MIC4685 3A SPAK SuperSwitcher™ Buck Regulator General Description Features The MIC4685 is a high-efficiency 200kHz stepdown (buck) switching regulator. Power conversion efficiency of above 85% is easily obtainable for a wide variety of applications. The MIC4685 achieves 3A of continuous current in the 7-pin SPAK package. The thermal performance of the SPAK allows it to replace TO-220s and TO-263s (D2PAKs) in many applications. The SPAK saves board space with a 36% smaller footprint than TO-263. High-efficiency is maintained over a wide output current range by utilizing a boost capacitor to increase the voltage available to saturate the internal power switch. As a result of this high-efficiency, only the ground plane of the PCB is needed for a heat sink. The MIC4685 allows for a high degree of safety. It has a wide input voltage range of 4V to 30V (34V transient), allowing it to be used in applications where input voltage transients may be present. Built-in safety features include over-current protection, frequency-foldback short-circuit protection, and thermal shutdown. The MIC4685 is available in a 7-pin SPAK package with a junction temperature range of –40°C to +125°C. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • • • • • • • • • • • Low 2mm profile SPAK package 3A continuous output current Wide 4V to 30V input voltage range (34V transient) Fixed 200kHz PWM operation Over 85% efficiency Output voltage adjustable to 1.235V All surface mount solution Internally compensated with fast transient response Over-current protection Frequency foldback short-circuit protection Thermal shutdown Applications • • • • • • • • Point-of-load power supplies Simple high-efficiency step-down regulators 5V to 3.3V/2A conversion 12V to 5V/3.3V/2.5V/1.8V 3A conversion Dual-output ±5V conversion Base stations LCD power supplies Battery chargers ___________________________________________________________________________________________________________ Typical Application V IN 8V to 30V MIC4685_R 2 5 CIN 33µF 35V IN EN BS 1 SW 6 FB 3 GND 4, Tab CBS 0.33µF/50V L1 39mH D1 3A 40V VOUT 1.8V/3A R1 3.01k R2 6.49k COUT 330µF 6.3V 1.8V Output Converter SuperSwitcher is a trademark of Micrel, Inc Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com January 2010 1 M9999-012610 Micrel, Inc. MIC4685 Ordering Information Part Number Voltage Junction Temp. Range Package MIC4685WR Adj. –40° to +125°C 7-Pin SPAK MIC4685WR EV Adj. Standard RoHS Compliant* MIC4685BR Evaluation Board * RoHS compliant with ‘high-melting solder’ exemption. Pin Configuration 7 6 5 4 3 2 1 NC SW EN GND FB IN BS 7-Pin SPAK (R) Pin Description Pin Number Pin Name 1 BS Pin Function Bootstrap Voltage Node (External Component): Connect to external boost capacitor. 2 IN Supply (Input): Unregulated +4V to 30V supply voltage (34V transient) 3 FB Feedback (Input): Outback voltage feedback to regulator. Connect to 1.235V tap of resistive divider. 4, Tab GND 5 EN Enable (Input): Logic high = enable; logic low = shutdown 6 SW Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Schottky diode. 7 NC No Connect. Tie this pin-to-ground. January 2010 Ground 2 M9999-012610 Micrel, Inc. Detailed Pin Description Switch (SW, Pin 6) The switch pin is tied to the emitter of the main internal NPN transistor. This pin is biased up to the input voltage, minus the VSAT, of the main NPN pass element. The emitter is also driven negative when the output inductor’s magnetic field collapses at turn-off. During the OFF time, the SW pin is clamped by the output Schottky diode typically to a –0.5V. Ground (GND, Pin 4, Tab) There are two main areas of concern when it comes to the ground pin, EMI and ground current. In a buck regulator or any other non-isolated