DEIC421 RF MOSFET DRIVER 20 Ampere Ultrafast RF MOSFET Driver With Kelvin Connection Features • Built using the advantages and compatibility of CMOS and IXYS HDMOS™ processes • Latch-Up Protected • High Peak Output Current: 20A Peak • Wide Operating Range: 8V to 30V • Rise and Fall Times of <4ns • Minimum Pulse Width of 8ns • High Capacitive Load Drive Capability: 4nF in <4ns • Matched Rise and Fall Times • 32ns Input to Output Delay Time • Low Output Impedance • Low Quiescent Supply Current • Kelvin input ground connection • Reduced internal inductance Applications • • • • • • • Driving RF MOSFETs Class D or E Switching Amplifier Drivers Multi-MHz Switch Mode Power Supplies (SMPS) Pulse Generators Acoustic Transducer Drivers Pulsed Laser Diode Drivers Pulse Transformer Driver Description The DEIC421 is a CMOS high speed high current gate driver specifically designed to drive MOSFETs in Class D, E, and RF applications at up to 45MHz, as well as other applications requiring ultrafast rise and fall times or short minimum pulse widths. The DEIC421 is an improved version of the DEIC420. The DEIC421 has a Kelvin ground connection on the input side to allow the use of a common mode choke to avoid problems with ground bounce. The internal layout of the package has been improved to reduce inductance. The DEIC421 can source and sink 20A of peak current while producing voltage rise and fall times of less than 4ns, and minimum pulse widths of 8ns. The input of the driver is compatible with +5V or CMOS and is fully immune to latch up over the entire operating range. Its features and wide safety margin in operating voltage and power make the DEIC421 unmatched in performance and value. The DEIC421 is packaged in DEI’s new 7 leaded low inductance RF package. The DEIC421 is a surface-mount device, and incorporates patented(1) RF layout techniques to minimize stray lead inductances for optimum switching performance. (1) DEI U.S. Patent #4,891,686 Figure 1 - DEIC421 Functional Diagram VCC IN IN GND OUT DGND DEIC421 RF MOSFET DRIVER Absolute Maximum Ratings Parameter Value Parameter Value Supply Voltage 30V Storage Temperature 65°C to 150°C Input Pin -5V to VCC+0.3V 300°C All Other Pins -0.3V to VCC+0.3V Soldering Lead Temperature (10 seconds maximum) Power Dissipation TAMBIENT ≤ 25°C Maximum Junction Temperature 150°C 2W Operating Temperature Range -40°C to 85°C 100W Thermal Impedance Rth(JC) (Junction to Case) 1.3°C/W TCASE ≤ 25°C Electrical Characteristics Unless otherwise noted, TA = 25 °C, 8V ≤ VCC ≤ 30V. All voltage measurements with respect to DGND. DEIC421 configured as described in Test Conditions. Symbol Parameter Test Conditions VIH High input voltage VIL Low input voltage VIN Input voltage range IIN Input current VOH High output voltage VOL Low output voltage ROH Output resistance @ output high IOUT = 10mA, VCC = 15V ROL Output resistance @ output low Min Typ Max 3.5 0V ≤ VIN ≤ VCC Units V 0.8 V -5 VCC + 0.3 V -10 10 mA VCC - .025 V 0.025 V 0.4 0.6 Ω IOUT = 10mA, VCC = 15V 0.4 0.6 Ω VCC = 15V 20 fMAX Peak output current Continuous output current Maximum frequency tR Rise time(1) CL = 1nF, VCC = 15V, VOH = 2V to 12V CL = 4nF, VCC = 15V, VOH = 2V to 12V 3 4 ns ns tF Fall time(1) CL = 1nF, VCC = 15V, VOH = 12V to 2V CL = 4nF, VCC = 15V, VOH = 12V to 2V 3 3.5 ns ns tONDLY On-time propagation delay(1) CL = 4nF, VCC = 15V 32 38 ns tOFFDLY Off-time propagation delay(1) CL = 4nF, VCC = 15V 29 35 ns PWmin Minimum pulse width FWHM, CL = 1nF, VCC = 15V +3V to +3V, CL = 1nF, VCC = 15V 8 9 VCC Power supply voltage ICC Power supply current IPEAK IDC (1) Refer to Figures 2 and 3 CL = 4nF, VCC = 15V 8 VIN = 3.5V VIN = 0V VIN = +VCC A 4 A 45 MHz ns ns 15 30 V 1 0 3 10 10 mA µA µA Specifications Subject To Change Without Notice DEIC421 RF MOSFET DRIVER Lead Description SYMBOL FUNCTION DESCRIPTION VCC Supply Voltage IN Input IN GND Input Ground OUT Output Driver output. For application purposes, this lead is connected directly to the gate of a MOSFET. GND Power Ground Power grounds should be connected to a low noise analog ground plane for optimum performance. Positive power-supply voltage input. These leads provide power to the entire chip. The range for this voltage is 8V to 30V. Input signal. TTL and CMOS compatible. 5V to 8V optimum. Input ground Kelvin connection. Note: Operating the device beyond parameters with listed “absolute maximum ratings” may cause permanent damage to the device. Typical values indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. The guaranteed specifications apply only for the test conditions listed. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. CAUTION: These devices are sensitive to electrostatic discharge; follow proper ESD procedures when handling and assembling this component. Figure 2 - Characteristics Test Diagram Vcc + 10uF Choke GND CL IN Vcc OUT IN GND Vcc GND Figure 3 - Timing Diagram 5V 90% INPUT 2.5V 10% 0V PWMIN tONDLY Vcc 90% OUTPUT 10% 0V tR tOFFDLY tF DEIC421 RF MOSFET DRIVER DEIC421 RF MOSFET DRIVER Fig. 11 Threshold vs. Supply Voltage Threshold Voltage (V) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 10.0 15.0 20.0 25.0 V C C Voltage ( V) Supply (V) 30.0 DEIC421 RF MOSFET DRIVER Typical Output Waveforms Unless otherwise noted, all waveforms are taken driving a 1nF load, 1 MHz repetition frequency, VCC = 15V, case temperature = 25°C Fig. 12 3ns Rise Time Fig. 14 <8ns Minimum Pulse Width Fig. 16 13.56MHz CW Repetition Frequency Fig. 13 3ns Fall Time Fig. 15 1MHz CW Repetition Frequency Fig. 17 50MHz Burst Repetition Frequency DEIC421 RF MOSFET DRIVER Applications Information Introduction Circuits capable of very high switching speeds and high frequency operation require close attention to several important issues. Key elements include circuit loop inductance, Vcc bypassing, and grounding. The common mode choke will provide a means of preventing ground bounce from affect the input to the driver. The selection of the common mode choke is related to the device being driven, the board layout, and the Vcc bypassing. Circuit Loop Inductance The Vcc to Vcc Ground current path defines the loop which will generate the inductive term. This loop must be kept as short as possible. The output lead must be no further than 0.375 inches (9.5mm) from the gate of the MOSFET. Furthermore, the output ground leads must provide a balanced symmetric coplanar ground return for optimum operation. Output Lead Inductance Of equal importance to supply bypassing and grounding are issues related to the output lead inductance. Every effort should be made to keep the leads between the driver and its load as short and wide as possible, and treated as coplanar transmission lines. Vcc Bypassing In order to turn a MOSFET on properly, the DEIC421 must be able to draw up to 20A of current from the Vcc power supply in 2-6ns (depending upon the input capacitance of the MOSFET being driven). Good performance requires very low impedance between the driver and the power supply. The most common method of achieving this low impedance is to bypass the power supply at the driver with a capacitance value much larger than the load capacitance. Usually, this is achieved by placing two or three different types of bypassing capacitors, with complementary impedance curves, very close to the driver itself. (These capacitors should be carefully selected, low inductance, low resistance, high-pulse-current-service capacitors.) Care should be taken to keep the lengths of the leads between these bypass capacitors and the DEIC421 to an absolute minimum. The bypassing should be comprised of several values of chip capacitors symmetrically placed on either side of the IC. Recommended values are .01uF and .47uF chips and at least two 4.7uF tantalums. Grounding In order for the design to turn the load off properly, the DEIC421 must be able to drain this 20A of current into an adequate grounding system. There are two paths for returning current that need to be considered: Path #1 is between the DEIC421 and its load, and path #2 is between the DEIC421 and its power supply. Both of these paths should be as low in resistance and inductance as possible, and thus as short as practical. The DEI421 has separate ground leads for input and power which allows the addition of a common mode choke in the input and input ground leads (see Fig. 2). In configurations where the optimum configuration of circuit layout and bypassing cannot be used, a series resistance of a few ohms in the gate lead may be necessary to prevent ringing. Heat Sinking For high power operation, the bottom side metalized substrate should be placed in compression against an appropriate heat sink. The substrate is metalized for improved heat dissipation, and is not electrically connected to the device or to ground. See the DEI technical note “DE-Series MOSFET and IC Mounting Instructions” on the IXYSRF website at www.ixysrf.com for detailed mounting instructions. DEIC421 RF MOSFET DRIVER Figure 18 - DEIC421 Package Outline IXYS RF An IXYS Company 2401 Research Blvd. Ste. 108, Ft. Collins, CO 80526 Tel: 970-493-1901; Fax: 970-493-1903 e-mail: [email protected] www.directedenergy.com IXYS RF reserves the right to change limits, test conditions and dimensions without notice. IXYS RF MOSFETS are covered by one or more of the following U.S. patents: 4,835,592 4,860,072 4,881,106 4,891,686 4,931,844 5,017,508 5,034,796 5,049,961 5,063,307 5,187,117 5,237,481 5,486,715 5,381,025 5,640,045 6,404,065 6,583,505 6,710,463 6,727,585 6,731,002