SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator FEATURES ■ Ultra-low 12μA Quiescent Current ■ 400mA Output Current at 2.6V Input: 3.3VOUT ■ 94% Efficiency from 2 Cell to 3.3VOUT ■ Wide Input Operating Voltage: 0.85V to 4.5V ■ 3.3V Fixed or Adjustable Output ■ Integrated Synchronous Rectifier: 0.3Ω ■ 0.3Ω Switch ■ Anti-Ringing Switch Technology ■ Programmable Inductor Peak Current ■ Logic Shutdown Control ■ Under Voltage Lock-Out at 0.61V ■ Programmable Low-Battery Detect ■ Single or Dual Cell Alkaline ■ Small 10 pin DFN Package and Industry Standard 10 pin MSOP VBATT 1 10 V OUT 9 LX LBI 2 SP6648 LBON 3 10 Pin DFN RLIM 4 8 P GND 7 GND SHDN 5 6 FB Now Available in Lead Free Packaging APPLICATIONS ■ Camera Flash LED Driver ■ Wireless Mouse ■ PDA's ■ Pagers ■ Medical Monitors ■ Handheld Portable Devices ■ MP3 Players DESCRIPTION The SP6648 is an ultra-low quiescent current, high efficiency step-up DC-DC converter ideal for single cell, dual cell alkaline and Li-Ion battery applications such as digital still cameras, PDAs, MP3 players, and other portable devices. The SP6648 combines the high-load efficiency associated with PWM control, with the low quiescent current and excellent light-load efficiency of PFM control. The SP6648 features 12μA quiescent current, synchronous rectification, a 0.3Ω charging switch, anti-ringing inductor switch, programmable low-battery detect, under-voltage lockout and programmable inductor peak current. The device can be controlled by a 1nA active LOW shutdown pin. TYPICAL APPLICATION CIRCUIT 500 10μH VBATT 450 400 + 350 1 LBI LBON 2 3 4 SHDN 1.87K SP6648 VBATT LBI LBON RLIM 5 SHDN VOUT 10 3.3VOUT + LX 9 PGND 8 47μF Io (mA) 47μF 300 250 200 1μF 205K GND 7 47pF 150 100 FB 6 Vout=3.3V, Ipk=0.85A 50 Vout=5.0V, Ipk=0.85A 0 124K 1.0 1.5 2.0 2.5 3.0 Vin (V) 3.5 4.0 4.5 Maximum Load Current in Operation Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 1 © 2006 Sipex Corporation ABSOLUTE MAXIMUM RATINGS Operating Temperature ................................................ -40°C to +85°C ESD Rating ........................................................................ 1.5kV HBM LX, Vo, VBATT , LBON, FB to GND pin ................................ -0.3 to 6.0V SHDN, LBI ........................................................... -0.3V to VBATT +1.0V Vo, GND, LX Current ....................................................................... 2A Reverse VBATT Current .............................................................. 220mA Forward VBATT Current .............................................................. 500mA Storage Temperature .................................................. -65 °C to 150°C 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. ELECTRICAL SPECIFICATIONS VBATT =VSHDN = 2.6V, VFB=0.0V, ILOAD = 0mA, TAMB = -40°C to +85°C, VOUT = +3.3V, typical values at 27°C unless otherwise noted. The ♦ denotes the specifications which apply over full operating temperature range -40°C to +85°C, unless otherwise specified. PARAMETER MIN Input Voltage Operating Range, VBATT 0.7 Output Voltage Range, VOUT 2.5 Start-up Input Voltage, VBATT TYP MAX UNITS ♦ CONDITIONS 4.5 V ♦ After Startup ♦ 5.5 V 0.85 1.1 V ♦ V ♦ Under Voltage Lock-out/UVLO 0.5 0.61 0.7 Output Voltage, VO 3.12 RLOAD = 3kΩ 3.30 3.48 V ♦ Quiescent Current into VO, IQO 12 25 μA ♦ VOUT = 3.3V, VFB = 1.5V, Toggle SHDN Quiescent Current into VBATT, IQB 250 750 nA ♦ VOUT = 3.3V, VFB = 1.5V VSHDN = 0.0V Shutdown Current into VO, ISDO 1 500 nA ♦ Shutdown Current into VBATT, ISDB 250 750 nA ♦ Efficiency 84 92 Inductor Current Limit, IPK = 1600/RLIM 650 1300 Output Current 800 1600 % % 1000 2000 mA mA Internal Feedback