switching regulator, the output capacitor(s) and diode(s) ground is referenced back to the switching regulator’s or controller’s ground pin. Any resistance between these reference points causes an offset voltage/IR drop proportional to load current and poor load regulation. This is why it’s important to keep the output grounds placed as close as possible to the switching regulator’s ground pin. To keep radiated EMI to a minimum, it is necessary to place the input capacitor ground lead as close as possible to the switching regulator’s ground pin. Input Voltage (VIN, Pin 2) The VIN pin is the collector of the main NPN pass element. This pin is also connected to the internal regulator. The output diode or clamping diode should have its cathode as close as possible to this point to avoid voltage spikes adding to the voltage across the collector. January 2010 MIC4685 Bootstrap (BS, Pin 1) The bootstrap pin, in conjunction with the external bootstrap capacitor, provides a bias voltage higher than the input voltage to the MIC4685’s main NPN pass element. The bootstrap capacitor sees the dv/dt of the switching action at the SW pin as an AC voltage. The bootstrap capacitor then couples the AC voltage back to the BS pin, plus the dc offset of VIN where it is rectified and used to provide additional drive to the main switch; in this case, a NPN transistor. This additional drive reduces the NPN’s saturation voltage and increases efficiency, from a VSAT of 1.8V, and 75% efficiency to a VSAT of 0.5V and 88% efficiency respectively. Feedback (FB, Pin 3) The feedback pin is tied to the inverting side of an error amplifier. The noninverting side is tied to a 1.235V bandgap reference. An external resistor voltage divider is required from the output-to-ground, with the center tied to the feedback pin. See Tables 1 and 2 for recommended resistor values. Enable (EN, Pin 5) The enable (EN) input is used to turn on the regulator and is TTL compatible. Note: connect the enable pin to the input if unused. A logic-high enables the regulator. A logiclow shuts down the regulator and reduces the stand-by quiescent input current to typically 150µA. The enable pin has an up-per threshold of 2.0V minimum and lower threshold of 0.8V maximum. The hysterisis provided by the upper and lower thresholds acts as an UVLO and prevents unwanted turn on of the regulator due to noise. 3 M9999-012610 Micrel, Inc. MIC4685 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) (1) .................................................+34V Enable Voltage (VEN)......................................... –0.3V to VIN Steady-State Output Switch Voltage (VSW) .......... –1V to VIN Feedback Voltage (VFB) ...............................................+12V Storage Temperature (Ts) .........................–65°C to +150°C EDS Rating(3) .................................................................. 2kV Supply Voltage (VIN) (4) ..................................... +4V to +30V Junction Temperature (TJ) ........................ –40°C to +125°C Package Thermal Resistance SPAK-7 (θJA) ...................................................11.8°C/W SPAK-7 (θJC).....................................................2.2°C/W Electrical Characteristics VIN = VEN = 12V; VOUT 5V; IOUT = 500mA; TA = 25°C, bold values indicate –40°C< TJ < +125°C, unless noted. Parameter Condition Min Typ Max Units (±2%) (±3%) 1.210 1.198 1.235 1.260 1.272 V V 8V ≤ VIN ≤ 30V, 0.1A ≤ ILOAD ≤ 1A, VOUT = 5V, Note 4 1.186 1.173 1.235 1.284 1.297 V V MIC4685 [Adjustable] Feedback Voltage Feedback Bias Current 50 nA % Maximum Duty Cycle VFB = 1.0V 94 Output Leakage Current VIN = 30V, VEN = 0V, VSW = 0V 5 500 µA VIN = 30V, VEN = 0V, VSW = 1V 1.4 20 mA 6 12 mA Quiescent