Test Procedures

The bq2400x enters preconditioning mode if the battery is below the LowV threshold. In this mode, the bq2400x trickle-charges with approximately 65 mA for approximately 23 minutes. If the battery does not reach the LowV threshold after this period, then the charge current is terminated and the bq2400x enters fault mode. The red LED flashes in fault mode. This feature is tested in the 0.5-A charge mode by using a 10-Ω , 5-W resistor in place of the battery. Fault mode is reset by toggling input power or enable pin.

Once the battery charges to the LowV-stop threshold, the battery enters fast charge mode and charges at the selected Ichg level (0.5 A/1 A).

The battery remains at the fast charge mode until either the selected time expires or the battery charges to the selected regulation voltage.

The timeout feature is tested in the 0.5-A charge mode by using a 14-Ω , 5-W resistor in place of the battery. Apply the resistor after the unit is powered up.

Once the battery voltage reaches voltage regulation (8.2 or 8.4 VDC), the charge current tapers off as the battery charges.

If the battery discharges down to the HighV threshold, the charger starts fast charging. The refresh feature is tested, in the 0.5-A charge mode, by using a 14-Ω 5-W resistor in parallel with a fully charged battery.

The circuit has an overvoltage comparator for added protection. If the battery voltage exceeds this threshold for 330 ms, then the charger goes into fault mode. This process may be tested by connecting an external power supply in place of the battery and adjusting the voltage above the threshold.

2-4

SLUU083A specifications

Texas Instruments SLUU083A, technically known as the "Application Report: PFC Design With TL497," is a seminal document that provides comprehensive insights into the design and implementation of power factor correction (PFC) circuits using the TL497 PWM controller. This application report is crucial for engineers focused on enhancing power efficiency in various applications, particularly in consumer electronics and industrial equipment.

One of the main features of the SLUU083A report is its detailed exploration of power factor correction, which helps in reducing energy consumption and minimizing the impact of harmonic distortion on electrical systems. The document outlines PFC methodologies that comply with international standards and regulatory requirements, ensuring that designers can create products that meet strict energy efficiency regulations.

The report introduces the TL497 as a versatile PWM controller that plays a pivotal role in managing power conversion processes. This controller offers features like a wide input voltage range, making it suitable for various applications from 85V AC to 265V AC. It also incorporates a high degree of integration, which simplifies designs and minimizes the size of PFC circuits.

The application report covers technologies such as continuous conduction mode (CCM) and discontinuous conduction mode (DCM), showcasing the advantages and trade-offs of each mode. Using CCM enhances efficiency under heavy loads, whereas DCM results in reduced power losses at light loads, presenting designers with options tailored to their specific requirements.

Another noteworthy characteristic of the SLUU083A report is its emphasis on component selection and layout guidelines that optimize performance and reliability. The report provides helpful calculations and design examples, illustrating how to achieve a desired output voltage and minimize losses.

In conclusion, Texas Instruments SLUU083A serves as an essential resource for engineers designing PFC circuits with the TL497 PWM controller. Its emphasis on efficiency, regulatory compliance, and practical design considerations makes it a valuable reference in the field of power management. The integration of innovative technologies and robust guidelines ensures that designers can create systems that not only comply with regulations but also provide reliable and effective power conversion. This combination of features and characteristics establishes SLUU083A as a go-to document for advancing power efficiency solutions in diverse applications.