IX6611 Evaluation Board

Transcription

1 IXUM The IX6611 Evaluation Board is created to simplify the IX6611 driver s accommodation in a new design. It is a standalone device that can be easily connected to any IGBT or MOSFET to evaluate its performance under different operating conditions. Description and Board Schematic The IX6611 is a secondary side, intelligent, high-speed gate driver designed to drive IXYS IGBTs and power MOSFET devices. The IX6611 gate driver contains the necessary circuit blocks for pulse transformer-isolated applications. High frequency, narrow pulses are used for bi-directional data transfer across the isolation boundary to avoid duty cycle restrictions and to prevent transformer saturation. The IX6611 includes the necessary monitoring and protection functions such as Supply Under-Voltage Lockout, Supply Over-Voltage Lockout, Thermal Shutdown, external IGBT Overcurrent and Overvoltage protection. For more information, see the IX6611 Datasheet. This Evaluation Board is a two-layer surface mount board with all components assembled on the top layer to simplify signal monitoring. It contains connectors for an input signal and power for input signal conditioner, and connectors to power the isolated IX6611 driver and an external IGBT/MOSFET connection. The Evaluation Board Electrical Schematic diagram is shown in Figure 1. Figure 1. Evaluation Board Electrical Schematic Diagram 1

2 It contains IX6611 driver U1 with the required decoupling/filtering capacitors and isolation transformer T1, which provides up to 4 kv DC isolation between a signal source and IX6611 driver. Logic IC U2 and U3 with R16C12 network and MOSFETs Q1, Q2 are used as a signal conditioner, which converts the typical PWM input signal into two short pulses representing rising and falling edges of the input signal. These pulses are applied to the primary winding of the transformer T1B to be transmitted to the secondary side, where IX6611 uses them to restore the gate drive pulse to the source pulse s shape. This helps avoid limitations to the maximum input pulse length. Test points P11 and P12 enable monitoring of these pulses on the T1B primary side, while test point P13 allows for comparison of their position with the input signal, as seen in Figure 2. Legend: Channel 1 (blue) INPUT signal P13 test point Channel 2 (magenta) P11 test point Channel 3 (green) P12 test point Channel 4 (red) IGBT gate pulse P1, P2 test pints shorted together Figure 2. PWM Signal Transmission Logic IC U2, U3 should be powered from an external power supply through connector J3 with V CC voltage in the range of 3.0 V to 5.0 V. Diodes D2 on the T1B secondary side are used to separate pulses representing rising and falling edges of the input signal before applying them to inputs of the IX6611 driver. Transformer T1A is used by the IX6611 driver to transmit fault conditions to the signal source level. Diodes D1 separate Fault 1 and Fault 2 signals, converting them to positive polarity pulses in respect to signal ground. Test points P3 and P8 allows for monitoring of Fault 1 and Fault 2 events as single short pulses. See the IX6611 Datasheet for more information about fault conditions and their representation. The IX6611 Gate driver U1 should be powered from an isolated (with respect to signal ground) power source with isolation that is equal to or exceeding the value expected during the evaluation. Power should be applied through connector J1. Because the common point of isolated power supply is connected directly or through low resistance current sensor to the IGBT s emitter, close attention should be paid to avoid electrical shock in case this point is at a high potential with respect to signal ground. Capacitor C13 rated at 6.3 kv is used to prevent electrostatic discharge. 2

