When CPU is running in turbo mode, the system peak power can exceed available power from adapter and battery together. The adapter current and battery discharge peak current, or system voltage drop is an indication that system power is too high. The charger processor hot function monitors these events, and PROCHOT pulse is asserted if the system power is too high. Once the CPU receives the PROCHOT pulse from the charger, the CPU slows down to reduce system power. The events monitored by the processor hot function include:

• ICRIT: adapter peak current, as 110% of I_LIM2
• INOM: adapter average current (110% of IIN_DPM)
• IDCHG1: battery discharge current level 1
• IDCHG2: battery discharge current level 2. Note that IDCHG2 threshold is always larger than IDCHG1 threshold, determined by IDCHG_TH2 register setting.
• VBUS_VAP: VBUS threshold to trigger PROCHOT in VAP mode
• VSYS: system voltage on VSYS.
• Adapter Removal: (When the adapter is removed, the prochot pin PROCHOT activates a single falling edge trigger when the VBUS falls below V_{VBUS_CONVENZ} and deglitch time is within 1μs. If triggered, the STAT_ADAPTER_REMOVAL bit is set to 1b, the bit is high until clear through host read or REG_RESET bit. The status bit is level trigger which means if VBUS is still below V_{VBUS_CONVENZ} when status bit gets cleared, then the status bit must be triggered again immediately)
• Battery Removal: (When the battery is removed, the prochot pin PROCHOT activates a single falling edge trigger when CELL_BATPRES pin voltage falls below V_{CELL_BATPRES_FALL} threshold and deglitch time is within 1μs. If triggered, the STAT_BATTERY_REMOVAL bit is set to 1b, the pin is locked until clear through host read or REG_RESET bit. The status bit is also falling edge trigger which means if CELL_BATPRES pin is still below V_{CELL_BATPRES_FALL} when status bit gets cleared, the status bit is still cleared to 0b)
• CMPOUT: Independent comparator output (CMPOUT pin HIGH to LOW)
• VINDPM: VBUS lower than 83%/91%/100% of VINDPM setting. The effective threshold PROCHOT_VINDPM is determined by combination of register PROCHOT_VINDPM_80_90 bit and LOWER_PROCHOT_VINDPM bit:
  • PROCHOT_VINDPM=VINDPM register setting: LOWER_PROCHOT_VINDPM=0b;
  • PROCHOT_VINDPM=83% VINDPM register setting: LOWER_PROCHOT_VINDPM=1b;PROCHOT_VINDPM_80_90=0b;
  • PROCHOT_VINDPM=91% VINDPM register setting: LOWER_PROCHOT_VINDPM=1b;PROCHOT_VINDPM_80_90=1b;
• EXIT_VAP: Every time when the charger exits VAP mode.
• THERMAL: If enabled (PP_THERMAL=1b), then when the CMPIN_TR pin voltage is lower than V_{TREG_PP} for 1s/100ms (THERMAL_DEG bit configurable) deglitch time. Then STAT_THERMAL is latched until clear through a host read or REG_RESET bit.

The thresholds of ICRIT, IDCHG1,IDCHG2,VSYS or VINDPM, and the deglitch times of ICRIT, INOM, IDCHG1, IDCHG2, or CMPOUT are programmable. Except for the PROCHOT_EXIT_VAP which is always enabled, the other triggering events can be individually enabled in ProchotOption1[7:0], PP_IDCHG2 and PP_VBUS_VAP. When any enabled event in PROCHOT profile is triggered, PROCHOT is asserted low for a single pulse with minimal width  programmable in PROCHOT_WIDTH register bits. At the end of the single pulse, if the PROCHOT event is still active, the pulse gets extended until the event is removed.

If the PROCHOT pulse extension mode is enabled by setting EN_PROCHOT_EXT= 1b, the PROCHOT pin is kept low until the host writes PROCHOT_CLEAR= 1b, even if the triggering event has been removed.

If the PROCHOT_VINDPM or PROCHOT_EXIT_VAP is triggered, the PROCHOT pin always stay low until the host clears the pin, regardless of whether the PROCHOT is in one pulse mode or in extended mode. To clear PROCHOT_VINDPM, the host needs to write a 0 to STAT_VINDPM. To clear PROCHOT_EXIT_VAP, the host needs to write a 0 to STAT_EXIT_VAP.

Figure 7-10 PROCHOT Profile