® PI2002-EVAL1 Cool-ORing ™ Series PI2002-EVAL1 Active ORing With Load Disconnect Evaluation Board User Guide Cool-ORing™ Series Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 1 PI2002 Product Description . . . . . . . . . . . . . . . . . . Page 2 Evaluation Board Terminal Description . . . . . . . . Page 2 Evaluation Board Schematic . . . . . . . . . . . . . . . . . Page 3 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 3 Evaluation Board Configuration . . . . . . . . . . . . . . Page 4 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4 PCB Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 10 Evaluation Board Mechanical Drawing . . . . . . . Page 10 The PI2002-EVAL1 Evaluation Board is intended to acquaint the user with the benefits and features of the Cool-ORingTM PI2002 Active ORing with Load Disconnect solution. It is not designed to be installed in end-use equipment. Please read this document before setting up the PI2002-EVAL1 Evaluation Board and refer to the PI2002 product data sheet for device specifications, functional description and characteristics. PI2002-EVAL1 Evaluation Board featuring the Cool-ORing PI2002 Active ORing controller. During operation, the power devices and surrounding structures can be operated safely at high temperatures. • Remove power and use caution when connecting and disconnecting test probes and interface lines to avoid inadvertent short circuits and contact with hot surfaces. • When testing electronic products always use approved safety glasses. Follow good laboratory practice and . . procedures. Introduction The PI2002-EVAL1 allows the user to test the basic principle and operational characteristics of an Active ORing with Load Disconnect function in a redundant power architecture, while also experiencing the benefits and value of the PI2002 solution versus conventional Active ORing solutions. The PI2002-EVAL1 evaluation board is configured to receive two independent power source inputs, per a typical redundant power architecture, through two Active ORing channels that are combined to form a redundant power output. Each channel contains a PI2002 controller and two N-channel power MOSFETs (configured back-to-back). The MOSFET footprints can take SO-8 or Power SO-8 MOSFET packages. Each channel is capable of up to 20 A. The PI2002-EVAL1 evaluation board is designed with optimized PCB layout and component placement to represent a realistic high density final design for an embedded Active ORing with Load Disconnect solution for ≤ 7 Vbus Picor Corporation • www.picorpower.com applications requiring up to 20 A. This evaluation board is intended as an easy and simple way to test the electrical and thermal performance of the PI2002 Active ORing with Load Disconnect controller. Both dynamic and steady state testing of the PI2002 can be completed on the PI2002-EVAL1 evaluation board, in addition to using the key features of the product. Dynamic testing can be completed under a variety of system level fault conditions to check for response time to faults. This document provides basic instructions for initial start-up and configuration of the evaluation board. Further information on the functionality of the PI2002 can be found in the PI2002 product data sheet. PI2002-EVAL1 User Guide Rev 1.0 Page 1 of 11 Cool-ORingTM PI2002 Product Description The Cool-ORing™ PI2002 with two external back-to-back configured industry standard N-channel MOSFETs is a complete Active ORing solution that also provides a Load Disconnect feature designed for use in redundant power system architectures. The PI2002 controls back-to-back MOSFETs providing true bi-directional switch capabilities to protect against both power source and load fault