Current VFB = 1.5V Bootstrap Drive Current VFB = 1.5V, VSW = 0V 250 380 Bootstrap Voltage IBS = 10mA, VFB = 1.5V, VSW = 0V 5.5 6.2 Frequency Fold Back VFB = 0V 30 70 120 kHz 180 200 225 kHz Oscillator Frequency Saturation Voltage IOUT = 1A Short Circuit Current Limit VFB = 0V, See Test Circuit Shutdown Current VEN = 0V Enable Input Logic Level regulator on V 0.59 3.5 150 V 6 A 200 µA 2 V regulator off Enable Pin Input Current mA VEN = 0V (regulator off) 16 VEN = 0V (regulator on) –1 Thermal Shutdown @ TJ 0.8 V 50 µA –0.83 mA 160 °C Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF. 4. 2.5V of headroom is required between VIN and VOUT. The headroom can be reduced by implementing a bootstrap diode as seen on the 5V to 3.3V circuit on page 1. January 2010 4 M9999-012610 Micrel, Inc. MIC4685 Test Circuit +12V 2 5 Device Under Test VIN SW EN BS 68µH 6 1 I FB GND 4, Tab 3 Current Limit Test Circuit Shutdown Input Behavior ON OFF 0.8V 0V 1.25V 2V 1.4V VIN(max) Enable Hysteresis January 2010 5 M9999-012610 Micrel, Inc. MIC4685 Typical Characteristics (TA = 25°C unless otherwise noted) EFFICIENCY (%) Efficiency vs. Output Current 100 VIN = 8V VIN = 12V 90 80 VIN = 30V 70 60 50 40 30 Standard 20 Configuration 10 VOUT = 5.0V 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT CURRENT (A) 90 EFFICIENCY (%) 80 Efficiency vs. Output Current VIN = 8V VIN = 24V 70 60 50 VIN = 30V 40 VIN = 12V 30 20 10 Standard Configuration VOUT = 1.8V 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT CURRENT (A) EFFICIENCY (%) 80 VIN = 5V VIN = 12V 70 60 50 VIN = 16V 40 30 20 Bootstrap Configuration VOUT = 1.8V 10 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT CURRENT (A) January 2010 Quiescent Current vs. Input Voltage 6.2 6.1 6 5.9 5.8 5.7 0 Bootstrap Drive Current vs. Input Voltage 12 300 VEN= 5V 5 10 15 20 25 30 35 40 INPUT VOLTAGE (V) Minimum Duty Cycle vs. Input Voltage 10 DUTY CYCLE (%) BOOTSTRAP CURRENT (mA) 350 6.3 INPUT CURRENT (mA) 90 Efficiency vs. Output Current 250 200 150 100 VIN = 12V VFB = 1.5V 50 0 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 6 8 6 4 2 0 0 VOUT = 1.8V 5 10 15 20 25 INPUT VOLTAGE (V) 30 M9999-012610 Micrel, Inc. FEEDBACK VOLTAGE (V) 1.250 Feedback Voltage vs. Input Voltage 1.245 1.240 1.235 1.230 1.225 1.220 1.215 IOUT = 10mA VOUT = 1.8V 1.210 1.205 0 1.258 FEEDBACK VOLTAGE (V) MIC4685 5 10 15 20 25 INPUT VOLTAGE (V) 30 Feedback Voltage vs. Temperature 1.248 1.238 1.228 1.218 1.208 IOUT = 10mA VIN = 12V VOUT = 1.8V 1.20 1.18 1.16 1.14 1.12 1.10 1.08 1.06 1.04 1.02 1.00 Enable Threshold vs. Temperature Upper Threshold Lower Threshold VIN = 12V VOUT = 5V IOUT = 100mA -60 -40 -20 0 20 40 60 80 100 120 140 THRESHOLD TRIP POINTS 1.198 -40 -20 0 20 40 60 80 100120140 TEMPERATURE °C) ( TEMPERATURE °C) ( January 2010 7 M9999-012610 Micrel, Inc. MIC4685 Typical Safe Operating Area (SOA) OUTPUT CURRENT (A) OUTPUT CURRENT (A) (SOA measured on the MIC4685 Evaluation Board*) Typical 5V Output SOA Standard Configuration Typical 3.3V Output SOA Typical 2.5V Output SOA Typical 1.8V Output SOA Standard Configuration Typical 5.0V Output SOA Typical 3.3V Output SOA Typical 2.5V Output SOA Typical 1.8V Output SOA 5.0 T = 25°C 4.5 A TJ = 125°C 4.0 D = Max 3.5 3.0 2.5 2.0 TA = 60°C 1.5 TJ = 125°C 1.0 D = Max 0.5 0.0 0 5 10 15 20 25 30 35 INPUT VOLTAGE (V) 5.0 T = 25°C 4.5 A TJ = 125°C 4.0 D = Max 3.5 3.0 2.5 2.0 1.5 TA = 60°C 1.0 TJ = 125°C 0.5 D = Max 0.0 0 5 10 15 20 25 30 35 INPUT VOLTAGE (V) * IOUT <3A, D1: Diode Inc. B340 (3A/40V) IOUT <3A, D1: SBM1040 (10A/40V) January 2010 8 M9999-012610 Micrel, Inc. MIC4685 Functional Characteristics Frequency Foldback The MIC4685 folds the switching frequency back during a hard short circuit condition to reduce the