IRDC3629A USER GUIDE FOR IR3629A EVALUATION BOARD (Vin=12V, Vo=1.8V, Io=25A) DESCRIPTION The IR3629A is a synchronous buck controller, providing a compact, high performance and flexible solution in a small 3mmx4mm MLPD package. An output over-current protection function is implemented by sensing the voltage developed across the on-resistance of the synchronous rectifier MOSFET for optimum cost and performance. Key features offered by the IR3629A include programmable soft-start ramp, precision 0.6V reference voltage, thermal protection, fixed 300kHz switching frequency requiring no external component, input under-voltage lockout for proper start-up, and pre-bias startup. This user guide contains the schematic and bill of materials for the IR3629A evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for the IR3629A integrated circuit is available in the IR3629A data sheet. BOARD FEATURES • Vin = +12V (13.2V Max) • Vout = +1.8V @ 0-25A • IRF6712 as Controller MOSFET • IRF6715 as Synchronous MOSFET • L = 0.6uH • Cin=2x270uF (OS-CON cap) + 2x10uF (ceramic 1206) • Cout=2x330uF(SP cap) • Optional external supply connection for Vc • Optional Power-good output connection 1 IRDC3629A CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to VIN+ and VIN-. connected to VOUT+ and VOUT-. The connection diagram is shown in Fig. 1 A maximum of 20A load can be IR3629A demo board can also be powered by two separate power supplies, one is the input voltage (Vin) between VIN+ and VIN-, the other is bias voltage (Vcc) between Vc-ext and PGND. In this case, a well regulated 5V~12V power supply should be connected to Vc-ext and PGND and R14 should be removed. Inputs and outputs of the board are listed in Table I. Table I. Connections Connection Signal Name VIN+ Vin (+12V) VIN- Ground of Vin Vc-ext Optional Vcc input PGND Ground for optional Vcc input VOUT- Ground of Vout VOUT+ Vout (+1.8V) GND Bias Voltage Ground LAYOUT The PCB is a 6-layer board. All of layers are 2 Oz. copper. Power supply decoupling capacitors, the chargepump capacitor and feedback components are located close to the IR3629A. The feedback resistors are connected to the output voltage at the point of regulation and are located close to the IC. The input and output energy storage capacitors and the power inductor are located on bottom side of the board, to improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. 2 IRDC3629A IR3629A Demo Board Vin= 12V Vo=1.8V Fig. 1 Connection diagram of the evaluation board for IR3629A (Top view) Fig. 2 Bottom view of the evaluation board for IR3629A 3 IRDC3629A IR3629A PCB Layers Top Layer Bottom Layer 4 IRDC3629A IR3629A PCB Layers AGND PGND Mid-layer1 Single point connection between PGND and AGND Mid-layer2 5 IRDC3629A IR3629A PCB Layers Mid-layer3 Mid-layer4 6 IRDC3629A PGND Vc-ext 1 1 IR3629A Demo Board Schematic Vin Vin+ 1 R14 1 1 C4 0.1uF 3 D1 C3 10uF C2 10uF C5 10uF C6 10uF C1 + 270uF 1 2 1 1 C22 C25 0.1uF 1uF 1 7 C11 R5 3.09K 39pF R1 26.7K 9 C26 8 GND PGood OCSet IR3629A Vsens LDrv Comp PGND Fb Thermal 1 2 6 7 HDrv 6 5 N3064730 5 Q1 12 3 Vout IRF6712 SQ C24 No Stuff IRF6715 MX Vout+ 1 SW Q2 N3065372 5 4 L1 N30652001 2 0.6uH 1 C21 330uF C20 C16 330uF No Stuff No Stuff No Stuff No Stuff No Stuff C17 C18 C19 C15 C14 0.1uF 1 R12 1nF 1 3.65K C9 N/A R9 0 C8 R4 3.57K 