TLS820F0

Block Description and Electrical Characteristics

Data Sheet

11

Rev. 1.1, 2015-07-27

5

Block Description and Electrical Characteristics

5.1

Voltage Regulation

The output voltage

V

reference and the pass transistor is driven accordingly.

The control loop stability depends on the output capacitor

C

internal circuit design. To ensure stable operation, the output capacitor’s capacitance and its equivalent series

resistor (ESR) requirements given in “Functional Range” on Page 9 have to be maintained. For details, also see

the typical performance graph “Output Capacitor Series Resistor ESR(CQ) versus Output Current IQ” on

Page 16. As the output capacitor also has to buffer load steps, it should be sized according to the application’s

needs.

An input capacitor

C

HF distortion at input side, an additional reverse polarity protection diode and a combination of several capacitors

for filtering should be used. Connect the capacitors close to the component’s terminals.

In order to prevent overshoots during start-up, a smooth ramp up function is implemented. This ensures almost

no output voltage overshoots during start-up, mostly independent from load and output capacitance.

Whenever the load current exceeds the specified limit, e.g. in case of a short circuit, the output current is limited

and the output voltage decreases.

The overtemperature shutdown circuit prevents the IC from immediate destruction under fault conditions (e.g.

output continuously short-circuit) by switching off the power stage. After the chip has cooled down, the regulator

restarts. This leads to an oscillatory behavior of the output voltage until the fault is removed. However, junction

temperatures above 150 °C are outside the maximum ratings and therefore significantly reduce the IC’s lifetime.

Figure 4

Voltage Regulation

Figure 5

Output Voltage vs. Input Voltage

LOAD

Supply

Regulated

Output Voltage

Bandgap

Reference

GND

Q

I

Temperature

Shutdown

EN

Enable

Reset

RO

RADJ

DT1

Watchdog

WI

WO

DT2

C

ESR

Current

Limitation

V

t