SS6642-27GXTB

SS6642G 3-Pin Simple Step-Up DC/DC Converter FEATURES A guaranteed start-up from less than 0.9 V. High efficiency. Low quiescent current. Fewer external components needed. Low ripple and low noise. Fixed output voltage: 2.7V, 3.0V, 3.3V, 3.7V, 4.5V and 5V. Space-saving packages: SOT-23, SOT-89 and TO-92. DESCRIPTION The SS6642G is a high efficiency step-up DC/DC converter for applications using 1 to 4 NiMH battery cells. Only three external components are required to deliver a fixed output voltage of 2.7V, 3.0V, 3.3V, 3.7V, 4.5V or 5V. The SS6642G starts up from less than 0.9V input with 1mA load. A Pulse Frequency Modulation scheme optimizes performance for applications with light output loading and low input voltages. The output ripple and noise are lower when compared with circuits operating in PSM mode. Pb-free, RoHS compliant. APPLICATIONS Pagers. Cameras. Wireless Microphones. Pocket Organizers. Battery Backup Suppliers. Portable Instruments. The PFM control circuit operating at a 100KHz (max.) switching rate results in smaller passive components. The space saving SOT-23, SOT89 and TO-92 packages make the SS6642G an ideal choice for DC/DC converter for space conscious applications, such as pagers, electronic cameras, and wireless microphones. TYPICAL APPLICATION CIRCUIT VIN L1 100µH D1 SS12 VOUT SS6642-xxG + C1 SW 22µF GND + VOUT C2 47µF One Cell Step-Up DC/DC Converter 1/15/2005 Rev.2.10 www.SiliconStandard.com 1 of 22 SS6642G ORDERING INFORMATION S S6 642-XX XXXX P acking type T R: T ape and reel T B: T ube P ackage type G U: R oHS-compliant S OT-23 G X: R oHS-compliant S OT-89 G Z: R oHS-compliant T O-92 PIN CONFIGURATION S OT-89 TOP VIEW 1: GND 2: VOUT 3: SW 1 2 3 O utput voltage 2 7: 2.7V 30: 3.0V 33: 3.3V 37: 3.7V 45: 4.5V 50: 5.0V T O-92 TOP VIEW 1: GND 2: VOUT 3: SW 1 2 3 SOT-23 TOP VIEW 1: GND 2: SW 3: VOUT 1 3 2 E xample: SS66 42-27 G XTR 2 .7V o utput v ersion, in R oHS-compliant S OT-89 s hipped on tape and reel. SOT-23 MARKING Part No. SS6642-27G SS6642-30G SS6642-33G SS6642-37G SS6642-45G SS6642-50G GU GM27P GM30P GM33P GM37P GM45P GM50P SOT-89 MARKING Part No. SS6642-27G SS6642-30G SS6642-33G SS6642-37G SS6642-45G SS6642-50G GX AM27P AM30P AM33P AM37P AM45P AM50P 1/15/2005 Rev.2.10 www.SiliconStandard.com 2 of 22 SS6642G ABSOLUTE MAXIMUM RATINGS Supply Voltage (VOUT pin) SW pin Voltage SW pin Switch Current Operating Temperature Range Maximum Junction Temperature Storage Temperature Range Lead Temperature (Soldering 10 Sec.) .6V 6V 0.6A -40°C to 85°C 125°C -65°C to 150°C 260°C Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. TEST CIRCUIT VIN IIN L1 100µH D1 SS12 VOUT IS SS6642 VOUT GND SW VSW SS6642-xxG + C2 22µF SW GND VOUT + C1 47µF VS Fig. 1 Test Circuit 1 Fig. 2 Test Circuit 2 SS6642 VS VOUT GND SW 100W FOSC Fig. 3 Test Circuit 3 1/15/2005 Rev.2.10 www.SiliconStandard.com 3 of 22 SS6642G ELECTRICAL CHARACTERISTICS (Note1) PARAMETER TEST CONDITIONS SS6642-27G SS6642-30G SS6642-33G Output Voltage SS6642-37G SS6642-45G SS6642-50G Start-Up Voltage