Overview
The BQ24450DWTR from Texas Instruments is a standalone integrated charge controller specifically designed for the optimal charging of valve-regulated lead-acid batteries. This IC contains all the necessary circuitry to safely and efficiently charge the battery, maximizing its capacity and life. It can be configured in various modes, including constant-voltage float charge, dual-voltage float-cum-boost charge, and dual-step current charge. The BQ24450DWTR is notable for its precision temperature-compensated voltage reference, which tracks the characteristics of lead-acid cells over a wide temperature range, ensuring optimal charging conditions without the need for external components.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage (VIN) | -0.3 | - | 40 | V |
| Input Current (IIN) at VIN = 10V | 1.6 | 3.3 | 3.6 | mA |
| Internal Reference Voltage (VREF) at 25°C | 2.275 | 2.300 | 2.325 | V |
| Temperature Coefficient of VREF | -3.5 | - | - | mV/°C |
| Output Current (DRVC, DRVE) | -80 | - | 80 | mA |
| Power Dissipation at TA = 25°C | - | - | 1000 | mW |
| Junction Temperature (TJ) | -40 | - | 150 | °C |
| Storage Temperature (TSTG) | -65 | - | 150 | °C |
Key Features
- Precision Temperature-Compensated Reference: The IC features a precision voltage reference that is temperature-compensated to track the characteristics of lead-acid cells, ensuring optimal charging voltage over a wide temperature range.
- Minimum External Components: The BQ24450DWTR requires only an external pass transistor and a minimal number of external passive components to implement a charger for sealed lead-acid batteries.
- Configurable Charging Modes: The IC can be configured as a simple constant-voltage float charge controller, a dual-voltage float-cum-boost charge controller, or a dual-step current charger.
- Low Current Consumption: The IC operates with low supply current, minimizing on-chip dissipation and allowing accurate temperature monitoring by avoiding self-heating effects.
- Pre-Charge Capability: The IC includes a pre-charge feature to safely charge deeply discharged batteries before switching to full charge current.
- Undervoltage Lock-Out (UVLO): An undervoltage lock-out circuit disables the driver transistor until the input voltage reaches a safe threshold.
- Support for Various Pass Transistors: The driver transistor can support both NPN and PNP pass transistors, providing flexibility in charger design.
Applications
- Emergency Lighting Systems: Ensures reliable battery charging for emergency lighting systems.
- Security and Alarm Systems: Provides optimal battery charging for security and alarm systems.
- Telecommunication Backup Power: Used in backup power systems for telecommunications equipment.
- Uninterruptible Power Supplies (UPS): Ensures battery health and longevity in UPS systems.
Q & A
- What is the primary function of the BQ24450DWTR?
The BQ24450DWTR is a standalone integrated charge controller designed to optimally control the charging of valve-regulated lead-acid batteries.
- What types of charging modes can the BQ24450DWTR be configured for?
The IC can be configured as a constant-voltage float charge controller, a dual-voltage float-cum-boost charge controller, or a dual-step current charger.
- What is the significance of the precision temperature-compensated reference in the BQ24450DWTR?
The precision temperature-compensated reference ensures that the charging voltage tracks the characteristics of lead-acid cells over a wide temperature range, optimizing battery charging.
- How does the BQ24450DWTR handle deeply discharged batteries?
The IC includes a pre-charge feature that safely charges deeply discharged batteries before switching to full charge current.
- What is the purpose of the undervoltage lock-out (UVLO) circuit in the BQ24450DWTR?
The UVLO circuit disables the driver transistor until the input voltage reaches a safe threshold, preventing damage to the system.
- Can the BQ24450DWTR support different types of pass transistors?
Yes, the driver transistor in the BQ24450DWTR can support both NPN and PNP pass transistors.
- What are some common applications of the BQ24450DWTR?
Common applications include emergency lighting systems, security and alarm systems, telecommunication backup power, and uninterruptible power supplies (UPS).
- What is the typical operating current of the BQ24450DWTR?
The typical operating current is 1.6 mA to 3.6 mA, depending on the input voltage and temperature.
- What is the junction temperature range for the BQ24450DWTR?
The junction temperature range is -40°C to 150°C.
- How does the BQ24450DWTR minimize self-heating effects?
The IC operates with low supply current, minimizing on-chip dissipation and allowing accurate temperature monitoring by avoiding self-heating effects.
