MP110 datasheet(15/23 Pages) MPS

15 / 23 page

MP110 – 900V OFFLINE SWITCHING REGULATOR

APPLICATION INFORMATION

Input Capacitor Choose

The bulk capacitors after the rectifier bridge filter

the rectified AC input which supply the DC input

voltage for the converter. Figure 6 shows the

typical DC bus voltage waveform of full bridge

rectifier.

Vin

DC input voltage

VDC(max)

AC input voltage

VDC(min)

VAC

Figure 6: Input voltage waveform

When the full-bridge rectifier is used, the input

capacitor is usually set as 2

μF/W for the

universal input condition (85~265VAC). Halve the

capacitor values for high voltage input (>185VAC)

application. The input power Pin can be estimated

as follow.

Where VO is the output voltage, IO is the rated

output current,

η is the estimated efficiency.

Generally, η is between 0.75 and 0.85 depending

on the input range and output application.

From the waveform above, the AC input voltage

VAC and DC input voltage VDC can be got as

follow.

V (V ,t)

2 V

×−

By setting VAC=VDC, t1 where DC bus voltage

reaches to its minimum value can be calculated.

So the minimum DC voltage is as follow.

DC(min)

AC(min)

V (V

,t1)

Very low DC input voltage could cause thermal

problem in full load. It’s recommend the minimum

DC voltage is higher than 70V, or the input

capacitor value should be increased.

As a 900V offline regulator, MP110 is very

suitable for very high voltage input application.

But the general input capacitors with 400V

voltage

rating

can

not

satisfy

the

safety

requirement. Thus the stack capacitors could be

used in very high input voltage application such

as 420VAC input which refers to the Figure7.

85~420VAC

Bus voltage

Figure 7: Input Stack Capacitor Circuit

The C1 and C2 endure the half of input DC

voltage rating respectively. The R1~R4 should be

use the same value resistor to equalize the C1,

voltage

stress.

And

the

R1~R4

recommended to use the 1206 package to satisfy

safety requirement. Also, the R1~R4 value

should be large enough for energy saving. For

example, the total value of R1~R4 is 20MΩ which

consumes about 18mW in 600VDC bus voltage.

Primary-Side Inductor Design (Lm)

Normally, the converter is designed to operate in

CCM under low input voltage. CCM is needed to

satisfy the output energy requirement in universal

input condition. With built-in slope compensation

function, MP110 can support CCM when duty

cycle exceeds 50%. Set the ratio (KP) of the

primary inductor ripple current amplitude vs. the

peak current value to 0<KP≤1, where KP=1 for

DCM. Figure 8 shows the relevant waveforms. A

larger inductor leads to a smaller KP, which can

MP110 Rev. 1.01

www.MonolithicPower.com

6/4/2014

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

MP110 Datasheet(PDF) 15 Page - Monolithic Power Systems

MP110 Datasheet(HTML) 15 Page - Monolithic Power Systems

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Datasheet Download

Link URL