TC429 データシートの表示（PDF） - TelCom Semiconductor Inc => Microchip

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TC429

6A SINGLE HIGH-SPEED, CMOS POWER MOSFET DRIVER

TelCom Semiconductor Inc => Microchip 

6A SINGLE HIGH-SPEED,

CMOS POWER MOSFET DRIVER

1

TC429

Three components make up total package power dissi-

pation:

(1) Capacitive load dissipation (PC)

(2) Quiescent power (PQ)

(3) 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 dissipa-

tion mode with only 0.5 mA total current drain. Logic high

signals raise the current to 5 mA maximum. The quiescent

power dissipation is:

PQ = VS (D (IH) + (1–D) IL),

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

IL = Quiescent current with input low (0.5 mA max)

D = Duty cycle.

Transition power dissipation arises because the output

stage N- and P-channel MOS transistors are ON simulta-

neously for a very short period when the output changes.

The transition package power dissipation is approximately:

PT = f VS (3.3 x 10–9 A · Sec).

An example shows the relative magnitude for each item.

Example 1:

C = 2500 pF

VS = 15V

D = 50%

f = 200 kHz

PD = Package power dissipation = PC + PT + PQ

= 113 mW + 10 mW + 41 mW

= 164 mW.

Maximum operating temperature = TJ – θJA (PD)

= 125°C,

where: TJ = Maximum allowable junction temperature

(+150°C)

θJA = Junction-to-ambient thermal resistance

(150°C/W, CerDIP).

NOTE: Ambient operating temperature should not exceed +85°C for

IJA devices or +125°C for MJA devices.

TELCOM SEMICONDUCTOR, INC.

Table 1. Maximum Operating Frequencies

VS

fMax

18V

500 kHz

15V

700 kHz

10V

1.3 MHz

5V

>2 MHz

CONDITIONS: 1. CerDIP Package (θJA = 150°C/W)

2. TA = +25°C

3. CL = 2500 pF

Thermal Derating Curves

1600

1400

1200

1000

8 Pin DIP

8 Pin CerDIP

800

8 Pin SOIC

600

400

200

0

0 10 20 30 40 50 60 70 80 90 100 110 120

AMBIENT TEMPERATURE (°C)

2

3

4

Peak Output Current Capability

5

6

POWER-ON OSCILLATION

7

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 ‘quick fix’ for most

8 applications which exhibit POWER-ON OSCILLATION prob-

lems is to place approximately 10 kΩ in series with the input

of the MOSFET driver.

4-179

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