Min. Hold-on Voltage No-Load Input Current VIN=1.8V VIN=1.8V VIN=2.0V V IN=2.0V VIN=3.0V VIN=3.0V 1 1 1 VSTART VHOLD IIN 15 42 50 60 65 2 IS1 70 90 µA 1 VOUT TEST CKT SYMBOL (TA=25°C, IOUT=10mA, unless otherwise specified) MIN. 2.633 2.925 3.218 3.607 4.387 4.875 TYP. 2.700 3.000 3.300 3.700 4.500 5.000 0.8 MAX. 2.767 3.075 3.382 3.792 4.613 5.125 0.9 0.7 UNIT V IOUT=1mA, VIN:0→2V IOUT=1mA, VIN:2→0V IOUT=0mA SS6642-27G SS6642-30G SS6642-33G SS6642-37G SS6642-45G SS6642-50G VS=VOUT x 0.95 Measurement of the IC input current (VOUT pin) SS6642-27G SS6642-30G SS6642-33G SS6642-37G V V µA Supply Current 7 7 7 7 2 IS2 7 7 µA Supply Current SS6642-45G SS6642-50G VS=VOUT + 0.5V Measurement of the IC input current (VOUT pin) SW Leakage Current VSW=6V, VS=VOUT + 0.5V 2 0.5 µA 1/15/2005 Rev.2.10 www.SiliconStandard.com 4 of 22 SS6642G ELECTRICAL CHARACTERISTICS PARAMETER TEST CONDITIONS SS6642-27G SS6642-30G SS6642-33G SW Switch-On Resistance SS6642-37G SS6642-45G SS6642-50G VS=VOUT x 0.95, VSW=0.4V VS=VOUT x 0.95 Oscillator Duty Cycle Measurement of the SW pin waveform VS=VOUT x 0.95 Max. Oscillator Freq. Efficiency Measurement of the SW pin waveform 3 1 FOSC η 80 105 85 130 KHz % 3 DUTY 65 75 85 % 2 RON (Continued) TEST CKT SYMBOL MIN. TYP. 2.2 2.1 2.0 2.0 1.9 1.9 MAX. UNIT Ω Note 1: Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating temperature range are assured by design, characterization and correlation with Statistical Quality Controls (SQC). TYPICAL PERFORMANCE CHARACTERISTICS Test circuit refer to typical application circuit Capacitor (C2) : 47 µ F (Tantalum Type) Diode (D1) : 1N5819 Schottky Type 2.8 85 80 2.7 O utput Voltage (V) VIN =1.5V V IN =1.2V 2.5 E fficiency (%) 2.6 VIN =1.8V VIN =2.0V 75 70 VIN =1.8V VIN =2.0V 2.4 65 V IN =0.9V 2.3 60 VIN =1.5V VIN =0.9V 2.2 0 55 VIN =1.2V 40 60 80 100 120 140 160 180 20 40 60 80 100 120 140 160 180 0 20 O utput Current (mA) Fig. 4 SS6642-27 Load Regulation (L=100µH CD54) Output current (mA) Fig. 5 SS6642-27 Efficiency (L=100µH CD54) 1/15/2005 Rev.2.10 www.SiliconStandard.com 5 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS (Continued) 2.8 85 80 2.7 75 Output Voltage (V) 2.6 Efficiency (%) VIN=1.2V 2.5 VIN=1.5V VIN=1.8V VIN=2.0V 70 VIN=2.0V 65 60 VIN=1.8V 2.4 VIN=1.2V 55 VIN=1.5V VIN=0.9V VIN=0.9V 2.3 0 20 40 60 80 100 120 140 160 180 200 220 240 50 0 20 40 60 80 100 120 140 160 180 200 220 240 Output Current (mA) Fig. 6 SS6642-27 Load Regulation (L=47µH CD54) Fig. 7 Output current (mA) SS6642-27 Efficiency (L=47µH CD54) 1.0 0.9 0.8 1.0 0.9 Start up 0.8 Start up Input Voltage (V) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 8 10 12 14 16 18 Input Voltage (V) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 8 10 12 14 16 18 Hold on Hold on Fig. 8 Output Current (mA) SS6642-27 Start-Up & Hold-ON Voltage (L=47µH CD54) Fig. 9 SS6642-27 Start-Up & Hold-ON Voltage (L=100µH CD54) Output Current (mA) 2.80 2.78 160 Switching Frequency (kHz) 2.76 140 Output Voltage (V) 2.74 2.72 2.70 2.68 2.66 2.64 2.62 120 100 80 60 2.60 -40 -20 0 20 