(R) SP6642/6643 Single Alkaline Cell, High Efficiency Step-Up DC-DC Converter 20mA Output Current at 1.2V Input +2V to +5.5V Output Range 0.85V Guaranteed Start-Up 83% High Efficiency 1.5A Quiescent Supply Current at VBATT Reverse Battery Protection Internal Synchronous Rectifier 5nA Logic Controlled Shutdown Current From VBATT For The SP6642 Low-Battery Detection Active LOW Output For The SP6643 Extremely Small SOIC Package Pin-to-pin Compatible With MAX1642 And MAX1643 DESCRIPTION The SP6642/6643 devices are high-efficiency, low-power step-up DC-DC converters for +1V inputs ideal for single alkaline cell applications such as pagers, remote controls, and other low-power portable end products. Designers can control the SP6642 device with a 1nA active LOW shutdown input. The SP6643 features an active LOW output for low-battery conditions. Both devices contain a 0.8 synchronous rectifier, an oscillator, a 0.6 N-channel MOSFET power switch, an internal voltage reference, circuitry for pulse-frequency-modulation, and an under voltage comparator. The output voltage for the SP6642/6643 devices is preset to +3.3V + 4% or can be adjusted from +2V to +5.5V by manipulating two external resistors. VBATT 1 SP6642 8 VOUT VBATT 1 7 LX PFI 2 BATTLO PFO PFI 2 PFO 3 6 GND SHDN 4 5 FB Rev. 10-6-00 8 VOUT 7 LX 3 6 GND 4 5 FB SP6642/6643 High Efficiency Step-Up DC-DC Converter 1 SP6643 (c) Copyright 2000 Sipex Corporation ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VBATT to GND.............................................-0.3 to 6.0V VOUT to GND..............................................-0.3 to 6.0V LX, SHDN, FB, BATTLO, PFO to GND....-0.3 to 6.0V PFI to GND...............................................-0.3 to 6.0V Reverse battery Current, TAMB=+25OC.............220mA (NOTE 1) VBATT forward current............................................0.5A VOUT, LX current......................................................1A Storage Temperature Range............-65C to +165C Lead Temperature (soldering 10s)..................+300C Operating Temperature.......................-40C to +85C Power Dissipation Per Package 8-pin SOIC (derate 4.85mW/OC above +70OC)..........390mW SPECIFICATIONS VBATT = VSHDN = 1.3V, ILOAD = 0mA, FB = GND, TAMB = -40OC to +85OC, and typical values are at TAMB = +25OC unless otherwise noted. PARAMETER MIN. TYP. Minimum Operating Input Voltage, VBATT(MIN) Maximum Operating Input Voltage, VBATT(MAX) Start-Up Input Voltage (VBATT), NOTE 2 MAX. 0.2 V 1.65 0.85 0.75 Start-Up Input Voltage (VBATT), Temperature Coefficient UNITS V V -2 CONDITIONS RL=3k RL=3k,TAMB=+25OC mV/OC SHDN Input Voltage VIL VIH 20 % % of VBATT for the SP6642 % of VBATT for the SP6642 SHDN Input Current 10 nA SP6642 FB Input Current 10 nA VFB=1.3V V external feedback FB Set Voltage, VFB 80 1.215 1.262 1.309 10 nA VPFI=650mV PFI Trip Voltage 590 614 632 mV falling PFI,hysteresis=1% BATTLO Trip Voltage 0.96 1.00 1.04 V VOUT = 3.3V, hysteresis = 2%, SP6643 Output Voltage, VOUT 3.16 3.30 3.44 V VFB<0.1V Output Voltage Range 2.0 PFI Input Current 5.5 V external feedback N-Channel On-Resistance 0.6 1.5 VOUT=3.3V P-Channel On-Resistance 0.8 2.2 VOUT=3.3V P-Channel Catch-Diode Voltage 0.8 V IDIODE=100mA,P-Channel switch off Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 2 (c) Copyright 2000 Sipex Corporation SPECIFICATIONS (continued) VBATT = VSHDN = 1.3V, ILOAD = 0mA, FB = GND, TAMB = -40OC to +85OC, and typical values are at TAMB = +25OC unless otherwise noted. PARAMETER MIN. TYP. MAX. UNITS CONDITIONS Quiescent Current into VOUT, IQOUT 13 20 A VOUT=3.5V Quiescent Current into VBATT, IQBATT 1.5 2.5 A VBATT=1.0V VOUT=3.5V for the SP6642 Shutdown Current into VOUT, ISHDNOUT 0.001 0.5 A Shutdown Current into VBATT, ISHDNBATT 0.005 0.1 A VBATT=1.0V for the SP6642 0.4 V VPFI=0V,VOUT=+3.3V,ISINK=1mA Low Output Voltage for PFO and BATTLO, VOL 1 A VPFI=650mV,VPFO=6V BATTLO Trip Voltage 0.96 1.0 1.04 V VOUT=+3.3V,hysteresis=2% for the SP6643 