SI-8005Q Step-Down Switching Regulator with Current-Mode Control Features and Benefits Description The SI-8005Q is a step-down switching regulator IC, designed as an output voltage regulator at the secondary stage of switch mode power supplies. The current-mode control system permits small ceramic capacitors to be used as output capacitors. Together with the compact HSOP8 package, this allows reduction of regulator circuitry area on the PCB by approximately 50% in comparison with conventional topologies. Current-mode control system employed Excellent line regulation (60 mV maximum) 165 m maximum on-resistance of built-in MOSFET Output current 3.5 A Wide range of input voltages (4.75 to 28 V), supports 24 V direct drive Output voltage 0.5 to 24 V, compatible with various IC power supply voltages, through low VREF of 0.5 V. High efficiency, 94% maximum at VIN = 8 V, VO = 5 V, and IO = 0.5 A Operating frequency 500 kHz, supports downsizing of smoothing choke coil Soft start and output on/off functions built-in Built-in protection: Drooping overcurrent protection Overtemperature protection Undervoltage lockout (UVLO) Package: HSOP8 surface mount with exposed thermal pad Designed to save power, losses in the SI-8005Q are reduced by controlling the maximum on-resistance of a built-in output MOSFET to as low as 165 m. Furthermore, die miniaturization has been accomplished through a proprietary BCD process. The SI-8005Q supplies an output current of 3.5 A and an output voltage that is variable from 0.5 to 24 V, which is easily set to a voltage compatible with the diverse reduced power supply voltages required by signal processing ICs. Accepting a wide input voltage range, from 4.75 to 28 V, the SI-8005Q can be driven directly by a 24 V power supply. Applications include power supplies for signal processing ICs for memories and microcomputers used in plasma display panel (PDP) TVs, liquid crystal display (LCD) TVs, computer hard drives, and DVD recorders. Not to scale Functional Block Diagram 9,1 26& 35(* 95() (1 &203 & YBOGR &XUUHQW 6HQVH $PS 2&3 %6 %RRW 5(* '5,9( 3:0 /2*,& 6: 293 76' YBOGR )% 9 89/2 *1' / 92 $PS & 'L 5 5 5 27469.058 ,1 & 9 21 2)) & 66 & SI-8005Q Step-Down Switching Regulator with Current-Mode Control Selection Guide Part Number Packing SI8005Q-TL 1000 pieces per reel Absolute Maximum Ratings Characteristic Symbol DC Input Voltage VIN DC Input Voltage VEN Remarks Allowable Power Dissipation PD Limited by internal thermal shutdown, mounted on a 30 mm x 30 mm glass epoxy PCB with 25 mm x 25 mm exposed copper area, TJ(max) = 125C Junction Temperature TJ Internal thermal shutdown activates at approximately 140C Storage Temperature Tstg Thermal Resistance (Junction to Ambient) RJA Thermal Resistance (Junction to Case) RJC Mounted on a 30 mm x 30 mm glass epoxy PCB with 25 mm x 25 mm exposed copper area Rating Unit 30 V 6 V 1.35 W -30 to 150 C -40 to 150 C 74 C/W 40 C/W Recommended Operating Conditions* Characteristic Symbol Remarks Min. Typ. Max. Units DC Input Voltage Range VIN VIN(min) is the greater of either 4.75 V or VO+1 V; except if VO + 0.5 VIN VO +1 V, then VIN(min) is set such that IO 2 A See remarks - 28 V DC Output Current Range IO Using the circuit defined in the Typical Application diagram and within PD limits 0 - 3.5 A -30 - 125 C -30 - 85 C Operating Junction Temperature Range TJOP Operating Temperature Range TOP Operation within PD limits *Recommended operating range indicates conditions which are required for maintaining normal circuit functions shown in the Electrical Characteristics table. Maximum Allowable Package Power Dissipation Results calculated as: 100 PD = VO x IO - 1 - VF x IO Hx 1.6 Power Dissipation, PD (W) 1.4 1.2 VO 1 - VIN where: 1.0 VO is the output voltage, 0.8 0.6 VIN is the Input voltage (0.4 V for these results), 0.4 IO is the Output current (0.3 A for these results), 0.2 x is the efficiency (%), which varies with VIN and IO (derived from the Efficiency curves in the Characteristic Performance section), and 0 -25 0 25 50 75 Ambient Temperature, TA (C) 100 125 VF is the diode forward voltage for D1, determination of the value for D1 should be made based on testing with the actual application (Sanken diode SJPB-D4 was used for these results). All performance characteristics given are typical values for circuit or system baseline design only and are at the nominal operating voltage and an ambient temperature, TA, of 25C, unless otherwise stated. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 SI-8005Q Step-Down Switching Regulator with Current-Mode Control ELECTRICAL CHARACTERISTICS1, valid at TA=25C, unless otherwise noted Characteristics Symbol Reference Voltage Conditions Min Typ Max Units 0.485 0.500 0.515 V VIN = 12 V, IO = 1.0 A, TA = -40C to 85C - 0.05 - mV/C VIN = 12 V, VO = 5 V, IO = 1 A - 90 - % fO VIN = 16 V, VO = 5 V, IO = 1 A 450 500 550 kHz - 10 60 mV VREF Output Voltage Temperature Coefficient VIN = 12 V, IO = 1.0 A VREF/T Efficiency2 Operating Frequency Line Regulation VLINE VIN = 8 to 28 V, VO = 5 V, IO = 1 A Load Regulation VLOAD VIN = 12 V, VO = 5 V, IO = 0.1 to 3.5 A Overcurrent Protection Threshold - 10 60 mV 3.6 - 6.0 A VIN = 12 V, VO = 5 V, IO = 0 A, VEN = open - 18 - mA VIN = 12 V, VO = 5 V, IO = 0 A,VEN = 0 V - - 20 A IS VIN = 12 V, VO = 5 V Quiescent Current 1 IIN Quiescent Current 2 IIN(off) Current3 SS Terminal Leakage ISSL VSSL = 0 V, VIN = 16 V - 5 - A EN Terminal High Level Voltage VCEH VIN = 12 V 2.8 - - V EN Terminal Low Level Voltage VCEL VIN = 12 V - - 2.0 V EN Terminal Leakage Current ICEH VEN = 0 V - 1 - A Error Amplifier Voltage Gain AEA - 1000 - V/ V Error Amplifier Transconductance GEA - 800 - A/V Current Sense To COMP Transimpedance 1/GCS - 0.35 - V/A Maximum Duty Cycle (On) DCMAX - 92 - % tMIN - 100 - ns Minimum On-Time 1Using circuit shown in Measurement Circuit diagram. 2Efficiency is calculated as: (%) = ([V x I ] x [V x I ]) x 100. O O IN IN 3SS terminal enables soft start when a an external capacitor is connected to it. Because a pull-up resistor is provided inside the IC, no external voltage can be applied to this terminal. Measurement Circuit Diagram IN BS EN 8 C1 C4 1 2 7 SW Di S I- 8005Q SS Component L1 3 R1 IIN IEN ISS GND 4 VIN VEN VSS IO C2 5 FB COM P VFB R2 VO RL 6 C3 R3 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com C1 C2 C3 C4 Di L1 R1 R2 R3 Rating 22 F / 50 V 47 F / 25 V 220 pF / 10 V 10 nF / 25 V SPB-G56S 10 H 46 k 5.1 k 62 k 3 SI-8005Q Step-Down Switching Regulator with Current-Mode Control Performance Characteristics at TA = 25C 100 100 8V 90 4.75 V 5V 70 8V 12 V 60 80 Efficiency versus Output Current VO = 3.3 V 6V (%) (%) 80 Efficiency versus Output Current VO = 1.2 V 16 V 24 V 28 V VIN 70 60 50 40 12 V 90 VIN 50 0 1 2 3 4 40 5 0 1 2 IO (A) 100 8V 90 4 5 16 V 20 V 80 20 V 28 V Efficiency versus Output Current VO = 12 V VIN 70 (%) (%) 80 70 60 50 50 1 2 3 4 5 VIN 28 V 60 0 5 100 16 V 40 4 12 V 90 Efficiency versus Output Current VO = 5 V 3 IO (A) 40 0 IO (A) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 1 2 3 IO (A) 4 SI-8005Q Step-Down Switching Regulator with Current-Mode Control Performance Characteristics at TA = 25C 6 6 0A 1A 5 5 2A Overcurrent Protection Load = CR 4 3A VO (V) VO (V) 4 Overcurrent Protection 3 IO 2 0 8V 12 V 24 V 28 V 15 V 3 2 1 20 V VIN 1 0 2 4 6 8 0 10 0 1 2 VIN (V) 3 4 5 6 IO (A) 5.05 25 5.04 VIN Load Regulation VO (V) 5.02 20 28 V 20 V 15 V 5.01 Quiescent Current versus Input Voltage IO = 0 A 5.00 4.99 12 V 8V 4.98 IO(Q) (mA) 5.03 15 10 4.97 5 4.96 4.95 0 1 2 3 4 0 5 0 10 IO (A) Overvoltage Protection VIN = 12 V IO = 0 A 5 4 3 160 20 30 40 3 2 2 1 1 OTP Off 0 10 20 30 0 120 40 130 VIN (V) 550 550 540 540 8V 12 V 15 V 530 520 VIN 530 520 510 Operating Frequency versus Input Voltage 500 490 fO (kHz) fO (kHz) 150 4 6 VO (V) IO(Q) (A) 7 20 V 24 V 28 V 480 510 500 490 480 470 