Divider VSHDN = 0.0V, VBATT = 2.6V VBATT = 1.3V, IOUT = 100mA, RLIM =2kΩ VBATT = 2.6V, IOUT = 200mA, RLIM =2kΩ ♦ ♦ RLIM = 2kΩ RLIM = 1kΩ 100 200 mA mA VBATT = 1.3V, RLIM = 4kΩ VBATT = 2.6V, RLIM = 4kΩ 150 400 mA mA VBATT = 1.3V, RLIM =2kΩ VBATT = 2.6V, RLIM =2kΩ Minimum Off-Time Constant KOFF 0.5 1.0 1.5 V*μs ♦ KOFF ≤ TOFF (VOUT- VBATT) Maximum On-Time Constant KON 2.5 4.0 5.5 V*μs ♦ KON ≥ TON (VBATT) Enable Valid to Output Stable 300 500 μs NMOS Switch Resistance 0.30 0.6 Ω ♦ INMOS = 100mA PMOS Switch Resistance 0.30 0.6 Ω ♦ IPMOS = 100mA 1.25 1.31 V ♦ External feedback 1 100 nA ♦ VFB =1.3V 0.61 0.66 V ♦ FB Set Voltage, VFB 1.19 FB Input Current LBI Falling Trip Voltage 0.56 LBI Hysteresis 25 Low Output Voltage for LBON, VOL Leakage current for LBON SHDN Input Voltage, Note 1 VIL VIH VIL VIH SHDN Input Current LX Pin Leakage mV 0.4 V ♦ VBATT = 1.3V, ISINK = 1mA 1 μA ♦ VBATT = 1.3V, VLBON = 3.3V ♦ ♦ ♦ ♦ VBATT = 1.3V VBATT = 1.3V VBATT = 2.6V VBATT = 2.6V 0.25 1.0 V 0.5 2.0 1 ILOAD = 1mA 100 nA 3 μA ♦ Note 1: SHDN must transition faster than 1V/100mS for proper operation. Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 2 © 2006 Sipex Corporation PIN DESCRIPTION PIN NUMBER PIN NAME 1 VBATT DESCRIPTION Battery Voltage. The startup circuitry is powered by this pin. Battery Voltage is used to calculate switch off time: tOFF = KOFF/ (VOUT - VBATT). When the battery voltage drops below 0.61V the SP6648 goes into an undervoltage lockout mode (UVLO), where the part is shut down. 2 LBI Low Battery Input. LBI below 0.61V causes the SP6648 pin to pull LBON pin down to ground. Use a resistor divider to program the low voltage threshold for a specific battery configuration. 3 LBON Low Battery Output Not. Open drain NMOS output that sinks current to ground when LBI is below 0.61V. 4 RLIM Current Limit Resistor. By connecting a resistor RLIM from this pin to ground the inductor peak current is set by IPEAK=1600/RLIM. The range for RLIM is 9kΩ (for 180mA) to 1.KΩ (for 1.6A). 5 SHDN Shutdown Not. Tie this pin high to VBATT, for normal operation. Pull this pin to ground to disable all circuitry inside the chip. In shutdown the output voltage will float down to a diode drop below the battery voltage. 6 FB Feedback. Connect this pin to GND for fixed +3.3V operation. Connect this pin to a resistor voltage divider between VOUT and GND for adjustable output operation. 7 GND 8 PGND 9 LX Inductor Switching Node. Connect one terminal of the inductor to the positive terminal of the battery. Connect the second terminal of the inductor to this pin. The inductor charging current flows into LX, through the internal charging N-channel FET, and out the PGND pin. 10 VOUT Output Voltage. The inductor current flows out of this pin during switch off-time. It is also used as the internal regulator voltage supply. Connect this pin to the positive terminal of the output capacitor. Date: 6/7/06 Rev B Ground. Connect to ground plane. Power Ground. The inductor charging current flows out of this pin. SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 3 © 2006 Sipex Corporation FUNCTIONAL DIAGRAM VBATT LX QKILL charge end IUC VO undercurrent comparator SHDN SDI 0.61V + c - TOFF + Min TOFF - c VBATT INTERNAL VBATT INTERNAL SUPPLY UVLO VOUT QKILL R switch buffer Q PMOS VO VBATT CHARGE VO NMOS Max Ton n Ref Block SDI IBIAS 1.25V REF + - + - c VOLOW S LX Qn current reference VO FB 0.61V c FB RLIM + - LOAD c overcurrent comparator SWITCH GROUND Ipkset LBI current control current reference PGND INTERNAL GROUND 0.61V + GND LBON c SP6648 THEORY OF OPERATION Detailed Description Control Scheme The SP6648 is a step-up DC-DC converter that can start up with input