On-Time Constant, K 17 25 35 V-s Leakage Current for PFO and BATTLO Off-Time Tracking Ratio (NOTE 3) Efficiency 1 1.5 83 0.9V<VBATT<1.5V (tON=K/VBATT) 0.9V<VBATT<1.5V,VOUT=+3.3V % ILOAD=20mA NOTE 1: The reverse battery current is measured from the Typical Operating Circuit's input terminal to GND when the battery is connected backward. A reverse current of 220mA will not exceed package dissipation limits but, if left for an extended time (more than 10 minutes), may degrade performance. NOTE 2: Start-up guaranteed by correlation to measurements of device parameters (i.e. switch on-resistance, on-times, and output voltage trip points. NOTE 3: tOFF = Ratio x tON x VBATT . This guarantees discontinous condition. VOUT - VBATT NOTE 4: Specifications to -40C are guaranteed by design, not production tested. Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 3 (c) Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS 100 100 90 80 90 Efficiency (%) Efficiency (%) Refer to the circuit in Figure 25 with VBATT = 1.2V, R1 + R2 = 1M, and TAMB = +25OC unless otherwise noted. 70 60 50 40 Vin = 1.6V 30 Vin = 1.2V 20 10 0 0.01 60 50 40 30 Vin = 1.6V Vin = 1.0V 20 Vin = 1.0V Vin = 0.85V 10 0 0.01 Vin = 0.85V 0.1 1 10 Output Current (mA) 100 100 90 90 80 80 70 70 Efficiency (%) 100 60 50 40 Vin = 1.6V 30 Vin = 1.2V 20 Vin = 1.0V 10 0 0.01 Vin = 0.85V 0.1 1 10 Vin = 1.2V 0.1 1 10 Output Current (mA) 100 Figure 2. Efficiency vs. Output Current (VOUT=2.4V) where L1=150H, TDK NLC565050T-151K Figure 1. Efficiency vs. Output Current (VOUT=2.4V) where L1=100H, Sumida CD54-101 Efficiency (%) 80 70 60 50 40 Vin = 1.6V 30 Vin = 1.2V 20 Vin = 1.0V 10 Vin = 0.85V 0 0.01 100 Output Current (mA) 0.1 1 10 100 Output Current (mA) Figure 4. Efficiency vs. Output Current (VOUT=3.3V) where L1=150H, TDK NLC565050T-151K Figure 3. Efficiency vs. Output Current (VOUT=3.3V) where L1=100H, Sumida CD54-101 Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 4 (c) Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS (continued) Refer to the circuit in Figure 25 with VBATT = 1.2V, R1 + R2 = 1M, and TAMB = +25OC unless otherwise noted. 70 60 50 40 30 20 10 0 0.01 Efficiency (%) Efficiency (%) 100 90 80 Vin = 1.6V Vin = 1.2V Vin = 1.0V Vin = 0.85V 0.1 1 10 Output Current (mA) 100 10000 Vin = 1.2V Vin = 1.0V Vin = 0.85V 0.1 1 10 Output Current (mA) 100 100 Quiescent Current (A) Quiescent Current (A) Vin = 1.6V Figure 6. Efficiency vs. Output Current (VOUT=5.0V) where L1=150H, TDK NLC565050T-151K Figure 5. Efficiency vs. Output Current (VOUT=5.0V) where L1=100H, Sumida CD54-101 Vout = 5.0V Vout = 3.3V Vout = 2.4V 1000 100 10 0.8 100 90 80 70 60 50 40 30 20 10 0 0.01 80 60 40 20 0 -40 1.0 1.2 1.4 1.6 -20 0 20 40 60 80 100 Temperature (oC) 1.8 Input Voltage (V) Figure 8. No-Load Battery Current vs. Temperature Where VBATT = 1.2V, VOUT = 3.3V Figure 7. No-Load Battery Current vs. Input voltage Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 5 (c) Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS (continued) Start-Up Input Voltage (V) Refer to the circuit in Figure 25 with VBATT = 1.2V, R1 + R2 = 1M, and TAMB = +25OC unless otherwise noted. Quiescent Current (A) 40 35 30 Iout 25 Ibatt 20 15 10 5 0 -40 -20 20 40 60 Temperature (oC) 80 6 8 10 12 14 Start-Up Input Voltage (V) 10 15 20 25 Output Current (mA) 30 Figure 10. Minimum Start-Up Input Voltage vs. Output Current where L1=100H, Sumida CD54-101 Maximum Output Current (mA) 4 5 100 Vout = 5V Vout = 3.3V Vout = 2.4V 2 Vout = 5V Vout = 3.3V Vout = 2.4V 0 0 Figure 9. VBATT and VOUT Pin Quiescent Currents vs. Temperature where VBATT = 1.2V, VOUT = 3.6V 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 16 40 35 30 25 20 15 Vout = 2.4V Vout = 3.3V 10 Vout = 5V 5 0 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Input Voltage (V) Output Current (mA) Figure 12. Maximum Output Current vs. Input Voltage where L1=100H, Sumida CD54-101 Figure 11. Minimum Start-Up Input Voltage vs. Output Current where L1=150H, TDK NLC565050T-151K Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 6 (c) Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS (continued) Maximum Output Current (mA) Refer to the circuit in Figure 25 with VBATT = 1.2V, R1 + R2 = 1M, and TAMB = +25OC unless otherwise noted. 