MP023GS datasheet(16/23 Pages) MPS

16 / 23 page

MP023 – PRIMARY-SIDE CC/CV CONTROLLER

MP023 Rev. 1.1

www.MonolithicPower.com

7/18/2016

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

Output Cable Compensation

The MP023 has an internal output cable

compensation (CP) circuit (see Figure 10). A

switching signal (VCS_Lim*Dons) is generated

internally and is synchronized with the switching

frequency. The duty on-time of this signal is

Dons, and the amplitude of this signal is

proportional to the current-limit threshold. This

signal is output to CP through a 1MΩ resistor. A

low pass filter can be implemented by placing

an external capacitor on CP, and then a DC

voltage (VCP) proportional to the output current

can be deducted on CP. Note that if cable

compensation function is needed, DS-Max is

default as 0.4 and can’t be programmable by

connecting external CP resistor.

Figure 10: Output Cable Compensation

Table 2 shows some typical voltage levels on

CP when a low pass filter is applied as

described above.

Table 2: Typical CP Voltage Levels (CCP = 1μF)

VLimit

Dons

VCP

500mV

0.4

1.6V

500mV

0.35

1.4V

400mV

0.3

0.96V

250mV

0.1

0.2V

An internal current sink in FB is proportional to

VCP. The voltage drop on the upper resistor of

the divider implements the output cable

compensation function.

The

equation

below

determines

the

compensation voltage:

P_ AU

Limit

FCP

V2 R

300 10



 



(10)

Where:

 VFCP is the secondary-side compensation

voltage drop,

 DS is the secondary-diode duty cycle,

 RUP is the upper resistor of resistor divider,

 NS is the number of turns for the secondary-

side transformer windings,

 NP_AU is the number of transformer auxiliary

winding turns,

 VLimit is the current limit,

Since CP is also used for DS-Max customization,

the cable compensation function is only

available when CP is connected to the

capacitors directly. If there is a non-zero

resistor connected to CP, all of the internal

blocks related to the cable compensation

function are disabled. During normal operation

under this condition, CP is clamped to GND

internally and there is no current flowing

through FB.

MP023GS Datasheet(PDF) 16 Page - Monolithic Power Systems

MP023GS Datasheet(HTML) 16 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