Application Note 1707 Authors: Kiran Bernard, Oscar Mansilla, and Eric Thomson Intersil’s Radiation Hardened FPGA Power Solutions Introduction The evolution of rad hard power solutions are being driven by changes implemented in the commercial market which have proven to provide higher efficiency and better performance. Space power is gradually adapting the distributed power architecture which dominates commercial power systems. Benefits of this architecture include reduction of distribution losses, improvement in regulation performance and a solution that can be modular. Another contribution that aids in the definition of radiation hardened power IC’s is the rapid qualification and/or development of high performance digital components for space applications such as FPGA’s and microprocessors. These digital IC’s rival commercial counterparts in computing performance, low supply voltage and increased power consumption. Couple-in the need for a smaller, light-weight power solution and you will find Intersil at the forefront developing leading edge point-of-load (POL) regulators that meet the demands of today’s space applications. This application note discusses the VIRTEX5MEZPWREV1Z board, Intersil’s reference design to power FPGA's in a radiation hardened environment. This particular board is optimized to power a Xilinx’s Virtex-5 FPGA and features the ISL70001SRH and ISL70002SRH, rad hard POL buck regulators along with the ISL75051RH rad hard LDO. FPGA Power Solution The Virtex-5 requires a core voltage of 1.0V, which is supplied by the ISL70002SRH, an auxiliary voltage of 2.5V, which is supplied by the ISL70001SRH, and an I/O voltage of 3.3V which is supplied by the ISL75051RH (see Figure 1). voltage. The ISL70001SRH can provide up to 6A (TJ ≤ +145°C) of output current while the ISL70002SRH can provide up to 12A (TJ ≤ +150°C) of output current. The ISL75051SRH is a radiation hardened, low voltage, high current, single output LDO specified for up to 3.0A of continuous output current. It can operate over an input voltage range of 2.2V to 6.0V and is capable of providing output voltages of 0.8V to 5V with an external resistor divider. Dropout voltages as low as 65mV can be realized with this device. Circuits Description The 5V AC-DC adapter provides the input source through the 2.1mm barrel-jack connector. Proper sequence during power-up is maintained by connecting the PGOOD line of the ISL70002SRH to the ISL70001SRH’s EN pin, which in turn has its PGOOD line tied to the EN pin of the ISL75051RH. This ensures that the core voltage is up first, followed by the auxiliary and then the I/O voltage (see Figure 3). The output capacitors for each device have been chosen to minimize ESR in an effort to maintain output ripple <1% of the regulated voltage (for ISL70001SRH and ISL70002SRH) and to optimize the stability of the systems. KEMET’s T530 series of tantalum capacitors offer ultra low ESR <15mΩ and are DLA certified. Provisions for stability measurements are included. By replacing R23, R35 and R36 with 10Ω to 100Ω resistors and injecting the AC signal across TP1/TP2 for the ISL70001SRH, TP3/TP4 for the ISL70002SRH and TP5/TP6 for the ISL75051RH, AC measurements of the loop may be taken. Radiation