voltages as low as 0.85V (typically) and operates with an input voltage down to 0.61V. Ultra low quiescent current of 12μA provides excellent efficiency, up to 94%. In addition to the main switch, a 0.3Ω internal MOSFET the SP6648 has an internal synchronous rectifier, increasing efficiency and reducing the space requirements of an external diode. An internal inductive-damping switch significantly reduces inductive ringing for low-noise, high efficiency operation. If the supply voltage drops below 0.61V the SP6648 goes into under voltage lock-out mode, thus opening both internal switches. An externally programmable low battery detector with open drain output provides the ability to flag a battery-low condition. The inductor peak current is externally programmable to allow for a range of inductor values. A minimum off-time, current limited pulse frequency modulation (PFM) control scheme combines the high output power and efficiency of a pulse width modulation (PWM) device with the ultra low quiescent current of the traditional PFM. At low to moderate output loads, the PFM control provides higher efficiency than traditional PWM converters are capable of delivering. At these loads, the switching frequency is determined by a minimum off-time (tOFF, MIN) and a maximum on-time (tON, MAX) where: Date: 6/7/06 Rev B tOFF ≥ KOFF / (VOUT - VBATT) and tON ≤ KON / VBATT with KOFF = 1.0Vμs and KON = 4.0Vμs. SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 4 © 2006 Sipex Corporation THEORY OF OPERATION: Continued At light loads (as shown in plot A in Figure 1) the charge cycle will last the maximum value for tON: For a 1V battery this would be as follows: Inductor Current vs. Load llim Ton Max. tON = KON / VBATT = 4.0Vμs / 1V = 4.0μs E Toff Min. E. Iripple=Toff* (Vo - Vi)/L llim Ton Max. The current built up in the coil during the charge cycle gets fully discharged in the discontinuous conduction mode (DCM). When the current in the coil has reached zero, the synchronous rectifier switch is opened and the voltage across the coil (from VBATT to LX) is shorted internally to eliminate inductive ringing. D Toff Min. D. Toff*= (Vo - Vi)/L<Iripple<Ton*Vi/L llim Ton Max. Toff Min. C. Iripple=Ton*Vi/L C llim Ton Max. With increasing load (as shown in plot B in Figure 1) this inductor damping time becomes shorter, because the output will quickly drop below its regulation point due to heavier load. If the load current increases further, the SP6648 enters continuous conduction mode (CCM) where there is always current flowing in the inductor. The charge time remains at maximum tON as long as the inductor peak current limit is not reached as shown in plot C in Figure 1. The inductor peak current limit can be programmed by tying a resistor RLIM from the RLIM pin to ground where: Toff Min. B. Iripple=Ton*Vi/L B llim Ton Max. Toff Min. A. Iripple=Ton*Vi/L A Figure 1. Inductor Current vs. Load which ends the charge cycle and starts the discharge cycle. However, full load is not yet achieved because at the end of the minimum discharge time the output was still within regulation. Maximum load is reached when this discharge time has shrunk to the minimum allowed value TOFF as shown in Plot E of Figure 1. IPEAK = 1600 / RLIM When the peak current limit is reached the charge time is short-cycled. In plot D of Figure 1, the switch current reaches the peak current limit during the charge period Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 5 © 2006 Sipex Corporation TYPICAL PERFORMANCE CHARACTERISTICS Refer to the Typical Application Circuit on page 1, TAMB=+25°C. 100 100 95 95 90 90 Efficiency (%) Efficiency (%) 85 80 75 Vi=3.0V Vi=2.6V