MPQ5069

– 7mΩ PROTECTION SWITCH WITH CURRENT MONITOR

MPQ5069 Rev. 1.1

www.MonolithicPower.com

16

11/19/2020

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APPLICATION INFORMATION

Setting the Current Limit (RSET)

The MPQ5069 current-limit value should exceed

the normal maximum load current, allowing for

the

tolerances

in

the

current-sense

value.

Estimate the current limit using Equation (2):

 4

LIMIT

SET

0.6(V)

I

=

20 10 (A)

R

(2)

Table 1 shows the bench results from the

evaluation board.

Table 1: Current Limit vs. Current Limit Resistor

Current Limit Resistor (k

Ω)

7.5

10

20

Current Limit (A)

15.9

12

6.08

Figure 5 shows the relationship between the set

resistance (RSET) and the current limit.

Figure 5: RSET vs. Current Limit

Current Monitoring

The MPQ5069 provides a MOSFET current-

monitoring function. Place a resistor (RMON) to

ground to set the gain of the output, calculated

with Equation (3):

 POWERFET

IMON

5

I

I

10

(3)

Where IPOWERFET is the power MOSFET current.

The IMON pin provides a voltage proportional to

the output current. Place a 10k

Ω resistor from the

IMON pin to GND to obtain a 100mV/A, which is

the voltage proportional to the output current.

Place a 100nF capacitor from IMON to GND to

smooth the indicator voltage.

Design Example

Figure

7

shows

the

detailed

application

schematic. For the typical performance and

circuit waveforms, see the Typical Performance

Characteristics section on page 8. For more

detailed device applications, refer to the related

evaluation board datasheet.