MPQ5850

– 36V, SMART DIODE CONTROLLER W/ REVERSE PROTECTION, AEC-Q100

MPQ5850 Rev. 1.1

MonolithicPower.com

25

2/9/2022

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frequency. CLOAD can be estimated with Equation

(9):

AC

R

LOAD

LOAD

AC

R

4 V

V

CI

4 V

f V

−





 

(9)

Where VAC is the SOURCE voltage ripple

amplitude (in V), f is the ripple frequency (in Hz),

CLOAD is the capacitance of the electrolytic

capacitor (in F), and ILOAD is the load current (in

A).

If the ripple voltage (VR) is below 2V, f is 5kHz,

VAC is 3V (6VPP), and ILOAD is 5A, then CLOAD is

417

μF.

Selecting the TVS Diode

The MPQ5850 can be damaged by the negative

pulse on the SOURCE pin, since the voltage of

the SOURCE pin is limited to -36V. Connect a

TVS diode between SOURCE and GND to

protect

the

part.

The

SMBJ24CA

is

recommended, as it can protect the MPQ5850

from

negative

pulses

and

over-voltage

conditions.

PCB Layout Guidelines (8)

An optimized PCB layout is very important for

proper operation. A four-layer layout is strongly

recommended to improve thermal performance.

For the best results, refer to Figure 3 and follow

the guidelines below:

1. Place SW close to the device with short,

direct, and wide traces.

2. Use

large

copper

areas

to

minimize

conduction loss and thermal stress.

3. Place the ceramic input capacitors as close

to the IN and GND pins as possible to

minimize high-frequency noise.

4. Route SW away from sensitive analog areas.

5. Use multiple vias to connect the power

planes to internal layer.

Note:

8) The recommended PCB layout is based on the circuit in Figure

4 on page 26.

Top Silk and Top Layer

Mid-Layer 1

Mid-Layer 2

Bottom Layer and Bottom Silk

Figure 3: Recommended PCB Layout