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| SP6641A/6641B Low Noise Evaluation Board Easy Evaluation for the SP6641A/6641B Single or Dual Cell Alkaline to 3.3V or 5V Output SP6641B provides up to 500mA output current with less than 50mVpp ripple High Efficiency: up to 87% SOT23-5 Package & SMT components for small, low SP6641A/6641B Evaluation Board Schematics J1 SHDN 1 2 3 4 SP6641A 1 OR 2 CELL BOOST U1 SP6641A SHDN VOUT GND 5 VBATT LX 3 2 1 1uF Cer. C3 C2 VOUT VBATT 0.9V to 3.3V C1 22uF Ceramic L1 22uH D1 SCHOTTKY DIODE 22uF Ceramic J1 SHDN 1 2 3 4 SP6641B 2 CELL BOOST U1 SP6641B SHDN VOUT GND 5 VBATT LX 3 2 1 1uF Cer. C3 C2 330uF 40mohm D1 L2 VOUT VBATT 1.8V to 3.3V C1 100uF 80mohm L1 10uH SM Bead VFILTER C4 10uF Ceramic SCHOTTKY DIODE USING THE EVALUATION BOARD 1) Powering Up the SP6641A/6641B Circuit The SP6641A/6641B Evaluation Board can be powered from inputs from a +0.9V to +3.3V from 1 or 2 alkaline cells or a power supply. Connect with short leads directly to the "Vbatt" and "Gnd" posts. Monitor the Output Voltage and connect the Load between the "Vout" post and the "GND" post. 2) Using the J1 Jumper: Enabling the SP6641A/6641B Output and using the Shutdown Mode The SP6641A/6641B output will be enabled if the J1 Jumper is in the upper or pin 1 to 2 position. If J1 is in the pin 2 to 3 position, the Shutdown pin is brought to GND, which puts the SP6641A/6641B in the low quiescent Shutdown Mode. 3) Selecting the Inductor In selecting an inductor, the saturation current specified for the inductor needs to be greater then the SP6641A/6641B peak current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. The SP6641A evaluation board uses a Sumida CDRH5D28 22uH inductor with an Isat value of 0.9A and a DCR of 0.095ohms, which easily handles the Ipeak of 0.33A of the SP6641A and will deliver high efficiencies. The SP6641B evaluation board uses a Sumida CDRH5D28 10uH inductor with an Isat value of 1.3A and a DCR of 0.065ohms, which easily handles the Ipeak of 1.0A of the SP6641B and will deliver high efficiencies. Other inductors could be selected provided their Isat is greater than the Ipeak of the SP6641A/6641B. 4) Selecting the Capacitors and Filter Components For the SP6641A, 22uF ceramic capacitors are used, which work well due to their inherently low ESR, which will help produce low peak to peak output ripple, and reduce high frequency spikes as well due to their low impedance. To obtain low peak to peak ripple for the SP6641B, the output capacitor needs to have ESR as low as 35 to 40 mohms and have a value of at least 100uF, for which the 330uF Sanyo POSCAP was chosen for its 40mohms max. ESR. Other ultra low ESR capacitors such the radial lead 100uF Sanyo OSCON or one of the new SM low ESR Polymer capacitors like the 100uF Panasonic UD series could be used. This low ripple is obtained with no output spikes through the use of a LC filter consisting of small 0805 SM bead core L2 and 10uF ceramic capacitor C3. POWER SUPPLY DATA Power supply data is provided for the "B" version of the SP6641B, which has a peak inductor current limit of 1A, with the 3.3V output option. Figure 1 shows the switching signals still present as 1.0V spikes on the 330uF capacitor C2. Note that no output spikes are seen in figures 2 and 3 through the use