B340B

Application Note 1636 Author: Paul Orfanu ISL85033-12VEVAL3Z Wide VIN Negative VOUT Buck-Boost Regulator With Up to 5A Output Current Hardware Description The ISL85033 is a wide input range, dual standard buck converter that can be configured to provide a negative output voltage. The ISL85033-12VEVAL3Z evaluation board is used in this application note to demonstrate the negative configuration. In this configuration, VIN can range from 4.5V to (28V - VOUT). The ISL85033 is offered in a 4mmx4mm 28 Ld TQFN package with 1mm maximum height. The complete converter occupies 6.25cm2 area. Evaluating the Other Output Voltages The ISL85033-12VEVAL3Z kit output is preset to -12V; however, output voltages can be adjusted from -3.3V to -15V. The output voltage programming resistor, R3, depends on the desired output voltage of the regulator. The value for the feedback resistor is typically between 0Ω and 142kΩ as shown in Equation 1. VOUT R3 = R2 ⎛ -------------- – 1⎞ ⎝ VFB ⎠ (EQ. 1) Key Features • Wide Input Voltage Range from 4.5V to (28V - VOUT) • Adjustable and Synchronizable Negative Output Voltage with Continuous Output Current up to 5A, depending on VOUT and VIN • Current Mode Control • Adjustable Switching Frequency from 300kHz to 2MHz • Power-Good Detection (referenced to VOUT) • Externally Adjustable Soft-start Time • Overcurrent and Hiccup Mode Short Circuit Protection, Thermal Overload Protection, UVLO • Boot Undervoltage Detection • Default Out-of-phase Channels Reduce Voltage Ripple and Component Size. User-selectable Phase Operation. Table 1 summarizes the external component selection for VOUT = -5V, VOUT = -12V, and VOUT = -15V. TABLE 1. COMPONENT SELECTION FOR VOUT VOUT -5V EXTERNAL COMPONENTS R3 = 43.2k; R5 = 20k; C4 = 2.7nF C20 = 22µF (1210 ceramic) C17 = 22µF (1210 ceramic) C19 = 68µF (15mΩ polymer EEFUD0K680R) R3 = 112k; R5 = 120k; C4 = 4.7nF C14, C17 = 22µF (2210 ceramic) C12, C19 = 68µF (70mΩ TaNbO2 TPSD686M020R0070) C20 = DNP R3 = 142k; R5 = 120k; C4 = 4.7nF C14, C17 = 22µF (2210 ceramic) C12, C19 = 68µF (70mΩ TaNbO2 TPSD686M020R0070) C20 = DNP -12V -15V Recommended Equipment The following materials are recommended to perform testing: • 0V to 30V power supply with at least 7A source current capability or a 5V battery • Electronic loads capable of sinking current up to 7A • Digital multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator The curves in Figure 1 indicate the maximum output current the converter can deliver as a function of the input voltage and the selected output voltage configuration. Figures 2, 3 and 4 show the efficiency for different VIN, VOUT and load combinations. Quick Setup Guide 1. Ensure that the circuit is correctly connected to the supply and loads prior to applying any power. 2. Connect the bias supply to VIN1, the plus terminal to VIN1, and the negative return to GND1. 3. Verify that the position is ON for S1. 4. Turn on the power supply. 5. Verify the output voltage is -12V for VOUT. July 27, 2011 AN1636.1 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. Copyright Intersil Americas Inc. 2011. All Rights Reserved. 