801 and TPS3809, are available with four different fixed threshold voltages, which are 2.25 V, 2.64 V, 2.93 V, and 4.55 V typically. If the customer needs another threshold voltage, it can be adjusted with two external resistors. -
Page 22: Higher Accuracy Supervision
Applications V in 1330 Ω TPS3809J25 V DD I TOTAL I DEVICE Supply of the IC 100 nF RESET Reset Logic 2210 Ω Figure 21. Higher Accuracy Supervision of 3.6 V This application has been built up and tested. The result of the evaluation is the measurement plot in Figure 22. -
Page 23: Worst Case Considerations For Application 1
Now R can be determined to 3.6 V 2.25 V trip 12.3 k Device Values with 1% tolerance are recommended, so the following resistor of the E96 series is well-suited: 12.4 k TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 24: Worst Case Considerations For Application 2
Applications V in 12.4 kΩ TPS3809J25 V DD I TOTAL I DEVICE Supply of the IC 100 nF RESET Reset Logic 22.5 kΩ Figure 23. Supervision of 3.6 V With Less Current Consumption 5.4.4 Worst Case Considerations for Application 2 The following assumptions have been made: Resistors with 1% tolerance are used and a supply current over process and temperature of 7 µA to 13 µA. -
Page 25: Mechanical Data And Layout Considerations
More detailed information about mechanical data can be found on the internet on the page: http://www.ti.com/sc/docs/psheets/mechanic/D.htm Choose DCK for pico package (TPS3801) and DBV – 3 Pins for SOT23-3 package (TPS3809). TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors... -
Page 26: Layout Considerations
(star-shape connection). Locate the supervisor circuit in an interference-free environment. The following two figures show layouts with the TPS3801 and TPS3809. The used capacitor is in a 0805-package ( L x W x H : 2 mm 1.25 mm 0.45 mm). -
Page 27: Summary
Summary 7 Summary The TPS3801 and TPS3809 have a very accurate voltage detection for the most common supply voltages. If the supply voltage falls below a specified threshold voltage the reset output becomes active. A defined reset signal is delivered from 1.1 V. - Page 28 SLVA075...