470 460 460 450 140 TJ (C) 5 8 Operating Frequency versus Output Current 40 OTP On 9 0 30 6 10 Quiescent Current versus Input Voltage VEN = 0 V 20 VIN (V) 0 1 2 3 4 5 IO (A) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 450 0 10 VIN (V) 5 SI-8005Q Step-Down Switching Regulator with Current-Mode Control Component Selection Diode Di A Schottky-barrier diode must be used for Di. If other diode types, such as like fast recovery diodes, are used, the IC may be destroyed because of reverse voltages applied by the recovery voltage or turn-on voltage. Choke Coil L1 If the winding resistance of the choke coil is too high, IC efficiency may go down to the extent that the resistance is beyond the rating. Because the overcurrent protection threshold current is approximately 4 A, attention must be paid to the heating of the choke coil by magnetic saturation due to overload or short-circulated load. Capacitors C1, C2, and C5 Because large ripple currents for SMPS flow across C1 and C2, capacitors with high frequency and low impedance must be used. Especially when the impedance of C2 is high, the switching waveform may not be normal at low temperatures. C5 is used to enable soft start. If the soft start function is not used, leave the SS terminal open. Resistors R1 and R2 R1 and R2 set the output voltage, VO. Select the resistor values to set IADJ to 0.1 mA. R1 and R2 are calculated by the following expression: R1 = (VO - VFB ) = (VO - 0.5)( )R 2 = 0.1x 10 -3 I ADJ 0.5 VFB = 5k ( ) I ADJ 0.1x 10 -3 For optimum performance, minimize the distance between components. Phase Compensation Components C3, C6, and R3 The stability and response of the loop is controlled through the COMP pin. The COMP pin is the output of the internal transconductance Typical Application Diagram VIN 2 1 BS IN 7 EN L1 SW 3 S I- 8005Q R1 C1 8 SS FB COM P 6 C5 G ND G ND 4 VFB 5 Di C2 R2 C3 C6 O P EN VO 5V C4 IA D J R3 Component Rating C1 (2 ea) C2 (2 ea) C3 C4, C5 Di L1 R1 R2 R3 10 F / 50 V 22 F / 16 V 220 pF 10 nF Manufacturer Murata, P/N GRM55DB31H106KA87 Murata, P/N GRM32ER71A226KE20 Murata, P/N GRM18 series Murata, P/N GRM18 series Sanken, P/N SPB-G56S or SJPB-L4 10 H 46 k 5.1 k 62 k G ND Recommended PCB Layout Recommended Solder Pad Layout R3 U nit: m m 4.30 1.35 0.54 FB C6 COMP C3 SS R2 R1 C5 1.27 EN 3.00 GND U1 C1 C2 Vin C4 Vout Vsw D1 L1 2.80 All external components should be mounted as closely as possible to the SI-8005Q. The ground of all components should be connected at one point. The exposed copper area on the PCB that is connected to the heat sink on the reverse side of package is ground. Enlarging the PCB copper area enhances thermal dissipation from the package. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 SI-8005Q Step-Down Switching Regulator with Current-Mode Control amplifier. The combination of a series-connected capacitor and resistor sets the combination of a pole and zero frequency point that decide the characteristics of the control system. The DC gain of the voltage feedback loop is calculated by the following equation: Adc = Rl x Gcs x AEA x VFB , Vout (1) where VFB is the feedback voltage (0.5 V), The optimal selection of phase compensation components can be determined using the following procedure: AEA is the error amplifier voltage gain, GCS is the current sense transconductance, and Rl is the load resistor value. The system has two important poles. One is set by the phase compensation capacitor (C3) and the output resistor of the error amplifier. The other is set by the output capacitor and load resistor. These poles are calculated by the following equations: fp1 = GEA 2 x C 3 x AEA , (2) fp 2 = 1 2 x C 2 x Rl , (3) where GEA is the error amplifier transconductance. The system has one important zero point. This is set by the phase compensation capacitor (C3) and phase compensation resistor (R3). The zero point is shown by the following equation: 1 fz1 = 2 x C 3 x R3 . (4) If the value of the output capacitor is the large or if it has a high ESR, the system may have another important zero point. This zero point would be set by the ESR and capacitance of the output capacitor. The zero point is shown by the following equation: fESR = 1 2 x C 2 x RESR . 