Tolerance Total Iodizing Dose 5V SUPPLY ISL70002SRH CORE ISL70001SRH AUX ISL75051SRH I/O RAD TOLERANT FPGA FIGURE 1. VIRTEX5MEZPWREV1Z BLOCK DIAGRAM The ISL70001SRH and ISL70002SRH are both radiation hardened and SEE hardened high efficiency, monolithic synchronous buck regulators with integrated MOSFETs. These single chip power solutions operate over an input voltage range of 3V to 5.5V and provide a tightly regulated output voltage that is externally adjustable from 0.8V to ~85% of the input October 21, 2011 AN1707.0 1 These circuits are fabricated on a 0.6μm BiCMOS junction isolated process optimized for power management applications. They were hardened by design to achieve a Total Ionizing Dose (TID) rating of at least 100krads(Si) at the standard 50 to 300rad(Si)/s high dose rate as well as the standard <10mrad(Si)/s low dose rate. Well known TID hardening methods were employed such as closed geometry NMOS devices to reduce leakage and optimized bias levels for bipolar devices to compensate for gain reduction. For further information on radiation performance please navigate to www.intersil.com/space. Single Event Effects All three IC’s were also hardened by design to a Linear Energy Transfer (LET) of 86.4MeV/mg/cm2 by employing various SEE hardening techniques such as proper device sizing, filtering and special layout constraints. All three devices exhibit no latch-up or burnout up to their respective input voltage at an LET of 86.4 MeV/mg/cm2. CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2011. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Application Note 1707 20 18 1.90 1.85 AMPLITUDE (V) Intersil is also the leader in Single Event Transient (SET) performance. The ISL70001SRH and the ISL70002SRH offer a <1% output voltage deviation due to SETs at an LET of 86.4MeV/mg/cm2 (see Figure 2). Modern processors and FPGA offer a 5% tolerance window for the supply voltage. In some cases, the 5% tolerance includes DC voltage tolerance and transients due to load step or release and transients due to SETs. 1.80 1.75 16 AMPLITUDE (V) 14 1.70 13 TRG = CH1 = ±15mV 1.65 10 -1 0 1 2 8 4 5 6 7 8 x10-5 TIME DIV (s) FIGURE 3. ISL75051SRH SET RESPONSE 6 4 Additional Design Features 2 0 3 -6 -4 -2 0 2 4 TIME (s) 6 8 10 12 14 x10-6 FIGURE 2. ISL70001SRH SET RESPONSE Take for example, the ISL70001SRH. The output voltage tolerance is specified at 2%, this includes line and load regulation, and reference voltage tolerance over-temperature and radiation. An additional 1% may be attributed to end of life for the external resistors needed to set the output voltage. Load transients and SETs, it can safely be said, would not occur at the same time. Therefore, 2% can be allotted to a load transient which can be met with proper output filter selection. A total output voltage tolerance of 4% can be achieved - this includes DC shifts due to line, load and reference and SETs transients. A 5% output voltage tolerance will be achieved when there is a load transient. Intersil’s rad hard POLs could easily meet the stringent requirements of modern space applications. The ISL75051SRH also has class leading SET performance without the need of additional external filters as seen in other rad hard linear