0.56nF R6 R2 31.6k R3 15.8K A 20 1 R10 No Stuff Vout+ Vout- 13 1 C10 0.1uF 1 AGND Vc SS/SD 1 R7 10K 10 Vcc 1 23 64 7 1 0.1uF 11 3 4 Vout 1 PGood 2 C23 Vin- C12 0.1uF U1 En R17 4.99K Vin- R15 N/A BAT54S PGND Vin+ 68 B R* 0 Fig. 3 Schematic of the IR3629A evaluation board with 12Vin and1.8V output voltage 7 Vout- IRDC3629A BILL OF MATERIALS Item Quantity Reference Value 1 1 C1 270uF 2 4 C2,C3, C5,C6 3 Description Size Manufacturer Part Number OS-CON CAP, 16V, 20% - Sanyo 16SVPC270M 10uF Ceramic, 25V, X7R, 10% 1206 Murata GRM31CR61C106KA88 6 C4,C10,C12 C14,C23,C2 5 0.1uF Ceramic, 25V, X7R, 10% 603 TDK C1608X7R1H104K 4 1 C8 560pF Ceramic, 50V, C0G, 5% 603 Murata GRM1885C1H561JA01D 5 1 C11 39pF Ceramic, 50V, C0G, 5% 603 Murata GRM1885C1H390JA01D 6 2 C20,C21 330uF SP-CAP, 2V, 6mOhm - Panasonic EEFSX0D331XE 7 1 C22 1uF Ceramic, 16V, X5R, 10% 603 TDK C1608X5R1C105K 8 1 C26 1000pF Ceramic, 50V, X7R, 10% 603 Panasonic ECJ1VB1H102K 9 1 D1 BAT54S Dual Schottky Diode SOT-23 Vishay BAT54S 10 1 L1 0.6uH 1.5mOhm - Delta MPL104-0R6 11 1 Q1 IRF6712 SQ NFET, 25V, 3.8mOhm, 12nC DirectFET SQ IR IRF6712SPbF 12 1 Q2 IRF6715 MX NFET, 25V, 1.3mOhm, 40nC DirectFET MX IR IRF6715MPbF 13 1 R9 0 Thick film, 1%, 1/10W 603 any any 14 1 R1 26.7K Thick film, 1%, 1/10W 603 any any 15 1 R2 31.6K Thick film, 1%, 1/10W 603 any any 16 1 R7 10K Thick film, 1%, 1/10W 603 any any 17 1 R3 15.8K Thick film, 1%, 1/10W 603 any any 18 1 R4 3.57K Thick film, 1%, 1/10W 603 any any 19 1 R5 3.09K Thick film, 1%, 1/10W 603 any any 20 1 R6 20 Thick film, 1%, 1/10W 603 any any 21 1 R12 3.65K Thick film, 1%, 1/10W 603 any any 22 1 R17 4.99K Thick film, 1%, 1/10W 603 any any 23 1 R14 68 Thick film, 1%, 1/4W 1206 any any 8 IRDC3629A BILL OF MATERIALS (cont.) Item Quantity 24 1 U1 IR3629A 25 2 C9, C24 No Stuff 603 26 6 C15,C16,C1 7,C18,C19 No Stuff 1206 27 2 R10, R15 No Stuff 603 28 29 30 2 1 1 Reference - - - Value Description PWM Controller Size Manufacturer Part Number MLPD 3x4 IR IR3629AMPbF - Banana Jack, Insulated, Solder Terminal, Black - Johnson Components 105-0853-001 - Banana Jack, Insulated, Solder Terminal, Red - Johnson Components 105-0852-001 - Banana Jack, Insulated, Solder Terminal, Green - Johnson Components 105-0854-001 9 IRDC3629A TRACKING OPERATING PERFORMANCE Vin=12.0V, Vo=1.8V, Fs=300kHz, Room Temperature, No Air Flow Fig. 4 Start Up at 25A Fig. 5 Prebias Start Up Ch1:PGood, Ch2:Vss, Ch3:Vin, Ch4:Vout Ch1:Vin, Ch2:Vout, Ch3:Vss Fig. 6 Output Voltage Ripple at 25A Load Fig. 7 Gate Signals at 25A Load Ch1:Vout, Ch3:SW Ch1:SW, Ch2:HDRV, Ch3:LDRV Fig. 8 Transient Response Fig. 9 Shorted Hiccup Condition Recovery Ch1:Vout, Ch4:Io(0-12.5A) Ch2:Vout, Ch3:Vss, Ch4:Io 10 IRDC3629A TYPICAL OPERATING PERFORMANCE Vin=12.0V, Vo=1.8V, Io=0-25A, Fs=300kHz, Air Flow=200LFM Fig. 10 Bode Plot of Control Loop 11 IRDC3629A TYPICAL OPERATING PERFORMANCE Vin=12.0V, Vo=1.8V, Fs=300kHz, Room Temp, No Air Flow IR3629A Efficiency 100 Efficiency(%) 90 80 70 60 50 40 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 Iout(A) Fig. 11 Efficiency vs. Load 2 1 Fig. 12 Thermal Image of IR3629A Demo Board at Io=20A (1: IR3629A, 2: IRF6715, 3: IRF6712) 12 IRDC3629A PCB Metal and Components Placement The lead land width should be equal to the nominal part lead width. The minimum lead to lead spacing should be ≥ 0.2mm to