TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 features typical applications D D D D D D D D Window-Watchdog With Programmable Delay and Window Ratio 6-Pin SOT-23 Package Supply Current of 9 µA (Typ) Power On Reset Generator With a Fixed Delay Time of 25 ms Precision Supply Voltage Monitor 2.5 V, 3 V, 3.3 V, 5 V Open-Drain Reset Output Temperature Range . . . –40°C to 85°C D D D Applications Using DSPs, Microcontrollers, or Microprocessors Safety Critical Systems Automotive Systems Heating Systems TPS3813 DBV PACKAGE (TOP VIEW) description The TPS3813 family of supervisory circuits provides circuit initialization and timing supervision, primarily for DSPs and processor-based systems. WDI 1 6 RESET GND 2 5 WDR WDT 3 4 VDD ACTUAL SIZE 3,00 mm x 3,00 mm During power on, RESET is asserted when supply voltage (VDD) becomes higher than 1.1 V. There after, the supervisory circuit monitors VDD and keeps RESET active as long as VDD remains below the threshold voltage (VIT). An internal timer delays the return of the output to the inactive state (high) to ensure proper system reset. The delay time, td = 25 ms typical, starts after VDD has risen above the threshold voltage (VIT). When the supply voltage drops below the threshold voltage (VIT), the output becomes active (low) again. No external components are required. All the devices of this family have a fixed-sense threshold voltage (VIT) set by an internal voltage divider. For safety critical applications the TPS3813 family incorporates a so-called window-watchdog with programmable delay and window ratio. The upper limit of the watchdog time-out can be set by either connecting WDT to GND, VDD, or using an external capacitor. The lower limit and thus the window ratio is set by connecting WDR to GND or VDD. The supervised processor now needs to trigger the TPS3813 within this window not to assert a RESET. typical operating circuit VDD 0.1 µF 0.1 µF R VDD WDR RESET VDD RESET TPS3813 WDT CWP WDI GND uC I/O GND Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 2001, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 description continued The product spectrum is designed for supply voltages of 2.5 V, 3 V, 3.3 V, and 5 V. The circuits are available in a 6-pin SOT–23 package. The TPS3813 devices are characterized for operation over a temperature range of –40°C to 85°C. PACKAGE INFORMATION DEVICE NAME THRESHOLD VOLTAGE MARKING TPS3813J25DBV 2.25 V PCDI PEZI TA –40 40_C to 85_C TPS3813L30DBV 2.64 V TPS3813K33DBV 2.93 V PFAI TPS3813I50DBV 4.55 V PFBI ordering information TPS381 3 J 25 DBV R Reel Package Nominal Supply Voltage Nominal Threshold Voltage Functionality Family TPS3813 FUNCTION/TRUTH TABLE VDD > VIT 0 RESET 1 H L functional schematic RESET Oscillator WDT Reset Logic and Timer Detection Circuit VDD GND Power to circuitry Watchdog Ratio Detection R1 + _ WDR R2 GND GND Bandgap Voltage Reference Rising Edge Detection GND 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 WDI TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 timing diagram VDD VIT 0.6 V t td td td RESET Output Condition Undefined Output Condition Undefined t WDI t 1st Window Without Lower Boundary 2nd Window With Lower Boundary 3rd Window With Lower Boundary Trigger Pulse 1st Window Lower Window Without Lower 2nd Window 1st Window Boundary Boundary With Lower Without Lower Boundary Boundary 3rd Window With Lower Boundary The lower boundary of the watchdog window starts with the rising edge of the WDI trigger pulse. At the same time, all internal timers will be reset. If an external capacitor is used, the lower boundary is impacted due to the different oscillator frequency. This is described in more detail in the following section. The timing diagram and especially the shaded boundary is prepared in a nonreal ratio scale to better visualize the description. Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION GND 2 I Ground RESET 6 O Open-drain reset output VDD WDI 4 I Supply voltage and supervising input 1 I Watchdog timer input WDR 5 I Selectable watchdog window ratio input WDT 3 I Programmable watchdog delay input POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 3 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 detailed description implemented window-watchdog settings There are two different ways to set up the watchdog window. The first way is to use the implemented timing which is a default setting. Or, the default settings can be activated by wiring the WDT and WDR pin to VDD or GND. There is a total of four different timings available with these settings. They are listed in the table below. WINDOW FRAME SELECTED OPERATION MODE WDR = 0 V WDT = 0 V WDR = VDD WDR = 0 V WDT = VDD WDR = VDD LOWER WINDOW FRAME Max = 0.3 s Max = 9.46 ms Typ = 0.25 s Typ = 7.86 ms Min = 0.2 s Min = 6.27 ms Max = 0.3 s Max = 2.43 ms Typ = 0.25 s Typ = 2 ms Min = 0.2 s Min = 1.58 ms Max = 3 s Max = 93.8 ms Typ = 2.5 s Typ = 78.2 ms Min = 2 s Min = 62.5 ms Max = 3 s Max = 23.5 ms Typ = 2.5 s Typ = 19.6 ms Min = 2 s Min = 15.6 ms To visualize the values named in the table, a timing diagram was prepared. It is used to describe the upper and lower boundary settings. For an application, the important boundaries are the tboundary,max and twindow,min. Within these values, the watchdog timer should be retriggered to avoid a timeout condition or a boundary violation in the event of a trigger pulse in the lower boundary. The values in the table above are typical and worst case conditions. They are valid over the whole temperature range of –40°C to 85°C. In the shaded area of Figure 1, it cannot be predicted if the device will detect a violation or not and release a reset. This is also the case between the boundary tolerance of tboundary,min and tboundary,max as well as between twindow,min and twindow,max. It is important to set up the trigger pulses accordingly to avoid violations in these areas. WDI Detection of Rising Edge tboundary, min tboundary, max ÎÎ ÎÎ ÎÎ ÎÎ Window Frame to Reset the WDI tboundary, typ twindow, typ twindow, min twindow, max Figure 1. Upper and Lower Boundary Visualization 4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 ÎÎ ÎÎ ÎÎ ÎÎ t TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 detailed description (continued) timing rules of window-watchdog After the reset of the supervisor is released, the lower boundary of the first WDI window is disabled. However, after the first WDI pulse low-to-high transition is detected, the lower boundary function of the window is enabled. All further WDI pulses will need to fit into the configured window frame. programmable window-watchdog by using an external capacitor The upper boundary of the watchdog timer can be set by an external capacitor connected between the WDT pin and GND. Common consumer electronic capacitors can be used to implement this feature. They should have low ESR and low tolerances since the tolerances have to be considered if the calculations are performed. The first formula is used to calculate the upper window frame. After calculating the upper window frame, the lower boundary can be calculated. As in the last example, the most important values are the tboundary,max and twindow,min. The trigger pulse has to fit into this window frame. The external capacitor should have a value between a minimum of 47 pF and a maximum of 63 nF. SELECTED OPERATION MODE WDT = external capacitor C((ext) t) t + window,typ ǒ Ǔ WINDOW FRAME twindow,max = 1.25 × twindow,typ twindow,min = 0.75 × twindow,typ WDR = 0 V and WDR = VDD C (ext) 15.55 pF )1 6.25 ms lower boundary calculation The lower boundary can be calculated based on the values given in the switching characteristics. Additionally, facts have to be taken into account to verify that the lower boundary is where it is expected. Since the internal oscillator of the window watchdog is running free, any rising edge at the WDI pin will be taken into account at the next internal clock cycle. This happens regardless of the external source. Since the shift between internal and external clock is not known, it is best to consider the worst case condition for calculating this value. SELECTED OPERATION MODE WDR = 0 V LOWER BOUNDRY OF FRAME tboundary,max = twindow,max / 23.5 tboundary,typ = twindow,typ / 25.8 tboundary,min = twindow,min / 28.7 tboundary,max = twindow,max / 51.6 WDT = external capacitor C((ext) t) WDR = VDD tboundary,typ = twindow,typ / 64.5 tboundary,min = twindow,min / 92.7 watchdog software considerations To benefit from the window watchdog feature and help the watchdog timer monitor the software execution more closely, it is recommended that the watchdog be set and reset at different points in the program rather than pulsing the watchdog input periodically by using the prescaler of a microcontroller or DSP. Furthermore, the watchdog trigger pulses should be set to different timings inside the window frame to release a defined reset, if the program should hang in any subroutine. This allows the window watchdog to detect timeouts of the trigger pulse as well as pulses that distort the lower boundary. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 detailed description (continued) application example A typical application example (see Figure 2) is used to describe the function of the watchdog in more detail. To configure the window watchdog function, two pins are provided by the TPS3813. These pins set the window timeout and ratio. The window watchdog ratio is a fixed ratio, which determines the lower boundary of the window frame. It can be configured in two different frame sizes. If the window watchdog ratio pin (WDR) is set to VDD, Position 1 in Figure 2, then the lower window frame is a value based on a ratio calculation of the overall window timeout size: For the watchdog timeout pin (WDT) connected to GND, it is a ratio of 1:124.9, for WDT connected to VDD, it is a ratio of 1:127.7, and for an external capacitor connected to WDT, it is a ratio of 1:64.5. If the window watchdog ratio pin (WDR) is set to GND, Position 2, the lower window frame will be a value based on a ratio calculation of the overall window timeout size: For the watchdog timeout pin (WDT) connected to GND, it will be a ratio of 1:31.8, for WDT connected to VDD it will be 1:32, and for an external capacitor connected to WDT it will be 1:25.8. The watchdog timeout can be set in two fixed timings of 0.25 seconds and 2.5 seconds for the window or can by programmed by connecting a external capacitor with a low leakage current at WDT. Example: If the watchdog timeout pin (WDT) is connected to VDD, the timeout will be 2.5 seconds. If the window watchdog ratio pin (WDR) is set in this configuration to a ratio of 1:127.7 by connecting the pin to VDD, the lower boundary is 19.6 ms. VDD 0.1 µF 0.1 µF VDD R Position 1 See Note A Position 2 See Note B NOTES: A. B. C. D. E. VDD RESET WDR WDT Position 5 See Note E Position 3 See Note C uC WDI GND VDD Watchdog window ratio Watchdog window ratio Watchdog timeout set to typical 2.5 sec Watchdog timeout programmed by external capacitor Watchdog timeout set to typical 0.25 sec Figure 2. Application Example 6 RESET TPS3813 Position 4 See Note D C(ext) VDD POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 I/O GND TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 absolute maximum ratings over operating free-air temperature (unless otherwise noted)† Supply voltage, VDD (see Note1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V All other pins (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 7 V Maximum low output current, IOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 mA Maximum high output current, IOH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –5 mA Input clamp current, IIK (VI < 0 or VI > VDD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA Output clamp current, IOK (VO < 0 or VO > VDD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 85°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C Soldering temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTE 1: All voltage values are with respect to GND. For reliable operation the device should not be operated at 7 V for more than t = 1000h continuously. DISSIPATION RATING TABLE PACKAGE TA <25°C POWER RATING DERATING FACTOR ABOVE TA = 25°C TA = 70°C POWER RATING TA = 85°C POWER RATING DBV 437 mW 3.5 mW/°C 280 mW 227 mW recommended operating conditions at specified temperature range MIN MAX UNIT Supply voltage, VDD 2 6 V Input voltage, VI 0 VDD + 0.3 V High-level input voltage, VIH 0.7 x VDD Low-level input voltage, VIL Input transition rise and fall rate, ∆t/∆V Pulse width of WDI trigger pulse, tw 50 Operating free-air temperature range, TA –40 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 V 0.3 x VDD V 100 ns/V 85 °C ns 7 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 electrical characteristics over