40 60 80 100 40 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 10 SS6642-27 Output Voltage vs. Temperature Temperature (°C) Fig. 11 SS6642-27 Switching Frequency vs. Temperature 1/15/2005 Rev.2.10 www.SiliconStandard.com 6 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 80 (Continued) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Maximum Duty Cycle (%) 78 76 74 72 70 -40 SW Turn ON Resistance (Ω) 0.0 -20 0 20 40 60 80 100 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 12 SS6642-27 Maximum Duty Cycle vs. Temperature Temperature (°C) Fig. 13 SS6642-27 SW Turn ON Resistance vs. Temperature 45 40 35 30 25 20 15 10 3.1 3.0 2.9 VIN=2.0V VIN=1.8V Output voltage VOUT(V) Supply Current (µA) 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 VIN=1.5V VIN=1.2V VIN=0.9V 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 5 -40 -20 0 20 40 60 80 100 2.0 Temperature (°C) Fig. 14 SS6642-27 Supply Current vs. Temperature Output Current (mA) Fig. 15 SS6642-30 Load Regulation (L=100µH, CD54) 85 80 75 3.1 3.0 2.9 Output Voltage (V) Efficiency (%) 2.8 2.7 2.6 2.5 2.4 VIN=1.2V VIN=1.5V VIN=1.8V VIN=2.0V 70 65 60 55 50 0 20 40 60 80 100 120 140 160 180 VIN=1.8V VIN=1.5V VIN=0.9V VIN=1.2V VIN=2.0 2.3 2.2 0 VIN=0.9V 20 40 60 80 100 120 140 160 180 200 220 Output Current (mA) Output Current (mA) Fig. 16 SS6642-30 Efficiency (L=100µH, CD54) Fig. 17 SS6642-30 Load Regulation (L=47µH CD54) 1/15/2005 Rev.2.10 www.SiliconStandard.com 7 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 85 80 75 (Continued) 1.0 0.9 0.8 Start up Input Voltage (V) Efficiency (%) 0.7 0.6 0.5 0.4 0.3 0.2 70 65 Hold on VIN=2.0V 60 55 VIN=1.8V VIN=1.5V VIN=0.9V VIN=1.2V 50 75 100 125 150 175 200 225 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20 50 0 25 Output Current (mA) Fig. 18 SS6642-30 Efficiency (L=47µH CD54) Fig. 19 Output Current (mA) SS6642-30 Start-up & Hold-on Voltage (L=100µH CD54) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20 3.10 Start up 3.08 3.06 Output Voltage (V) Input Voltage (V) 3.04 3.02 3.00 2.98 2.96 2.94 2.92 2.90 -40 -20 0 20 No Load Hold on 40 60 80 100 Output Current (mA) Fig. 20 SS6642-30 Start-up & Hold-on Voltage (L=47µH CD54) Temperature (°C) Fig. 21 SS6642-30 Output Voltage vs. Temperature 80 160 Switching Frequency (kHz) 140 120 Maximum Duty Cycle (%) -20 78 76 100 74 80 72 60 40 -40 0 20 40 60 80 100 70 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 22 SS6642-30 Switching Frequency vs. Temperature Temperature (°C) Fig. 23 SS6642-30 Maximum Duty Cycle vs. Temperature 1/15/2005 Rev.2.10 www.SiliconStandard.com 8 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 45 40 35 30 25 20 15 10 5 -40 (Continued) 1.8 1.6 SW Turn ON Resistance (Ω) 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -40 -20 0 20 40 60 80 100 Supply Current (µA) 1.4 -20 0 20 40 60 80 100 Fig. 24 Temperature (°C) SS6642-30 SW Turn ON Resistance vs. Temperature Temperature (°C) Fig. 25 SS6642-30 Supply Current vs. Temperature 3.4 3.3 3.2 90 VIN=2.0V 85 80 Output Voltage (V) 