MP100L EASYPOWER

APPLICATION INFORMATION

COMPONENT SELECTION

Setting the Output Voltage

The output voltage is set to 12V by internal large

feedback resistors. Adjust VOUT by choosing

appropriate external feedback resistors. The

recommended output voltage is between 1.5V

and 15V. Defining the upper and lower feedback

picture in Typical Application section):

=

×−

UP

LW

VOUT

R

R

(

1)

1.235

For the external resistors to dominate over the

internal resistors, select relatively small values of

However, to minimize the load consumption,

avoid very small external resistors. For most

Ω. To accurately

counter

the internal upper-feedback

resistor

value of 1M

Ω. The table below lists typical

resistor values for different output voltages:

Table 1: Resistors Selecting vs. Output Voltage

Setting

VOUT(V)

(kΩ)

(kΩ)

1.5

2.21(1%)

10.2(1%)

3.3

16.9(1%)

10.2(1%)

5

30.9(1%)

10.2(1%)

15

121(1%)

10.2(1%)

SELECTION OF VD CAPACITOR

The bypass capacitor on the VD pin needs to be

sufficiently large to provide a stable current.

Calculate the capacitance (in

μF) based on the

following equation:

×τ

s

VD

ripple

I

C

V

s

based on the type of input rectifier—for example,

s

the VD capacitor—normally the ripple is limited to

2V to 3V. For best results, use a small ceramic

capacitor and a large aluminum capacitor in

parallel.

Output Power Capability

The maximum input power to the VD capacitor is

limited by the fixed charging window. Considering

the LDO power loss, the MP100L has a limited

maximum output power.

The following factors influence the MP100L’s

maximum output power: the input rectifier (full

bridge or half-wave); the VD capacitor connected

between VD and GND; the output voltage; and

the

MP100L’s

temperature-rise

requirement,

which is relative to the different application

environments.

GND

GND

Full Bridge Rectifier Half-wave Rectifier

Figure depicts the relationship between the

maximum output power and the VIN voltage

when the output voltage is 12V, 5V and 3.3V,

respectively. The plots account for full bridge

rectifiers, the temperature rise of MP100L is less

than 60°C on the test board in 25°C room

temperature test in the open frame.

Figure 2: Output Power vs. Input Voltage

Line Transformer

MP100L can work well when connected to AC

line or programmable AC source. But when using

an isolation transformer or a variable transformer

as source, because of the high inductance of the

MP100L Rev. 1.0

www.MonolithicPower.com

12

11/3/2014

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