energy per cycle and protect the device. January 2010 9 M9999-012610 Micrel, Inc. MIC4685 Functional Diagram V IN IN Bootstrap Charger Enable Internal Regulator 200kHz Oscillator ⎛ R1 ⎞ VOUT = VREF ⎜ + 1⎟ ⎝ R2 ⎠ ⎛V ⎞ R1 = R2 ⎜ OUT –1⎟ ⎝ VREF ⎠ Current Limit Thermal Shutdown VREF = 1.235V Comparator VOUT SW Driver COUT Reset R1 FB Error Amp 1.235V Bandgap Reference R2 MIC4685 Figure 1. Adjustable Regulator A higher feedback voltage increases the error amplifier output voltage. A higher error amplifier voltage (comparator inverting input) causes the comparator to detect only the peaks of the sawtooth, reducing the duty cycle of the comparator output. A lower feedback voltage increases the duty cycle. The MIC4685 uses a voltagemode control architecture. Functional Description The MIC4685 is a variable duty cycle switch-mode regulator with an internal power switch. Refer to the above block diagram. Supply Voltage The MIC4685 operates from a +4V to +30V (34V transient) unregulated input. Highest efficiency operation is from a supply voltage around +12V. See the efficiency curves in the “Typical Characteristics” section on page 5. Output Switching When the internal switch is ON, an increasing current flows from the supply VIN, through external storage inductor L1, to output capacitor COUT and the load. Energy is stored in the inductor as the current increases with time. When the internal switch is turned OFF, the collapse of the magnetic field in L1 forces current to flow through fast recovery diode D1, charging COUT. Enable/Shutdown The enable (EN) input is TTL compatible. Tie the input high if unused. A logic-high enables the regulator. A logic-low shuts down the internal regulator which reduces the current to typically 150µA when VEN = 0V. Feedback In the adjustable version, an external resistive voltage divider is required from the output voltage to ground, center tapped to the FB pin. See Table 1 and Table 2 for recommended resistor values. Output Capacitor External output capacitor COUT provides stabilization and reduces ripple. Return Paths During the ON portion of the cycle, the output capacitor and load currents return to the supply ground. During the OFF portion of the cycle, current is being supplied to the output capacitor and load by storage inductor L1, which means that D1 is part of the high-current return path. Duty Cycle Control A fixed-gain error amplifier compares the feedback signal with a 1.235V bandgap voltage reference. The resulting error amplifier output voltage is compared to a 200kHz sawtooth waveform to produce a voltage controlled variable duty cycle output. January 2010 10 M9999-012610 Micrel, Inc. MIC4685 The efficiency is used to determine how much of the output power (POUT) is dissipated in the regulator circuit (PD). Application Information Adjustable Regulators Adjustable regulators require a 1.235V feedback signal. Recommended voltage-divider resistor values for common output voltages are detailed in Table 1. For other voltages, the resistor values can be determined using the following formulas: ⎛ R1 ⎞ VOUT = VREF ⎜ + 1⎟ ⎝ R2 ⎠ POUT − POUT η PD = 7.5W − 7. 5 W 0.84 PD = 1.43W A worst-case rule of thumb is to assume that 80% of the total output power dissipation is in the MIC4685 (PD(IC)) and 20% is in the diode-inductor-capacitor circuit. PD(IC) = 0.8 PD PD(IC) = 0.8 × 1.43W PD(IC) = 1.14W Calculate the worst-case junction temperature: TJ = PD(IC) θJC + (TC – TA) + TA(max) where: TJ = MIC4685 junction temperature PD(IC) = MIC4685 power dissipation θJC = junction-to-case thermal resistance. The θJC for the MIC4685’s 7-pin SPAK is approximately 2.2°C/W. TC = “pin” temperature measurement taken at the Tab. TA = ambient temperature TA(max) = maximum