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 0 25 Efficiency (%) VIN=1.5V VIN=1.8V VIN=2.0V 75 70 65 60 VIN=1.2V VIN=1.8V VIN=1.2V VIN=0.9V 0 25 50 75 100 VIN=1.5V VIN=0.9V 50 75 100 125 150 175 200 55 50 125 150 175 200 Output Current (mA) Fig. 26 SS6642-33 Load Regulation (L=100µH, CD54) Fig. 27 Output Current (mA) SS6642-33 Efficiency (L=100µH, CD54) 3.4 3.3 3.2 90 85 80 Output Voltage (V) Efficiency (%) 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 0 25 VIN=1.5V VIN=1.8V VIN=2.0V 75 70 65 60 55 VIN=2.0V VIN=1.2V VIN=0.9V 50 75 100 125 150 175 200 225 VIN=1.5V VIN=0.9V VIN=1.2V VIN=1.8V 50 45 40 0 25 50 75 100 125 150 175 200 225 250 Output Current (mA) Fig. 28 SS6642-33 Load Regulation (L=47µH, CD54) Output Current (mA) Fig. 29 SS6642-33 Efficiency (L=47µH,CD54) 1/15/2005 Rev.2.10 www.SiliconStandard.com 9 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 1.1 1.0 3.50 3.45 (Continued) 0.8 Output Voltage Vout (V) 0.9 Start up 3.40 3.35 3.30 3.25 3.20 3.15 3.10 3.05 Input Voltage (V) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20 No Load Hold on 3.00 -40 -20 0 Output Current (mA) Fig. 30 SS6642-33 Start-up & Hold-on Voltage (L=100µH CD54) Temperature (°C) 20 40 60 80 100 Fig. 31 SS6642-33 Output Voltage vs. Temperature 80 160 Switching Frequency (kHz) 140 120 Maximum Duty Cycle (%) -20 78 76 100 74 80 60 72 40 -40 0 20 40 60 80 100 70 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 32 SS6642-33 Switching Frequency vs. Temperature Fig. 33 Temperature (°C) SS6642-33 Maximum Duty Cycle vs. Temperature 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -40 -20 0 20 40 60 80 100 45 40 SW Turn ON Resistance (Ω) Supply Current IDD1 (µA) 35 30 25 20 15 10 -40 -20 0 20 40 60 80 100 Fig. 34 Temperature (°C) SS6642-33 SW Turn ON Resistance vs. Temperature Temperature (°C) Fig. 35 SS6642-33 Supply Current vs. Temperature 1/15/2005 Rev.2.10 www.SiliconStandard.com 10 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 0 (Continued) 90 85 80 Output Voltage (V) VIN=1.2V VIN=1.8V VIN=2.5V 75 Efficiency (%) VIN =2.0V 70 65 60 55 50 VIN =2.5V VIN=1.2V VIN=1.8V VIN=0.9V VIN=2.0V VIN =0.9V 25 50 75 100 125 150 175 200 225 250 275 45 40 0 25 50 75 100 125 150 175 200 225 250 Output Current (mA) Fig. 36 SS6642-37 Load Regulation (L=100µH) Output Current (mA) Fig. 37 SS6642-37 Efficiency (100µH) 3.8 3.7 3.6 3.5 3.4 90 85 80 Output Voltage (V) 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 0 25 VIN=1.8V Efficiency (%) 3.3 VIN=2.5V VIN=2.0V 75 70 65 60 55 50 VIN=2.5V VIN=1.8V VIN=0.9V VIN=1.2V VIN=2.0V VIN=1.2V VIN=0.9V 50 75 100 125 150 175 200 225 250 275 45 40 0 25 50 75 100 125 150 175 200 225 250 275 Output Current (mA) Fig. 38 SS6642-37 Load Regulation (L=47µH) Output Current (mA) Fig. 39 SS6642-37 Efficiency (47µH) 1.6 1.4 1.2 4.00 3.95 3.90 3.85 Input Voltage (V) Start up 1.0 0.8 0.6 0.4 0.2 0.0 Output Voltage (V) 3.80 3.75 3.70 3.65 3.60 3.55 3.50 3.45 No Load Hold on 0 5 10 15 20 3.40 -40 -20 0 20 40 60 80 100 Output Current (mA) Fig. 40 SS6642-37 Start-up & Hold-on