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MATCHING MOSFET DRIVERS TO MOSFETs

MATCHING MOSFET DRIVERS TO MOSFETs

MATCHING MOSFET DRIVERS TO MOSFETs
APPLICATION NOTE 30
MATCHING MOSFET DRIVERS TO MOSFETs
AN-30
INTRODUCTION
TelCom offers many sizes of MOSFET drivers. This allows the designer to best match the switching performance of the driver / MOSFET to the application.
MOSFET DIE SIZES
Unlike bipolar transistors in which die size is primarily a function of current, MOSFETs have die sizes that are a function of both current and voltage.
INPUT 1 µF 50V V-
TC4424
DIE SIZE EFFECT ON GATE CAPACITANCE
Figure 2. Use of a Resistor to Limit Peak Current
DRIVER FAMILIES
TC4424
INPUT 1 µF 50V V-
Figure 1. Typical Drive Circuit
TC4426
PEAK CURRENT REQUIREMENTS
AN30-2
Figure 3. Use of Zener Diode to Clamp Voltage on Long Output Lead
MATCHING MOSFET DRIVERS TO MOSFETs AN-30
TYPICAL APPLICATIONS
+12V 1 µF 50V TYPICAL USE IN CIRCUIT WITH LARGE TRACE / LEAD INDUCTANCE +12V 1 µF 50V 2.2-22 12V 12V
SIMPLE, DIRECT DRIVER
+12V 1 µF 50V A TC170 CMOS PWM B
+300V
IRF450
TC4427
FORWARD CONVERTER WITH TC4427 DRIVING UPPER AND LOWER FETs
Another important improvement in the second generation families is their ability to have the input signal go below the negative rail by as much as 5V. This guaranteed parameter is very useful in systems where the control circuit ground is not closely tied to the power or source ground of the MOSFET. These two grounds often move relative to one another. The TC1426 is a special, low-cost version of the 426 family that is latch-up resistant but does not have the below-rail protection on the input. It is a good choice for large volume OEMs. Following the same part numbering pattern as the 1.5A TC426 family, the TC4423 family of dual drivers has a 3A output capacity. The TC4424 is a dual non-inverting driver and the TC4425 is one inverting plus one noninverting driver. The TC4429 is a single inverting driver (like its predecessor the TC429), while the TC4420 is non-inverting.
This family has a 6A drive capability at 18V. The TC4429 can slew a 10, 000 pF load at 15V in 60 ns. The table on the following page shows the performance of the various drivers under production test methods. The characteristics of the drivers are more fully described in their individual data sheets. This table is intended only as a guide for comparing specifications. Refer to the individual data sheets for more complete information. The following families of power drivers are made with a CMOS process to interface between low-level control functions and high-power switching devices, particularly power MOSFETs. The devices are also an optimum choice for capacitive drivers where 1.2A-9A may be switched. With both inverting and non-inverting inputs available, logic signals of either polarity may be accepted.
MATCHING MOSFET DRIVERS TO MOSFETs AN-30
Selecting MOSFET Drivers Rise Time @ Rated Load (ns) 30 30 30 25 25 25 25 25 25 40 40 50 50 30 30 30 Fall Time @ Rated Load (ns) 20 20 20 25 25 25 25 25 25 35 35 48 48 30 30 30 Rising Edge Prop. Delay (ns) 55 55 55 33 33 33 33 33 33 50 50 30 30 35 35 35 Falling Edge Prop. Delay (ns) 80 80 80 38 38 38 38 38 38 55 55 33 33 35 35 35 Input Protected Latchto 5V Up Below Proof Gnd Rail Yes No Yes No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Device No. TC1426 TC1427 TC1428 TC4426 TC4427 TC4428 TC4423 TC4424 TC4425 TC4420 TC4429 TC4421 TC4422 TC4469 TC4468 TC4467
Drive Current (Peak) 1.2A 1.2A 1.2A 1.5A 1.5A 1.5A 3.0A 3.0A 3.0A 6.0A 6.0A 9.0A 9.0A 1.2A 1.2A 1.2A
Rated Load Inverting Non-Invert. (pF) Dual 1000 Dual 1000 Single Single 1000 Dual 1000 Dual 1000 Single Single 1000 Dual 2200 Dual 2200 Single Single 2200 Single Non-invert 4700 Single Inverting 4700 Single 10, 000 Single 10, 000 - Quad - 1000 - Quad AND - 1000 - Quad NAND - 1000
Output Number and Type
MOSFET Die Size vs Suggested Drive Family MOSFET Size Hex 0 Hex 1 Hex 2 Hex 3 Hex 4 Hex 5 Hex 6 Hex 7 Parallel Modules Die Size (mm) 0.89 x 1.09 1.75 x 2.41 3.40 x 2.21 4.44 x 2.79 7.04 x 4.32 6.45 x 6.45 283 x 321 mil 283 x 348 mil Various Total C of MOSFET (pF) 400 750 1500 3000 6000 12, 000 15, 000 16, 000 Up to 48, 000 Suggested Driver Family (@ 12V) TC1426 / 4426 / 4469 TC1426 / 4426 / 4469 TC1426 / 4426 / 4469 TC1426 / 4426 TC4423 TC4423 TC4429 / 4420 TC4429 / 4420 TC4421 / 4422 Faster Rise / Fall Times
TC4423 TC4423 TC4429 TC4429 TC4421 / 4422 TC4421 / 4422
CONCLUSIONS
Printed in the U.S.A. 3 / 30 / 95
MATCHING MOSFET DRIVERS TO MOSFETs AN-30
Sales Offices
TelCom Semiconductor 1300 Terra Bella Avenue P.O. Box 7267 Mountain View, CA 94039-7267 TEL: 650-968-9241 FAX: 650-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TelCom Semiconductor Austin Product Center 9101 Burnet Rd. Suite 214 Austin, TX 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom Semiconductor H.K. Ltd. 10 Sam Chuk Street, Ground Floor San Po Kong, Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957
Printed in the U.S.A. 9 / 5 / 95