MCP1406-ESLASHAT datasheet(11/22 Pages) MICROCHIP

11 / 22 page

DS22019A-page 11

MCP1406/07

The MCP1406/07 devices have two pins each for VDD,

OUTPUT, and GND. Both pins must be used for proper

operation. This also lowers path inductance which will,

along with proper decoupling, help minimize ringing in

the circuit.

Placing a ground plane beneath the MCP1406/07 will

help as a radiated noise shield as well as providing

some heat sinking for power dissipated within the

device.

4.5

Power Dissipation

The total internal power dissipation in a MOSFET driver

is the summation of three separate power dissipation

elements.

4.5.1

CAPACITIVE LOAD DISSIPATION

The power dissipation caused by a capacitive load is a

direct function of frequency, total capacitive load, and

supply voltage. The power lost in the MOSFET driver

for a complete charging and discharging cycle of a

MOSFET is:

4.5.2

QUIESCENT POWER DISSIPATION

The power dissipation associated with the quiescent

current draw depends upon the state of the input pin.

The MCP1406/07 devices have a quiescent current

draw when the input is high of 0.13 mA (typ) and

0.035 mA (typ) when the input is low. The quiescent

power dissipation is:

4.5.3

OPERATING POWER DISSIPATION

The operating power dissipation occurs each time the

MOSFET driver output transitions because for a very

short period of time both MOSFETs in the output stage

are on simultaneously. This cross-conduction current

leads to a power dissipation describes as:

PL PQ PCC

Where:

PT = Total power dissipation

PL = Load power dissipation

PQ = Quiescent power dissipation

PCC = Operating power dissipation

fCT

VDD

Where:

f = Switching frequency

CT = Total load capacitance

VDD = MOSFET driver supply voltage

IQH DIQL

1 D

–

()

() V

Where:

IQH = Quiescent current in the high state

D = Duty cycle

IQL = Quiescent current in the low state

VDD = MOSFET driver supply voltage

PCC

CC f

VDD

Where:

CC = Cross-conduction constant (A*sec)

f = Switching frequency

VDD = MOSFET driver supply voltage

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