MP163 datasheet(14/23 Pages) MPS

14 / 23 page

MP163 – 700V, NON-ISOLATED, OFFLINE REGULATOR WITH INTEGRATED LDO

MP163 Rev. 1.01

www.MonolithicPower.com

8/11/2017

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

Frequency Foldback and Peak Current

Compression

The MP163 remains highly efficient at light-load

condition by reducing the switching frequency

automatically.

Under light-load or no-load conditions, the

output voltage drops very slowly, which

increases the MOSFET off time

, and the

frequency decreases with the load.

The switching frequency

in CCM is determined

with Equation (3):

peak

V )

2L(I

I ) V







(3)

The switching frequency in discontinuous

conduction mode (DCM) is determined with

Equation (4):





peak

2(V

V ) I V

(4)

As the peak current limit decreases from ILimit,

the off time increases. In standby mode, the

frequency and the peak current are both

minimized, allowing for a smaller dummy load.

As a result, peak current compression helps

further reduce no-load consumption. The peak

current limit can be estimated

with Equation (5):

Peak

off

min off

Limit

I(1 0.0038 (T

) / s) I





 

 

(5)

Where τoff is the off time of the power

module.

Error Amplifier (EA) Compensation

The MP163 has an internal error amplifier (EA)

compensation loop

that samples the feedback

voltage 6µs after the MOSFET turns off and

regulates the output based on the 2.55V

reference voltage.

Ramp Compensation

An internal ramp compensation circuit improves

the load regulation. An exponential voltage

signal is added to pull down the reference

voltage of the feedback comparator (see Figure

4). The ramp compensation is a function of the

load conditions

. The compensation is about

1mV/µs

in full-load condition and increases

exponentially as the peak current decreases.

Figure 4: EA and Ramp Compensation

Over

load Protection (OLP)

The maximum output power of the MP163 is

limited by the maximum switching frequency

and peak current limit. If the load current is too

large, the output voltage drops, causing the FB

voltage to drop.

When

FB voltage drops below VFB_OLP, this is

considered

to be an error flag, and the timer

starts. If the timer reaches 220ms (fS = 28kHz),

overload protection (OLP) occurs. This timer

duration

prevents OLP from being triggered

when the power supply starts up or the load

transitions. The power supply should start up in

less than 220ms (fS = 28kHz). The OLP delay

time is calculated using Equation (6):

Delay

28kHz

220ms





(6)

Short-Circuit Protection (SCP)

The MP163 monitors the peak current and

shuts down

the MOSFET when the peak

current rises above the

short-circuit protection

(SCP) threshold. The power supply resumes

operation with the removal of the fault.

Thermal Shutdown

To prevent thermal

-induced damage, the

MP163 stops switching when the junction

temperature exceeds 150

°C. During thermal

shutdown, the VCC capacitor is discharged to

VCCpro, and then the internal high-voltage

regulator re-charges.

The MP163 recovers

when the junction temperature drops below

120°C.

MP163 Datasheet(PDF) 14 Page - Monolithic Power Systems

MP163 Datasheet(HTML) 14 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