Voltage (L=100µH) Temperature (°C) Fig. 41 SS6642-37 Output Voltage vs. Temperature 1/15/2005 Rev.2.10 www.SiliconStandard.com 11 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 80 160 (Continued) Switching Frequency (KHz) 140 120 100 80 60 40 -40 Maximum Duty Cycle (%) -20 0 20 40 60 80 100 78 76 74 72 70 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 42 SS6642-37 Switching Frequency vs. Temperature Temperature (°C) Fig. 43 SS6642-37 Maximum Duty Cycle vs Temperature 4.6 4.4 4.2 90 85 80 Output Voltage (V) 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 0 50 100 150 200 250 300 VIN=1.5V VIN=2.0V Efficiency (%) VIN=3.0V 75 70 VIN=3.0V VIN=0.9V VIN=1.2V 65 60 55 50 VIN=0.9V VIN=1.2V VIN=2.0V VIN=1.5V 350 400 0 50 100 150 200 250 300 350 400 Output Current (mA) Fig. 44 SS6642-45 Load Regulation (L=100µH) Output Current (mA) Fig. 45 SS6642-45 Efficiency (L=100µH) 4.6 4.4 4.2 1.6 1.4 1.2 Output Voltage (V) 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 0 50 Input Voltage (V) 4.0 VIN=3.0V VIN=1.5V VIN=2.0V Start up 1.0 0.8 0.6 0.4 0.2 0.0 Hold on VIN=0.9V VIN=1.2V 100 150 200 250 300 350 400 0 5 10 15 20 Output Current (mA) Fig. 46 SS6642-45 Load Regulation (L=100µH) Output Current (mA) Fig. 47 SS6642-45 Start-up & Hold-On Voltage (L=100µH) 1/15/2005 Rev.2.10 www.SiliconStandard.com 12 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 5.0 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 (Continued) 90 80 Supply Current (µA) 40 60 80 100 Output Voltage (V) 70 60 50 40 30 20 10 No Load -40 -20 0 20 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 48 SS6642-45 Output Voltage vs. Temperature Temperature (°C) Fig. 49 SS6642-45 Supply Current vs. Temperature 80 160 Switching Frequency (kHz) 140 120 Maximum Duty Cycle (%) 78 76 100 74 80 60 72 40 -40 -20 0 20 40 60 80 100 70 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 50 SS6642-45 Switching Frequency vs. Temperature Temperature (°C) Fig. 51 SS6642-45 Maximum Duty Cycle vs. Temperature 1.8 1.6 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 -40 -20 0 20 40 60 80 100 0 50 100 150 200 250 300 350 400 SW Turn ON Resistance (Ω) Output Voltage (V) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 VIN=2.0V VIN=3.0V VIN=1.5V VIN=1.2V VIN=0.9V Temperature (°C) Fig. 52 SS6642-45 SW Turn ON Resistance vs. Temperature Output Current (mA) Fig. 53 SS6642-50 Load Regulation ( L=100µH CD54) 1/15/2005 Rev.2.10 www.SiliconStandard.com 13 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 100 90 5.5 5.0 (Continued) Output Voltage (V) 80 4.5 4.0 3.5 3.0 2.5 2.0 1.5 0 Efficiency (%) 70 60 50 40 30 20 VIN=2.0V VIN=3.0V VIN=2.0V VIN=0.9V VIN=1.5V VIN=1.2V VIN=3.0V VIN=1.5V VIN=1.2V VIN=0.9V 0 50 100 150 200 250 300 350 400 50 100 150 200 250 300 350 400 Fig. 54 Output Current (mA) SS6642-50 Efficiency (L=100µH CD54) Output Current (mA) Fig. 55 SS6642-50 Load Regulation (L=47µH CD54) 90 85 80 1.4 1.8 1.6 Input Voltage (V) Efficiency (%) 75 70 65 60 55 50 45 0 1.2 1.0 0.8 0.6 0.4 0.2 VIN=3.0V VIN=2.0V VIN=0.9V