minimize shorting. The lead land length should be equal to maximum part lead length + 0.3 mm outboard extension + 0.05mm inboard extension. The outboard extension ensures a large and inspectable toe fillet, and the inboard extension will accommodate any part misalignment and ensure a fillet. The center pad land length and width should be equal to maximum part pad length and width. However, the minimum metal to metal spacing should be ≥ 0.17mm for 2 oz. Copper (≥ 0.1mm for 1 oz. Copper and ≥ 0.23mm for 3 oz. Copper). Two 0.30mm diameter via should be placed in the center of the pad land and connected to ground to minimize the noise effect on the IC. 13 13 IRDC3629A Solder Resist The solder resist should be pulled away from the metal lead lands by a minimum of 0.06mm. The solder resist misalignment is a maximum of 0.05mm and it is recommended that the lead lands are all Non Solder Mask Defined (NSMD). Therefore pulling the S/R 0.06mm will always ensure NSMD pads. The minimum solder resist width is 0.13mm. At the inside corner of the solder resist where the lead land groups meet, it is recommended to provide a fillet so a solder resist width of ≥ 0.17mm remains. The land pad should be Non Solder Mask Defined (NSMD), with a minimum pullback of the solder resist off the copper of 0.06mm to accommodate solder resist mis-alignment. Ensure that the solder resist in-between the lead lands and the pad land is ≥ 0.15mm due to the high aspect ratio of the solder resist strip separating the lead lands from the pad land. Each via in the land pad should be tented or plugged from bottom boardside with solder resist. 14 14 IRDC3629A Stencil Design The stencil apertures for the lead lands should be approximately 80% of the area of the lead lands. Reducing the amount of solder deposited will minimize the occurrence of lead shorts. Since for 0.5mm pitch devices the leads are only 0.25mm wide, the stencil apertures should not be made narrower; openings in stencils < 0.25mm wide are difficult to maintain repeatable solder release. The stencil lead land apertures should therefore be shortened in length by 80% and centered on the lead land. The land pad aperture should deposit approximately 50% area of solder on the center pad. If too much solder is deposited on the center pad the part will float and the lead lands will be open. The maximum length and width of the land pad stencil aperture should be equal to the solder resist opening minus an annular 0.2mm pull back to decrease the incidence of shorting the center land to the lead lands when the part is pushed into the solder paste. 15 15 IRDC3629A IR3629A MLPD Package 3x4-12Lead D E/2 E S Y M B O L A A3 SEATING PLANE A1 D2 E2 Terminal 1 Identifier A A1 A3 b D2 D E E2 L e N ND VGED-4 MILLIMETERS MIN NOM MAX 0.80 0.90 1.00 0.00 0.02 0.05 0.20 REF 0.18 0.25 0.30 INCHES NOM MAX .035 .039 .0008 .0019 .008 REF .0118 .0071 .0096 3.0 .118 3.70 _ 4.00 BSC 3.00 BSC 1.40 _ 1.80 0.30 0.40 0.50 0.50 PITCH 12 6 MIN .032 .000 _ .145 .157 BSC .118 BSC .055 _ .070 .016 .012 .019 .020 PITCH 10 6 Leads on 2 sides e b L (ND-1) x e TAPE & REEL ORIENTATION Figure A IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 This product has been designed and qualified for the Industrial market. Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 02/01 16