Document
5-V Low-Drop Voltage Regulator
Preliminary Data
Features
q Low-drop voltage q Low quiescent current q Reset output q Protection against reverse polarity q Overvoltage protection 70 V q Short-circuit proof q Suited for automotive electronics q Inhibit input q Wide temperature range
TLE 4258
Bipolar IC
P-TO220-7-1
Type TLE 4258
Ordering Code Q67000-A8238
Package P-TO220-7-1
The TLE 4258 is a very low drop voltage regulator which provides two regulated 5-V output voltages. The main regulator can be loaded with 750 mA and is turned on and off by pin 5 (pin 5 unconnected = main regulator off). In addition, the main regulator incorporates a short-circuit current limitation and is turned off in case of overvoltage (VI > VI OFF). The standby regulator can be loaded with 35 mA, it does not incorporate a short-circuit current limitation and remains permanently active at positive input voltage independent of the turn-off functions of the main regulator.
If the main regulator output voltage is less than 4.5 V, the reset output is switched to low without delay. As soon as the reset threshold has been exceeded, a delay time to be set by an external capacitor expires and afterwards the reset output switches to high again.
If the lines to the controller are long, the oscillating circuit of line inductance and input capacitance C I can be attenuated by a resistor ≤ 1 Ω connected in series to C I.
Circuit Description
The TLE 4258 incorporates a main and standby-control regulator: The amplifiers regulate the output voltage by comparing the output voltage (from the voltage divider) with a highly precise reference voltage. The standby regulator directly controls the base of a PNP series transistor and the main regulator via a buffer that can be turned off with inhibit pulse at pin 5. If the output voltage VQ at pin 7 drops below 4.5 V, a reset signal is released which can only be disabled after a delay time to be set at pin 6. The main output is current-limited and remains active up to the input voltage VI OFF.
Semiconductor Group
1
09.94
Pin Configuration (top view)
TLE 4258
Pin Definitions and Functions
Pin Symbol Function
1 VI Input of voltage regulator
2 Q RES Reset output; open-collector output NPN to pin 4. If the output voltage VQ drops below the reset threshold, the output stage becomes conductive.
3
Q ST
Standby output, connect with a capacitor ≥ 10 µF
4
GND
Ground; reference potential
5 INH Inhibit (main regulator ON/OFF), input for turning on/off main regulator, connected to a 22-kΩ series resistor. With open input, the main regulator remains turned off.
6 D RES Reset delay; pin for reset capacitor; the size of this capacitor determines the delay time of the reset signal typ. 175 ms/µF.
7 VQ REG Main regulator output, connected to a capacitor ≥ 22 µF.
Semiconductor Group
2
TLE 4258
Block Diagram Semiconductor Group
3
TLE 4258
Absolute Maximum Ratings TA = – 40 to 150 ˚C
Parameter
Symbol
Input (Pin 1)
Supply voltage Polarity .