ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter ■General description ELM93xxxB is CMOS step-up DC/DC converter which consists of reference voltage source, error amplifier, oscillation circuit, start-up circuit, PFM control circuit, switching transistor and output voltage setting resistor. For external parts, coil, diode and capacitor are possible choices; with external parts, ELM93 series is able to acquire constant output voltage higher than input voltage. The standard output voltages are 2.7V, 3.0V, and 3.3V; ELM93 series can also be designed as semi-custom IC within the range of 1.8V to 3.8V by 0.1V step. ■Features • • • • • • ■Application Output voltage range Low voltage operation Low power operation High efficiency High output voltage accuracy Output current (e.g.) • Package : 1.8V to 3.8V (by 0.1V) : Vin≥0.9V (RL=30kΩ) : 24μW (Typ. ELM9330xB) : Typ. 85% : ±2.5% : 40mA (When Vin=1.5V, Vout=3.0V) : SOT-89, SOT-23 • Constant voltage source for batteryoperated devices • Constant voltage source for cameras • Portable communications equipments • Local regulator ■Maximum absolute ratings Parameter Apply voltage to LX pin Apply voltage to VOUT pin Output current of LX pin Power dissipation Symbol Vlx Vout Ilx Pd Operating temperature Storage temperature Top Tstg Limit 5 4 200 300 (SOT-89) 200 (SOT-23) -40 to +85 -55 to +125 Unit V V mA mW °C °C ■Selection guide ELM93xxxB-x Symbol a, b Output voltage c Package d Product version e Taping direction e.g. : 27: Vout=2.7V 30: Vout=3.0V 33: Vout=3.3V A: SOT-89 B: SOT-23 B S : Refer to PKG file N : Refer to PKG file 8-1 ELM93 x x x B - x ↑ ↑ ↑ ↑ ↑ a b c d e ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter ■Pin configuration SOT-89 (TOP VIEW) Pin No. 1 2 3 SOT-23 (TOP VIEW) Pin name VSS VOUT LX Pin No. 1 2 3 Pin name VSS LX VOUT ■Standard circuit 㪤㪘㪎㪉㪈 㪊㪊㪇㱘㪟 㪭㫀㫅 㪣㪯 㪜㪣㪤㪐㪊㫏㫏㫏㪙 㪂 㪭㪦㪬㪫 㪭㫆㫌㫋 㪂 㪚㫀㫅 㪉㪉㱘㪝 㪭㪪㪪 㪚㫆㫌㫋 㪉㪉㱘㪝 Cin : The circuit can operate without Cin, but adding Cin to the circuit can lower the feedback noise to the Input; this method is also effective in improving efficiency because input voltage drop during switching can be eased. Under the condition of Iout≤10mA, please connect tantalum capacitor of 10μF to 47μF to a coil as close as possible. ■Block diagram 㪣㪯 㪧㪅㪝㪅㪤㪅㩷㩷㪦㪪㪚 㪭㪦㪬㪫 㪂㪄 㪭㫉㪼㪽 㪪㫋㪸㫉㫋㪄㫌㫇 㪭㪪㪪 8-2 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter ■Electrical characteristics Vout=2.7V (ELM9327xB) Parameter Starting voltage Holding voltage Current consumption Output voltage Output current of LX pin Leakage current of LX pin Oscillating frequency Duty ratio Symbol Vst Vhold Iss Vout Ilx Ilxl Fosc Duty L=330μH, Cin=Cout=22μF, D=MA721, Vss=0V, Top=25°C Condition Min. Typ. Max. Unit RL=30kΩ 0.9 V Iout=1mA 0.7 V Iout=100μA, Vin=1.5V 8.0 16.0 μA Iout=1mA, Vin=1.5V 2.63 2.70 2.77 V Vout=2.6V, Vlx=0.4V 60 mA Vout=3.5V, Vlx=3.5V 1.0 μA Vout=2.6V 80 100 120 kHz