MP100 – OFFLINE INDUCTOR-LESS REGULATOR

MP100 Rev. 1.04

www.MonolithicPower.com

9

1/23/2014

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2014 MPS. All Rights Reserved.

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. If PG is used, then the maximum output

voltage must be limited to 14V due to the

maximum rating of PG. Defining the upper and

respectively (refer to the picture in Typical

Application section):

=×

−

UP

LW

VOUT

RR

(

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

counter the internal upper-feedback resistor

value of 1MΩ. The table below lists typical

resistor values for different output voltages:

Table 1: Resistors Selecting vs. Output Voltage

Setting

VOUT(V)

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 MP100 has a limited

maximum output power.

The following factors influence the MP100’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 MP100’s temperature-rise requirement, which

is

relative

to

the

different

application

environments.

GND

GND

Full Bridge Rectifier

Half-wave Rectifier

Figure 2 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 both full

bridge and half-wave rectifiers, The temperature

rise of MP100 is less than 60°C on the test board

in 25°C room temperature test.

0

50

100

150

200

250

300

350

400

450

500

550

80 110 140 170 200 230 260 290 320

Figure 2: Output Power vs. Input Voltage