22 20 18 16 14 12 10 8 Vout = 2.4V 6 Vout = 3.3V Vout = 5V 4 2 0 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Input Voltage (V) 10msec/div Figure 14. Switching Waveforms: VOUT=3.3V, VIN=1.2V, IOUT=12mA where 1: LX, 2V/div, L1=TDK NKLC565050T-151K 2: VOUT, 20mV/div, 3.3V DC offset 3: Inductor Current, 100mA/div Figure 13. Maximum Output Current vs. Input Voltage where L1=150H, TDK NLC565050T-151K 500sec/div 500sec/div Figure 16. Line-Transient Response: VOUT=3.3V, LOAD=15mA where 1: VOUT, 50mV/div, 3.3V DC offset 2: VBATT, 1V to 5V, 500mV/div Figure 15. Load-Transient Response: VOUT=3.3V, VBATT=1.2V where 1: VOUT, 20mV/div, 3.3V DC offset 2: LOAD, 2mA to 20mA, 10mA/div Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 7 (c) Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS (continued) Refer to the circuit in Figure 25 with VBATT = 1.2V, R1 + R2 = 1M, and TAMB = +25OC unless otherwise noted. 10msec/div Figure 17. Shutdown Response and Inductor Current: VOUT=3.3V, VBATT=1.2V, IOUT=5mA where 1: VOUT, 1V/div 2: SHDN, 2v/div 3: Inductor Current, 200mA/div PIN NUMBER NAME FUNCTION SP6642 SP6643 Battery Supply. For the SP6643, this pin ties to the sensor input of the BATTLO comparator. 1 1 Power-Fail Input. When the voltage on PFI drops below 614mV, PFO sinks current. 2 2 Open-Drain Battery-LOW Output. When the voltage at VBATT drops below 1V, BATTLO sinks current. - 3 PFO Open-Drain Power-Fail Output. Sinks current when PFI drops below 614mV. 3 4 SHDN Active-LOW Shutdown Input. Connect to VBATT for normal operation. 4 - Feedback Input. Input for adjustable-output operation. Connect this input pin to an external resistor voltage divider between VOUT and GND. Connect to GND for fixed-output operation. 5 5 Connect to the lowest circuit potential, typically ground. 6 6 LX Coil. An inductor is connected from VBATT to the N-Channel MOSFET switch drain and the P-Channel synchronous-rectifier drain through this pin. 7 7 VOUT Power Output. Feedback input for fixed 3.3V operation and IC power input. Connect filter capacitor close to VOUT. 8 8 VBATT PFI BATTLO FB GND Table 1. SP6642/6643 Pin Descriptions Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 8 (c) Copyright 2000 Sipex Corporation VBATT 1 SP6642 8 VOUT 7 LX PFI 2 PFO 3 6 GND SHDN 4 5 FB VBATT 1 8 VOUT 7 LX Figure 18. Pinout for the SP6642 SP6643 PFI 2 BATTLO 3 6 GND PFO 4 5 FB Figure 19. Pinout for the SP6643 Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 9 (c) Copyright 2000 Sipex Corporation DESCRIPTION The on-time and minimum off-times are varied as a function of the input and output voltages: The SP6642/6643 devices are high-efficiency, low-power step-up DC-DC converters ideal for single alkaline cell applications such as pagers, remote controls, and other low-power portable end products. tON = tOFF(MIN) = The SP6642 features a 5nA logic-controlled shutdown mode. The SP6643 features dedicated low-battery detector circuitry. Both devices contain a 0.8 synchronous rectifier, an oscillator, a 0.6 N-channel MOSFET power switch, an internal voltage reference, circuitry for pulse-frequency-modulation, and an under voltage comparator. The output voltage for the SP6642/6643 devices can be adjusted from +2V to +5.5V by manipulating two external resistors. The output voltage is preset to +3.3V. 1.2 x K VOUT - VBATT where tON is the on-time, K is the on-time constant typically 25V-s, VBATT is the supply voltage, tOFF(MIN) is the minimum off-time, and VOUT is the output voltage. This allows the SP6642/6643 devices to maintain a high efficiency over a wide range of loads and input/output voltages. The DC-DC converter is powered from VOUT. In a state where the error