Vout=2.6V, Switch"ON" 65 75 85 % Symbol Vst Vhold Iss Vout Ilx Ilxl Fosc Duty L=330μH, Cin=Cout=22μF, D=MA721, Vss=0V, Top=25°C Condition Min. Typ. Max. Unit RL=30kΩ 0.9 V Iout=1mA 0.7 V Iout=100μA, Vin=1.5V 8.0 16.0 μA Iout=1mA, Vin=1.5V 2.92 3.00 3.08 V Vout=2.9V, Vlx=0.4V 70 mA Vout=3.5V, Vlx=3.5V 1.0 μA Vout=2.9V 80 100 120 kHz Vout=2.9V, Switch"ON" 65 75 85 % Symbol Vst Vhold Iss Vout Ilx Ilxl Fosc Duty L=330μH, Cin=Cout=22μF, D=MA721, Vss=0V, Top=25°C Condition Min. Typ. Max. Unit RL=30kΩ 0.9 V Iout=1mA 0.7 V Iout=100μA, Vin=1.5V 8.0 16.0 μA Iout=1mA, Vin=1.5V 3.21 3.30 3.39 V Vout=3.2V, Vlx=0.4V 80 mA Vout=3.5V, Vlx=3.5V 1.0 μA Vout=3.2V 80 100 120 kHz Vout=3.2V, Switch"ON" 65 75 85 % Vout=3.0V (ELM9330xB) Parameter Starting voltage Holding voltage Current consumption Output voltage Output current of LX pin Leakage current of LX pin Oscillating frequency Duty ratio Vout=3.3V (ELM9333xB) Parameter Starting voltage Holding voltage Current consumption Output voltage Output current of LX pin Leakage current of LX pin Oscillating frequency Duty ratio 8-3 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter ■Marking SOT-89 㪸 㪹 㪺 㪻 a : the integer digit of the output voltage Mark 1 2 3 Vout 1.*V 2.*V 3.*V b : the decimal digit of the output voltage Mark 0 1 2 3 4 5 6 7 8 9 SOT-23 㪸㪹㪺㪻 Vout *.0V *.1V *.2V *.3V *.4V *.5V *.6V *.7V *.8V *.9V c, d : 50 to 99 (Assembly lot No.) ■External parts To design DC/DC converters using ELM93 series, coil, diode, and capacitor are necessary. (Refer to the standard circuit configuration.) 1) Coil When choosing choke coil, please select that whose core is not magnetically saturated, DC resistance is low, and which has sufficient margin for rated current. For ELM93 series, ELM recommends following coil. • CM-5/CM-5N (Sumida Electric Co., Ltd.) 2) Diode When choosing diode, please select that whose forward voltage is small, switching speed is high and which has sufficient margin for rated current. For ELM93 series, ELM recommends schottoky diodes. 8-4 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter 3) Capacitor When choosing capacitor, please select that which is generally used for smoothing power supply circuit, with comparatively large capacity and whose rated voltage is at least three times larger than rated output voltage of used ELM93 series. For ELM93 series, ELM recommends Aluminum electrolytic or Tantalum capacitor. Under different conditions, such as different input voltage, load current, etc. larger output voltage ripple may happen and thus result in intermittent switching. To solve this, using capacitors with larger capacity can prevent output voltage ripple from becoming larger. Inserting resistor, as shown in the following circuit, may also be effective. 