Datasheet ATA663431, ATA663454 (Microchip) - 14

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ATA663431/54 1.6 Watchdog
it is possible to switch on some external devices in the case of a watchdog failure independent from the The watchdog anticipates a trigger signal from the microcontroller and the VCC voltage. During power up microcontroller at the NTRIG (negative edge) input or after a wake-up from Sleep mode the LH output is within a time window of twd. The trigger signal must switched off. If a watchdog reset occurs, the LH output exceed a minimum time of ttrigmin > 200 ns. If a trigger transistor switches on immediately, and it switches off signal is not received, a reset signal is generated at only after three correct consecutive watchdog trigger output NRES and the LH output transistor switches on. pulses have been occurred at the NTRIG pin. The timing basis of the watchdog is provided by the internal oscil ator. Its time period t As the watchdog is only working in Normal mode and osc is adjustable via the external resistor R Fail-Safe mode, the state of the LH output transistor WDOSC (34 kΩ to 120 kΩ). During Silent mode or Sleep mode the watchdog is switched can change only in these two modes. In Silent mode, off to reduce current consumption. The minimum time the LH output remains in the same state as it was for the first watchdog pulse is required after the before switching into Silent mode. When the watchdog undervoltage reset at NRES disappears. It is defined is disabled via a high level at the mode pin or during as lead time t Sleep or Unpowered mode, the LH output is also d. After wake-up from Sleep mode, the lead time t disabled. d starts with the rising edge at the NRES output. After a wake-up from Silent mode, the lead time The behavior of the LH output when the watchdog is td starts with the falling edge at the TXD pin. active during Fail-Safe mode and Normal mode is The Limp Home output LH is a high voltage NMOS depicted in
Figure 1-14
. open drain structure which is signaling watchdog failures. It works independently of the VCC voltage. So
FIGURE 1-14: LIMP HOME (LH) STATE DIAGRAM
3rd Trigger LH OFF LH Set Active State State 0 3 wd_reset Power-up or wake-up from sleep mode wd_reset 2nd Trigger wd_reset LH Set Active LH Set Active State 0: LH output is switched OFF 1st Trigger State 1: LH output is switched ON State State State 2: LH output is switched ON 1 2 State 3: LH output is switched ON In Sleep mode and Unpowered mode, the watchdog and therefore the LH output are deactivated. In Silent mode the LH output remains in the same state as it was before switching into Silent mode. DS50002820B-page 14  2018 Microchip Technology Inc. Document Outline Features General Description Package Types Block Diagram 1.0 Functional Description 1.1 Physical Layer Compatibility 1.2 Operating Modes FIGURE 1-1: Operating Modes TABLE 1-1: Operating Modes (Mode Pin Is Always Low) 1.2.1 Normal Mode 1.2.2 Silent Mode FIGURE 1-2: Switching to Silent mode 1.2.3 Sleep Mode FIGURE 1-3: Switching to Sleep Mode 1.2.4 Fail-Safe mode TABLE 1-2: Signaling in Fail-safe Mode 1.3 Wake-up Scenarios from Silent Mode or Sleep Mode 1.3.1 Remote Wake-up via LIN Bus 1.3.1.1 Remote Wake-up from Silent Mode FIGURE 1-4: LIN Wake-up from Silent Mode 1.3.1.2 Remote Wake-up from Sleep Mode FIGURE 1-5: LIN Wake-up from Sleep Mode 1.3.2 Local Wake-up via WKin Pin FIGURE 1-6: Local Wake-up via WKin pin from Sleep Mode FIGURE 1-7: Local Wake-up via WKin pin from Silent Mode 1.3.3 Local Wake-up via CL15 1.3.4 Wake-up Source Recognition TABLE 1-3: Signaling in Fail-Safe Mode 1.4 Behavior under Low Supply Voltage Conditions FIGURE 1-8: VCC and NRES versus VS (Ramp-up) for ATA663431 FIGURE 1-9: VCC and NRES versus VS (Ramp-down) for ATA663431 FIGURE 1-10: VCC and NRES versus VS (Ramp-up) for ATA663454 FIGURE 1-11: VCC and NRES versus VS (Ramp-Down) for ATA663454 1.5 Voltage Regulator FIGURE 1-12: VCC Voltage Regulator: Supply Voltage Ramp-up and Ramp-down FIGURE 1-13: Power Dissipation: Safe Operating Area: Regulator’s Output Current IVCC versus Supply Voltage VVS at Different Ambient Temperatures (RthvJA = 45 K/W assumed) 1.6 Watchdog FIGURE 1-14: Limp Home (LH) State Diagram 1.6.1 Typical Timing Sequence with RWDOSC = 51 kΩ EQUATION 1-1: FIGURE 1-15: Timing Sequence with RWDOSC = 51 kΩ 1.6.2 Worst-Case Calculation with RWDOSC = 51 kΩ EQUATION 1-2: TABLE 1-4: Typical Watchdog Timings 1.7 Pin Descriptions TABLE 1-5: Pin Description 1.7.1 Bus Data Output Pin (RXD) 1.7.2 Enable Input Pin (EN) 1.7.3 Undervoltage Reset Output Pin (NRES) 1.7.4 Bus Data Input/Output (TXD) 1.7.5 NTRIG Input Pin 1.7.6 Mode Input Pin (MODE) 1.7.7 WDOSC Output Pin 1.7.8 High-side Switch Pins (HSout, HSin) 1.7.9 Limp Home Watchdog Failure Output (LH) 1.7.10 CL15 Pin 1.7.11 Wake Input Pin (WKin) 1.7.12 Ground Pin (GND) 1.7.13 Bus Pin (LIN) 1.7.14 Supply Pin (VS) 1.7.15 Voltage Regulator Output Pin (VCC) Typical Application Circuit 2.0 Electrical Characteristics 2.1 Absolute Maximum Ratings† Electrical Characteristics FIGURE 2-1: Definition of Bus timing Characteristics Temperature Specifications 3.0 Packaging Information 3.1 Package Marking Information LIN SBC including LIN Transceiver, Voltage Regulator, Window Watchdog and High-Side Switch Appendix A: Revision History Revision A (November 2018) Revision B (November 2018) Product Identification System AMERICAS Corporate Office Atlanta Austin, TX Boston Chicago Dallas Detroit Houston, TX Indianapolis Los Angeles Raleigh, NC New York, NY San Jose, CA Canada - Toronto ASIA/PACIFIC Australia - Sydney China - Beijing China - Chengdu China - Chongqing China - Dongguan China - Guangzhou China - Hangzhou China - Hong Kong SAR China - Nanjing China - Qingdao China - Shanghai China - Shenyang China - Shenzhen China - Suzhou China - Wuhan China - Xian China - Xiamen China - Zhuhai ASIA/PACIFIC India - Bangalore India - New Delhi India - Pune Japan - Osaka Japan - Tokyo Korea - Daegu Korea - Seoul Malaysia - Kuala Lumpur Malaysia - Penang Philippines - Manila Singapore Taiwan - Hsin Chu Taiwan - Kaohsiung Taiwan - Taipei Thailand - Bangkok Vietnam - Ho Chi Minh EUROPE Austria - Wels Denmark - Copenhagen Finland - Espoo France - Paris Germany - Garching Germany - Haan Germany - Heilbronn Germany - Karlsruhe Germany - Munich Germany - Rosenheim Israel - Ra’anana Italy - Milan Italy - Padova Netherlands - Drunen Norway - Trondheim Poland - Warsaw Romania - Bucharest Spain - Madrid Sweden - Gothenberg Sweden - Stockholm UK - Wokingham Worldwide Sales and Service