TLS205B0

Application Information

Data Sheet

25

Rev. 1.2, 2015-01-15

The TLS205B0 is a 500 mA low dropout regulator with very low quiescent current and Enable-functionality. The

device is capable of supplying 500 mA at a dropout voltage of 320 mV. Output voltage noise numbers down to

24

µV

capacitor. The usage of a reference bypass capacitor will additionally improve transient response of the regulator,

lowering the settling time for transient load conditions. The device has a low operating quiescent current of typical

30 µA that drops to less than 1 µA in shutdown (EN-pin pulled to low level). The device also incorporates several

protection features which makes it ideal for battery-powered systems. It is protected against both reverse input

and reverse output voltages.

6.1

Adjustable Operation

The adjustable version of the TLS205B0 has an output voltage range of 1.22 V to 20 V -

V

is set by the ratio of two external resistors, as it can be seen in Figure 6. The device controls the output to maintain

the ADJ pin at 1.22 V referenced to ground. The current in R1 is then equal 1.22 V / R1 and the current in R2

equals the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, which is ~60 nA @ 25 °C, flows

through R2 into the ADJ pin. The value of R1 should be not greater than 250 kΩ in order to minimize errors in the

output voltage caused by the ADJ pin bias current. Note that when the device is shutdown (i.e. low level applied

to EN pin) the output is turned off and consequently the divider current will be zero. For details of the ADJ Pin Bias

current see also the corresponding typical performance graph “Adjust Pin Bias Current versus Junction

Temperature TJ” on Page 20.

6.2

Kelvin Sense Connection

For the fixed voltage version of the TLS205B0 the SENSE pin is the input to the error amplifier. An optimum

regulation will be obtained at the point where the SENSE pin is connected to the output pin Q of the regulator. In

critical applications however small voltage drops may be caused by the resistance

R

may lower the resulting voltage at the load. This effect may be eliminated by connecting the SENSE pin to the

output as close as possible at the load (see Figure 7). Please note that the voltage drop across the external PC

trace will add up to the dropout voltage of the regulator.

Figure 7

Kelvin Sense Connection

6.3

Bypass Capacitance and Low Noise Performance

The TLS205B0 regulator may be used in combination with a bypass capacitor connecting the output pin Q to the

providing a low frequency noise pole. The noise pole provided by such a bypass capacitor will lower the output

1) a good quality low leakage capacitor is recommended.

I

GND

Q

EN

SENSE

BYP

TLS205B0

V

I

R

Load

C

Q

R

P

R

P