ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter ■General description ELM600LA is high efficiency synchronous step down DC/DC converter operated with current mode and 1.4MHz constant frequency; internal switch and synchronous rectifier are integrated for high efficiency. In application, ELM600LA does not require any external Schottky diode. Internal current consumption under operation of ELM600LA is as low as 200µA and drops to less than 1µA in shutdown mode. With supply voltage from 2.5V to 6V, ELM600LA can supply load current of 800mA; the output voltage can be regulated as low as 0.6V. With 1.4MHz switching frequency, ELM600LA makes it possible to adopt small surface amount inductors and capacitors. Switch duty cycle would be on continuously and 100% at maximum when input voltage is set be to lower than output voltage. ■Features ■Application • • • • • • • • • • • • • • • • • Current mode operation Thermal shutdown protection and short circuit protection Constant frequency : Typ.1.4MHz : 800mA Output current : Max.95% High efficiency : Max.1µA(Ven=0V, Vin=6V) Shutdown current Supply voltage : 2.5V to 6V Low quiescent current : Typ.200µA : 0 to 100% (in dropout) Full duty ratio Package : TSOT-25 Cellular phone PDA and smart phone MP3 player Digital camera Wireless and DSL card Microcomputer and DSP power supply Portable machine ■Maximum absolute ratings Parameter VIN power supply voltage Apply voltage to SW Apply voltage to EN Apply voltage to FB SW peak current Power dissipation Operating temperature range Storage temperature range Symbol Vin Vsw Ven Vfb Isw Pd Top Tstg Limit -0.3 to +6.5 GND-0.3 to Vin+0.3 GND-0.3 to Vin+0.3 GND-0.3 to Vin+0.3 1.7 200 -40 to +85 -65 to +150 Caution:Permanent damage to the device may occur when ratings above maximum absolute ones are used. Unit V V V V A mW °C °C ■Selection guide ELM600LA-S, ELM600LA-xx-S Symbol a b Package Product version c, d Output voltage e Taping direction * Taping direction is one way. • Adj. version L: TSOT-25 A e.g. : 12: Vout=1.2V, 18: Vout=1.8V S: Refer to PKG file 10 - 1 ELM600LA - S ↑↑ ↑ ab e • Fixed version ELM600 LA - x x - S ↑↑ ↑ ↑ ↑ ab c d e Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter ■Pin configuration TSOT-25(TOP VIEW) Pin No. 1 2 3 4 5 4 5 3 2 1 Pin name EN GND SW VIN FB Pin description Enable control input Ground Power switch output Main supply Voltage feedback ■Block diagram Vin Shut down control ● + _ Current sense amplifier ● Reference M1 0.6V FB + _ ● PWM PWM Logic Comparator Error amplifier Oscillator ● ● SW ● GND M2 Clock Zero-current comparator + _ EN Slope Comp ■Standard circuit • Adjustable output voltage Vout L=2.2µH ● ● R1 ● Cout=22µF Vin 4 ● R2 Cin=10µF 5 VIN SW GND FB EN ELM600LA 3 2 1 Enable Vout=0.6×(1+R1/R2) Vout=3.3V, R1=300KΩ, R2=68KΩ Vout=1.8V, R1=1MΩ, R2=499KΩ 10 - 2 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter • Fixed output voltage Vout=1.2V/1.8V L=2.2µH ● Cout=22µF Vin 4 ● Cin=10µF 5 VIN SW GND FB EN ELM60012LA ELM60018LA 3 2 1 Enable * Passive components without specified values in the above figure are optional. ■Electrical characteristics(Adjustable output voltage) Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted. Parameter Symbol Test condition Min. Typ. Max. Unit Supply voltage Vin 2.5 6.0 V Output voltage Adjustable 0.6 6.0 V Vout Feedback current Ifb -30.0 30.0 nA Regulated feedback voltage Vfb -40°C ≤ Top ≤ +85°C 0.582 0.600 0.618 V Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V 0.04 0.40 %/V Output voltage line regulation ∆Vout/∆Vin Vin=2.5V to 6V 0.04 0.40 %/V Output voltage load regulation Vlr 0.5 % Shutdown current Is Ven=0V, Vin=6V 0.01 1.00 µA Ven=Vin, Vfb=0.65V Quiescent current Iq 200 µA No switching Ven=0V, Vfb=0.65V Ileak SW leakage current -1 1 µA Vsw=0V or 6V RdsonP Isw=100mA 0.35 Ω PMOSFET on resistance NMOSFET on resistance RdsonN Isw=-100mA 0.24 Ω Duty cycle=100% PMOSFET current limit IPcl 0.8 1.1 1.5 A Current pulse width<1ms Oscillator frequency Fosc 1.12 1.40 1.68 MHz Tsd 145 °C Thermal shutdown threshold EN high level input voltage Venh -40°C ≤ Top ≤ +85°C 1.1 V Venl -40°C ≤ Top ≤ +85°C 0.3 V EN low level input voltage EN input current Ien Ven=0V to Vin -1 1 µA 10 - 3 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter ■Test circuits(Adjustable output voltage) L=2.2µH VIN ELM600LA Vin Cout= 22µF GND FB Vout SW EN R1 RL Cin=10µF R2 ■Electrical characteristics(Fixed output voltage) Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted. Parameter Symbol Test condition Min. Typ. Max. Unit Supply voltage Vin 2.5 6.0 V Feedback current Ifb -30.0 30.0 nA Regulated