conditions. The gate drive output turns the MOSFETs on in normal steady state operation, while achieving high-speed turn-off under a variety of potential system-level fault conditions, per conventional Active ORing solutions with auto-reset once the fault clears. The PI2002 has the added benefit of being able to protect against output load fault conditions that may induce excessive forward current and device overtemperature by removing gate drive from the MOSFETs with an auto-retry programmable off-time. The back-to-back MOSFETs drain-to-drain voltage is monitored to detect normal forward, excessive forward, light load and reverse current flow. The PI2002 provides an active low fault flag output to the system during excessive forward current, reverse current, light load, under-voltage, over-voltage and over-temperature. A temperature sensing function turns off the MOSFETs and indicates a fault if the junction temperature exceeds 145°C. Figure 1 shows a photo of the PI2002-EVAL1 evaluation board, with two PI2002 controllers and four N-channel MOSFETs used to form the two Active ORing channels that also feature a Load Disconnect function. The board is built with two identical Active ORing circuits with options and features that enable the user to fully explore the capabilities of the PI2002 universal Active ORing with Load Disconnect controller. Terminals Rating Vin1, Vin2 Vaux1, Vaux2, (R11 = R19 = 10 Ω) 8 V / 20 A -0.3 V to 17.3 V / 40 mA FT1, FT2 -0.3 V to 17.3 V / 10 mA Figure 1 – PI2002-EVAL1 Evaluation Board (1.8" x 1.8") Terminal Description Vin1 Power Source Input #1 or bus input designed to accommodate up to 20 A continuous current. Vaux1 Auxiliary Input Voltage #1 to supply PI2002 VC power. Vaux1 should be equal to Vin1 plus 5 V or higher. See details in Auxiliary Power Supply (Vaux) section of the PI2002 data sheet. Rtn1 Vaux1 Return Connection: Connected to Ground plane Gnd Vin & Vout Return Connection: Three Gnd connections are available and are connected to a common point, the Ground plane. Input supplies Vin1 & Vin2 and the output load at Vout should all be connected to their respective local Gnd connection. Vin2 Power Source Input #2 or bus input designed to accommodate up to 20 A continuous current. Vaux2 Auxiliary Input Voltage #2 to supply PI2002 VC power. Vaux2 should be equal to Vin2 plus 5 V or higher. See details in Auxiliary Power Supply (Vaux) section of the PI2002 data sheet. Rtn2 Vaux2 Return Connection: Connected to Ground plane FT1 PI2002 (U1) Fault Pin: Monitors U1 fault conditions FT2 PI2002 (U2) Fault Pin: Monitors U2 fault conditions Vout Output: Q2 and Q4 MOSFET Drain pins connection, connect to the load high side. Table 1 – PI2002-EVAL1 Evaluation Board terminals description Jumper J5, J6 Description SCD Jumpers: Connect jumper across the two pins to the input side (GND) for maximum Gate charge current or across the two pins on the output side to connect to the resistive voltage divider to the output. Table 2 – PI2002-EVAL1 Evaluation Board jumpers description Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 2 of 11 Q1 FDS8812NZ R2 13.3k 1% C3 R5 0 Not Installed 3 2 1 4 R1 8.45K 1% 3 2 1 Q2 FDS8812NZ 8 7 6 5 Vout 4 Vin1 Vin1 Vaux1 8 7 6 5 Out1 Out2 C4 R7 Not Installed 0 R6 Vaux1 Gnd3 Vaux1 R8 5 Not Installed Gnd4 9 10 R11 10 8 FT1 IC1 PI2002 SN G SP 2 7 Gnd1 UV VC OV FT VC1 3 FT1 6 Red LED R10 4.99K R4 2.00k 1% SCD C2 18nF D1 5 J5 R9 C1 1uF Not Installed 1 R3 2.00k 1% OCT GND 4 Rtrn1 Vin2 C7 Not Installed 4 Not Installed R18 0 C9 22uF C8 R16 R17 R19 0 Not Installed Vaux2 5 SP 9 10 2 7 Gnd2 R22 10 FT2 8 Vaux2 G Vaux2 R13 13.3k 1% 3 2 1 IC2 PI2002 SN R12 8.45k 1% 3 2 1 Q4 FDS8812NZ 8 7 6 5 4 Vin2 Q3 FDS8812NZ 8 7 6 5 UV VC OV FT 3 6 VC2 