MCP14E3 datasheet(12/26 Pages) MICROCHIP

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MCP14E3/MCP14E4/MCP14E5

DS22062B-page 12

4.0

APPLICATION INFORMATION

4.1

General Information

MOSFET drivers are high-speed, high current devices

which are intended to source/sink high peak currents to

charge/discharge the gate capacitance of external

MOSFETs or IGBTs. In high frequency switching power

supplies, the PWM controller may not have the drive

capability to directly drive the power MOSFET. A MOS-

FET driver like the MCP14E3/MCP14E4/MCP14E5

family can be used to provide additional source/sink

current capability.

An additional degree of control has been added to the

MCP14E3/MCP14E4/MCP14E5

family.

There

are

separate enable functions for each driver that allow for

the

immediate

termination

the

output

pulse

regardless of the state of the input signal.

4.2

MOSFET Driver Timing

The ability of a MOSFET driver to transition from a fully

off state to a fully on state are characterized by the

drivers rise time (tR), fall time (tF), and propagation

delays (tD1 and tD2). The MCP14E3/MCP14E4/

MCP14E5 family of drivers can typically charge and

discharge a 2200 pF load capacitance in 15 ns along

with a typical matched propagation delay of 50 ns.

Figure 4-1 and Figure 4-2 show the test circuit and

timing waveform used to verify the MCP14E3/

MCP14E4/MCP14E5 timing.

FIGURE 4-1:

Inverting Driver Timing

Waveform.

FIGURE 4-2:

Non-Inverting Driver Timing

Waveform.

4.3

Enable Function

The ENB_A and ENB_B enable pins allow for indepen-

dent control of OUT A and OUT B respectively. They

are active high and are internally pulled up to VDD so

that the default state is to enable the driver. These pins

can be left floating for normal operation.

When an enable pin voltage is above the enable pin

high threshold voltage, VEN_H (2.4V typical), that driver

output is enabled and allowed to react to changes in

the INPUT pin voltage state. Likewise, when the enable

pin voltage falls below the enable pin low threshold

voltage, VEN_L (2.0V typical), that driver output is dis-

abled and does not respond the changes in the INPUT

pin voltage state. When the driver is disabled, the out-

put goes to a low state. Refer to Table 4-1 for enable

pin logic. The threshold voltages of the enable function

are compatible with logic levels. Hysteresis is provided

to help increase the noise immunity of the enable

function, avoiding false triggers of the enable signal

during driver switching. For robust designs, it is

recommended that the slew rate of the enable pin

signal be greater than 1 V/ns.

There are propagation delays associated with the

driver receiving an enable signal and the output

reacting. These propagation delays, tD3 and tD4, are

graphically represented in Figure 4-3.

0.1 µF

+5V

10%

90%

10%

90%

10%

90%

18V

1µF

MCP14E3

CL = 2200 pF

Input

Output

tD1

tD2

Output

DD = 18V

Ceramic

Input

(1/2 MCP14E5)

90%

Input

tD1

tD2

Output

10%

+5V

18V

90%

0.1 µF

1µF

MCP14E4

CL = 2200 pF

Input

Output

DD = 18V

Ceramic

Input

(1/2 MCP14E5)

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