TLE42502G Low-Drop Voltage Regulator: Technical Overview and Application Circuit Design
The TLE42502G from Infineon Technologies is a monolithic integrated low-drop voltage regulator designed to deliver a fixed 5V output with a maximum current of up to 250mA. Housed in a compact and thermally efficient PG-TO263-5 package, it is particularly suited for automotive and industrial applications where robustness, reliability, and precise voltage regulation are paramount. Its ability to operate with a very low dropout voltage makes it an excellent choice for scenarios where the input voltage is only slightly higher than the regulated output.
A key feature of this LDO is its extremely low quiescent current in normal operation, which minimizes the power loss and is crucial for battery-powered systems. The device incorporates a wide array of internal protection mechanisms, including short-circuit protection, overtemperature shutdown, and reverse polarity protection. Furthermore, an integrated reset circuit with a programmable delay time provides a crucial function for monitoring microcontrollers or processors, ensuring they only start or reset under stable supply voltage conditions.
Typical Application Circuit Design
A standard application circuit for the TLE42502G is straightforward, requiring only a few external components for stable operation.
1. Input Capacitor (C_IN): A ceramic capacitor, typically in the range of 100nF to 1µF, should be placed as close as possible to the input pin (VIN) and ground. This capacitor stabilizes the input voltage and suppresses high-frequency noise.
2. Output Capacitor (C_Q): A capacitor on the output (VQ) is essential for stability and load transient response. The datasheet recommends a minimum value of 1µF with an ESR between 0.1Ω and 10Ω. A standard ceramic capacitor is usually sufficient.
3. Reset Delay Capacitor (C_RD): The timing of the reset output signal (RD) is set by an external capacitor connected to the CRD pin. The reset delay time `t_RD` is calculated by the formula: t_RD ≈ 115 C_RD (with C_RD in µF and t_RD in ms). For example, a 100nF capacitor will yield a delay of approximately 11.5ms.
4. Enable Pin (EN): This pin allows for the external enabling or disabling of the regulator. It can be tied directly to VIN for always-on operation or connected to a microcontroller for power management control.
The circuit operates by regulating the input voltage (VIN), which can range from approximately 5.5V to 42V, down to a stable 5V output. The reset output (RD) remains low during power-up, during an overtemperature event, or if the output voltage falls below a certain threshold, providing a clear warning signal to the connected microprocessor.
The TLE42502G stands out as a highly reliable and feature-complete LDO regulator. Its combination of very low dropout voltage, comprehensive protection features, and the integrated microprocessor reset function makes it an ideal power management solution for demanding automotive electronic control units (ECUs), sensor modules, and industrial systems. Its simple application design minimizes external part count, reducing both board space and overall system cost.
Keywords:
Low-Dropout (LDO) Regulator
Voltage Regulation
Quiescent Current
Reset Circuit
Application Circuit Design