FT2 Red LED R21 4 R15 2.00k 1% C6 SCD D2 5 J6 R20 18nF Not Installed 1 R14 2.00k 1% OCT GND 4.99K C5 1uF Rtrn2 Figure 2 – PI2002-EVAL1 Evaluation Board schematic. Item QTY Reference Designator Value 1 2 C1, C2 1 µF 2 1 C9 22 µF 3 4 C3, C4, C7, C8 4 2 C2, C3 5 2 6 6 7 8 8 2 D1, D2 FT1, FT2, Rtn1, Rtn2, Vaux1, Vaux2 Gnd1, Gnd2, Gnd3, Gnd4, Vin1, Vin2, Vout1, Vout2 J5, J6 9 4 Q1, Q2, Q3, Q4 10 11 12 13 14 15 16 2 2 4 6 2 2 2 R1, R12 R2, R13 R3, R4, R14, R15 R5, R6, R7, R16, R17, R18 R8, R9, R19, R20 R10, R21 R11, R22 17 2 U1, U2 18 nF 8.45 KΩ 13.3 KΩ 2.00 Ω 0Ω Not Installed 4.99 kΩ 10 Ω PI2002 Description Capacitor, MLCC X5R, 1 µF,16 V Capacitor, MLCC X7R, 22 µF, 25 V Not installed Capacitor, MLCC X5R, 18 nF,25 V LED, Super Red Footprint THIN 0603 Turret Test point TURRET-1528 Turret Test point TURRET-1502 Header Pins 0.1" pitch FDS8812NZ 30 V, 20 A, N-MOSFET Resistor,8.45 KΩ,1% Resistor,13.3 KΩ,1% Resistor, 2.00 Ω, 1% Resistor, 0 Ω 2 x 3mm Manufacturer 0603 1210 1206 0603 Resistor, 4.99 Ω, 5% Resistor, 10 Ω, 5% Picor Active ORing with Load Disconnect Controller Lite-On, Inc., Keystone Electronics Keystone Electronics SO-8 Fairchild 0603 0603 0603 0603 0603 0603 0603 3 mm x 3 mm; 10-TDFN PICOR Table 3 – PI2002-EVAL1 Evaluation Board bill of materials Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 3 of 11 Reference Designator C1, C5 C9 C3, C4, C7, C8 C2, C6 D1, D2 J5, J6 Q1, Q2, Q3, Q4 R1, R12 R2, R13 R11, R22 R10, R21 R3, R14 R4, R15 R7, R14 U1, U2 Value 1 µF 22 µF Not installed 18 nF LED Jumper N-MOSFET 8.45 KΩ 13.3 KΩ 10 Ω 4.99 KΩ 2.00 KΩ 2.00 KΩ Not Installed PI2002 Functional Description VC Bypass Capacitor Output (Load) Capacitor Snubber to reduce voltage ringing when the device turns off OCT off timer Capacitor To indicate a fault exist when it is on SCD to select for Gate high charge current or Gate low charge current ORing Main Switch UV Voltage Divider Resistor ( R2UV in Figure 4) OV Voltage Divider Resistor ( R2OV in Figure 4) VC Bias resistor LED Current Limiter UV Voltage Divider Resistor ( R1UV in Figure 4) OV Coltage Divider Resistor ( R1OV in Figure 4) SCD Ground connecting Resistor Picor Active ORing with Load Disconnect Controller Table 4 – Component functional description Initial Test Set Up To test the PI2002-EVAL1 evaluation board it is necessary to configure the jumpers (J5 and J6) first based on the required board configuration. Failure to configure the jumpers prior to the testing may result in improper circuit behavior. Baseline Test Procedure (Refer to Figure 3) 1.0 Recommended Equipment 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Two DC power supplies - 0-10 V; 25 A. DC power supply 12 V; 100 mA. DC electronic load - 30 A minimum. Digital Multimeter Oscilloscope. Appropriately sized interconnect cables. Safety glasses. PI2002 Product Data sheet. Figure 3 – Layout configuration for a typical redundant power application, OCD configured for fast gate turn on. Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 4 of 11 Before initial power-up follow these steps to configure the evaluation board for specific end application requirements: 2.0 Undervoltage (UV) and Overvoltage (OV) resistors set up: Vin 2.1 UV and OV programmable resistors are configured for a 3.3 V Vin (BUS voltage) application in a two-resistor voltage divider configuration as shown in Figure 4. UV is set to 2.6 V and OV is set for 3.8 V, R1OV and R1UV are 2.00 KΩ 1%. If PI2002-EVAL1 is required to be used in a different Vin voltage application please follow the following steps to change the resistor values. UV R1UV PI2002 R2OV OV R1OV 2.1.1 It is important to consider the maximum current that will flow in the resistor divider and maximum error due to UV and OV input . current. R1UV = V_Logic R2UV V(UVTH) IRUV 2.1.2 Set R1UV and R1OV value based on system allowable minimum current and 1% error; IRUV ≥ 100 µA FT FT GND Ref. Desg. U1 U2 R1UV R3 R14 R2UV R1 R12 R1OV R4 R15 R2OV R2 R13 Figure 4 – UV & OV two-resistor divider configuration R2UV = R1UV ( V(UV) –1 V(UVTH) ) Where: V(UVTH) : UV threshold voltage V(UV) : UV voltage set (0.5 V typ) IRUV: R1UV current R2OV = R1OV ( V(OV) –1 V(OVTH) ) Where: V(OVTH) : OV threshold voltage V(OV) : OV voltage set (0.5 V typ) IROV: R1OV current 2.1.3 Example for 2.0 V Vin (BUS voltage), to set UV and OV for ±10% Vin set UV at 1.8 V and OV at 2.2 V. R2UV= R1UV ( ) ( 1.8 V 0.5 V –1 = 5.20 KΩ (or 5.23 KΩ % standard value) R2OV= R1OV ( V(OV ) ) ( 2.2 V –1 = 6.80 KΩ (or 6.81 KΩ % standard value) V(UV) –1 = 2.00 KΩ* V(UVTH) V(OV) TH –1 = 2.00 KΩ* Picor Corporation • www.picorpower.com 0.5 V ) ) PI2002-EVAL1 User Guide Rev 1.0 Page 5 of 11 3.0 Over Current Timer: OCT The OCT off-time is set with the OCT capacitor, where the specific value can be determined from Figure 5. Every time an overcurrent condition occurs the PI2002 pulls the Gate pin low, discharges the OCT capacitor and then starts to charge it again over the programmed off-time. Only when the OCT capacitor voltage reaches the OCT threshold (1.75 V) will the Gate pin then start to charge the MOSFET gates. 4.0 Short Circuit Detect: SCD SCD pin can be connected to the load directly or programmed to a higher voltage with a resistor divider. SCD function allows the user to define the (Hard Short) voltage level expected if a non-ideal short circuit occurs at the load. This feature enables distinguishing between a faulted load versus powering capacitive and low resistive loads without entering the OCT mode. This pin can be grounded to provide a fast gate charge or pulled to Vc for lower gate current to drive highly capacitive loads with resulting slow gate charge under the fault condition. 5.0 Auxiliary Power Supply (Vaux): 5.1 The PI2002 Controller has a separate input (VC) that provides power to the control circuitry and the gate driver. An internal voltage regulator (VC) clamps the VC voltage to 15.5 V typically. 5.2 Connect independent power source to Vaux inputs of PI2002-EVAL1 Evaluation Board to supply power to the VC input. The Vaux voltage should be 5V higher than Vin (redundant power source output voltage) to fully enhance the MOSFET. If the MOSFET is replaced with a different MOSFET, make sure that the Vaux voltage is equal to Vin + 0.5 V + the required voltage to enhance the MOSFET. 5.3 10 Ω bias resistors (Rbias, reference designators R11 and R22) are installed on the PI2002-EVAL1 between each Vaux input and VC pin of one of the PI2002 controller. 5.4 If Vaux is higher than the Clamp voltage, 15.5 V typical, the Rbias value has to be changed using the following equations: 5.4.1 Select the value of Rbias using the following equations: Rbias = Vauxmin – VCclampMAX ICmax 5.4.2 Calculate Rbias maximum power dissipation: PdRbias = (Vauxmax – VCclampMIN)2 ICmax Where: Vauxmin : Vaux minimum voltage Vauxmax : Vaux maximum voltage VCClampMAX : Maximum controller clamp voltage, 16.0 V VCClampMIN : Minimum controller clamp voltage, 14.0 V ICmax : Controller maximum bias current, use 4.2 mA Figure 5 – OCT off time vs. OCT capacitor value Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 6 of 11 5.4.3. For example, if the minimum Vaux = 22 V and the maximum Vaux = 28 V Rbias = PdRbias = Vauxmin – VCclampMAX ICmax = (Vauxmax – VCclampMIN)2 22 V – 16 V = 1.429 KΩ, use 1.43 KΩ 1% resistor 4.2 mA = Rbias (28 V – 14.0 V)2 = 137 mW 1.43 KΩ Note: Minimize the resistor value for low Vaux voltage levels to avoid a voltage drop that may reduce the VC voltage lower than required to drive the gate of the internal MOSFET. 