TC429 Datasheet, PDF(7/14 Page) TelCom Semiconductor, Inc – 6A SINGLE HIGH-SPEED, CMOS POWER MOSFET DRIVER

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TC429 Datasheet, PDF (7/14 Pages) TelCom Semiconductor, Inc – 6A SINGLE HIGH-SPEED, CMOS POWER MOSFET DRIVER

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Three components make up total package power

dissipation:

â¢ Capacitive load dissipation (PC)

â¢ Quiescent power (PQ)

â¢ Transition power (PT)

The capacitive load-caused dissipation is a direct func-

tion of frequency, capacitive load and supply voltage.

The package power dissipation is:

PC = f C VS2

Where:

f = Switching frequency

C = Capacitive load

VS = Supply voltage

Quiescent power dissipation depends on input signal

duty cycle. A logic low input results in a low-power

dissipation mode with only 0.5mA total current drain.

Logic high signals raise the current to 5mA maximum.

The quiescent power dissipation is:

PQ = VS (D (IH) + (1 â D) IL)

Where:

IH = Quiescent current with input high (5mA max)

IL = Quiescent current with input low

(0.5mA max)

D = Duty cycle

Transition power dissipation arises because the output

stage N- and P-channel MOS transistors are ON

simultaneously for a very short period when the output

changes.

The transition package power dissipation is

approximately:

PT = f VS (3.3 x 10â9 A â¢ Sec)

An example shows the relative magnitude for each

item.

C = 2500pF

VS = 15V

D = 50%

f = 200kHz

PD = Package power dissipation = PC + PT + PQ

= 113mW + 10mW + 41mW

= 164mW

Maximum operating temperature = TJ â Î¸JA (PD)

= 125Â°C

TC429

Where:

TJ = Maximum allowable junction temperature

(+150Â°C)

Î¸JA = Junction-to-ambient thermal resistance

(150Â°C/W, CERDIP)

Note:

Ambient operating temperature should not

exceed +85Â°C for IJA devices or +125Â°C for

MJA devices.

TABLE 3-1: MAXIMUM OPERATING

FREQUENCIES

fMAX

18V

500kHz

15V

700kHz

10V

1.3MHz

>2MHz

CONDITIONS: 1. CERDIP Package (Î¸JA =150Â°C/W)

2. TA = +25Â°C

3. CL = 2500pF

FIGURE 3-5:

PEAK OUTPUT

CURRENT CAPABILITY

5V/DIV

INPUT

500mV/DIV

(5 AMP/DIV)

OUTPUT

VS = 18V

RL = 0.1â¦

500mV

5Âµs

TIME (5Âµs/DIV)

3.5 POWER-ON OSCILLATION

Note:

It is extremely important that all MOSFET

Driver applications be evaluated for

the possibility of having High-Power

Oscillations occurring during the power-on

cycle.

Power-on oscillations are due to trace size and layout

as well as component placement. A âquick fixâ for most

applications which exhibit power-on oscillation

problems is to place approximately 10kâ¦ in series with

the input of the MOSFET driver.

DS21416B-page 7

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