ambient operating temperature for the specific design. Calculating the maximum junction temperature given a maximum ambient temperature of 60°C: TJ = 1.14 × 2.2°C + (46°C – 25°C) + 60°C TJ = 83.5°C This value is within the allowable maximum operating junction temperature of 125°C as listed in “Operating Ratings.” Typical thermal shutdown is 160°C and is listed in “Electrical Characteristics.” Also refer to the “Typical Safe Operating Area (SOA)” graphs in this document. ⎛V ⎞ R1 = R2⎜⎜ OUT − 1⎟⎟ ⎝ VREF ⎠ VREF = 1.235V Thermal Considerations The MIC4685 is capable of high current due to the thermally optimized SPAK package. One limitation of the maximum output current on any MIC4685 design is the junction-to-ambient thermal resistance (θJA) of the design (package and ground plane). Examining θJA in more detail: θJA = (θJC + θCA) where: θJC = junction-to-case thermal resistance θCA = case-to-ambient thermal resistance θJC is a relatively constant 2.2°C/W for a 7-pin SPAK. θCA is dependent upon layout and is primarily governed by the connection of pins 4, and Tab to the ground plane. The purpose of the ground plane is to function as a heat sink. Checking the Maximum Junction Temperature: For this example, with an output power (POUT) of 7.5W, (5V output at 1.5A with VIN = 12V) and 60°C maximum ambient temperature, what is the junction temperature? Referring to the “Typical Characteristics: 5V Output Efficiency” graph, read the efficiency (η) for 1.5A output current at VIN = 12V or perform you own measurement. η = 84% January 2010 PD = 11 M9999-012610 Micrel, Inc. MIC4685 V IN +4V to +30V (34V transient) CIN 7-pin SPAK Bootstrap Diode The bootstrap diode provides an external bias source directly to the main pass element, this reduces VSAT thus allowing the MIC4685 to be used in very low head-room applications i.e., 5VIN to 3.3VOUT with high efficiencies. Bootstrap diode not for use if VIN exceeds 16V, VIN. See Figure 2. MIC4685_R 2 IN BS 1 5 6 EN SW COUT FB 3 GND 4,Tab 4, Tab VOUT L1 39µH D1 R1 R2 Load Layout Considerations Layout is very important when designing any switching regulator. Rapidly changing currents, through the printed circuit board traces and stray inductance, can generate voltage transients which can cause problems. To minimize stray inductance and ground loops, keep trace lengths as short as possible. For example, keep D1 close to pin 6 and pin 4, and Tab, keep L1 away from sensitive node FB, and keep CIN close to pin 2 and pin 4, and Tab. See “Applications Information: Thermal Considerations” for ground plane layout. The feedback pin should be kept as far way from the switching elements (usually L1 and D1) as possible. A circuit with sample layouts are provided. See Figure 6. Gerber files are available upon request. GND Figure 2. Critical Traces for Layout January 2010 12 M9999-012610 Micrel, Inc. MIC4685 Recommended Components for a Given Output Voltage (Bootstrap Configuration) VOUT IOUT* R1 R2 VIN C1 D1 D2 L1 C4 5.0V 2.1A 3.01k 976Ω 7.5V – 16V 47µF, 20V Vishay-Dale 595D476X0020D2T 3A, 30V Schottky + Vishay B330A 1A, 20V Schottky B120-E3 39µH Sumida CDRH127R-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 3.3V 2.2A 3.01k 1.78k 6.0V – 16V 47µF, 20V Vishay-Dale 595D476X0020D2T 3A, 30V Schottky B330A 1A, 20V Schottky B120-E3 39µH Sumida CDRH127R-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 2.5V 2.0A 3.01k 2.94k 5.0V – 16V 47µF, 20V Vishay-Dale 595D476X0020D2T 3A, 30V Schottky B330A 1A, 20V Schottky B120-E3 39µH Sumida CDRH127R-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 1.8V 2.0A 3.01k 6.49k 5.0V – 16V 47µF, 20V Vishay-Dale 595D476X0020D2T 3A, 30V Schottky + Vishay B330A 1A, 20V Schottky B120-E3 39µH Sumida