Frequent Questions

  • [FAQ] BQ2517x: When does the BQ25172 (NiMH) start or refuse to start a charging cycle, and how does the recharge voltage threshold (VRECHG) work? BQ25172 BQ25171-Q1

    Part Number: BQ25172 At power-up and after each charge cycle, the BQ25172 checks the battery voltage against VRECHG = 1.33V/cell : Battery voltage < VRECHG: Charging starts immediately (full charge cycle). Battery voltage > VRECHG: Battery is…

  • [FAQ] BQ2517x: How does the BQ2517x terminate a NiMH charge cycle, and why doesn't it use −DeltaV detection? BQ25172, BQ25171-Q1

    Part Number: BQ25172 Other Parts Discussed in Thread: BQ25171-Q1 , The BQ2517x NiMH chargers (BQ25172, BQ25171-Q1) use a timer-based termination method. Charging ends when: The safety/charge timer expires (set by TMR resistor; range 4–22 hours…

  • [FAQ] BQ2517x: Why does charge current appear lower than configured, and how can this be verified? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 Reduced charge current is most commonly caused by thermal regulation (TREG) limiting output current to protect the die. Other causes include: A current meter (ammeter) placed in series with the output — even a low-resistance…

  • [FAQ] BQ2517x: How should the PCB be designed to minimize heating of BQ2517x devices? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 Because the BQ2517x ICs are linear regulators, thermal PCB layout is critical: Exposed thermal pad: Must be soldered to GND with good coverage. Thermal vias: Use multiple vias near/under the IC to connect top-side copper…

  • [FAQ] BQ2517x: Why does the charge current become lower than configured, and what is thermal regulation (TREG)? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 The BQ2517x family are linear (LDO) chargers . Power dissipation = (VIN − VOUT) × IOUT. When this dissipation causes the die temperature to reach ~125°C (TREG threshold), the device automatically reduces output current to prevent…

  • [FAQ] BQ2517x: What is the correct STAT pin behavior and what voltage reference should be used for the STAT pin pull-up? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 STAT pin states (open-drain, active low): Charging in progress: STAT pulled LOW (LED on if pull-up connected) Charge complete / Standby: STAT HIGH (LED off) Fault (VIN OVP, BAT OVP, BAT OCP): STAT blinks at 1Hz Thermal…

  • [FAQ] BQ2517x: Why does the STAT pin behave unexpectedly (always ON or cycling) when no battery is connected? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 When no battery is connected, the BQ2517x family does not have a battery detection feature. Instead, the IC charges the output capacitor toward the BAT OVP threshold, then shuts off. The output capacitor discharges back through…

  • [FAQ] BQ2517x: What causes the STAT pin to blink at 1Hz, and does it continue blinking as long as the fault persists? BQ25171-Q1, BQ25173-Q1, BQ25170, BQ25172, BQ25173, BQ25176J, BQ25176K, BQ25176M, BQ25175

    Part Number: BQ25172 The STAT pin blinks at 1Hz to indicate a fault condition. Fault conditions that trigger 1Hz blinking include: VIN OVP, BAT OVP, BAT OCP, and Open/Short on VSET, ISET, or TMR pins. When no battery is connected, the output capacitor…

  • [FAQ] FAQ: TPS3424 and TPS3423 Push-Button ordering options

    Part Number: TPS3424 Other Parts Discussed in Thread: TPS3423 , Please provide a decoder for TPS3424 and TPS3423 orderables.

  • [FAQ] AM6XX:How to Port SBL UART UNIFLASH for a custom board

    Part Number: AM62x Other Parts Discussed in Thread: UNIFLASH , AM62P The UART UNIFLASH tool provided in the MCU+SDK will only work for TI EVMs out of the box as it is configured according to Flash and DDR part used in a particular EVM, this FAQ provides…

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