MP110 – 900V OFFLINE SWITCHING REGULATOR

Over Load Protection (OLP)

MP110 shuts when the power supply undergoes

an overload. OLP is achieved by continuously

monitoring the FB voltage. A fault signal is

value) and after 82ms delay (8192 switching

present, MP110 shuts down. When the fault

disappears, the power supply resumes operation.

The OLP delay time can be attained below.

Delay

S

82ms 100kHz

T

f

×

=

Short Circuit Protection (SCP)

By monitoring the CS Pin, MP110 shuts down

typical value) to indicate a short circuit. The

MP110 enters a safe low-power mode that

prevents any thermal damage or stress damage.

As soon as the fault disappears, the power

supply resumes operation.

Thermal shutdown (OTP)

When the junction temperature of the IC exceeds

150℃,

the

over

temperature

protection

is

activated and stops output driver switching to

prevent MP110 from any thermal damage. As

soon as the junction temperature drops below

120℃, the regulator resumes operation. During

the protection period, the regulator enters auto-

recovery mode. The VCC voltage is discharged

high voltage current source.

Burst Operation

To minimize stand-by power consumption, the

MP110 implement burst mode at no load and

light load. As the load decreases, the FB voltage

decreases. The IC stops switching when the FB

As the load power increases, the output voltage

drops at a rate dependent on the load. This

causes the FB voltage to rise again due to the

negative feedback control loop. Once the FB

switching pulse resumes. The FB voltage then

decreases and the whole process repeats. Burst-

mode operation alternately enables and disables

the switching pulse of the MOSFET. Hence

switching loss at no load and light load conditions

is greatly reduced. Figure 4 shows the burst

mode operation of MP110.

0.7V

0.5V

Figure 4: Burst Mode Operation

PRO Pin

The PRO pin provides extra protection against

abnormal conditions. Use the PRO pin for input

OVP or other protections (input UVP, over-

temperature protection for key component and so

typical value), the IC shuts down to enter auto-

recovery mode. As soon as the fault disappears,

the power supply resumes operation.

Peak Current Limit

In normal operation, the primary peak current is

sensed by a sensing resistor between the Source

pin and Ground. The turn-off threshold of the

When the sensing resistor voltage reaches the

current-set-point division ratio.

During over-load condition, the primary peak

current threshold is internally limited to the

output power and lower the switch voltage rating.

During start-up period, the primary peak current

threshold internally increases to the maximum

Leading Edge Blanking

In order to avoid turning off the MOSFET from

mis-trigger spikes shortly after the switch turns

MP110 Rev. 1.01

www.MonolithicPower.com

13

6/4/2014

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