1-888-INTERSIL or 1-888-468-3774 | 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 1636 6 5 4 IOUT (A) 3 2 1 0 5 7 9 11 13 15 VIN (V) 17 19 21 23 25 95 90 VOUT = -5V EFFICIENCY (%) 85 80 75 70 65 60 0 0.5 1.0 IOUT (A) 1.5 2.0 2.5 VIN = 5V VIN = 12V VOUT = -12V VOUT = -15V FIGURE 1. ISL85033-12VEVAL3Z BUCK BOOST: RECOMMENDED MAXIMUM IOUT (VIN) 95 VIN = 12V 90 VIN = 15V FIGURE 2. ISL85033-12VEVAL3Z EFFICIENCY: V OUT = -15V 95 90 85 VIN = 6V VIN = 12V EFFICIENCY (%) EFFICIENCY (%) 85 VIN = 5V 80 75 70 65 60 0 VIN = 5V 80 75 70 65 60 VIN = 15V 0.5 1.0 IOUT (A) 1.5 2.0 2.5 0 0.5 1.0 IOUT (A) 1.5 2.0 2.5 FIGURE 3. ISL85033-12VEVAL3Z EFFICIENCY: VOUT = - 12V FIGURE 4. ISL85033-12VEVAL3Z EFFICIENCY: VOUT = -5V If the output voltage desired is -0.8V, then R3 is shorted. The value for R2 is typically between 1k and 10k. Note that if VOUT < |2.5V| (i.e., -0.8V), the switching frequency and compensation must be changed to accommodate the 300kHz operation, due to minimum on-time limitation. Please refer to the ISL85033 data sheet for further information. Disabling/Enabling Function The ISL85033-12VEVAL3Z evaluation board contains an S1 switch that enables or disables both channels, thus allowing a low quiescent current state. Table 2 details this function. TABLE 2. SWITCH SETTINGS S1 ON OFF Enable VOUT Disable VOUT ON/OFF CONTROL Frequency Control The ISL85033-12VEVAL3Z evaluation board has an FS pin that controls the frequency of operation. Programmable frequency allows for optimization between efficiency and external component size. Default switching frequency is 500kHz when FS is tied to VCC (R9 = 0). By removing R9 and connecting R10 to the most negative potential on the board (VOUT), the switching frequency could be changed from 300kHz (R10 = 383k) to 2MHz (R10 = 40.2k). See the ISL85033 data sheet for information about calculating the value of R10. Do not leave this pin floating. NOTE: If driven externally, the EN signal (the same as all input logic signals) is referenced to VOUT (the most negative potential on the board) and not to GND. Therefore, the source cannot be GND referenced, and input level shifting is required. 2 AN1636.1 July 27, 2011 ISL85033-12VEVAL3Z Schematic PG1 FS VNEG SI SO PG2 R12 VCC DNP SYNCIN PGOOD1 FS PGOOD2 VNEG NC1 R13 DNP 28 27 26 25 24 23 COMP1 22PF COMP2 A 22 JVO2 OPEN VNEG R3 113K C13 R5 SYNCOUT PGOOD2 SGND PGOOD1 SYNCIN NC FS VNEG C4 C15 OPEN VNEG OPEN OPEN R14 C16 OPEN 1 2 A 4 1 22 3 4 COMP1 FB1 SS1 PGND1 BOOT1 COMP2 FB2 SS2 PGND2 21 0 19 18 17 16 15 R15 OPEN 3 A 5600PF VIN1 VIN1 VIN2 VCC EN1 JLX1 GNDO1 VNEG 4 1 2 29 EN2 EP VIN2 3 3 8 9 10 12 13 11 14 12 10UH C1 TBD A C12 68UF 12 C14 22UF 21 EN VCC EN D1 D2 10UH C17 22UF 21 12 100UF VCC A C18 10UF C6 10UF A 4.7UF R19 DNP R20 DNP AA A PGOOD1 PGOOD2 EN VCC R7 R4 100K 2 EN R8 OPEN VNEG 0 3 FB1 R2 8.06K 4700PF 120K R11 C10 FB2 C11 SS2 R16 OPEN SS1 C3 SS1 U1 SS2 VNEG VNEG1 VNEG BOOT1 C5 5 6 7 ISL85033IRTZ BOOT2 PHASE2 PHASE2 BOOT2 C9 0.01UF 5600PF Application Note 1636 VNEG VNEG L1 12 PHASE1 PHASE1 VNEG VNEG L2 VNEG VNEG2 0.01UF -12V 1 2 4 JLX2 A VNEG -12V (ADJUSTABLE) FB1 R23 0 GNDO2 FB2 A 2 1 C19 68UF C20 TBD A B340B VIN B340B VIN VIN C2 VNEG VNEG COMP1 R24 0 COMP2 C7 C8 10UF GND1 SS1 R25 DNP SS2 OPEN R9 R17 DNP SS1 3 SS2 FS R10 DNP