comparator detects that the output voltage at VOUT is too low, the internal N-channel MOSFET switch is turned on until the on-time is satisfied. Refer to Figures 20, 21, 22 and 23. During the on-time, current ramps up in the inductor, storing energy in a magnetic field. When the MOSFET turns off, during the second half of each cycle the magnetic field collapses. This causes the inductor voltage to force current through the synchronous rectifier transferring the stored energy from the inductor to the output filter capacitor and the load. The output filter capacitor stores charge while current from the inductor is high and holds the output voltage high until the second half of the next switching cycle, smoothing power flow to the load. THEORY OF OPERATION The SP6642/6643 devices are ideal for end products that function with a single alkaline cell, such as remote controls, pagers, and other portable consumer products. Designers can implement the SP6642/6643 devices into applications with the following power management operating states: 1. where the primary battery is good and the load is active, and 2. where the primary battery is good and the load is sleeping. In the first operating state where the primary supply is good and the load is active, the SP6642/ 6643 devices typically offer 80% efficiency, drawing tens of milliamps. Internal Bootstrap Circuitry The internal bootstrap circuitry contains a low-voltage start-up oscillator that pumps up the output voltage to approximately 1.9V so the main DC-DC converter can function. At lower battery supply voltages, the circuitry can start up with low-load conditions. Designers can reduce the load as needed to allow start-up with input voltages below 1V. Refer to Figures 10 to 13. Once started, the output voltage can maintain the load as the battery voltage decreases below the initial start-up voltage. The start-up oscillator is powered by VBATT driving a charge pump and NMOS switch. During start-up, the P-channel synchronous rectifier remains off and either its body diode or an external diode is used as an output rectifier. Applications will predominantly operate in the second state where the primary supply is good and the load is sleeping. The SP6642/6643 devices draw a very low quiescent current while the load in its disabled state will draw typically hundreds of microamps. The pulse-frequency-modulation (PFM) circuitry provides higher efficiencies at low to moderate output loads than traditional PWM converters are capable of delivering. Rev. 10-6-00 K VBATT SP6642/6643 High Efficiency Step-Up DC-DC Converter 10 (c) Copyright 2000 Sipex Corporation TIMING VOUT VBATT T-ON VREF EN FB T-OFF LOGIC DRV-P P DRV-N START UP OSC SHDN VREF N VREF LX 0.5VREF N VOUT PFO 1.9V 0.5VREF PFI SP6642 Figure 20. Internal Block Diagram of the SP6642 100H 350mA 0.85V to 1.65V Input 22F VBATT 0.1F LX PFI OUT +3.3VOUT SP6642 0.1F 22F PFO SHDN GND FB Figure 21. SP6642 +3.3V Typical Application Circuit Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 11 (c) Copyright 2000 Sipex Corporation TIMING VTH VOUT VBATT T-ON VREF EN FB T-OFF LOGIC DRV-P SP6642 P DRV-N R3 VREF VREF 0.5VREF 1.0V START UP OSC PFI N LX N BATTLO R4 1.0V GND PFO 0.5VREF PFI SP6643 Figure 22. Internal block diagram of the SP6643 Figure 24. Power-Fail Detection Circuitry 100H 350mA 0.85V to 1.65V Input 22F VBATT 0.1F LX OUT +3.3VOUT SP6643 0.1F 22F PFO BATTLO PFI GND FB Figure 23. SP6643 +3.3V Typical Application Circuit BATTLO for the SP6643 The SP6643 device has an internal comparator for low-battery detection. If VBATT drops below 1V, BATTLO will sink current. BATTLO is an open-drain output. BATTLO used in conjunction with the power-fail detection circuitry (PFI/ PFO) will monitor both the input and output voltages. Power-Fail Detection Circuitry The SP6642/6643 devices have an internal comparator for power-fail detection. This comparator can detect a loss of power at the input or output. If the voltage at PFI falls below 