regulators. Figure 3 shows superimposed plots of LDO response during SETs. The upper and lower limits correlate to a 4% voltage perturbation. It can be seen that a -50mV deviation was the worst deviation seen in this run. This section discusses two additional features that may be added to further improve reliability and enhance the power capability of the reference design. Current Sharing for the ISL70002SRH Modern digital components are requiring greater supply currents to meet the demands for the ever increasing need of processing power in space systems. For applications where the core voltage requires more than 12A of continuous current, the ISL70002SRH may be used in a multiphase solution. Two ISL70002SRH’s can current share and provide up to 19A of continuous current to the processor, FPGA, or any other load. The current share architecture features triple redundancy for single event transient mitigation. For a detailed description on current sharing refer to the ISL70002SRH datasheet. Power-on Reset The addition of a rad tolerant POR chip such as the ISL705ARH could further improve reliability by allowing proper sequence to initiate only after the 5V intermediate voltage has reached its optimal steady-state condition. With the added feature of a watchdog timer, the ISL705ARH will also monitor the FPGA or processor for proper execution and send a reset signal if not toggled within 1.0s. Intersil also offers the ISL706XRH series of voltage supervisors dedicated to 3.3V rails. For more information on the ISL705XRH and ISL706XRH see datasheet FN7662. Related Literature • ISL70001SRH Datasheet FN6947 • ISL70002SRH Datasheet • ISL75051SRH Datasheet 2 AN1707.0 October 21, 2011 Application Note 1707 FIGURE 4. RADIATION HARDENED FPGA POWER SOLUTIONS REFERENCE DESIGN 3 AN1707.0 October 21, 2011 Application Note 1707 Typical Performance Curves I/O AUX VOUT CORE CORE FIGURE 5. START-UP SEQUENCE FIGURE 6. ISL70002SRH CORE OUTPUT VOLTAGE RIPPLE LOAD VOUT AUX CORE VOLTAGE FIGURE 7. ISL70001SRH AUXILIARY VOLTAGE RIPPLE ILOAD FIGURE 8. CORE VOLTAGE 3A LOAD TRANSIENT RESPONSE ILOAD AUX VOLTAGE I/O VOLTAGE FIGURE 9. AUXILIARY VOLTAGE 3A LOAD TRANSIENT RESPONSE 4 FIGURE 10. I/O VOLTAGE 1.5A LOAD TRANSIENT RESPONSE AN1707.0 October 21, 2011 Application Note 1707 80 180 150 70 150 60 120 60 90 50 40 60 40 60 30 30 30 30 20 0 PHASE GAIN 20 0 GAIN (dB) 180 70 PHASE (°) 80 50 PHASE 120 90 10 -30 0 -60 0 -10 -90 -10 -90 -20 -120 -20 -120 -30 -40 10 -150 -30 -40 10 -150 100 1k 10k -180 1M 100k 10 -30 GAIN 100 1k 10k -60 100k -180 1M FREQUENCY (Hz) FREQUENCY (Hz) FIGURE 11. ISL70002SRH AC RESPONSE AT 12A LOAD FIGURE 12. ISL70001SRH AC RESPONSE AT 6A LOAD 60 180 50 150 40 120 90 PHASE 20 10 60 30 GAIN 0 0 -10 -30 -20 -60 -30 -90 -40 -120 -50 -60 500 -150 5k 50k 500k 5M PHASE (°) 30 GAIN (dB) GAIN (dB) (Continued) PHASE (°) Typical Performance Curves -180 FREQUENCY (Hz) FIGURE 13. ISL75051SRH AC RESPONSE AT 3A LOAD 5 AN1707.0 October 21, 2011 1K R27 1UF C41 C4 1UF 47UF C40 C3 47UF 22 47UF 33 C2 C1 11 J1 150UF ISL70001SRH Schematic LED1 1UF C9 LX5 2 1UF C15 47UF C14 47UF C13 C12 330UF P4 D1 MBRS320T3 LX 34 33 VIN 32 31 0 TP1 35 TP2 LX GND PGND5 30 29 PGND6 PGND6 PGND5 28 27 26 PVIN6 LX6 25 VIN 24 FB EN 22 19 20 