MP5087

– 5.5V, 7A LOW RDSON LOAD SWITCH WITH CURRENT MONITORING

MP5087 Rev. 1.2

www.MonolithicPower.com

13

8/16/2017

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APPLICATION INFORMATION

IMON Resistor Selection

The current limit value can be set by IMON

resistor. The current limit can be gotten by

equation (1).

The current limit threshold is suggested to 10%

~ 20% higher than maximum load current. For

example, if the system’s full load is 7A, set the

current limit to 7.7A.

IMON Capacitor Selection

The internal advanced auto-zero comparator

bring a high accuracy of current monitor. The

auto-zero will also cause some little jitter on

IMON pin. To get a more stable IMON, a small

ceramic capacitor can be mounted between

IMON and ground. Suggested place an IMON

capacitor less than 1nF.

Soft Start Capacitor Selection

There is an internal 9µA constant current

source charge SS cap and ramps up the

voltage on the SS pin. The output voltage rises

follow the slew rate of SS voltage.

If the inrush on output current reached the

current limit during start up (like with large

output cap or very large load), MP5087 will limit

the output current and the same time, SS time

will be increased (Fig 2 and Fig 3).

Component Selection

Soft Start @ Different Load

Soft Start @ No Load

Soft Start @ Half Load

Soft Start @ Very large Load

Current Limit

Current Limit

Current Limit

Figure 2: Soft Start Periods at different load