SYNCIN R18 0 ON S1 1 OPEN OFF AN1636.1 July 27, 2011 VNEG VNEG VNEG Application Note 1636 Bill of Materials PART NUMBER 131-4353-00 TPSD686K020R00 070-T B340B C5750X7R1E226M EEE-FK1V101P-T GMK325BJ106KN GT13MCBE REFERENCE DESIGNATOR JLX1, JLX2, JVO2 C12, C19 D1, D2 C14, C17 C2 C6, C8 S1 QUANTITY 3 2 2 2 1 2 1 22µF 100µF 10µF 20% 20% 10% 25V 35V 35V 68µF 20% 20V VALUE TOLERANCE VOLTAGE POWER PACKAGE TYPE CONN SMD SMD2 2220 SMD 1210 SW JEDEC TYPE TEK1314353-00 CAP_TANT DO_SMA CAP_2220 CAPAE_315X 402 CAP_1210 SW_GT13MC BE CAP_0402 CAP_0402 CAP_0402 CAP_0603 CAP_0603 CAP_0805 CAP_1206 CAP_1210 RES_0603 RES_0603 RES_0603 MANUFACTURER TEKTRONIX AVX DIODES TDK PANASONIC TAIYO YUDEN C&K DESCRIPTION Scope Probe Test Point PCB Mount TQC Series Hi-Volt Low ESR Capacitor 3A Low VF SCHOTTKY BARRIER RECTIFIER Ceramic Cap AL LYTIC FK SERIES CAP (RoHS COMP.) Ceramic Chip Cap SPDT On-Off-On Ultraminiature Toggle Switch Multilayer Cap Multilayer Cap Multilayer Cap Multilayer Cap Multilayer Cap Multilayer Cap Multilayer Cap Ceramic Chip Cap Metal Film Chip Resistor Metal Film Chip Resistor (Do Not Populate) Metal Film Chip Resistor (Do Not Populate) Thick Film Chip Resistor Thick Film Chip Resistor Thick Film Chip Resistor Thick Film Chip Resistor Thick Film Chip Resistor Thick Film Chip Resistor WIDE VIN DUAL STANDARD BUCK REGULATOR (Pb-FREE) 0.100 Pad with 0.037 Plated Thru Hole H1044-0022050V5 H1044-0047250V10 H1044-OPEN H1045-0010350V10 H1045-0056250V10 H1046-0047510V20 H1065-0010625V10-T H1082-TBD-TBD H2505-01003-1/ 16WR1 H2505-DNP-DNP-1 H2505-DNP-DNPR1 H2510-011331/16W1 H2510-012031/16W1 H2510-080611/16W1 H2510-ROPENOPEN H2511-00R001/16W H2511-00R001/16W1 ISL85033IRTZ C13 C4 C10, C15, C16 C5, C9 C3, C11 C7 C18 C1, C20 R4 R10, R17 R12, R13, R19, R20, R25 R3 R5 R2 R7, R8, R11, R14-R16 R23, R24 R9, R18 U1 1 1 3 2 2 1 1 2 1 2 5 22PF 4700PF OPEN 0.01µF 5600PF 4.7µF 10µF TBD 100k DNP DNP 5% 10% OPEN 10% 10% 20% 10% TBD 0.10% 1% 0.10% 50V 50V OPEN 50V 50V 10V 25V TBD 1/16W DNP DNP 402 402 402 603 603 805 SMD 1210 603 603 603 GENERIC GENERIC GENERIC GENERIC GENERIC GENERIC VENKEL GENERIC GENERIC GENERIC GENERIC 1 1 1 6 2 2 1 113k 120k 8.06k OPEN 0 0 1% 1% 1% 1% 0% 1% 1/16W 1/16W 1/16W OPEN 1/16W 1/16W 402 402 402 402 603 603 QFN RES_0402 RES_0402 RES_0402 RES_0402 RES_0603 RES_0603 QFN28_157X 157_157_EP PAD-100 GENERIC GENERIC GENERIC GENERIC GENERIC GENERIC INTERSIL PAD_100 EN, FS, SI, SO, PG1, PG2, SS1, SS2, VNEG 9 THOLE GENERIC 4 AN1636.1 July 27, 2011 Application Note 1636 Bill of Materials (Continued) PART NUMBER PAD_150 REFERENCE DESIGNATOR VIN, GND1, GNDO1, GNDO2, VNEG1, VNEG2 L1, L2 QUANTITY 6 VALUE TOLERANCE VOLTAGE POWER PACKAGE TYPE THOLE JEDEC TYPE PAD-150 MANUFACTURER GENERIC DESCRIPTION 0.150 Pad with 0.110 Plated Thru Hole SQ1004 2 10µH 25% 4.8A SMD IND_SQ10XX FALCO SMT SHIELDED POWER INDUCTOR ISL85033-12VEVAL3Z Layout FIGURE 5. TOP LAYER COMPONENTS FIGURE 6. TOP LAYER ETCH FIGURE 7. SECOND LAYER ETCH FIGURE 8. THIRD LAYER ETCH 5 AN1636.1 July 27, 2011 Application Note 1636 ISL85033-12VEVAL3Z Layout (Continued) FIGURE 9. BOTTOM LAYER ETCH FIGURE 10. BOTTOM LAYER COMPONENTS 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 6 AN1636.1 July 27, 2011