Gan Systems GS66508T-EVBHB User Manual Download Page 6

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GS66508T-EVBHB 650V

GaN E-HEMT Half Bridge Evaluation Board

User’s Guide

_____________________________________________________________________________________________________________________

GS66508T-EVBHB UG rev. 150917

www.gansystems.com 6

Please refer to the Evaluation Board/Kit Important Notice on page 21

Gate driver circuit

Figure 7 - Half bridge gate driver circuit

Gate drive power supply

A low side adjustable LDO (U5) steps down the input 9-12V to 6.5V for optimal gate drive. Bootstrap
diode (D1) and capacitor (C4) are used to create a floating gate drive power supp

y for the high side gate

drive circuit. The bootstrap voltage on C4 is then regulated by LDO (U2) to create a nominal 6.5V for
optimal gate drive.

Gate resistance

Turn-on gate resistors, R7/R18, are populated with 24.9

resistors. These resistors can be adjusted to

control the turn-on slew rate. Generally it is recommended to select turn-on gate resistance between 15-
25

Ω for optim

al performance. Smaller turn-on gate resistor values may create fast switching speeds

causing unnecessary Miller turn-on and oscillation. For turn-off it is recommended to use a small value
of less than 2

for the turn-off gate resistors R10/R21. This will provide a strong pull-down during turn-

off and reduce the Miller voltage effects.

6.5V Gate Drive

VIN

600V 1A
P/N: ES1J

SMA

1uF

0VGDH

GND

OUT

MIC5225YM5

VDRVH

0VGDH

ADJ

42K2

10K

0VGDH

TP2

TP4

24R9

VDD

ANODE

VO1

VO2

GND

R10

8261

BAC

0VGDH

2.2uF

CATH

N/C2

332R

N/C1

0VGDH

FB1

15R@100MHz

PMEG2010

0VGDH

TP8

GOH

R11

10K

TP7

VDDH

TP6

INH

TP11

HIGH SIDE FLOATING
GROUND

TP10

0VH

TP12

0VGDH

VGH

VSSH

GNDH

VIN

C14

1uF

GND

OUT

MIC5225YM5

VDRVL

ADJ

R15

42K2

R17

10K

24R9

VDD

ANODE

VO1

VO2

GND

R18

R21

8261

BAC

C16

2.2uF

CATH

N/C2

332R

N/C1

FB2

15R @100MHz

PMEG2010

R19

TP18

GOL

R23

10K

TP17

VDDL

TP16

INL

TP21

TP20

0VL

TP22

VGL

VSSL

GNDL

DZ4 (C18)

SOD323

6.8V 200mW

DZ3 (C11)

SOD323

6.8V 200mW

Summary of Contents for GS66508T-EVBHB

Page 1: ...version of this user s guide DANGER Electrical Shock Hazard Hazardous high voltage may be present on the board during the test and even brief contact during operation may result in severe injury or death Follow all locally approved safety procedures when working around high voltage Never leave the board operating unattended After it is de energized always wait until all capacitors are discharged b...

Page 2: ...nce design for the gate driver circuit half bridge PCB layout and thermal management Functional Overview Please refer to the circuit schematic in appendix for all signal names circuit nodes and test points The block diagram of the GS66508T EVBHB can be seen in Figure 1 All components are mounted on the top side except for E HEMTs Q1 and Q2 which are mounted on the bottom side of the EVB A heatsink...

Page 3: ..._____________________________________________________________________________ GS66508T EVBHB UG rev 150917 2015 GaN Systems Inc www gansystems com 3 Please refer to the Evaluation Board Kit Important Notice on page 21 Figure 2 Board overhead view Figure 3 Board bottom view showing 2x GS66508T with heatsink removed ...

Page 4: ...the logic circuit and 6 5V for the gate driver Gate input J2 J5 Figure 5 Gate signal input J2 J5 Set signal generator output level to 5V with 50Ω impedance for the gate PWM signal input on connector J5 The high side gate drive signal can be configured by jumper J3 By default J3 is set to the INT position internal created by an on board circuit The on board logic circuit inverts the PWM input on J5...

Page 5: ...G rev 150917 2015 GaN Systems Inc www gansystems com 5 Please refer to the Evaluation Board Kit Important Notice on page 21 Dead time control Figure 6 Dead time control circuit Dead time is controlled by two RC delay circuits R16 C15 and R22 C19 By default 100ns dead time is used Additionally two potentiometers locations are provided TR1 TR2 not included to allow fine adjustment of the dead time i...

Page 6: ...ded to select turn on gate resistance between 15 25Ω for optimal performance Smaller turn on gate resistor values may create fast switching speeds causing unnecessary Miller turn on and oscillation For turn off it is recommended to use a small value of less than 2Ω for the turn off gate resistors R10 R21 This will provide a strong pull down during turn off and reduce the Miller voltage effects 6 5...

Page 7: ...n between clamping diode and the gate if to suppress any unwanted gate oscillation is observed Ferrite bead Ferrite bead on the gate helps to damp the gate ringing and reduce the risk of gate oscillation On the other hand adding ferrite bead increases the gate inductance and risk of miller turn on A small surface mount device SMD EMI suppression ferrite bead with impedance of 10 20Ω 100MHz is suff...

Page 8: ... J4 high side VGH and J7 low side VGL for gate drive signal measurements WARNING ALWAYS use high voltage differential or isolated probes for measuring high side floating signals Attaching probe to high side gate signal may affect the switching behaviors due to the added parasitic and coupling capacitance introduced by the probe To obtain best switching performance it is recommended to only measure...