CDRH127R-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T * Maximum output current at minimum input voltage. See SOA curves for maximum output current vs. Input voltage. Table 1. Recommended Components for Common Output Voltages JP3 J1 VIN C1 47µF 20V J3 GND D2 MBRX120 1A/20V U1 MIC4685_R 2 IN SW 6 ON OFF C2 0.1µF 50V BS 1 5 EN L1 39µH C3 0.33µF 50V J2 VOUT R1 FB 3 GND 4, Tab D1 B330A or SS33 R2 C4* optional C5 330µF 6.3V C7 0.1µF 50V J4 GND * C4 can be used to provide additional stability and improved transient response. Note: optimized for 5VOUT Figure 3. Schematic Diagram January 2010 13 M9999-012610 Micrel, Inc. MIC4685 Recommended Components for a Given Output Voltage (Standard Configuration) VOUT IOUT* R1 R2 VIN C1 D1 L1 C5 5.0V 2.0A 3.01k 976Ω 8V – 30V 33µF, 35V Vishay-Dale 595D336X0035R2T 3A, 40V Schottky B340A-E3 39µH Sumida CDRH127-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 3.3V 2.4A 3.01k 1.78k 8V – 26V 33µF, 35V Vishay-Dale 595D336X0035R2T 3A, 40V Schottky B340A-E3 39µH Sumida CDRH127-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 2.5V 2.35A 3.01k 2.94k 7V – 23V 33µF, 35V Vishay-Dale 595D336X0035R2T 3A, 40V Schottky B340A-E3 39µH Sumida CDRH127-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T 1.8V 2.0A 3.01k 6.49k 6V – 16V 33µF, 35V Vishay-Dale 595D336X0035R2T 3A, 40V Schottky + Vishay B340A-E3 39µH Sumida CDRH127-390MC 330µF, 6.3V Vishay-Dale 594D337X06R3D2T * Maximum output current at minimum input voltage. See SOA curves for maximum output current vs. Input voltage. Table 2. Recommended Components for Common Output Voltages JP3 J1 VIN (34V transient) C1 33µF 35V J3 GND D2*** B340 U1 MIC4685_R 2 IN ON OFF C2 0.1µF 50V SW 6 BS 5 EN FB 1 J2 VOUT 2A L1 39µH C3 0.33µF 50V R1 3.01k 3 GND 4, Tab D1 B340A 1 2 R2 6.49k 3 JP1a 1.8V 4 C4* optional R3 2.94k 5 JP1b 2.5V 6 R4 1.78k 7 JP1c 3.3V 8 R5 976W JP1d 5.0V C5 330µF 6.3V C6** C7 0.1µF 50V J4 GND * C4 can be used to provide additional stability and improved transient response. Note: optimized for 5VOUT ** C6 Optional *** D2 is not used for standard configuration and JP3 is open. Figure 4. Evaluation Board Schematic Diagram January 2010 14 M9999-012610 Micrel, Inc. MIC4685 Printed Circuit Board Figure 5a. Top Layer Figure 5b. Bottom Layer January 2010 15 M9999-012610 Micrel, Inc. MIC4685 Abbreviated Bill of Materials (Critical Components) Item C1 C2, C7 C3 Part Number 594D336X0035R2T Manufacturer (1) Vishay Sprague 33µF 35V 1 2 VJ0805Y104KXAAB Vitramon 0.1µF 50V Murata(5) 0.33µF, 50V ceramic capacitor VJ1206Y334KXAAT Vishay(1) 0.33µF, 50V ceramic capacitor 1800pF, 50V ceramic 1 Vishay Sprague(1) 330µF, 6.3V, tantalum 1 Optional C5 594D337X06R3D2T B340A Diode Inc B340LA-EA D1 SSA34A B120-EA D2 (2) Schottky 3A 40V 1 (1) Schottky 3A 40V 1 (1) Vishay Schottky 3A 40V 1 Vishay(1) Schottky 3A 40V 1 (1) Schottky 3A 40V 1 Vishay B340A R1 Qty. GRM426X7R334K50 C4* L1 Description Vishay B340A Diode Inc (2) Schottky 3A 40V MBRX120 Micro Commercial Component(4) Schottky 1A 20V CDRH127-390MC Sumida(3) CRCW08053011FKEY3 1 39µH 1 (1) 3K01, 1%, 1/10W, 805 1 (1) Vishay R2 CRCW08056491FKEY3 Vishay 6K49, 1%, 1/10W, 805 1 R3 CRCW08052941FKEY3 Vishay(1) 2K94, 1%, 1/10W, 805 1 CRCW08051781FKEY3 (1) 1K78, 1%, 1/10W, 805 1 R4 R5 CRCW08051781FKEY3 U1 MIC4685BR/WR Vishay (1) Vishay Micrel, Inc.(6) 976Ω, 1%, 1/10W, 805 1 3A 200kHz SPAK Buck Regulator 1 Notes: 1. Vishay Sprague, Inc.: www.vishay.com 2. Diodes Inc.: www.diodes.com 3. Sumida: www.sumida.com 4. Micro Commercial Component: www.mccsemi.com 5. Murata: www.murata.com 6. Micrel, Inc.: www.website.com January 2010 16 M9999-012610 Micrel, Inc. MIC4685 Package Information 7-SPAK (R) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel, Incorporated. January 2010 17 M9999-012610