FOD3181_08 Datasheet, PDF (10/12 Pages) Fairchild Semiconductor – 0.5A Ouput Current, High Speed MOSFET Gate Driver Optocoupler

Reflow Profile
300
245 C, 10–30 s
250
260 C peak
200
150
100
Time above 183C, <160 sec
50
Ramp up = 2–10C/sec
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Time (Minute)
• Peak reflow temperature: 260 C (package surface temperature)
• Time of temperature higher than 183 C for 160 seconds or less
• One time soldering reflow is recommended
Output Power Derating
The maximum package power dissipation is 295mW. The
package is limited to this level to ensure that under normal
operating conditions and over extended temperature
range that the semiconductor junction temperatures do
not exceed 125°C. The package power is composed of
three elements; the LED, static operating power of the
output IC, and the power dissipated in the output power
MOSFET transistors. The power rating of the output IC is
250mW. This power is divided between the static power of
the integrated circuit, which is the product of I_DD times the
power supply voltage (V_DD – V_EE). The maximum IC
static output power is 150mW, (V_DD – V_EE) = 25V, I_DD =
6mA. This maximum condition is valid over the opera-
tional temperature range of -40°C to +100°C. Under these
maximum operating conditions, the output of the power
MOSFET is allowed to dissipate 100mW of power.
The absolute maximum output power dissipation versus
ambient temperature is shown in Figure 12. The output
driver is capable of supplying 100mW of output power
over the temperature range from -40°C to 87°C. The out-
put derates to 90mW at the absolute maximum operating
temperature of 100°C.
Fig. 12 Absolute Maximum Power Dissipation
vs. Ambient Temperature
0.15
VDD – VEE = Max. = 25V
IDD = 6mA
LED Power = 45mW
0.1
The output power is the product of the average output
current squared times the output transistor’s R_DS(ON):
P_O(AVG) = I_O(AVG)2 • R_DS(ON)
The I_O(AVG) is the product of the duty factor times the
peak current flowing in the output. The duty factor is
the ratio of the ‘on’ time of the output load current divided
by the period of the operating frequency. An R_DS(ON) of
2.0Ω results in an average output load current of 200mA.
The load duty factor is a ratio of the average output time
of the power MOSFET load circuit and period of the driv-
ing frequency.
The maximum permissible, operating frequency is deter-
mined by the load supplied to the output at its resulting
output pulse width. Figure 13 shows an example of a
0.03µF gate to source capacitance with a series resis-
tance of 40Ω. This reactive load results in a composite
average pulse width of 1.5µs. Under this load condition it
is not necessary to derate the absolute maximum output
current out to 250kHz.
Fig. 13 Output Current Derating vs. Frequency
1.5
TA = -40°C to 100°C
Load = 0.03µF + 40Ω
VDD = 20V
IF = 12mA
1 ^{LED Duty Factor = 50%}
Output Pulse Width = 1.5µs
0.5
0.05
0
-40
-20
0
20
40
60
80 85
T_A – AMBIENT TEMPERATURE (°C)
0
1
10
250
F – FREQUENCY (kHz)
©2003 Fairchild Semiconductor Corporation
FOD3181 Rev. 1.0.8
10
www.fairchildsemi.com