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(R)
SP6642/3
Evaluation Board Manual
s Easy Evaluation for the
SP6642/3 Single Cell to 2V to 5V Converter
s Only 0.37 sq. in. of Board
Space needed for DC-DC Converter Circuit
s High Efficiency: 83% s 0.75V Start-Up Voltage s Extremely Small SOIC Package s Pin-to-pin Compatible
with MAX1642/3
s Connects easily to AAA Battery or
Standard Power Supply Terminals
DESCRIPTION The SP6642/3 Evaluation Board is designed to help the user evaluate the performance of the SP6642/3 for use as a single cell battery input to 2V to 5V output DC-DC Converter. The SP6642/3 starts up from VIN > 0.75V and when started accepts input voltages much less than +0.75V to as high as +1.65V and produces a regulated +3.3V output at up to 20mA. With very low quiescent current of 1.5A at VBATTERY, and up to 85% power efficiency, the SP6642/3 provides maximum battery life for portable applications. The evaluation board is a completely assembled and tested surface mount board which provides easy probe access points to all SP6642/3 Inputs and Outputs so that the user can quickly connect and measure electrical characteristics and waveforms.
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SP6642/3 EVALUATION BOARD
The next two sections describe the SP6642/3 Board Layout and Using the SP6642/3 Evaluation Boards. A table of SP6642/3 Pin Assignments is also included with details on Input/Output pin function. A SP6642/3 Evaluation Board List of Materials table is provided with some manufacturers part numbers to use as a reference. Finally, a schematic is included of the SP6642/3 Evaluation Board.
Powering Up the SP6642/3 Circuit VIN - U1-1 - Connect VIN post on bottom of board directly to external Power Supply binding post positive. VIN = +0.85 to +1.65V. Or, connect AAA Battery to clip labeled "+". GND - U1-6 - Connect GND post on bottom of board directly to external Power Supply binding post negative. Or, connect AAA Battery to clip labeled "-". VOUT - U1-8 - Connect to Load, Meter or Scope. VOUT = +3.3V. (Or, 2V to 5V if feedback is used with R1 & R2 on FB pin. See Datasheet.) GND - U1-6 - Second GND Connection to Load, Meter or Scope GND. Using the Shutdown Jumper J1 (SHDN only works with the SP6642) The jumper J1 has 2 positions, as described below. Shutdown is a feature on the SP6642, not the SP6643. Connecting a logic low to SHDN shuts off the internal switching MOSFET and the synchronous rectifier opens to prevent current from flowing back into the part. But, the output can still drift to one diode drop below VBATTERY, since there is still a forward path from input to output through the synchronous rectifier body diode. J1 -- To start the SP6642, connect Shunt on J1 to the 1-2 position. The correct output voltage (+3.3V) should appear on VOUT. To shutdown the SP6642, connect J1 to the 2-3 position. Using the Power Fail Comparator, PFI VTH -- The SP6642EB is setup to trip the PFI comparator when the input voltage is at the PFI trip voltage (0.614V +/-3%). The threshold voltage VTH (=VIN) connects to a voltage divider R3 & R4, which sets a threshold voltage for PFI comparator input pin 6 of U1. The user may set a different trip voltage by selecting a resistor for R4 (now open) using the equation: R4 = R3*VPFI /(VTH - VPFI) where VPFI = 0.614V Note: To detect loss of power at the output, the VTH threshold pin connection to VIN can be severed leaving a connection to R3, which can be used to connect to the output pin VIN.
(c) Copyright 2000 Sipex Corporation
BOARD LAYOUT
The SP6642/3 Evaluation Board has been designed to easily and conveniently provide access to all Inputs and Outputs of the SP6642/3 device under test. Position the board with the silkscreen lettering upright (also see the drawing on the front page of this manual) and you will see the SP6642 SOIC labeled U1 in the center of the board, and above it the Capacitors C1,2,3 and Inductor L1 forming the DC-DC Converter circuit. The SP6642/3 Evaluation Board provides convenient battery clips to connect the input to an AAA Battery. Or, use the VIN and GND posts to directly connect to standard Power Supply binding post outputs. The Input and Output connections are made with raised female pin receptacles which can accommodate easy-hook connection leads for power and meter connections, as well as scope probe hooks and grounds for waveform measurements.