Vi=2.0V Vi=1.3V Vi=1.0V 70 65 85 80 75 Vi=4.2V Vi=3.2V Vi=2.6V Vi=2.0V Vi=1.6V Vi=1.0V 70 65 60 0.1 1.0 10.0 100.0 60 1000.0 0.1 1.0 Iload (mA) 3.400 3.340 Vi=4.2V Vi=3.2V Vi=2.6V Vi=2.0V Vi=1.6V Vi=1.0V 5.080 5.060 5.040 5.020 Vout (V) 3.320 VOUT (V) 1000.0 5.100 Vi=3.0V Vi=2.6V Vi=2.0V Vi=1.3V Vi=1.0V 3.360 100.0 Efficiency vs. Current Load, VOUT=5.0V Efficiency vs. Load Current, VOUT=3.3V 3.380 10.0 Iload (mA) 3.300 3.280 5.000 4.980 3.260 4.960 3.240 4.940 3.220 4.920 4.900 3.200 0 100 200 300 400 0 500 100 200 300 400 500 Iload (mA) ILOAD(mA) Line/Load Rejection vs. Load Current, VOUT = 3.3V Line/Load Rejection vs. Load Current, VOUT = 5.0V 100 300 250 80 200 Iin (uA) Iin (uA) 60 150 40 100 20 50 0 0 1.0 1.5 2.0 2.5 1.0 3.0 1.5 2.0 2.5 3.0 Vin (V) 3.5 4.0 4.5 Vin (V) No Load Battery Current, VOUT=3.3V Date: 6/7/06 Rev B No Load Battery Current, VOUT=5.0V SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 6 © 2006 Sipex Corporation TYPICAL PERFORMANCE CHARACTERISTICS Refer to the Typical Application Circuit on page 1, TAMB=+25°C. 400 500 450 350 400 300 350 300 Io (mA) Io (mA) 250 200 250 200 150 150 100 100 50 50 0 0 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0 Vin (V) Vin (V) Maximum Resistive Load Current in Startup, VOUT=3.3V 3.5 4.0 4.5 Maximum Resistive Load Current in Startup, VOUT=5.0V VOUT (AC) VOUT (AC) Inductor Current (0.2A/DIV) Inductor Current (0.2A/DIV) Output Ripple, VIN=2.6V, ILOAD=200mA, VOUT=5.0V 5.0 5.0 4.0 4.0 Kon (V*usec) Kon (V*usec) Output Ripple, VIN=2.6V, ILOAD=200mA, VOUT=3.3V 3.0 2.0 1.0 0.0 0.9 3.0 2.0 1.0 1.2 1.5 1.8 2.1 2.4 Vin (V) 2.7 3.0 0.0 0.9 3.3 KON vs. VIN , VOUT=3.3V Date: 6/7/06 Rev B 1.4 1.9 2.4 2.9 3.4 Vin (V) 3.9 4.4 4.9 KON vs. VIN , VOUT=5.0V SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 7 © 2006 Sipex Corporation TYPICAL PERFORMANCE CHARACTERISTICS 2.0 2.0 1.5 1.5 Koff (V*usec) Koff (V*usec) Refer to the Typical Application Circuit on page 1, TAMB=+25°C. 1.0 0.5 0.5 0.0 0.9 1.0 1.2 1.5 1.8 2.1 2.4 Vin (V) 2.7 3.0 0.0 0.9 3.3 1.4 1.9 2.4 2.9 3.4 Vin (V) 3.9 4.4 4.9 KOFF vs. VIN , VOUT=5.0V KOFF vs. VIN , VOUT=3.3V VIN VIN VOUT VOUT IIN (1A/div) IIN(1A/div) Startup, VIN=2.6V, VOUT=3.3V, RLOAD = 100Ω Startup, VIN=4.2V, VOUT=5.0V, RLOAD = 100Ω VOUT (AC) VOUT(AC) LX LX IOUT(0.2A/div) IOUT (0.5A/DIV) Load Step, 0.1A to 0.3A, VIN = 2.6V, VOUT = 3.3V Date: 6/7/06 Rev B Load Step, 0.3A to 0.5A, VIN = 4.2V, VOUT = 5.0V SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 8 © 2006 Sipex Corporation APPLICATIONS INFORMATION Circuit Layout ripple for the SP6648 to regulate the output. Designers should select input and output capacitors with a rating exceeding the inductor current ripple, which is typically set by the inductor value and the KON value as given in the following relationship: Printed circuit board layout is a critical part of a power supply design. Poor designs can result in excessive EMI on the feedback paths and 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 SP6648 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 SP6648 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 from sensitive RF and analog input stages. Noisy traces, such as from the LX pin, should be kept away from the voltage-feedback VOUT node and separated from it using grounded copper to minimize EMI. See the SP6648EB Evaluation Board Manual for PC Board Layout design details. IL(RIPPLE) = KON/L For the example of the 10μH inductor the inductor current ripple would be 330mA, while for the 22μH inductor the inductor current ripple value would be 150mA. Do not allow tantalum capacitors to exceed their ripple-current ratings. An input filter capacitor can reduce peak