PORSEL PVIN6 PVIN5 PVIN5 36 GND P3 1K PVIN4 AGND AGND 3 43 44 PVIN2 46 45 PVIN2 47 PGND2 LX2 1 2 48 PGND2 PGND1 PGND1 4 LX 37 DGND R3 C8 PGND4 PVIN4 ISL70001SRHF 23 17 38 R23 DGND 39 PGND4 2V5 1UH R6 DVDD 15 PGND3 LX4 L1 LX 40 4700PF 14 41 FB LX R7 DVDD 42 316 SS 13 Q1 WURTH ELEKTRONIK 744 311 100 C11 12 AVDD 1 U1 PGOOD 18 VIN LX1 TDO 16 S1 PGND3 REF 1UF C7 VIN LX3 21 1K R1 1 R2 0.01UF C5 DVDD PVIN3 1 P2 PVIN3 TDI 11 2N7002 PGOOD1 P1 Application Note 1707 9 C6 2V5 VIN ZAP 10 0.1UF 5 M/S 8 PGOOD1 PVIN1 6 7 PVIN1 SYNC 3 VIN LX 6 SYNC VIN GND PJ_002AH 0.22UF R20 DVDD FB 0 PGOOD2 R4 C10 1K R5 499 0.01UF S1 DRAWN BY: DATE: KIRAN BERNARD 06/22/2011 RELEASED BY: DATE: UPDATED BY: DATE: ENGINEER: KIRAN BERNA TITLE: VIRTE AN1707.0 October 21, 2011 ISL70002SRH Schematic VIN R12 VIN EN2 PVIN6 ISL70002SRHVF PVIN7 SS LX8 NC ISHEN 38 37 36 LX2 33 D GND LX2 0 R35 1UF C33 C28 4700PF P7 LED2 1V0 PVIN8 32 PGOOD2 1 Q2 2N7002 2 31 P5 VIN 30 29 LX2 27 VIN 28 25 GND 26 22 VIN 23 LX2 24 GND 21 20 19 18 17 DVDD2 0 1K 1.5K VIN LX2 D R17 R19 VIN 35 34 C32 R18 GND 3 PORSEL FSEL PGND8 M/S ISHSL LX9 15 PVIN9 PGND7 PGND10 PGND9 LX7 ISHCOM LX10 PGOOD 14 SYNC PVIN10 13 39 47UF LX6 TP4 D2 MBRS320T3 FB2 DGND 40 LX2 C31 10 41 VIN TP3 47UF PGND6 42 P6 1K PGND5 AGND 43 LX2 C30 AVDD 9 LX5 44 GND 330UF 8 U2 45 1V0 0.52UH 744 310 055 WURTH ELEKTRONIK R28 ISHREFC 46 LX2 C29 7 47 330UF PVIN5 L2 48 1 PVIN4 ISHC LX4 DVDD C27 VIN 49 50 NC 51 52 SC1 SC0 ISHREFB 6 11 0.01UF R13 SC1 SC0 LX2 53 PVIN2 GND 55 54 LX2 57 56 PGND1 PGND2 59 58 PVIN1 LX1 60 61 5 16 D 62 PGND4 ISHB ZAP GND 1UF C26 C25 0.01UF ISHREFA TDI 1UF C24 0.1UF PGND3 TDO 1 R16 1K R15 1 R14 C23 D ISHA 4 12 PGOOD2 LX3 DVDD2 SYNC DVDD2 DNP R31 DNP R29 R33 0 SC1 DRAWN BY: R34 DNP 0 R32 0 R30 SC0 DATE: KIRAN BERNARD RELEASED BY: 06/22/2011 DATE: UPDATED BY: ENGINEER: VIRTEX5MEZPWREV1ZA DATE: TIM KLEMANN EVALUATION BOARD 07/08/2011 TESTER SCHEMATIC MASK# FILENAME: DATE: KIRAN BERNARD TITLE: REV. HRDWR ID SHEET 2 A 3 Application Note 1707 D DVDD2 PVIN3 2 3 VIN OCSSB EN 2 FB OCB 1 OCA REF FB2 OCSSA C22 0.22UF 63 R11 4.02K 64 R10 19.6K OCB R9 19.6K OCSSB R8 4.02K OCSSA C21 6800PF OCA 7 C20 6800PF OCA OCSSA OCB OCSSB EN2 VIN LX2 GND 10.2K 1UF 1UF C19 C44 C43 47UF C42 47UF C18 47UF C17 47UF C16 150UF 56.2K AN1707.0 October 21, 2011 ISL75051RH Schematic VIN R26 1K LED3 3 3V3 8 PGOOD3 Q3 1 2N7002 2 P10 U3 R36 7 8 4.32K 9 100PF C36 768 R22 C37 R21 0 5.49K 16 15 14 13 12 VIN 11 10 ISL75051SRH PGOOD1 0.1UF 6 0.18UF P9 TP6 TP5 5 17 C39 4 220UF C35 0.1UF C34 P8 VOUT 3 VOUT 4 VOUT 5 VOUT 6 VOUT 7 VOUT 8 ADJ 9 BYP VIN 220UF 2 3 R25 18 C38 2 PGOOD 18 VIN 17 VIN 16 VIN 15 VIN 14 VIN 13 VIN 12 OCP 11 EN 10 511 1 GND Application Note 1707 3V3 1 R24 GND AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Bill of Materials REF DES. Q1 Q2, Q3 TP1-TP6 LED1-LED3 PART NUMBER QTY MANUFACTURER DESCRIPTION 2N7002-7-F 1 FAIRCHILD N-Channel EMF Effect Transistor (Pb-Free) 2N7002L 2 ON Semi N-Channel 60V 115mA MOSFET 5002 6 KEYSTONE Miniature White Test Point 0.100 Pad 0.040 Thole 597-3311-407 3 Dialight Surface Mount Green LED 8 PANASONIC Thick Film Chip Resistor R17, R20, R23, R30, R32, R33, ERJ3GEY0R00V R35, R36 C37 GRM188R71E184KA88 1 GENERIC Multilayer Cap C36 H1045-00101-50V5 1 GENERIC Multilayer