VIN=1.5V VIN=1.2V 100 150 200 250 300 350 400 Start up Hold on 50 0.0 0 2 4 6 8 10 12 14 16 18 20 Output Current (mA) Fig. 56 SS6642-50 Efficiency (L=47µH CD54) Output Current (mA) Fig. 57 SS6642-50 Start-up & Hold-on Voltage (L=100µH CD50) 5.3 5.2 160 Output Voltage VOUT (V) 5.1 5.0 4.9 4.8 4.7 4.6 4.5 4.4 -40 -20 0 20 40 60 80 100 Switching Frequency (kHz) 140 No Load 120 100 80 60 Temperature (°C) Fig. 58 SS6642-50 Output Voltage vs. Temperature 40 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 59 SS6642-50 Switching Frequency vs. Temperature 1/15/2005 Rev.2.10 www.SiliconStandard.com 14 of 22 SS6642G TYPICAL PERFORMANCE CHARACTERISTICS 80 (Continued) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Maximum Duty Cycle (%) 78 76 74 72 70 -40 SW Turn ON Resistance (Ω) -20 0 20 40 60 80 100 0.0 -40 -20 0 20 40 60 80 100 Temperature (°C) Fig. 60 SS6642-50 Maximum Duty Cycle vs. Temperature Temperature (°C) Fig. 61 SS6642-50 SW Turn ON Resistance vs. Temperature 100 90 80 VOUT 50mV/div Supply Current IDD1 (µA) 70 60 50 40 30 20 10 -40 10mA Load Step 50mA/div -20 0 20 40 60 80 100 Temperature (°C) Fig. 62 SS6642-50 Supply Current vs. Temperature Fig. 63 Load Transient Response (L1=100µH, C2=47µF, VIN=2V) VOUT 20mv/div VIN 0.5V/div Fig. 64 Line Transient Response (L1=100µH, C2=47µF) 1/15/2005 Rev.2.10 www.SiliconStandard.com 15 of 22 SS6642G BLOCK DIAGRAM V OUT 1M 1 .25V REF. SW + E nable G ND O SC, 100KHz PIN DESCRIPTIONS PIN 1 : GND - Ground. Must be low impedance; solder directly to ground plane. PIN 2 : VOUT - IC supply pin. Connect VOUT to the regulator output. PIN 3 : SW –Drain of the internal N-channel MOSFET switch. 1/15/2005 Rev.2.10 www.SiliconStandard.com 16 of 22 SS6642G APPLICATION INFORMATION GENERAL DESCRIPTION The SS6642G PFM (pulse frequency modulation) controller IC combines a switch-mode regulator, Nchannel power MOSFET, precision voltage reference, and voltage detector in a single monolithic device. It offers extremely low quiescient current, high efficiency, and very low gate threshold voltage to ensure start-up with low battery voltage (0.8V typ.). Designed to maximize battery life in portable products, it minimizes switching losses by only switching as needed to service the load. PFM controllers transfer a discrete amount of energy per cycle and regulate the output voltage by modulating the switching frequency with a constant turn-on time. Switching frequency depends on load, input voltage, and inductor value, and it can range up to 100KHz. The SW on-resistance is typically 1.9 to 2.2Ω to minimize switch losses. When the output voltage drops, the error comparator enables t he 1 00kHz oscillator that turns on the MOSFET for around 7.5us and off for 2.5us. Turning on the MOSFET allows inductor current to ramp up, storing energy in a magnetic field. When the MOSFET turns off, inductor current is forced through the diode to the output capacitor and load. As the stored energy is depleted, the current ramps down until the diode turns off. At this point, the inductor