1 2 x C 6 x R3 . 1. Choose the phase compensation resistor (R3) to adjust the required crossover frequency. R3 value is calculated by the following equation: R3 = 2 x C 2 x fc Vout 2 x C 2 x 0.1x fs Vout x < x , (7) GEA x GCS VFB GEA x GCS VFB where fc is the required crossover frequency. This is usually adjusted to less than one-tenth of the switching frequency. 2. Choose the phase compensation capacitor (C3) to get the required phase margin. For applications that have typical inductor values, adjusting the compensation zero point to less than onequarter of crossover frequency provides sufficient phase margin. The value of C3 is calculated by the following equation: C3 > 4 2 x R3 x fc , (8) where R3 is the phase compensation resistor. 3. It is necessary to determine whether a second compensation capacitor (C6) is required. It is required if the ESR zero point of the output capacitor is less than half of the switching frequency, expressed as follows: 1 fs < 2 x C 2 x RESR 2 . (5) In this case a third pole, which is set by the phase compensation capacitor (C6) and phase compensation resistor (R3), is used to compensate the effect of the ESR zero point on the loop gain. The pole is shown by the following equation: fp 3 = The goal of phase compensation design is to shape the converter transfer function to get the required loop gain. The system crossover frequency, where the feedback loop has unity gain, is important. Lower crossover frequencies result in slower line and load transient responses. On the other hand, higher crossover frequencies cause system instability. A good standard is to adjust the crossover frequency to approximately one-tenth of the switching frequency. (9) If this is the case, add the second compensation capacitor (C6) and adjust ESR zero frequency (fp3). C6 value is calculated by the following equation: (6) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com C6 = C 2 x RESR . R3 (10) 7 Step-Down Switching Regulator with Current-Mode Control Package Outline Drawing 5.20 8 0.15 Tracking number in dimple 6.20 4.40 Branding area 0.40 1 2 1.50 0.08 0.08 0.05 0.05 0.695 TYP 0.40 1.27 2.90 2.70 SI-8005Q Dimensions in millimeters Branding codes (exact appearance at manufacturer discretion): 1st line, type: 8005Q 2nd line, lot: SK YMDD Where: Y is the last digit of the year of manufacture M is the month (1 to 9, O, N, D) DD is the date 3rd line, control : NNNN Leadframe plating Pb-free. Device composition complies with the RoHS directive. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 SI-8005Q Step-Down Switching Regulator with Current-Mode Control Packing Specification Empty tape Trailer IC occupied tape Empty Tape Leader Cover Tape Units More than 160mm 1,000pcs 160mm (1,000 pockets) 4 2 mm More than 400mm Direction of reel 8 1.55 5.5 12 5.6 (4.75) 7 2 60 Void 60 Void 10 Void Void Void Void 13 0.3 15.4 0.1 Center extension 2 5 4 10.5 13 5 11.9 3 R22 Void 60 180 13 0.2 B 3 Void R22 10 60 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 30 60 9 SI-8005Q Step-Down Switching Regulator with Current-Mode Control Cautions In general, the junction temperature level of surface mount package ICs is dependent upon the area and material of the PC board and its copper area. Therefore, please design the PCB to allow sufficient margin for heat dissipation. Thermal Shutdown The SI-8000Q series has a thermal protection circuit. This circuit keeps the IC from the damage by overload. But this circuit cannot guarantee the long-term reliability against the continuous overload conditions. Parallel Operation Parallel operation of multiple products to increase the current is not allowed. ESD Susceptibility Take precautions against damage by static electricity. The products described herein are manufactured in Japan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc. Sanken and Allegro reserve the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Therefore, the user is cautioned to verify that the information in this publication is current before placing any order. When using the products described herein, the applicability and suitability of such products for the intended purpose shall be reviewed at the users responsibility. Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems against any possible injury, death, fires or damages to society due to device failure or malfunction. Sanken products listed in this publication are designed and intended for use as components in general-purpose electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Their use in any application requiring radiation hardness assurance (e.g., aerospace equipment) is not supported. When considering the use of Sanken products in applications where higher reliability is required (transportation equipment and its control systems or equipment, fire- or burglar-alarm systems, various safety devices, etc.), contact a company sales representative to discuss and obtain written confirmation of your specifications. The use of Sanken products without the written consent of Sanken in applications where extremely high reliability is required (aerospace equipment, nuclear power-control stations, life-support systems, etc.) is strictly prohibited. The information included herein is believed to be accurate and reliable. Application and operation examples described in this publication are given for reference only and Sanken and Allegro assume no responsibility for any infringement of industrial property rights, intellectual property rights, or any other rights of Sanken or Allegro or any third party that may result from its use. Copyright (c) 2007 Allegro MicroSystems, Inc. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 10 Step-Down Switching Regulator with Current-Mode Control SI-8005Q January, 2008 <Worldwide Contacts> Asia Pacific China Sanken Electric Hong Kong Co., Ltd. Suite 1026 Ocean Centre, Canton Road, Tsimshatsui, Kowloon, Hong Kong Tel: 852-2735-5262 Fax: 852-2735-5494 Sanken Electric (Shanghai) Co., Ltd. Room3202, Maxdo Centre, Xingyi Road 8, Changning district, Shanghai, China Tel: 86-21-5208-1177 Fax: 86-21-5208-1757 Taiwan Sanken Electric Co., Ltd. Room 1801, 18th Floor, 88 Jung Shiau East Road, Sec. 2, Taipei 100, Taiwan R.O.C. Tel: 886-2-2356-8161 Fax: 886-2-2356-8261 India Saket Devices Pvt. Ltd. Office No.13, First Floor, Bandal - Dhankude Plaza, Near PMT Depot, Paud Road, Kothrud, Pune - 411 038, India Tel: 91-20-5621-2340 91-20-2528-5449 Fax: 91-20-2528-5459 Japan Sanken Electric Co., Ltd. Overseas Sales Headquaters Metropolitan Plaza Bldg. 1-11-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-0021, Japan Tel: 81-3-3986-6164 Fax: 81-3-3986-8637 Korea Sanken Electric Korea Co., Ltd. Mirae Asset Life Bldg. 6F, 168 Kongduk-dong, Mapo-ku, Seoul, 121-705, Korea Tel: 82-2-714-3700 Fax: 82-2-3272-2145 Singapore Sanken Electric Singapore Pte. Ltd. 150 Beach Road, #14-03 The Gateway West, Singapore 189720 Tel: 65-6291-4755 Fax: 65-6297-1744 Sanken Electric Co., Ltd. I02-010EA-080130 Step-Down Switching Regulator with Current-Mode Control SI-8005Q January, 2008 Europe United Kingdom Sanken Power Systems (UK) Limited Pencoed Technology Park Pencoed, Bridgend CF35 5HY. UK Tel: 44-1656-869-100 Fax: 44-1656-869-162 North America United States Allegro MicroSystems, Inc. 115 Northeast Cutoff, Worcester, Massachusetts 01606, U.S.A. Tel: 1-508-853-5000 Fax: 1-508-853-3353 Allegro MicroSystems, Inc. (Southern California) 14 Hughes Street, Suite B105, Irvine, CA 92618 Tel: 1-949-460-2003 Fax: 1-949-460-7837 Sanken Electric Co., Ltd. I02-010EA-080130