currents drawn from the battery and improve efficiency. For most applications, use the same 47μF tantalum capacitor as used for the input. Low-ESR aluminum electrolytic capacitors are acceptable, provided they meet the ESR requirement of 0.2Ω to 0.3Ω, and we list an appropriate 100μF aluminum electrolytic in the component selection table, but standard aluminum electrolytic capacitors are not recommended. In selecting an inductor, the saturation current specified for the inductor needs to be greater than the SP6648 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 Sumida CDRH5D28 10μH inductor with an ISAT value of 1.3A and a DCR of 0.065Ω, which easily handles the IPEAK of 0.85A of the SP6648 and will deliver high efficiencies. Other inductors could be selected provided their ISAT is greater than the IPEAK of the SP6648. Component Selection Selection of capacitors for SP6648 power supply circuits can be made through the use of the Component Selection Table. Capacitor equivalent series resistance (ESR) in the range of 0.2Ω to 0.3Ω is a requirement for obtaining sufficient output voltage ripple for the SP6648 to properly regulate under load. For ESR values in this range, low ESR tantalum capacitors are recommended. For example, in the SP6648 application circuit a 47μF, 10V, low-ESR, surfacemount tantalum output filter capacitor typically provides 50mV output ripple when stepping up from 2.6V to 3.3V at 200mA. Ceramic capacitors have ESR too low to produce enough output Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 9 © 2006 Sipex Corporation APPLICATIONS INFORMATION: Continued INDUCTORS - SURFACE MOUNT Inductor Specification Inductance (μH) Manufacturer/Part No. Series R Ω ISAT (A) Size LxWxH (mm) Intuctor Type Manufacturer Website 10 Sumida CDRH5D28-100 0.065 1.30 5.7x5.5x3.0 Shielded Ferrite Core 10 TDK RLF5018T-100MR94 0.067 0.94 5.6x5.2x2.0 Shielded Ferrite Core www.sumida.com 10 Sumida CD43-100 0.180 1.04 4.0x4.5x3.5 Unshileded Ferrite Core www.sumida.com 22 Sumida CDRH5D28-220 0.122 0.90 5.7x5.5x3 Shileded Ferrite Core www.sumida.com 22 TDK RLF5018T-220MR63 0.067 0.63 5.6x5.2x2.0 Shielded Ferrite Core 22 Sumida CD43-220 0.378 0.68 4.0x4.5x3.5 Unshielded Ferrite Core www.tdk.com www.tdk.com www.sumida.com CAPACITORS - SURFACE MOUNT & LEADED Capacitor Specification Capacitance Manufacturer Part No. (μF) ESR Ω(max) Ripple Current (A) @ 85°C Size LxWxH (mm) Voltage (V) Capacitor Type Manufacturer Website 47 Kemet T494C476K010AS 0.300 1.06 6.0x3.2x2.5 10 SMT Tantalum www.kemet.com 47 Kemet T494V476K010AS 0.300 0.99 7.3x4.3x2.0 10 SMT Tantalum www.kemet.com 100 Sanyo 25MV100AX 0.220 0.30 6.3DX11L 25 Radial Al Electrolytic www.sanyovideo.com Note: Components highlighted in bold are those used on the SP6648EB Evaluation Board. Component Selection Table VBATT L1 10µH R3 549K C1 + R5 1.0M 47µF U1 SP6648 1 R4 LBON 249K 2 3 4 5 VBATT VOUT LBI LX LBON RLIM PGND GND SHDN FB 3.3VOUT 10 9 8 7 C4 1µF R1 205K C3 + C2 47pF 47µF 6 R2 RLIM 1.87K 124K SP6648EB Evaluation Board Schematic Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 10 © 2006 Sipex Corporation APPLICATIONS INFORMATION : Continued VOUT Programming resistor R5 to VOUT. When the LBI comparator falling threshold of 0.61V is reached, the LBON output goes low as determined by the relationship: The SP6648 can be programmed as either a voltage source or a current source. To program the SP6648 as a voltage source, the SP6648 requires 2 feedback resistors R1 & R2, as shown in the SP6648EB evaluation board schematic, to control the output voltage. To set VOUT in the voltage mode, use the equation: VLOWBATT = 0.61 * [(R3 + R4)/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. R1 = [(VOUT/1.25)-1] * R2 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: UVLO the Under Voltage Lock-Out Function Once started up, the SP6648 will regulate the output until the input battery is completely discharged or until the under voltage lock-out (UVLO) occurs at VBATT = 0.61V. The UVLO function will completely open all switches until the battery again rises above the 0.61V threshold. IPEAK = 1600/RLIM The saturation current specified for the inductor needs to be greater than 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 = 850mA 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. Maximum Startup Current It should be noted that for low input voltages the SP6648 startup circuit cannot support large load currents at startup. In startup the SP6648 needs to boost the output from zero volts using the input voltage. Once the output is greater than 1.9V, the operating circuit takes over and the SP6648 can supply much more current. Curves of maximum load current in startup for the SP6648 are shown in the typical performance characteristics and can be compared with the page one curve for maximum load current in operation. Using the LBON - Low Battery Output Function The SP6648 will regulate the output until the input battery is completely discharged or until the under voltage lock-out (UVLO) occurs at VBATT = 0.61V. To provide a low battery warning, the Low Battery Output function of the SP6648 can be used. 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 1MΩ Date: 6/7/06 Rev B For 1-cell battery applications, it is recommended to apply any large load current after the SP6648 has started up, typically in a few milliseconds. This is typically not a problem in many applications where the load is a processor whose load current is low until the processor voltage comes up. SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 11 © 2006 Sipex Corporation APPLICATIONS INFORMATION where VREF is around 0.61V, IF is the operating current of the LumiLED. To set the operating current to be about 350mA, Rb is selected as 1.8 Ω as shown in the following schematic. The efficiency of the SP6648 LumiLED circuit is improved by the use of a silicon diode D1 and resistor R1 to set the voltage at the current sense resistor R2 to 0.61V instead of the higher 1.25V at the FB pin. An efficiency curve follows showing the SP6648 efficiency driving 350mA output current into the high brightness LumiLED. SP6648LEDEB Evaluation Board with LumiLED High Brightness White LED For the high brightness LumiLED white LED application, the SP6648 is generally programmed as a current source. The bias resistor Rb is used to set the operating current of the white LED in the equation: Rb = VREF/IF VBATT L1 10µH 1.8-3.2V C1 10µF 1 2 3 4 5 VBATT LBI VOUT SP6648 LX LBON PGND RLIM GND SHDN FB Important: 1µF Ceramic Cap at VOUT Pin needed for stable regulation 10 C4 1µF 9 8 C2 10µF R1 16.2k D2 1W LED 350mA 7 6 R5 10K RLIM 1.87K D1 1N4148 (R5 optional) VREF = 0.61V Rb 1.8Ω IOUT=0.61V/Rb SP6648LEDEB Evaluation Board Schematic 100 As shown in following scope photos, if the SP6648 is powered up before the LumiLED is plugged in, the circuit will bring the Feedback pin to 0.0V and the SP6648 has a feature to set the output voltage to be 3.3V. Once the LumiLED is plugged in, the Feedback pin will go up to 1.25V and begin to regulate. The output voltage will go from 3.3V to 3.68V (=VF+0.61V), where VF is the forward voltage of the LumiLED. When the LumiLED is open, the Feedback pin voltage will go to 0.0V and the output voltage will go to 3.3V which will protect the part. 95 Efficiency (%) 90 85 80 75 70 65 60 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 Battery Voltage (V) SP6648LEDEB Efficiency Curve Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 12 © 2006 Sipex Corporation APPLICATIONS INFORMATION VOUT VOUT VREF VREF Plug in the LumiLED Unplug the LumiLED Brightness Control One approach to control LED brightness is to apply a PWM signal to the SHDN input of the SP6648. In this case, the output current will be equal to the product of 350mA and the average duty cycle at the SHDN pin. An optional 10KΩ potentiometer (R5) may also be used for dimming the LED current by varying the potentiometer between low brightness and full brightness. PINOUTS VBATT 1 LBI 2 SP6648 LBON 3 10 Pin DFN 10 V OUT 9 LX VBATT 1 LBON 3 SHDN 5 RLIM 4 8 P GND 7 GND SHDN 5 6 FB Date: 6/7/06 Rev B LBI 2 RLIM 4 10 VOUT 10 Pin MSOP SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 13 9 LX SP6648 8 PGNDV 7 GND 6 FB © 2006 Sipex Corporation PACKAGE: 10 PIN MSOP FRONT VIEW TOP VIEW D D/2 ø1 R1 Gauge Plane e1 R L2 10 8 9 7 6 ø E/2 E L Seating Plane c ø1 E1 2 1 (L1) 1 2 e 3 4 Seating Plane 5 A1 10 Pin MSOP SYMBOL A1 c R R1 ø ø1 A A2 b D E E1 e e1 L L1 L2 JEDEC MO-187 Dimensions in Millimeters: Controlling Dimension MIN 0.00 0.08 0.07 0.07 0º 5º 0.75 0.17 NOM 0.85 3.00 BSC 4.90 BSC 3.00 BSC 0.50 BSC 2.00 BSC 0.40 0.60 0.95 REF 0.25 BSC SIDE VIEW b Variation BA Dimensions in Inches Conversion Factor: 1 Inch = 25.40 mm MAX 0.15 0.23 8º 15º 1.10 0.95 0.33 MIN 0.000 0.004 0.003 0.003 0º 5º 0.030 0.007 0.80 0.016 SIPEX Pkg Signoff Date/Rev: Date: 6/7/06 Rev B A2 A Pin #1 designator to be within this INDEX AREA (D/2 * E1/2) NOM 0.034 0.118 BSC 0.193 BSC 0.118 BSC 0.020 BSC 0.079 BSC 0.024 0.037 REF 0.010 BSC MAX 0.006 0.009 8º 15º 0.043 0.038 0.013 0.032 JL Aug09-05 RevA SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 14 © 2006 Sipex Corporation PACKAGE: 10 PIN DFN D D/2 ø E/2 A (A3) E A1 Seating Plane SIDE VIEW Pin1 Designator to be within this INDEX AREA (D/2 x E/2) TOP VIEW D2 D2/2 1 2 3 4 5 INDEX AREA (D/2 x E/2) E2/2 E2 K L 10 9 8 7 e 6 b BOTTOM VIEW 3x3 10 Pin DFN SYMBOL JEDEC MO-229 Dimensions in Millimeters: Controlling Dimension NOM 0.90 0.02 0.20 REF 0.20 0º b 0.18 0.25 D 3.00 BSC D2 2.20 E 3.00 BSC E2 1.40 e 0.50 BSC L 0.30 0.40 SIPEX Pkg Signoff Date/Rev: A A1 A3 K ø Date: 6/7/06 Rev B MIN 0.80 0.00 MAX 1.00 0.05 14º 0.30 2.70 1.75 0.50 VARIATION VEED-5 Dimensions in Inches Conversion Factor: 1 Inch = 25.40 mm MIN NOM MAX 0.032 0.036 0.039 0.000 0.001 0.002 0.008 REF 0.008 0º 14º 0.008 0.010 0.012 0.119 BSC 0.087 0.106 0.119 BSC 0.056 0.069 0.020 BSC 0.012 0.016 0.020 JL Aug09-05 / RevA SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 15 © 2006 Sipex Corporation ORDERING INFORMATION Part Number Top Mark Operating Temperature Range Package Type SP6648EU ................................ SP6648EU..................-40°C to +85°C ...................................... 10 Pin MSOP SP6648EU/TR .......................... SP6648EU..................-40°C to +85°C ..................................... 10 Pin MSOP SP6648ER ............................... SP6648ERYWW..........-40°C to +85°C ........................................ 10 Pin DFN SP6648ER/TR ......................... SP6648ERYWW..........-40°C to +85°C ....................................... 10 Pin DFN Available in lead free packaging. To order add "-L" suffix to part number. Example: SP6648EU/TR = standard; SP6648EU-L/TR = lead free /TR = Tape and Reel Pack quantity is 2,500 for MSOP and 3,000 for DFN. Sipex Corporation Headquarters and 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. Date: 6/7/06 Rev B SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator 16 © 2006 Sipex Corporation