6.0 Hook Up of the Evaluation Board 6.1 OV and UV resistors values are configured for a 3.3 V input voltage. If you are using the evaluation board in a different input voltage level you have to adjust the resistor values by replacing R1, R2, R12 and R13, or remove R2, R3, R13 and R14 to disable UV and OV. Please refer to the UV/OV section for details to set R1, R2, R12 and R13 proper values. 6.2 Verify that the jumpers J5 and J6 are installed for high gate current [across the two pins at Vin side]. 6.3 Connect the positive terminal of PS1 power supply to Vin1. Connect the ground terminal of PS1 to its local Gnd. Set the power supply to 3.3 V. Keep PS1 output disabled (OFF). 6.4 Connect the positive terminal of PS2 power supply to Vin2. Connect the ground terminal of PS2 to its local Gnd. Set the power supply to 3.3 V. Keep PS2 output disabled (OFF). 6.5 Connect the positive terminal of PS3 power supply to Vaux1 and Vaux2. Connect the ground terminal of this power supply to Rtn1 and Rtn2. Set the power supply to 12 V. Keep PS3 output disabled (OFF). 6.6 Connect the electronic load to the output between Vout and Gnd. Set the load current to 10 A. 6.7 Enable (turn ON) PS1 power supply output. 6.8 Turn on the electronic load. 6.9 Verify that the electronic load input voltage reading is 0V. 6.10 Enable (turn ON) PS3 power supply output. 6.15 Increase PS1 output to 3.3 V, D1 should turn off and output voltage is 3.3V. Then increase PS1 output to 4 V, D1 should turn on indicating an over-voltage fault condition and output voltage should go to 0 V indicating that the MOSFETs are turned off. 6.16 Verify that Vin2 is at 0 V. This verifies that the PI2002 (U2) MOSFETs are off. 6.17 D2 should be on. This is due to a reverse voltage fault condition caused by the bus voltage being high with respect to the input voltage (Vin2). 6.18 Enable (turn ON) PS2 output. 6.19 Verify that both PS1 and PS2 are sharing load current evenly by looking at the supply current. 6.20 Disable (turn OFF) PS1, PS2 and PS3 outputs. 6.21 Enable (turn ON) PS2 output then Enable PS3 output. 6.22 Verify that the electronic load voltage reading is few millivolts below 3.3 V. This verifies that the MOSFET is in conduction mode. 6.23 D2 should be off. This verifies that there is no fault condition. 6.24 Reduce PS2 output voltage to 2 V, 6.25 D2 should turn on, and the output voltage is 0V, this verifies that the circuit is in an under-voltage fault condition and the MOSFETs are turned off. 6.26 Increase PS2 output to 3.3 V, D2 should turn off and output voltage goes back to 3.3V. Then increase PS2 output to 4 V, D2 should turn on indicating an over voltage fault condition and ouput voltage goes to 0V indicating that its MOSFETs are off. 6.11 Verify that the electronic load voltage reading is few millivolts below 3.3 V. This verifies that the MOSFETs are in conduction mode. 6.27 Verify that Vin1 is at 0V. This verifies that the MOSFETs (Q1 and Q2) are off. 6.12 D1 should be off. This verifies that there is no fault condition. 6.28 D1 should be on. This is due to a reverse voltage fault condition caused by the output voltage being high with respect to the input voltage (Vin1). 6.13 Reduce PS1 output voltage to 2 V, 6.14 D1 should turn on, and the output voltage is 0V, this verifies that the circuit is in an under-voltage fault condition and the MOSFETs are turned off. Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 7 of 11 7.0 Output short circuit test 7.1 Apply a short at one of the outputs. The short can be applied electronically using a MOSFET connected between Vout and Gnd or simply by connecting Vout to Gnd. Monitor the voltage across the MOSFETs [V(D1) – V(D2)] with differential probe if available. Then measure the response time between when [V(D1) – V(D2)] reaches the forward overcurrent threshold (114 mV) and when the MOSFETs are disconnected (or turned off). An example for PI2002 response time to an output short circuit is shown in Figure 6. Figure 6 – Plot of PI2002 response time to forward overcurrent detection Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 8 of 11 8.0 Input short circuit test 8.1 To emulate a real application, the BUS supplies for this test should have a solid output source such as DC-DC converter that supplies high current and can be connected very close to the evaluation board to reduce stray parasitic inductance. Or use the prospective supply sources of the end application where the PI2002 will be used. 8.2 Stray parasitic inductance in the circuit can contribute to significant voltage transient conditions, particularly when the MOSFETs are turned-off after a reverse current fault has been detected. When a short is applied at the output of the input power sources and the evaluation board input (Vin), a large reverse current is sourced from the evaluation board output through the ORing MOSFETs. The reverse current in the MOSFET may reach over 60 A in some conditions before the MOSFETs are turned off. Such high current conditions will store high energy even in a small parasitic element, and can be represented as ½ Li2. A 1 nH parasitic inductance with 60 A reverse current will generate 1.8 µJ. When the MOSFETs are turned off, the stored energy will be released and will produce a high negative voltage at D1 and high positive voltage at D2. This event will create a high voltage difference across the MOSFETs. 8.3 Apply a short at one of the inputs (Vin1 or Vin2). The short can be applied electronically using a MOSFET connected between Vin and Gnd or simply by connecting Vin to Gnd. Then measure the response time between when the short is applied and the MOSFETs are disconnected (or turned off). An example for PI2002 response time to an input short circuit is shown in Figure 7. Figure 7 – Plot of PI2002 response time to reverse current detection Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 9 of 11 Figure 8a – PI2002-EVAL1 layout top layer. Scale 2.0:1 Figure 8b – PI2002-EVAL1 layout mid layer 2. Scale 2.0:1 1.600 1.450 1.000 0.150 0.000 Mechancial Drawing 1.600 1.400 1.400 Vin1 1.200 Vaux1 IC1 R2 C1 Gnd 1.100 1.000 FT1 R4 J1 J2 0.850 0.750 SL1 SL2 0.600 0.600 Vin2 0.400 Vaux2 IC2 R8 C2 R12 D2 0.200 Gnd R11 R9 R7 R10 0.300 0.200 FT2 J3 PI2002-EVAL1 rA 4/2007 Picor Corporation • www.picorpower.com Q4 Gnd Q3 0.000 R5 R3 R1 R6 D1 1.000 Q2 Vout Q1 Cool-ORing 0.000 PI2002-EVAL1 User Guide Rev 1.0 Page 10 of 11 Vicor’s comprehensive line of power solutions includes high-density AC-DC & DC-DC modules and accessory components, fully configurable AC-DC & DC-DC power supplies, and complete custom power systems. Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its use. No license is granted by implication or otherwise under any patent or patent rights of Vicor. Vicor components are not designed to be used in applications, such as life support systems, wherein a failure or malfunction could result in injury or death. All sales are subject to Vicor’s Terms and Conditions of Sale, which are available upon request. Specifications are subject to change without notice. Vicor Corporation 25 Frontage Road Andover, MA 01810 USA Picor Corporation 51 Industrial Drive North Smithfield, RI 02896 USA Customer Service: [email protected] Technical Support: [email protected] Tel: 800-735-6200 Fax: 978-475-6715 Picor Corporation • www.picorpower.com PI2002-EVAL1 User Guide Rev 1.0 Page 11 of 11