may ring due to residual energy and stray capacitance. The output capacitor stores charge when the current flowing through the diode is high, and releases it when the current is low, thereby maintaining a steady voltage across the load. As the load increases, the output capacitor discharges faster and the error comparator initiates cycles sooner, increasing the switching frequency. The maximum duty cycle ensures adequate time for energy transfer to the output during the second half of each cycle. Depending on the circuit, a PFM controller can operate in either discontinuous mode or continuous conduction mode. Continuous conduction mode means that the inductor current does not ramp down to zero during each cycle. VIN IIN SW + EXT Isw Ico VOUT ID IOUT VEXT IIN IPK ISW Charge Co. ID TDIS Discharge Co. IOUT VSW t Discontinuous Conduction Mode 1/15/2005 Rev.2.10 www.SiliconStandard.com 17 of 22 SS6642G VEXT In the continuous mode, the switching frequency is fSW = 1 (VOUT + VD − VIN) TON (VOUT + VD − VSW ) x VIN − VSW * [1 + ( )] 2 VOUT + VD − VSW 1  VOUT + VD − VIN  ≅   TON  VOUT + VD − VSW  IIN IPK ISW where Vsw = switch drop and is proportional to output current. IOUT ID Inductor Selection To operate as an efficient energy transfer element, the inductor must fulfill three requirements. First, the inductance must be low enough for the inductor to store adequate energy under the worst-case condition of minimum input voltage and switch ON time. Second, the inductance must also be high enough so that the maximum current rating of the SS6642 and the inductor are not exceeded at the other worstcase condition of maximum input voltage and ON time. Lastly, the inductor must have sufficiently low DC resistance so excessive power is not lost as heat in the windings. Unfortunately, this is inversely related to physical size. Minimum and maximum input voltage, output voltage and output current must be established in advance and then the inductor can be selected. In discontinuous mode operation, at the end of the switch ON time, peak current and energy in the inductor build according to RON + Rs  VIN    IPK =  * TON)   * 1 − exp( − L  RON + Rs    x  VIN   ≅  * (TON) * 1 −  2 L  ≅ VIN TON L VSW t Continuous Conduction Mode Continuous Conduction Mode At the boundary between continuous and discontinuous modes, output current (IOB) is determined by  VIN  1 VIN IOB =  * TON * (1 − x ) * *  VOUT  2 L where Vd is the diode drop, x = (RON + RS ) * TON L RON= Switch turn-on resistance, RS= Inductor DC resistance TON = Switch ON time In the discontinuous mode, the switching frequency (Fsw) is Fsw = 2 * (L) * (VOUT + VD − VIN) * (IOUT) VIN 2 × TON 2 (1 + x ) (simple loss equation), TON L where x = (RON + RS ) * 1/15/2005 Rev.2.10 www.SiliconStandard.com 18 of 22 SS6642G EL = 1 L × Ipk 2 2 The power supplied by the inductor per cycle must be equal to or greater than PL/fSW = (VOUT + VD − VIN) * (IOUT) * ( 1 ) fsw When loading is over IOB, the PFM controller operates in continuous mode. Inductor peak current can be derived