Page 9: ...y electrically connected to the Source of the device Forced air cooling is recommended for power testing The airflow direction should be controlled from the left side as shown in Figure 9 for best cooling performance CAUTION Device temperature must be closely monitored during the test Never operate the board with device temperature exceeding TJ_MAX 150 C Power Stage Setup Power connections CON1 6 ...

Page 10: ...as free wheeling device sync which is driven synchronously Figure 10 shows an example of the PWM input signal and pulse test switching waveforms for the pulse test mode Since a bootstrap circuit is used to create the high side gate voltage the low side device Q2 must be turned on first before the first testing pulse to ensure that the high side gate driver is powered up This can be implemented by ...

Page 11: ...s attached between VBUS and VBUS the board is converted into a boost mode circuit and can be used for Synchronous Boost DC DC Totem pole bridgeless PFC Quick start procedure pulse test mode 1 Equipment and components you will need to get started Four channel oscilloscope with 500MHz bandwidth or higher high bandwidth 500MHz or higher passive probe high bandwidth 500MHz high voltage probe 600V AC D...

Page 12: ...nfirm that gate drive signals VGL and VGH are present and the gate voltage levels are correct 5 Connect the probes as shown in Figure 11 for the following measurements a VGL J7 low side gate signal passive probe b VDS J6 low side drain voltage HV probe c VGH J4 high side gate signal HV differential probe optional d IL current probe for inductor current 6 Set the High Voltage HV DC supply voltage l...

Page 13: ...test VDS 400V IMAX 30A TON 2us N 5 L 120uH Pulse test results show that the gate driver is stable for the entire operating range from 0 30A with no oscillation and minimum drain voltage overshoot Figure 12 Pulse Test waveforms 400V 30A The measured rise time for turn on is 10ns and the fall time at 30A turn off is 6ns The miller voltage is under good control with a peak value of 0 8V which is lowe...

Page 14: ... Important Notice on page 21 a Turn on waveforms 400V 22A b Turn off waveforms 400V 30A Figure 13 Pulse test switching waveforms turn on and turn off Synchronous Buck Test L 120uH VIN 400V VOUT 200V D 50 FSW 100 kHz POUT 0 2kW The board is converted to a synchronous buck DC DC converter and demonstrates efficiency 98 5 from 1kW to 2kW With forced air cooling the peak device temperature TJ_MAX was ...

Page 15: ...___________________________________________________ GS66508T EVBHB UG rev 150917 2015 GaN Systems Inc www gansystems com 15 Please refer to the Evaluation Board Kit Important Notice on page 21 Figure 15 Synchronous Buck switching waveforms CCM POUT 1500W Figure 16 Thermal image showing Q1 and Q2 temperature POUT 1500W TJMAX 80 C TAMB 25 C ...

Page 16: ...V MKP1848 0V D G S GS66508T Q2 GANPX T G CON1 CON3 VSW VIN 0V C14 1uF IN GND OUT MIC5225YM5 VDRVL 0V ADJ EN R15 42K2 R17 10K 24R9 VDD ANODE VO1 VO2 GND R18 0R R21 SI8261BAC 0V C16 2 2uF CATH N C2 332R N C1 D3 0V FB2 15R 100MHz DZ4 C18 0V PMEG2010 0V U5 R19 SOD323 TP18 GOL R23 10K TP17 VDDL TP16 INL TP21 TP20 0VL TP22 0VGDH J4 0V J7 VOUT VGH WARNING USE HV DIFFERENTIAL PROBES ON HIGH SIDE SIGNALS V...

Page 17: ...___________________________________________________________________________________________________________________ GS66508T EVBHB UG rev 150917 2015 GaN Systems Inc www gansystems com 17 Please refer to the Evaluation Board Kit Important Notice on page 21 PCB Layout Top layer ...

Page 18: ...e _____________________________________________________________________________________________________________________ GS66508T EVBHB UG rev 150917 2015 GaN Systems Inc www gansystems com 18 Please refer to the Evaluation Board Kit Important Notice on page 21 Bottom Layer ...

Page 19: ...___________________________________________________________________________________________________________________ GS66508T EVBHB UG rev 150917 2015 GaN Systems Inc www gansystems com 19 Please refer to the Evaluation Board Kit Important Notice on page 21 Assembly Drawing Top ...

Page 20: ... ELECTRONICS 74279268 FB2 R10 R21 32 RES SMD 0 0 OHM JUMPER 1 10W VISHAY DALE CRCW06030000Z0EA J1 1 TERM BLOCK HDR 2POS R A 5 08MM TE CONNECTIVITY 796638 2 J2 J5 J6 3 CONN BNC JAC STR 50 OHM AMPHENOL 112538 DNP J2 J3 1 CONN HEADER 3POS 2 54MM WURTH ELECTRONICS 61300311121 J4 J7 2 CONN SMA JACK SMD VERT 50OHM LINX CONSMA001 SMD G Q1 Q2 2 TRANS GAN E HEMT 650V 30A GAN SYSTEMS INC GS66508T E01 R1 1 R...

Page 21: ... board kit may be returned within 30 days from the date of delivery for a full refund THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED IMPLIED OR STATUTORY INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE EXCEPT TO THE EXTENT OF THIS INDEMNITY NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR A...

Page 22: ...nents are not designed authorized or warranted for use in lifesaving life sustaining military aircraft or space applications nor in products or systems where failure or malfunction may result in personal injury death or property or environmental damage The information given in this document shall not in any event be regarded as a guarantee of performance GaN Systems hereby disclaims any or all war...

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