LX8213

PRODUCTION DATASHEET

Microsemi

Analog Mixed Signal Group

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 10

Copyright

© 2009

Rev. 1.1, 2009-03-24

300mA Low Noise CMOS LDO Regulator

TM

®

APPLICA T ION IN F O RM ATION

Description

The LX8213 is a family of CMOS based LDO (Low Drop-Out)

regulators in a small 5 pin SOT-23 package that provides a

compact and cost effective solution. The LX8213 is offered with

fixed output voltages of 1.2V or 3.3V, in addition to an adjustable

version with an output voltage range of 1.2V to 5.5V.

The

LX8213 features low power consumption over a wide supply

voltage range, high output voltage accuracy, low dropout,

excellent line and load regulation, fast transient response, and low

noise. Please refer to the Electrical Characteristics Table for the

specifications.

Input Capacitor

To improve load transient response and noise rejection, an

input bypass capacitor is recommended, but it is not required

for stability. There are no requirements for the ESR

(Equivalent Series Resistor) on the input capacitor, but

tolerance and temperature coefficient must be considered

when selecting the capacitor to ensure the capacitor will be

around 1µF over the entire operating temperature range.

Capacitors with X5R or X7R characteristics are recommended.

Output Capacitor

For stability of the regulator, use a minimum 1uF capacitor to

bypass from VOUT to GND. Note that the LX8213 is stable

using low ESR ceramic capacitors. Capacitors with X5R or

X7R

characteristics

generally

perform

well

and

are

recommended.

Adjustable Output Voltage

The LX8213-00 output voltage can be set within the range of

1.2V to 5.5V by connecting the FB pin to an external resistor

divider (See Figure 3). The output voltage can be calculated

using:

⎥⎦

⎤

⎢⎣

⎡

+

=

R2

R1

1

0.8

V

OUT

R2 is chosen to minimize the power dissipated by the resistor

divider network while providing enough FB input bias current.

A value of 8.06kΩ is recommended.

Shutdown (

resistor to GND of 3MΩ will automatically disable the device.

Upon shutdown, an internal MOSFET connected from VOUT

to GND will be turned ON to discharge the output capacitor.

specification on minimum and maximum logic high levels,

please refer to the Electrical Characteristics Table.

Foldback Current Limit

The LX8213 uses a foldback current limit. When the load current

exceeds approximately 400mA, the output voltage is reduced

along with the output current, minimizing power dissipated and

protecting the device from excessive heating.

Short Circuit Current Protection

Under conditions where the output of the LX8213 is shorted to

ground, internal circuitry will limit the device to source only about

50mA.

Temperature Protection

The thermal protection shuts down the LX8213 when the junction

temperature exceeds approximately 165°C, with a hysteresis of

about 30˚C.

Thermal Consideration

Thermal shutdown protects the integrated circuit from thermal

overload caused from a rise in junction temperature during power

dissipation. This means the protection is intended for fault

protection only and not as a means of current or power limiting

during normal application usage. Proper thermal evaluation

should be done to ensure that the junction temperature dose not

150°C can impact reliability. Due to variation in individual device

electrical characteristics and thermal resistance, the built in

thermal overload protection may be activated at power levels

slightly above or below the rated dissipation.

Power dissipation for regulator can be calculated using the

following equation:

(Note: power dissipation resulting from quiescent current is

negligible)

For the SOT23 package, thermal resistance,

when mounted on a FR4 copper clad PCB. Junction temperature

of the integrated circuit can be calculated using:

Calculated values:

Junction Temperature