of a small LC filter after the 330uF capacitor. The SP6641B's low output ripple of 45 to 50mVpp is shown for a typical input of 2.0V to 3.0V and an output load of 300mA. Figure 1. SP6641B Switching Signals on 330uF: Vin = 2.0V, Iout = 300mA, Spikes = 1.0Vpp Figure 2. SP6641B Output Ripple: Vin = 2.0V, Iout = 300mA, Vout ripple = 42mVpp, 51kHz Figure 3. SP6641B Output Ripple: Vin = 3.0V, Iout = 500mA, Vout ripple = 54mVpp, 50kHz FIGURE 4: SP6641A/6641B COMPONENT PLACEMENT FIGURE 5: SP6641A/6641B PC LAYOUT TOP SIDE FIGURE 6: SP6641A/6641B PC LAYOUT BOTTOM SIDE TABLE1: SP6641A BILL OF MATERIALS Ref. Des. Qty. 1 1 2 1 1 1 5 1 Layout Size LxWxH Sipex Corp. 146-6447-03 1"x1.5" Sipex Corp. SP6641AEK-3.3 or 5.0 SOT23-5 TDK Corp C3225X5R0J226K 1210 TDK Corp C2012X5R1A105K 805 Sumida CDRH5D28-220 5.7x5.5x3mm STMicroelectronics STPS0520Z SOD-123 Mill-Max 0300-115-01-4727100 .042 Dia Sullins PTC36SAAN .23x.12 Manufacturer Part Number Component SP6641 Eval PC Board 5-pin SOT23 Step-Up DC/DC Conv Ceramic 6.3V 22uF SM 0.005ohm ESR Ceramic 10V 1uF SM 0.02ohm ESR 22uH, 0.90A, 0.095ohm, SM Inductor Schottky diode 0.5A, 0.385V Test Point Female Pin 3-Pin Header Vendor Sipex 978-667-8700 Sipex TDK 847-803-6100 TDK 847-803-6100 Sumida 847-956-0666 STMicro 847-585-3023 800-Digi-Key 800-Digi-Key U1 C1,C2 C3 L1 D1 TP J1 TABLE2: SP6641B BILL OF MATERIALS Ref. Des. Qty. 1 1 1 1 1 1 1 1 1 5 1 1 Manufacturer Sipex Corp. Sipex Corp. Sanyo Video Sanyo Video TDK Corp TDK Corp Sumida Panasonic Zetex Mill-Max Sullins Sullins Layout Size Component LxWxH 146-6447-03 1"x1.5" SP6641 Eval PC Board SP6641BEK-3.3 or 5.0 SOT23-5 5-pin SOT23 Step-Up DC/DC Conv 10TPA100M 7343 POSCAP 10V 100uF SM 0.080ohm Max. ESR 6TPB330M 7343 POSCAP 6.3V 330uF SM 0.040ohm Max. ESR C2012X5R1A105M 805 Ceramic 10V 1uF SM 0.02ohm ESR C3216X5R0J106M 1206 Ceramic 6.3V 10uF SM 0.005ohm ESR CDRH5D28-100 5.7x5.5x3 10uH, 1.3A, 0.065ohm, SM Inductor EXC-ML20A390U 805 SM Bead Core 100MHz ZCHS2000 SOT23-6 Schottky diode 2A, 0.42V 0300-115-01-4727100 .042 Dia Test Point Female Pin PTC36SAAN .23x.12 3-Pin Header STC02SYAN .2x.1 Shunt Part Number Vendor Sipex 978-667-8700 Sipex Sanyo 978-922-6573 Sanyo 978-922-6573 TDK 847-803-6100 TDK 847-803-6100 Sumida 847-956-0666 800-Digi-Key Zetex 631-360-2222 800-Digi-Key 800-Digi-Key 800-Digi-Key U1 C1 C2 C3 C4 L1 L2 D1 TP J1 ORDERING INFORMATION Model Temperature Range Package Type SP6641AKEB-3.3................................-40C to +85C...............SP6641A 3.3V Evaluation Board SP6641AEK-3.3.....................................-40C to +85C......................................5-pin SOT23 SP6641AKEB-5.0.................................. -40C to +85C...........SP6641A 5.0V Evaluation Board SP6641AEK-5.0.....................................-40C to +85C......................................5-pin SOT23 SP6641BKEB-3.3.................................. -40C to +85C...........SP6641B 3.3V Evaluation Board SP6641BEK-3.3.....................................-40C to +85C......................................5-pin SOT23 SP6641BKEB-5.0.................................. -40C to +85C...........SP6641B 5.0V Evaluation Board SP6641BEK-5.0.....................................-40C to +85C......................................5-pin SOT23 |
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