TC429_13 Datasheet, PDF (10/20 Pages) Microchip Technology – 6A Single High-Speed, CMOS Power MOSFET Driver

TC429
The device capacitive load dissipation is:
EQUATION
PC = fCVS2
Where:
f = Switching frequency
C = Capacitive load
V_S = Supply voltage
Quiescent power dissipation depends on input signal
duty cycle. A logic low input results in a low-power
dissipation mode with only 0.5 mA total current drain.
Logic-high signals raise the current to 5 mA maximum.
The quiescent power dissipation is:
EQUATION
PQ = VSDIH + 1 – DIL
Where:
I_H = Quiescent current with input high
(5 mA max)
I_L = 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
simultaneously for a very short period when the output
changes.
The device transition power dissipation is approxi-
mately:
EQUATION
PT = fVS3.3  10^–9A  Sec
An example shows the relative magnitude for each
item.
C = 2500 pF
V_S = 15V
D = 50%
f = 200 kHz
P_D = Package power dissipation:
= P_C + P_T + P_Q
= 113 mW + 10 mW + 41 mW
= 164 mW
Maximum ambient operating temperature:
= T_J – _JA (P_D)
= 150ºC - (150ºC/W)(0.164W)
= 125C
Where:
T_J = Maximum allowable junction temperature
(+150C)
_JA = Junction-to-ambient thermal resistance
(150C/W, CERDIP)
DS21416D-page 10
Note:
Ambient operating temperature should not
exceed +85ºC for EPA or EOA devices or
+125ºC for MJA devices.
TABLE 4-1: MAXIMUM OPERATING
FREQUENCIES
V_S
f_MAX
18V
500 kHz
15V
700 kHz
10V
1.3 MHz
5V
>2 MHz
Conditions:
1. CERDIP Package (_JA =150C/W)
2. T_A = +25C
3. C_L = 2500 pF
5V/DIV
INPUT
500mV/DIV
(5 AMP/DIV)
OUTPUT
V_S = 18V
R_L = 0.1Ω
5V
500mV
5μs
TIME (5μs/DIV)
FIGURE 4-5:
Capability.
Peak Output Current
4.5 POWER-ON OSCILLATION
Note:
It is extremely important that all MOSFET
driver applications be evaluated for the
possibility of having high-power oscillations
occur during the power-on cycle.
Power-on oscillations are due to trace size, layout and
component placement. A ‘quick fix’ for most applica-
tions that exhibit power-on oscillation problems is to
place approximately 10 k in series with the input of
the MOSFET driver.
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