MP2019 - 40V, 300mA, LOW QUIESCENT-CURRENT LINEAR REGULATOR

MP2019 Rev. 1.01

www.MonolithicPower.com

13

1/10/2018

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© 2018 MPS. All Rights Reserved.

APPLICATION INFORMATION

COMPONENT SELECTION

Setting the Output Voltage

Set the output voltage of the MP2019 by using a

resistor divider (see Fig. 3).

MP2019

OUT

FB

R1

R2

GND

Choose

R2=1M

Ω to maintain a 1.215µA

minimum load. Calculate the value for R1 using

the following equation:













OUT

V

R1 R2

1

1.25V

For

a fixed-output

version,

VOUT

can

be

adjusted by adding an external resistor divider

(see Fig. 4). When choosing an external divider,

take

the

internal

FB

resistor

divider

into

consideration.

MP2019

OUT

FB

R1

R2

GND

R1_IN

R2_IN

Figure 4. FB Divider for Fixed-Output Version

When R2 is selected, R1 can be calculated with

the equation below:









OUT

R1_ IN

R1

1.25 R1_ IN

R2 R2 _ IN

1

V

1.25

R2 R2 _ IN

















Table 1 below shows the internal FB resistor

dividers for different fixed-output versions.

Table 1. Internal FB Resistor Divider

Fixed-Output Voltage

R1_IN

R2_IN

3.3V

1.64M

Ω

1M

Ω

5V

3M

Ω

1M

Ω

Table 2 below shows various output voltages for

a fixed-output version with an external FB divider..

Table 2. 3.3V Fixed-Output Version with External

FB Divider

R1 (k

)

R2 (k

)

11

80.6

10

8.5

59

10

8

54.9

10

6.5

43

10

5

30.1

10

Enable Control (EA)

EN is a digital control pin that turns the regulator

on and off. When EN is pulled below 0.3V, the

chip shuts down. When EN is pulled above 1.8V,

the chip starts up. If this function is not used, EN

can be connected to VIN directly.

Input Capacitor

For efficient operation, place a ceramic capacitor,

(C1) between 1µF and 10µF of dielectric type

(X5R or X7R) between the input pin and ground.

Larger values in this range improve line transient

response.

Output Capacitor

For stable operation, use a ceramic capacitor (C2)

of type X5R or X7R between 1µF and 22µF.

Larger values in this range improve load transient

response and reduce noise. Output capacitors of

other dielectric types may be used, but they are

not recommended as their capacitance can

deviate greatly from their rated value over

temperature.

To improve load transient response, add a small

ceramic (X5R, X7R, or Y5V dielectric) 2.2nF

feed-forward capacitor in parallel with R1. The

feed-forward capacitor is not required for stable

operation.

Output Noise

The MP2019 exhibits noise on the output during

normal operation. This noise is negligible for

most applications. However, in applications that

include analog-to-digital converters (ADCs) of

more than 12 bits, c

onsider the ADC’s power

supply rejection specifications. The feed-forward

capacitor C2 across R1 reduces significantly the

output noise.