614mV, the PFO output sinks current to ground. Hysteresis at the power-fail input is 1%. The power-fail monitor's threshold voltage is determined by two resistors, R3 and R4. Refer to Figure 24. The power-fail monitor threshold voltage can be set using the following equation: R3 = R4 x Shutdown for the SP6642 A logic LOW at SHDN will drive the SP6642 into a shutdown mode where PFO goes into a high-impedance state, the internal switching MOSFET turns off, and the synchronous rectifier turns off to prevent reverse current from flowing from the output back to the input. Designers should note that in shutdown, the output can drift to one diode drop below VBATT because there is still a forward current path through the VTH -1 VPFI where R3 and R4 are the resistors in Figure 24, VTH is the desired threshold voltage of the powerfail detector, and VPFI is the 614mV reference of the power-fail comparator. Since PFI leakage is 10nA max, select feedback resistor R4 in the 100k to 1M. Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 12 (c) Copyright 2000 Sipex Corporation 100H 350mA 0.88V to 1.65V Input 22F VBATT 0.1F LX PFI VOUT VOUT= 2V to 5.2V SP6642 22F 100pF* PFO SHDN 0.1F R1 *optional compensation FB R2 GND Figure 25. Adjustable Output Voltage Circuitry diode in series with an internal 5 resistor limits any reverse current to less than 220mA preventing damage to the devices. Prolonged operation above 220mA reverse-battery current can degrade performance of the devices. synchronous-rectifier body diode from the input to the output. To disable the shutdown feature, designers can connect SHDN to VBATT. Adjustable Output Voltage Driving FB to ground (logic LOW) will drive the output voltage to the fixed-voltage operation of +3.3V + 4%. Connecting FB to a voltage divider between VOUT and ground will select an adjustable output voltage between +2V and +5.5V. Refer to Figure 25. FB regulates to +1.23V. The Inductor It is recommended that designers implement a 100H inductor for typical application of the SP6642/6643 devices. Lower inductor values down to 68H will increase the maximum output current. Higher inductor values up to 220H will reduce peak inductor current and any consequent ripple and noise. The saturationcurrent rating of the inductor selected must exceed the peak current limit synthesized by the SP6642/6643 devices' timing algorithms. This can be calculated with the following equation: Since the FB leakage current is 10nA maximum, designers should select the feedback resistor R2 in the 100k to 1M range. R1 can be determined with the following equation: R1 = R2 x VOUT -1 VREF IPEAK = KMAX LMIN where R3 and R4 are the feedback resistors in Figure 25, VOUT is the output voltage, and VREF is 1.23V. where IPEAK is the peak current, KMAX is 35V-s, and LMIN is the minimum inductance selected. The maximum recommended IPEAK is 350mA. To optimize efficiency, select an inductor with a series resistance less than 1. Battery Reversal Protection The SP6642/6643 devices will tolerate singlecell battery reversal up to the package powerdissipation limits noted in the ABSOLUTE MAXIMUM RATINGS section. An internal Rev. 10-6-00 Table 1 lists surface mount inductor information for the user, including series resistance and saturation current rating. SP6642/6643 High Efficiency Step-Up DC-DC Converter 13 (c) Copyright 2000 Sipex Corporation It is suggested designers select the largest inductor value possible that will satisfy the load requirement and minimize peak switching current and any resultant noise and voltage ripple. A closed-core inductor, such as a toroid or shielded bobbin, will minimize any fringe magnetic fields or EMI. from sensitive RF and analog input stages. The external voltage-feedback network should be placed very close to the FB pin (within 0.2in or 5mm). Any noisy traces, such as from the LX pin, should be kept away from the voltagefeedback network and separated from it using grounded copper to minimize