TLE 4471

Data Sheet

15

Rev. 1.6, 2009-02-03

Output Voltage

To obtain an output voltage of

V

an input voltage in the range of 5.5 V <

V

5 V with 450 mA current capability. For stability it requires an output capacitor of at least

22

µF and a maximum ESR of 3 Ω. The two outputs Q2 and Q3 are tracked to Q1 and

can supply currents of 100 mA and 50 mA. So any undervoltage condition or shutdown

of Q1 will cause the same effect to Q2 and Q3. For Stability both outputs require an

output capacitor of at least 10

µF with ESR < 3 Ω each. Q2 is switched on and off

simultaneously with Q1, while the tracked output Q3 can be enabled or disabled

individually.

Two reference outputs REF2, REF3 with voltages of

V

also available. In case of an overvoltage at the tracker outputs, the voltage references

are limited internally to 4.5 V.

Output Current

The output current is a function of the input voltage. For high input voltages above 22 V,

the output current is reduced linear. This is designed into the regulator for protection.

Above 42 V the regulator is switched off. The thermal shutdown switches the regulator

off, if it exceeds the thermal threshold of 160

°C typical. It is switched on again, as soon

as the regulator is cooled down by typical 10 K (thermal hysteresis). Please note the

device should not be operated above a junction temperature of 150

°C for long term

reliability.

Enable Function

The TLE 4471 includes the possibility of enabling the main and tracked outputs.

Three ORed enable inputs E1, E2, E3 are used to control the main output Q1 and the

tracked output Q2. E1 and E3 can be supplied from the battery line or ignition key with

input voltages up to 16 V. The enable inputs should be protected by a series resistor and

a capacitor, e.g.

R

the microcontroller. A logic HIGH at any enable input will switch on the related regulator

and/or tracker.

A separate enabling pin EN is available to switch on and off the second tracked output

Q3 separately by the microcontroller.

Reset

The power on reset feature is necessary for a defined start of the microprocessor during

power up. When the output voltage of the main regulator has reached the reset threshold

voltage the reset delay capacitor

C

t

output goes HIGH.