3 Gate drive voltage applied to J1 is directly transmitted to the IGBT/MOSFET s gate, so its recommended value should be in the range of +12 V to +18 V for positive voltage and 5 V to 7 V for negative voltage. Positive voltage outside this range may trigger overvoltage or undervoltage protection, as described in the IX6611 Datasheet. If negative voltage is not required for MOSFET operation, pin #3 of the connector J1 should be shorted to pin #2 of the same connector. This Evaluation Board contains gate current limiting resistors R2 and R3 for positive and negative gate voltage. Its value is set at 1 Ohm and serial resistors should be added, if required, to accommodate the IGBT/MOSFET used to get the best performance. The Evaluation Board also contains current sense resistor R10 equal to 0.1 Ohm, which is enough to trigger overcurrent protection at 3 A IGBT/MOSFET current. If overcurrent protection is used, the IGBT s emitter should be connected to pin #4 of J2 and bus voltage should be connected to pin #5 of J3 (see Figure 2a). If higher current value is required, an additional shunt resistor should be connected in parallel between pins #4 and #5 of the connector J2 (see Figure 2b). If overcurrent protection is not used, IGBT s emitter and bus voltage should be connected to pin #5, while pin #4 should be left open or shorted to pin #5 (see Figure 2c). If the IGBT desaturation event is used as an overcurrent trigger, internal current sense resistor R10 should be removed and external resistive divider with Zener protection diode should be used as shown in Figure 2d. Zener s diode threshold should not exceed 5 V to prevent IX6611 internal logic damage. A typical IGBT connection in case of ACL utilization is shown in Figure 3. (a) (b) (c) (d) Legend: a) Internal 0.1 Ohm current sense resistor used b) External shunt resistor R3 added to increase current rating c) Over-current protection is not used d) Over-current protection with IGBT de-saturation monitoring - internal current sense resistor removed Figure 3. IGBT Connection for Overcurrent Protection Utilization Network R6C7 is used to filter high frequency noise from the current sense resistor. Resistive divider R4/R9 sets the active clamping (ACL) threshold. If ACL is used, serial resistor Rs should be connected to pin #3 of the connector J2 to set the appropriate ACL threshold. ACL starts when the IGBT is in an off state with the gate driven low by negative voltage supply and the collector voltage exceeding the threshold set by Zener diodes Vc = Vzd1+ Vzd2 + Vzd3 - Vn with respect to the emitter. A current flowing through Zener diodes and resistor R2 creates a voltage drop across ZD3, which turns ACL protection on. Because the ACL threshold is set at 3.1 V with respect to negative power supply, serial resistor Rs value required to trigger ACL at this moment is equal. Rs = Vzd3 / 3.1 2, kohm where Vzd3 is a ZD3 diode stabilization voltage. 3

4 Figure 4. IGBT Connection for ACL Utilization When ACL activates, the IX6611 gate driver s outputs become tri-state and the IGBT gate starts charging by Zeners diodes current. When IGBT becomes active, the collector voltage drops, ACL disables and negative voltage applies to the IGBT gate, again disabling it. If energy stored in the inductor is very high, this sequence of operations may repeat until the remaining energy in the inductor is not enough to trigger ACL protection. Diodes D2, D3 protect the IGBT gate from going above the power supply voltage. However, if the power supply used is not able to sink the current, Zener diodes should be used for gate protection. The dimensions of the Evaluation Board are 1.5 x 3.0 x 0.8 (L x W x H). The location of the Evaluation Board components is shown in Figure 5. Figure 5. Evaluation Board Components Location Using the Test Board Installation This Evaluation Board contains four connectors to provide power and accommodate IGBT/MOSFET, which should be installed prior to the start of an evaluation. The recommended IGBT/MOSFET connection schematic diagrams are shown in Figures 3 and 4. Connector J1 of the Evaluation Board should be powered from an isolated power supply with respect to a signal ground and isolation voltage above expected during the test. 4

5 It is recommended to apply V CC voltage to the connector J3 and power to connector J1 before the input signal is applied to the connector J4. Powering Device Warning! This Evaluation Board does not have reverse polarity protection. Close attention should be paid to the correct polarity of the power supply connection to prevent damage to the Evaluation Board. 5

6 Warranty and Use IXYS CORP. MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES. IXYS Corp. products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the IXYS Corp. product could create a situation where personal injury or death may occur. IXYS Corp. reserves the right to make changes to or discontinue any product or service described herein without notice. Products with data sheets labeled "Advance Information" or "Preliminary" and other products described herein may not be in production or offered for sale. IXYS Corp. advises customers to obtain the current version of the relevant product information before placing orders. Circuit diagrams illustrate typical semiconductor applications and may not be complete. IXYS Corp Buckeye Dr. Milpitas, CA Phone: Fax: