lm9061mx National Semiconductor Corporation, lm9061mx Datasheet - Page 16

• Manufacturer Part Number: lm9061mx
• Description: Power Mosfet Driver With Lossless Protection
• Manufacturer: National Semiconductor Corporation

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Application Information
DRIVING MOSFET ARRAYS
The LM9061 is an ideal driver for any application that re-
quires multiple parallel MOSFETs to provide the necessary
load current. Only a few “common sense” precautions need
to be observed. All MOSFETs in the array must have identi-
cal electrical and thermal characteristics. This can be solved
by using the same part number from the same manufacturer
for all of the MOSFETs in the array. Also, all MOSFETs
should have the same style heat sink or, ideally, all mounted
on the same heat sink. The electrical connection of the
MOSFETs should get special attention. With typical R
values in the range of tens of milli-Ohms, a poor electrical
connection for one of the MOSFETs can render it useless in
the circuit.
Also, the MOSFET dissipation during the Normal-OFF dis-
charge of the gate capacitance, 70 µA minimum and 110 µA
typical, needs consideration.
(Continued)
FIGURE 7. Driving Multiple MOSFETs
DS(ON)
16
One particular caution is that, in the event of a fault condi-
tion, the Latch-OFF current sink, 10 µA typical, may not be
able to discharge the total gate capacitance in a timely
manner to prevent damage to the MOSFETs.
Figure 7 shows a circuit with four parallel NDP706A MOS-
FETs. This particular MOSFET has a typical R
0.013Ω with a T
With the V
circuit will provide a typical maximum load current of 150A at
25˚C, and a typical maximum load current of 100A at 125˚C.
The maximum dissipation, per MOSFET, will be nearly 20W
at 25˚C, and 12.5W at 125˚C. With up to 20W being dissi-
pated by each of the four devices, an effective heat sink will
be required to keep the T
near the maximum load currents.
DS
threshold voltage being set to 500 mV, this
J
of 25˚C, and 0.020Ω with a T
J
as low as possible when operating
01231715
J
of +125˚C.
DS(ON)
of