EMI. APPLICATION NOTES Capacitor equivalent series resistance is a major contributor to output ripple, usually greater than 60%. Low ESR capacitors are recommended. Ceramic capacitors have the lowest ESR. Low-ESR tantalum capacitors may be a more acceptable solution having both a low ESR and lower cost than ceramic capacitors. Designers should select input and output capacitors with a rating exceeding the peak inductor current. Do not allow tantalum capacitors to exceed their ripple-current ratings. A 22F, 6V, low-ESR, surface-mount tantalum output filter capacitor typically provides 60mV output ripple when stepping up from 1.3V to 3.3V at 20mA. An input filter capacitor can reduce peak currents drawn from the battery and improve efficiency. Low-ESR aluminum electrolytic capacitors are acceptable in some applications but standard aluminum electrolytic capacitors are not recommended. Printed circuit board layout is a critical part of design. Poor designs can result in excessive EMI on the voltage gradients and feedback paths on the ground planes with applications involving high switching frequencies and large peak currents. Excessive EMI can result in instability or regulation errors. All power components should be placed on the PC board as closely as possible with the traces kept short, direct, and wide (>50mils or 1.25mm). Extra copper on the PC board should be integrated into ground as a pseudo-ground plane. On a multilayer PC board, route the star ground using component-side copper fill, then connect it to the internal ground plane using vias. For the SP6642/6643 devices, the inductor and input and output filter capacitors should be soldered with their ground pins as close together as possible in a star-ground configuration. The VOUT pin must be bypassed directly to ground as close to the SP6642/6643 devices as possible (within 0.2in or 5mm). The DC-DC converter and any digital circuitry should be placed on the opposite corner of the PC board as far away Designers should add LC pi filters, linear post-regulators, or shielding in applications necessary to address excessive noise, voltage ripple, or EMI concerns. The LC pi filter's cutoff frequency should be at least a decade or two below the DC-DC converters's switching frequency for the specified load and input voltage. Table 1. Surface-Mount Inductor Information INDUCTOR SPECIFICATION INDUCTANCE (H) VENDOR/PART RESISTANCE () ISAT (mA) 68 Coilcraft DO1608-683 Sumida CD54-680 Coilcraft DO1608-104 Sumida CD54-101 TDK NLC565050T-101K Coilcraft DO1608-154 Sumida CD54-151 TDK NLC565050T-151K Coilcraft DO1608-224 Sumida CD54-221 0.75 0.46 1.1 0.7 1.6 1.7 1.1 2.2 2.3 1.57 400 610 310 520 250 270 400 210 220 350 100 150 220 Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 14 (c) Copyright 2000 Sipex Corporation All package dimensions in inches 0.0256 BSC 12.0 4 0.012 0.003 0.0965 0.003 0.008 0 - 6 0.006 0.006 0.006 0.006 R .003 0.118 0.004 0.16 0.003 12.0 4 0.01 0.020 0.020 1 0.0215 0.006 0.037 Ref 3.0 3 2 0.116 0.004 0.034 0.004 0.116 0.004 0.040 0.003 0.013 0.005 0.118 0.004 0.118 0.004 0.004 0.002 50 SOIC devices per tube P W 8-pin SOIC 13" reels: P = 8mm, W = 12mm Rev. 10-6-00 pkg min qty per reel std qty per reel max qty per reel EU 500 2500 3000 SP6642/6643 High Efficiency Step-Up DC-DC Converter 15 (c) Copyright 2000 Sipex Corporation ORDERING INFORMATION Model Temperature Range Package Type SP6642EU ............................................. -40OC to +85OC ......................................... 8-Pin SOIC SP6643EU ............................................. -40OC to +85OC ......................................... 8-Pin SOIC Please consult the factory for pricing and availability on a Tape-On-Reel option. 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 herein; neither does it convey any license under its patent rights nor the rights of others. Rev. 10-6-00 SP6642/6643 High Efficiency Step-Up DC-DC Converter 16 (c) Copyright 2000 Sipex Corporation