MP2166

– 6V, DUAL 2A/2A OR 3A/1A, SYNC, BUCK REGULATOR WITH PG AND SS

MP2166 Rev. 1.0

www.MonolithicPower.com

17

3/14/2017

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© 2017 MPS. All Rights Reserved.

Power Dissipation

IC power dissipation is important in circuit

design, not only because of efficiency concerns,

but also because of the chip’s thermal

requirements. Several parameters influence

power dissipation, such as conduction loss

(Cond), dead time (DT), switching loss (SW),

MOSFET driver current (DR), and supply

current (S).

Based on these parameters, we can estimate

the power loss with Equation (7):

S

DR

SW

DT

Cond

LOSS

P

P

P

P

P

P











(7)

Thermal Regulation

Changes

in

IC

temperatures

change

the

electrical characteristics, especially when the

temperature exceeds the IC’s recommended

operating

range.

Managing

the

IC’s

temperature requires additional considerations

to ensure that the IC runs within the maximum

allowable temperature junction. Specific layout

designs can improve the thermal profile while

limiting

costs

to

either

the

efficiency

or

operating range.

For the MP2166, connect the ground pin on the

package to a ground plane on top of the PCB to

use this plane as a heat sink. Connect this

ground plane to the ground planes beneath the

IC using vias to improve heat dissipation.

However, given that these ground planes can

introduce unwanted EMI noise and occupy

valuable PCB space, design their size and

shape

to

match

the

thermal

resistance

requirement.

Connecting the ground pin to a heat sink cannot

guarantee that the IC will not exceed its

recommended

temperature

limits

(i.e.:

the

ambient

temperature

exceeds

the

IC’s

temperature

limits).

If

the

ambient

air

temperature approaches the IC’s temperature

limit, the IC can be de-rated to operate using

less power and help prevent thermal damage

and unwanted electrical characteristics.