MP020-5 – OFFLINE, PRIMARY-SIDE REGULATOR WITH CC/CV CONTROL AND A 700V FET

MP020-5 Rev. 1.05

www.MonolithicPower.com

12

1/23/2014

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OVP & OCkP

The MP020-5 includes over-voltage protection

(OVP) and open-circuit protection (OCkP). If the

voltage at the FB pin exceeds 6.35V for 3.5µs,

or the FB input’s 0.15V falling edge cannot be

monitored, the MP020-5 immediately shuts off

the driving signals and enters hiccup mode. The

MP020-5 resumes normal operation when the

fault has been removed.

Thermal Shutdown (TSD)

When the temperature of the IC exceeds 150°C,

over-temperature protection (OTP) triggers and

the IC enters the auto recovery mode. When

the temperature falls below 120°C, the IC will

recover.

Output Cable Compensation

In order to compensate the secondary side

cable voltage drop for a more precise output

voltage, the MP020-5 has an internal output

cable compensation circuit as shown in Figure

8. The internal ZCD sample can detect the duty

of the secondary-side diode. A low-pass filter

that changes as the load current varies.

the output cable compensation. When the

system operates in maximum load, the CP pin

voltage reaches a maximum of 2V.

CP

+ -

*

*

T1

Vo

FB

Figure 8: Output Cable Compensator

The

equation

below

determines

the

compensation voltage:

P_ AU

SS

FCP

UP

3

5.6 D

N

V2 R

360 10

N

×

=× ×

×

×

;

Where:

voltage drop,

mode (0.4 for the MP020-5),

side transformer windings, and

winding turns.