from  x  VOUT+ VD − VSW x   VIN− VSW IPK =  −  * IOUT+   * TON * 1−  VIN− VSW 2 2L   2   in order for the converter to regulate the output. Valley current (Iv) is  VOUT+ VD − VSW x   VIN− VSW   x IV =  −  * IOUT−   * TON* 1−  2L  2  VIN− VSW   2 Table 1 Indicates resistance and height for each coil. Power Inductor Type Inductance ( µH ) 22 Coilcraft SMT Type (www.coilcraft.com) DO3316 Sumida SMT Type CD54 Hold SMT Type PM54 Hold SMT Type PM75 DS1608 47 100 22 47 47 100 47 100 33 Resistance ( Ω ) 0.10 0.18 0.38 0.08 0.14 0.25 0.50 0.25 0.50 0.11 Rated Current (A) 0.7 0.5 0.3 2.7 1.8 0.7 0.5 0.7 0.5 1.2 5.2 4.5 4.5 5.0 2.9 Height (mm) Capacitor Selection A poor choice for an output capacitor can result in poor efficiency and high output ripple. Ordinary aluminum electrolytics, while inexpensive may have unacceptably poor ESR and ESL. There are low-ESR aluminum capacitors for switch mode DC-DC converters which work much better than general types. Tantalum capacitors provide still better performance but are more expensive. OSCON capacitors have extremely low ESR and small size. If capacitance is reduced, output ripple will increase. Most of the input supply is applied to the input bypass capacitor, so the capacitor voltage rating should be at least 1.25 times greater than the maximum input voltage. Diode Selection Speed, forward drop, and leakage current are the three main considerations in selecting a rectifier diode. Best performance is obtained with Schottky rectifier diodes such as the 1N5819. SSC also has Schottkies for surface-mount. For lower output power a 1N4148 can be used, although efficiency and start-up voltage will suffer substantially. 1/15/2005 Rev.2.10 www.SiliconStandard.com 19 of 22 SS6642G Component Power Dissipation Operating in discontinuous mode, power loss in the winding resistance of the inductor can be approximated to PD L = 2  TON   VOUT + VF   * (POUT )  * (RD ) *   3 L   VOUT  The power dissipated in the MOSFET switch is PDSW = 2  TON   VOUT + VD − VIN   * (POUT )  * (RON) *   3 L  VOUT   The power dissipated in the rectifier diode is  VD  PDd =   * (POUT )  VOUT  where POUT=VOUT * IOUT; RS=Inductor DC R; VD = Diode drop. 1/15/2005 Rev.2.10 www.SiliconStandard.com 20 of 22 SS6642G PHYSICAL DIMENSIONS (unit: mm) All package options are Pb-free, RoHS compliant. SOT-23 (GU) D SYMBOL A 0.25 MIN 0.95 0.05 0.90 0.30 0.08 2.80 2.60 1.50 0.95 BSC 1.90 BSC 0.30 0.60 REF 0˚ MAX 1.45 0.15 1.30 0.50 0.22 3.00 3.00 1.70 A1 A2 b c D E E1 E1 e e1 E c L L1 θ A2 A A1 b e e1 L L1 θ 0.60 8˚ SOT-89 (GX) D D1 C A SYMBOL A B B1 C MIN 1.40 0.44 0.36 0.35 4.40 1.50 2.29 1.50 BSC 3.00 BSC 3.94 0.89 MAX 1.60 0.56 0.48 0.44 4.60 1.83 2.60 H E D D1 E L e e1 B B1 e e1 H L 4.25 1.20 1/15/2005 Rev.2.10 www.SiliconStandard.com 21 of 22 SS6642G TO-92 (GZ) SYMBOL A A D MIN 4.32 0.36 4.45 3.18 2.42 1.15 3.43 12.70 2.03 MAX 5.33 0.47 5.20 4.19 2.66 1.39 2.66 b D E e b S E e1 j L S L j e1 e Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties. 1/15/2005 Rev.2.10 www.SiliconStandard.com 22 of 22