L99VR02XP datasheet(23/50 Pages) STMICROELECTRONICS

23 / 50 page

Input ceramic capacitors C2_1,2 ≥ 4.7 μF are necessary for the regulator to operate properly. The other input

capacitors C1_1,2 can be used as backup supply for the application. The C0 capacitors, connected to the output

pins, are for bypassing to GND the high-frequency noise and it guarantees stability even during sudden line and

load variations. Suggested value is C0 = 3.3 µF.

The ESR of the SMD output ceramic capacitor has a negligible effect on the stability of the L99VRx family for

capacitors with low ESR. A ceramic SMD capacitor is recommended on VO pin.

4.1

Voltage regulator

Two embedded voltage regulators use p-channel MOSFET transistors as regulating elements. With this structure,

a very low dropout voltage at current up to IO_LDO1,2 = 250 mA in split output voltages is obtained.

The high-precision of the output voltage (±2%) is obtained with a pretrimmed reference voltage. The voltage

regulator automatically adapts its own quiescent current to the output current level. In light load conditions the

quiescent current goes down to Iqn_0_LDO1,2 = 115 µA only (low consumption mode). The L99VR02XP operates

with reduced input voltage (post regulation) minimizing the internal power dissipation and maximizing the output

current.

4.2

Output current limitation

Output current limitation is present to protect the regulator and the application from overload condition, such as

short to ground.

Figure 40. Behavior of regulated voltage VO_LDO1,2 versus output current

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Iout_LDO1,2 (A)

Vo_5V

Vo_3.3V

Vo_2.8V

Vo_2.5V

Vo_1.8V

Vo_1.5V

Vo_1.2V

Vo_0.8V

Vs = 13.5V

Ta = 25 ⁰C

The Ishort current can be set in the range between 110 mA (typ) to 405 mA (typ) through an external resistor Rsh

connected between Ishort pin and ground.

L99VR02XP

Application information

DS14686 - Rev 1

page 23/50

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