TLE4270D Electronic IC Chips Low-Drop Fixed Voltage Regulator

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5-V Low-Drop Fixed Voltage Regulator            TLE4270

Features

• Output voltage tolerance ≤ ± 2 %

• Low-drop voltage

• Integrated overtemperature protection

• Reverse polarity protection

• Input voltage up to 42 V

• Overvoltage protection up to 65 V (≤ 400 ms)

• Short-circuit proof

• Suitable for use in automotive electronics

• Wide temperature range

• Adjustable reset time

• ESD protection > 4000 V

Functional Description

This device is a 5-V low-drop fixed-voltage regulator. The maximum input voltage is 42 V (65 V, ≤ 400 ms). Up to an input voltage of 26 V and for an output current up to 550 mA it regulates the output voltage within a 2 % accuracy. The short circuit protection limits the output current of more than 650 mA. The device incorporates overvoltage protection and temperature protection that disables the circuit at unpermissibly high temperatures.

Application Description

The IC regulates an input voltage in the range of 5.5 V < V_I < 36 V to V_Qnom = 5.0 V. Up to 26 V it produces a regulated output current of more than 550 mA. Above 26 V the save-operating-area protection allows operation up to 36 V with a regulated output current of more than 300 mA. Overvoltage protection limits operation at 42 V. The overvoltage protection hysteresis restores operation if the input voltage has dropped below 36 V. A reset signal is generated for an output voltage of V_Q < 4.5 V. The delay for power-on reset can be set externally with a capacitor.

Design Notes for External Components

An input capacitor C_I is necessary for compensation of line influences. The resonant circuit consisting of lead inductance and input capacitance can be damped by a resistor of approx. 1 Ω in series with C_I. An output capacitor C_Q is necessary for the stability of the regulating circuit. Stability is guaranteed at values of C_Q ≥ 22 µF and an ESR of < 3 Ω.

Circuit Description

The control amplifier compares a reference voltage, which is kept highly accurate by resistance adjustment, to a voltage that is proportional to the output voltage and drives the base of a series transistor via a buffer. Saturation control as a function of the load current prevents any over-saturation of the power element.

If the output voltage decreases below 4.5 V, an external capacitor C_D on pin 4 (D) will be discharged by the reset generator. If the voltage on this capacitor drops below V_DRL, a reset signal is generated on pin 2 (RO), i.e. reset output is set low. If the output voltage rises above 4.5 V, C_D will be charged with constant current. After the power-on-reset time the voltage on the capacitor reaches V_DU and the reset output will be set high again. The value of the power-on-reset time can be set within a wide range depending of the capacitance of C_D.

The IC also incorporates a number of internal circuits for protection against:

• Overload

• Overvoltage

• Overtemperature

• Reverse polarity

Pin Configuration (top view)

Block Diagram