recommended operating free-air temperature range (unless otherwise noted) PARAMETER VOL VIT TEST CONDITIONS Low-level output voltage VDD = 2 V to 6 V, VDD = 3.3 V Power up reset voltage (see Note 2) VDD = 6 V, VDD ≥ 1.1 V, Negative g -ggoingg input threshold voltage (see Note 3) Hysteresis High-level input current IIL Low level input current Low-level IOH High-level output current IDD MAX IOL = 2 mA IOL = 4 mA IOL= 50 µA 0.4 V V 2.2 2.25 2.3 2.58 2.64 2.7 2.87 2.93 3 4.45 4.55 4.65 TA = –40°C 40°C – 85°C TPS3813J25 30 TPS3813L30 35 TPS3813K33 40 TPS3813I50 60 WDI = VDD = 6 V, WDR = VDD = 6 V WDT = VDD = 6 V, VDD > VIT RESET = High WDT WDI, WDR WDI = 0 V, WDR = 0 V, VDD = 6 V WDT WDT = 0 V, VDD > VIT, RESET = High mV –25 25 –100 100 –25 25 –100 100 nA VDD = VIT + 0.2 V, VOH = VDD VDD = 2 V output unconnected Supply current V 0.2 TPS3813L30 TPS3813K33 UNIT 0.4 TPS3813J25 WDI, WDR IIH TYP 0.2 TPS3813I50 Vhys MIN IOL = 500 µA 25 VDD = 5 V output unconnected VI = 0 V to VDD 9 13 20 25 nA µA Ci Input capacitance 5 pF NOTES: 2. The lowest supply voltage at which RESET becomes active. tr,VDD ≥ 15 µs/V. 3. To ensure best stability of the threshold voltage, a bypass capacitor (ceramic, 0.1 µF) should be placed near to the supply terminals. timing requirements at RL = 1 MΩ, CL = 50 pF, TA = –40°C to 85°C PARAMETER tw TEST CONDITIONS Pulse width at VDD VDD = VIT– + 0.2 V, MIN VDD = VIT– – 0.2 V TYP MAX UNIT µs 3 switching characteristics at RL = 1 MΩ, CL = 50 pF, TA = –40°C to 85°C PARAMETER td tt(out) TEST CONDITIONS VDD ≥ VIT + 0.2 V, See timing diagram WDT = 0 V Delay time Watchdog time-out Upper U er limit WDT = VDD Propagation (delay) time, high-to-low-level output 0.2 0.25 0.3 2 2.5 3 1:31.8 1:124.9 1:127.7 VIH = VIT + 0.2 V POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 ms s ms 1:32 WDR = VDD, WDT = VDD VIL = VIT – 0.2 V, UNIT 1:25.8 WDR = VDD, WDT = 0 V NOTES: 4. 155 pF < C(ext) < 63 nF 5. (C(ext) ÷ 15.55 pF + 1) x 6.25 ms 8 30 WDR = 0 V, WDT = 0 V WDR = 0 V, WDT = programmable VDD to RESET delay MAX 25 See Note 5 WDR = VDD, WDT = programmable tPHL TYP 20 WDT = programmable (see Note 4) WDR = 0 V, WDT = VDD Watchdog window ratio MIN 1:64.5 30 50 µs TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 TYPICAL CHARACTERISTICS LOW-LEVEL OUTPUT VOLTAGE vs LOW-LEVEL OUTPUT CURRENT SUPPLY CURRENT vs SUPPLY VOLTAGE 2 20 I DD – Supply Current – µ A 18 VOL – Low-Level Output Voltage – V WDI = GND, WDT = GND, WDR = GND 16 85°C 14 12 25°C 10 8 –40°C 6 0°C 4 1.50 25°C 1.25 1 0.75 85°C 0°C 0.50 –40°C 0.25 2 0 VDD = 2 V, WDI = GND, WDT = GND, WDR = GND 1.75 0 1 2 3 4 5 0 6 0 1 Figure 3 VIT – Normalized Input Threshold Voltage – V (25 ° C) 800 I – Input Current – nA 25°C 400 85°C 0°C 0 –200 –40°C –400 I VDD = 6 V, WDI = GND, WDR = GND –600 –800 –1000 0 1 2 3 4 5 6 7 NORMALIZED INPUT THRESHOLD VOLTAGE vs FREE-AIR TEMPERATURE AT VDD 1000 200 3 Figure 4 INPUT CURRENT vs INPUT VOLTAGE AT WDT 600 2 IOL – Low-Level Output Current – mA VDD – Supply Voltage – V 4 5 6 VI – Input Voltage at WDT – V 1.001 1.000 0.999 0.998 0.997 WDI = Triggered, WDR = GND, WDT = GND 0.996 0.995 –40 –20 0 20 40 60 80 TA – Free-Air Temperature At VDD – °C Figure 5 Figure 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 9 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 TYPICAL CHARACTERISTICS MINIMUM PULSE DURATION AT VDD vs VDD THRESHOLD OVERDRIVE VOLTAGE t W – Minimum Pulse Duration at VDD – µ s 20 18 16 14 12 10 8 6 4 2 0 0 0.2 0.4 0.6 0.8 1 1.2 VDD – Threshold Overdrive Voltage – V Figure 7 10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1.4 TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50 PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG SLVS331A – DECEMBER 2000 – REVISED APRIL 2001 MECHANICAL DATA DBV (R-PDSO-G6) PLASTIC SMALL-OUTLINE 0,95 6X 6 0,50 0,25 0,20 M 4 1,70 1,50 1 0,15 NOM 3,00 2,60 3 Gage Plane 3,00 2,80 0,25 0°–8° 0,55 0,35 Seating Plane 1,45 0,95 0,05 MIN 0,10 4073253-5/F 10/00 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion. Leads 1, 2, 3 are wider than leads 4, 5, 6 for package orientation. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 11 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 acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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