Cap C5, C10 H1045-00103-16V10 2 GENERIC Multilayer Cap C25, C27 H1045-00103-25V10 2 GENERIC Multilayer Cap C6 H1045-00104-16V10 1 GENERIC Multilayer Cap C24, C34, C39 H1045-00104-25V10 3 GENERIC Multilayer Cap C7, C8 H1045-00105-16V20 2 GENERIC Ceramic Cap C9, C22 H1045-00224-16V10 2 GENERIC Multilayer Cap C11, C28 H1045-00472-50V10 2 GENERIC Multilayer Cap C20, C21 H1045-00682-50V10 2 GENERIC Multilayer Cap C2, C3, C13, C14, C17, C18, C31, C32, C40, C42, C43 H1046-00476-16V20 11 GENERIC Multilayer Cap H2505-DNP-DNP-1 3 GENERIC Metal Film Chip Resistor (Do Not Populate) R2, R3, R14, R16 H2511-00010-1/10W1 4 GENERIC Thick Film Chip Resistor R1, R5, R6, R27 H2511-01001-1/16W1 4 GENERIC Thick Film Chip Resistor R21 H2511-04321-1/16W1 1 GENERIC Thick Film Chip Resistor R24 H2511-05110-1/16W1 1 GENERIC Thick Film Chip Resistor R25 H2511-05491-1/16W1 1 GENERIC Thick Film Chip Resistor R12 H2511-05622-1/16W1 1 GENERIC Thick Film Chip Resistor R22 H2511-07680-1/16W1 1 GENERIC Thick Film Chip Resistor U1 ISL70001SRHF 1 INTERSIL 4.2A/6A Synchronous Buck Regulator U2 ISL70002SRHVF 1 INTERSIL 12A Synchronous Buck Regulator w/MOSFET MBRS320T3 2 ON-SEMI 3A 20V Schottky Power Rectifier MCR03EZPFX1001 1 ROHM Metal Film Chip Resistor PJ-002AH 1 CUI-INC DC Power Jack R13 RG1608P-1022-B-T5 1 SUSUMU Thick Film Chip Resistor R18 S0603CA1001BEB 1 State of the Art Thick Film Chip Resistor R29, R31, R34 D1, D2 R26 J1 9 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Bill of Materials REF DES. PART NUMBER QTY (Continued) MANUFACTURER DESCRIPTION R19 S0603CA1501BEZ 1 State of the Art 25ppm Thin Film Chip Resistor R9, R10 S0603CA1962BEZ 2 State of the Art 25ppm Thin Film Chip Resistor R7 S0603CA3160BEB 1 State of the Art Thick Film Chip Resistor R8, R11 S0603CA4021BEZ 2 State of the Art 25ppm Thin Film Chip Resistor R15, R28 S0603CPX1001F10 2 State of the Art Thick Film Chip Resistor R4 S0603CPX4990F10 1 State of the Art Thick Film Chip Resistor C35, C38 T525D227M010ATE025 2 KEMET Ripple 3000mA ESR 25mΩ Polymer Tantalum Capacitor C1, C16 T530X157M016ATE015 2 KEMET High Capacitance Ultra-Low ESR Tantalum SMD Cap C12, C29, C30 T530X337M010ATE005 3 KEMET High Capacitance Ultra-Low ESR Tantalum SMD Cap 8 Taiyo Yuden Ceramic Cap 1 INTERSIL 18 Pin Flat-Pack Package K18.A PAD_80 10 GENERIC 0.080 Pad with .037 Plated Thru Hole L1 744311100 1 Wurth Elektronik SMT Power Inductor L2 744310055 1 Wurth Elektronik SMT Power Inductor C4, C15, C19, C23, C26, C33, TMK107BJ105KA-T C41, C44 U3 P1-P10 ISL75051SRH 10 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout FIGURE 14. TOP COMPONENTS 11 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 15. BOTTOM LAYER (MIRRORED) 12 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 16. 1 ST LAYER 13 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 17. 2 ND LAYER 14 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 18. 3 RD LAYER 15 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 19. 4 TH LAYER 16 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 20. 5 TH LAYER 17 AN1707.0 October 21, 2011 Application Note 1707 VIRTEX5MEZPWREV1Z Board Layout (Continued) FIGURE 21. 6 TH LAYER Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 18 AN1707.0 October 21, 2011