USING THE EVALUATION BOARD
The SP6642/3 Evaluation Board can be powered from a battery or a power supply. Connect an AAA battery using the battery clips labeled "+ " and "-". Or, directly connect the SP6642/3EB board to a standard pair of power supply binding posts (0.75" spacing) using the "VIN" and "GND" posts (upper portion of the board with connections on the bottom). It is good practice to not switch power on until power connections are made to the evaluation board.
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PFO - U1-3 - SP6642 or U1-4 - SP6643 Open Drain Power Fail Output. Sinks current when PFI falls below 0.614V. The SP6642EB has this pin pulled up to V OUT through 100k resistor R5, which will draw 30A when power fail is asserted low. Evaluating Output Voltages Other than 3.3V FB - U1-5 - Connects to R1, R2 output feedback divider. The SP6642/3EB is set for 3.3V output since R1 is open on the board, and R2 shorts FB to GND. To set an output voltage in the range 2V to 5V, first cut the short on the board across R2, then connect surface mount resistors R1 & R2 according to the voltage divider equation: R1 = R2 (VOUT/VREF - 1) where R2 should be 100K to 1M since FB leakage = 10nA max and VREF = 1.25V Evaluating the SP6643 Circuit The SP6642EB comes with a SP6642EU installed. To evaluate a SP6643, you need to order samples of the SP6643EU and install one on the board. Instead of having the SHDN function, the SP6643 has a BATTLO function, which gives a low battery detection when the battery voltage drops below 1V. Be sure to remove the Shunt in J1 when using the SP6643. There are two pins on the SP6643 that differ from the SP6642, so note their use and label names differ as shown below: BATTLO - U1-3 Use the post labeled PFO. The BATTLO on the SP6643 is an Open Drain Battery-Low Output which is pulled up to VOUT by 100k resistor R5. When the voltage at the BATT pin is less than 1V, BATTLO goes to close to 0V indicating Low Battery. PFO - U1-4 Use the post labeled SHDN. Remove the Shunt from J1. The PFO function on the SP6643 behaves the same as the SP6642 as described previously in the section "Using the Power Fail Comparator PFI".
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SP6642/3 Evaluation Board Pin Assignments
Pin # Pin Name Pin Function SP6642 1 2 3 4 5 6 7 8 BATT PFI PFO SHDN FB GND LX OUT IC Battery-Power Input Power-Fail Input Open-Drain Power-Fail Output Active-Low Shutdown Input Feedback Input Ground Inductor Switching Node Power Output SP6643 1 2 3 4 5 6 7 8 BATT PFI BATTLO PFO FB GND LX OUT IC Battery-Power Input Power-Fail Input Open-Drain Battery Low Output Open Drain Power-Fail Output Feedback Input Ground Inductor Switching Node Power Output GND LX VOUT VIN, + VTH PFO SHDN GND LX VOUT VIN, + VTH PFO SHDN Input/Output Pin Name
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SP6642/3 Evaluation Board List of Materials
Ref. Qty. Manufacturer Des. 1 U1 C1, 2 C3 C4 L1 1 2 1 0 1 Sumida CD54-101KC Sipex Corp. Sipex Corp. Part Number 146-6373-00 SP6642CU Layout Size 2" X 2" uSO-8 Component Vendor
SP6642/3 Sipex Eval PC Board 978-667-7800 8 pin SOIC Step-Up DC/DC Conv. Sipex
Sprague Corp. 595D226X96R3B2 "B" size Tantalum 6.3V Sprague 22F SM 207-490-7259 Low ESR Panasonic ECJ-VB1E104K 1206 1206 X7R Ceramic Digi-Key 0.1F 800-344-4539 25V SM Open
5X5mm 100H, 520mA Sumida Power Inductor, 847-956-0666 SM 1206 Open 100K Thick FilmChip 1/8W 5% 1206 Digi-Key Digi-Key Digi-Key Digi-Key 1206
R1,2,4 0 R3,5 +,J1 2 1 1 1 Panasonic Keystone Sullins Sullins ERJ-8GEYJ104 82 PZC36SFAN STC02SYAN
.27X.37 Snap-In Battery Clips for AAA .32X.12 .2X.1 3-Pin Header Post Shunt
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SP6642/3 Evaluation Board Schematic
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ORDERING INFORMATION
Model SP6642UEB Package SP6642 Evaluation Board
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation Headquarters and Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
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