MP20056 – LOW-NOISE, HIGH-PSRR, 250mA LINEAR REGULATOR

MP20056 Rev.1.1

www.MonolithicPower.com

12

12/17/2015

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APPLICATION INFORMATION

Setting the Output Voltage

The output voltage of the MPQ20055 is preset to

1.8V, 2.5V or 3.3V by internal resistor divider.

The output voltage also can be adjusted by using

an external resistor divider (R1 and R2 in Figure

2).

MP20056

R1

R2

VOUT

FB

GND

Figure 2: Setting the Output Voltage

However, the sum of R1 and R2 should not

exceed 10kΩ to minimize their impact on the

internal resistor divider. For an accurate output-

voltage setting, use 1kΩ (±1%) for R2, and

determine R1 with:



















FB

FB

OUT

V

V

V

2

R

1

R

For example, for a 1.1V output voltage, R2 is 1kΩ,

and R1 is 374Ω. You can select a standard 374Ω

(±1%) resistor for R1.

Power Dissipation

The power dissipation for any package depends

on the thermal resistance of the case and circuit

board, the temperature differential between the

junction and ambient air, and the rate of air flow.

The power dissipation across the device can be

represented by the equation:



OUT

OUT

IN

I

V

V

P







The

allowable

power

dissipation

can

be

calculated using the following equation:





JA

Ambient

Junction

(MAX)

T

T

P







/

differential

between

the

junction

and

the

resistance from the junction to the ambient

environment. Connecting the exposed GND pad

to a large ground pad or plane helps to channel

away heat.

Output Capacitor Selection

The MP20056 is specifically designed to work

with a standard ceramic output capacitor to save

space and improve performance. Use a 4.7µF

ceramic capacitor for most applications. Larger

output capacitors will improve load transient

response and reduce noise at the cost of

increased size.