SP6648EB SIPEX | Alldatasheet
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Technical content
DESCRIPTION
The SP6648 Evaluation Board is designed to help the user evaluate the performance of the SP6648 for use as a single or dual cell input to +3.3V output DC-DC Converter. The output of the SP6648 is preset to +3.3V or can be adjusted from +2V to +5.5V by manipulating two external resistors. The evaluation board is a completely assembled and tested surface mount board which provides easy probe access points to all SP6648 Inputs and Outputs so that the user can quickly connect and measure electrical characteristics and waveforms. SP6648 EVALUATION BOARD SCHEMATIC RLIM 1.87K LBON VBATT + C2 47uF 3.3Vout L1 10uH 47pF SP6648 5 6 10VBATT LBI RLIM SHDN FB GND PGNDLBON LX VOUT 124K LBI SHDN 205K 1uF 47uF /square4 Easy Evaluation for the SP6648 Single or Dual Cell Alkaline to 2V to 5V Output /square4 Provides 300mA output at 3.3V output for 2.0V Input /square4 High Efficiency: 94% /square4 µSOIC Package & SMT components for small, low profile Power Supply SP6648 Evaluation Board Manual
USING THE EVALUATION BOARD 1) Powering Up the SP6648 Circuit The SP6648 Evaluation Board can be powered from inputs from a +0.95V to +3.3V from 1 or 2 alkaline cells. 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 2nd “GND” post. 2) Using the J1 Jumper: Enabling the SP6648 Output and using the Shutdown Mode The SP6648 output will be Enabled if the J1 Jumper is in the top 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 SP6648 in the low quiescent Shutdown Mode. 3) Using the Rlim Function The peak inductor current, IPEAK, is programmed externally by the RLIM resistor connected between the RLIM pin and GND. The peak inductor current is defined by: IPEAK = 1400/RLIM The SP6648 datasheet specifications for RLIM give a range of 1750 to 4000 ohms. Using the IPEAK equation above gives an IPEAK range of IPEAK range = 350 to 800mA. The saturation current specified for the inductor needs to be greater then the peak current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. The SP6648 evaluation board uses a Rlim value of 1.87K for an Ipeak = 750mA to allow the circuit to deliver up to 180mA for 1.3V input and 400mA for 2.6V input. Other values could be selected using the above relationships. 4) Using the LBON - Low Battery Output Function The Low Battery Output function, LBON, is programmed externally by the R3 and R4 resistor divider connected between Vbatt, the LBI input pin and GND. The LBON is an open drain output, which is active low and is pulled up by a 1M resistor R5 to Vout. When the LBI comparator falling threshold of 0.625V is reached, the LBON output goes low as determined by the relationship: LBON falling = Vbatt*R4/(R3 +R4) The SP6648 evaluation board R3 & R4 resistors have been set to trip for a falling battery threshold of about 2.0V. Using this relationship, other low battery threshold values can be set by the user.
TABLE1: SP6648EB LIST OF MATERIALS
ORDERING INFORMATION
Model Temperature Range Package Type Ref. Des. Qty. Manufacturer Part Number Layout Component Vendor Size 1S ipex Corp. 146-6479-00 1"x1.5" SP6648UEB Eval PC Board Sipex 978-667-7800 U1 1 Sipex Corp. SP6648EU uSO-8 10-pin uSOIC Step-Up DC/DC Conv Sipex C1,2 2 Kemet T494C476K010AS "D" size 47uF 10V SM 0.3ohm ESR Kemet 847-517-1030 C1,2 2 Kemet T494V476K010AS "V" size 47uF 10V low profile SM 0.3ohm ESR Kemet 847-517-1030 C3 1 TDK Corp C1608SL1H470K 0603 Ceramic 16V 47pF SM TDK 847-803-6100 C4 1 TDK Corp C1608X5R1A105M 0603 Ceramic 10V 1uF SM 0.02ohm ESR TDK 847-803-6100 R1 1 Panasonic ERJ-3EKF2053 0603 205K ohm 1/8W 1% 0603 SM Digi-Key 800-344-4539 R2 1 Panasonic ERJ-3EKF2493 0603 124K ohm 1/8W 1% 0603 SM 800-Digi-Key R3 1 Panasonic ERJ-3EKF5493 0603 549K ohm 1/8W 1% 0603 SM 800-Digi-Key R4 1 Panasonic ERJ-3EKF2493 0603 249K ohm 1/8W 1% 0603 SM 800-Digi-Key R5 1 Panasonic ERJ-3GEYJ105 0603 1M ohm 1/8W 5% 0603 SM 800-Digi-Key RLIM 1 Panasonic ERJ-3EKF1871 0603 1.87K ohm 1/8W 1% 0603 SM 800-Digi-Key TP 5 Mill-Max 0300-115-01-4727100 .042 Dia Test Point Female Pin 800-Digi-Key J1 1 Sullins PTC36SAAN .23x.12 3-Pin Header 800-Digi-Key 1 Sullins STC02SYAN .2x.1 Shunt 800-Digi-Key