MP6619

– 5.4V TO 28V, 5A, H-BRIDGE MOTOR DRIVER

MP6619 Rev. 1.0

www.MonolithicPower.com

10

1/21/2021

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© 2021 MPS. All Rights Reserved.

APPLICATION INFORMATION

Selecting the Input Capacitor

The input capacitor reduces the surge current

drawn from the input supply and the switching

noise from the device. The input capacitor

impedance at the switching frequency should

be less than the input source impedance to

prevent the high-frequency switching current

from passing through to the input. Ceramic

capacitors with X5R or X7R dielectrics are

recommended for their low ESR and small

temperature

coefficients.

A

higher-value

capacitor is helpful for reducing input voltage

ripple and noise. For most applications, two

22µF

ceramic

capacitors

in

parallel

are

sufficient. It is recommended to connect one

capacitor to each VIN pin.

Setting the Output Current limit

If a resistor is connected between ISET and

GND, the output current limit value can be

calculated with Equation (2):

 

 

OUT

ISET

ISEN

40

1

I

0.2

Rk

Ω

R

Ω







(2)

If ISET is left floating, the current limit setting

formula is calculated with Equation (3):

 

OUT

ISEN

0.2

I

R

Ω



(3)

For example, if RISET is 80kΩ, then the trip

voltage is 100mV. For better accuracy, a

40kΩ

to 80kΩ resistance is recommended to achieve

a 200mV to 100mV current trip voltage.

Setting the Sense Resistor

The

power

loss

of

the

sensing

resistor

(PLOSS_RIFB) can be calculated with Equation (4):

 

2

ITRIP

LOSS_RIFB

ISEN

V

P

R

Ω



(4)

To

guarantee

a

current

reference,

the

nominated power rating of the sensing resistor

is recommended to be twice the calculated

power loss with at least a 1% accuracy resistor.

PCB Layout Guidelines

Efficient

PCB

layout

is

critical

for

stable

operation. For the best results, refer to Figure 2

on page 11 and follow the guidelines below:

1. Place the input capacitor close to VIN.

2. Use a wide copper plane for the input,

output,

and

GND

connecting

wire

to

improve thermal performance.

3. Place as many GND vias near the output

and input capacitor as possible to improve

thermal performance.

4. Keep the sense resistor loop as short as

possible.

5. Keep the current-sense feedback signal far

away from noise sources.