㪈㪅㪇㱅 㪣㪯 㪜㪣㪤㪐㪊㫏㫏㫏㪙 㪭㫆㫌㫋 㪂 㪭㪦㪬㪫 㪫㪸㫅㫋㪸㫃㫌㫄 㪚㪸㫇㪸㪺㫀㫋㫆㫉 㪭㪪㪪 ■Design of DC/DC converter In the DC/DC converter which consists of ELM93 series and above-mentioned external parts, the output is acquired as follows: 1) Output current of DC/DC converter The current from the output terminal (Vout) of the circuit is: 9Vin 2 Iout = K * Duty=75% 32 • L • Fosc • (Vout-Vin) K: the efficiency of whole circuit (≈75% to ≈85%) 2) Remedies for noise This DC/DC converter may cause electromagnetic noise due to switching of coil under large current. Solution is necessary especially when the IC is used in wireless devices. To reduce noise, this IC is designed in consideration of the coil switching characteristics. The following methods are also effective to reduce noise. • Use shield-type, or magnetic shield coil. • Locate coil and diode to the LX terminal of IC as close as possible. • Select ground wire as thick and short as possible. • Connect ground wire of circuit to one point. 8-5 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter ■Typical characteristics • Vout=2.7V (ELM9327xB) (Top=25°C, L=330μH, D=MA721, Cin=Cout=22μF) Vout - Iout 3.5 3 3 Vout (V) Vout (V) Vout - Vin 3.5 2.5 2 Iout=10mA 1.8V 2.5 Vin=0.9V 1.1V 2 1.3V 1.5 1.5V 1.5 3mA 1mA 1 0 1 1 0.1 2 1 10 100 Iout (mA) Vin (V) EFFICIENCY - Iout EFFICIENCY - Vin 100 100 EFFICIENCY (%) EFFICIENCY (%) 90 90 Iout=1mA 80 100˩A 70 1.8V 80 Vin=0.9V 70 1.1V 60 1.3V 50 60 0 1 1.5V 40 0.1 2 1 VOLTAGE RIPPLE - Vin 100 Iout(max.) - L 100 70 60 80 Iout(max.) (mA) VOLTAGE RIPPLE (mV) 10 Iout (mA) Vin (V) 60 40 Iout=1mA Vin=1.5V 50 40 30 1.1V 1.0V 20 0.9V 20 10 0 1 2 0 Vin (V) 200 400 600 L (˩H) 8-6 800 1000 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter • Vout=3.0 (VELM9330xB) (Top=25°C, L=330μH, D=MA721, Cin=Cout=22μF) Vout - Iout Vout - Vin 3.5 3.5 3 3 1.8V Vout (V) Vout (V) 1.1V 2.5 2 Iout=10mA Vin=0.9V 2.5 1.3V 2 1.5V 1.5 1.5 3mA 1mA 1 0 1 2 1 0.1 3 1 10 100 Iout (mA) Vin (V) EFFICIENCY - Iout EFFICIENCY - Vin 100 100 EFFICIENCY (%) EFFICIENCY (%) 90 90 Iout=1mA 80 100˩A 70 1.8V 80 Vin=0.9V 70 1.1V 60 1.5V 1.3V 50 60 0 1 2 40 0.1 3 1 VOLTAGE RIPPLE - Vin 100 Iout(max.) - L 100 70 60 80 Iout(max.) (mA) VOLTAGE RIPPLE (mV) 10 Iout (mA) Vin (V) Iout=1mA 60 40 Vin=1.5V 50 40 30 1.1V 1.0V 20 0.9V 20 10 0 1 2 3 0 Vin (V) 200 400 600 L (˩H) 8-7 800 1000 ELM93xxxB CMOS High efficiency PFM step-up DC/DC converter • Vout=3.3V (ELM9333xB) (Top=25°C, L=330μH, D=MA721, Cin=Cout=22μF) Vout - Iout Vout - Vin 3.5 3.5 3 3 1.1V Vout (V) Vout (V) Iout=10mA 2.5 3mA 2 Vin=0.9V 2.5 1.3V 2 1.5V 1.8V 1mA 1.5 1.5 1 0 1 2 1 0.1 3 1 10 100 Iout (mA) Vin (V) EFFICIENCY - Iout EFFICIENCY - Vin 100 100 EFFICIENCY (%) EFFICIENCY (%) 90 90 Iout=1mA 80 100˩A 70 1.8V 80 Vin=0.9V 70 1.1V 60 1.5V 1.3V 50 60 0 1 2 40 0.1 3 1 VOLTAGE RIPPLE - Vin 100 Iout(max.) - L 100 70 60 80 Iout(max.) (mA) VOLTAGE RIPPLE (mV) 10 Iout (mA) Vin (V) 60 Iout=1mA 40 50 Vin=1.5V 40 30 20 1.1V 1.0V 0.9V 20 10 0 1 2 3 0 Vin (V) 200 400 600 L (˩H) 8-8 800 1000