feedback voltage Vfb -40°C ≤ Top ≤ +85°C 0.582 0.600 0.618 V Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V 0.04 0.40 %/V 0.04 0.40 %/V Output voltage line regulation ∆Vout/∆Vin Vin=2.5V to 6V Output voltage load regulation Vlr 0.5 % Output range (Fixed voltage) Vout Vin=2.5V to 6V 1.164 1.200 1.236 V Shutdown current Is Ven=0V, Vin=6V 0.01 1.00 µA Ven=Vin,Vfb=0.65V, No switching 200 µA Quiescent current Iq Ven=0V, Vfb=0.65V SW leakage current Ileak -1 1 µA Vsw=0V or 6V PMOSFET on resistance RdsonP Isw=100mA 0.35 Ω NMOSFET on resistance RdsonN Isw=-100mA 0.24 Ω Duty cycle=100% PMOSFET current limit IPcl 0.8 1.1 1.5 A Current pulse width < 1ms Oscillator frequency Fosc 1.12 1.40 1.68 MHz Thermal shutdown threshold Tsd 145 °C EN high level input voltage Venh -40°C ≤ Top ≤ +85°C 1.1 V EN low level input voltage Venl -40°C ≤ Top ≤ +85°C 0.3 V EN input current Ien Ven=0V to Vin -1 1 µA Vout=1.2V 10 - 4 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted. Parameter Symbol Test condition Min. Typ. Max. Unit Supply voltage Vin 2.5 6.0 V Feedback current Ifb -30.0 30.0 nA Regulated feedback voltage Vfb -40°C ≤ Top ≤ +85°C 0.582 0.600 0.618 V Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V 0.04 0.40 %/V 0.04 0.40 %/V Output voltage line regulation ∆Vout/∆Vin Vin=2.5V to 6V Output voltage load regulation Vlr 0.5 % Output range (Fixed voltage) Vout Vin=2.5V to 6V 1.764 1.800 1.836 V Shutdown current Is Ven=0V, Vin=6V 0.01 1.00 µA Ven=Vin,Vfb=0.65V, No switching 200 µA Quiescent current Iq Ven=0V, Vfb=0.65V SW leakage current Ileak -1 1 µA Vsw=0V or 6V PMOSFET on resistance RdsonP Isw=100mA 0.35 Ω NMOSFET on resistance RdsonN Isw=-100mA 0.24 Ω Duty cycle=100% PMOSFET current limit IPcl 0.8 1.1 1.5 A Current pulse width<1ms Oscillator frequency Fosc 1.12 1.40 1.68 MHz Thermal shutdown threshold Tsd 145 °C EN high level input voltage Venh -40°C ≤ Top ≤ +85°C 1.1 V EN low level input voltage Venl -40°C ≤ Top ≤ +85°C 0.3 V EN input current Ien Ven=0V to Vin -1 1 µA Vout=1.8V ■Marking TSOT-25 abcde a to e : Assembly lot No. A to Z (I, O, X excepted) and 0 to 9 10 - 5 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter ■Application notes ELM600LA is constant frequency current mode PWM step down converter which is suitable for applications that require high efficiency and small assembly area and use low voltage, such as Li-ion battery. By external resistor divider, output voltage of ELM600LA can be set within the range from 0.6V to 6V. To provide operation with high efficiency, ELM600LA consists of main switch and synchronous rectifier while external Schottky diode is not necessary. Duty cycle of ELM600LA can reach upto 100%. Duty cycle D of step down converter is defined as follows: D = Ton × Fosc × 100% ≈ (Vout/Vin) × 100% Ton=main switch on time; Fosc=oscillator frequency (1.4MHz); Vout=output voltage;Vin=input voltage 1) Current mode PWM control Slope compensated current mode control PWM provides superior load and line response, and protection of internal main switch and synchronous rectifier to current limit by stable switching and switch cycle. ELM600LA switches at a constant frequency (1.4MHz) and regulates output voltage. During each cycle, the PWM comparator modulates the power transferred to load by changing inductor peak current which is based on the feedback error voltage. Under normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and off when inductor peak current is above error voltage. When the main switch is turned off, the synchronous rectifier will be turned on immediately and stay on until either the next cycle begins or the inductor current drops to zero. With light load, ELM600LA would skip pulses to improve efficiency. 2) Dropout operation ELM600LA allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping under the output voltage. When duty cycle reaches 100%, the main switch transistor would be on continuously to supply current to output until current limit generates. Output voltage then is input voltage minus voltage drop across main switch and inductor. 3) Short circuit protection ELM600LA consists of short circuit protection; when output is short to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the P MOSFET current limit. The frequency will return to normal values once the short circuit condition is recovered and the feedback voltage goes back to 0.6V. 4) Maximum load current ELM600LA can operate when input voltage is down to 2.5V; however, the maximum load current would descend because of the increase IR drop which results from the ON resistor of main switch and synchronous rectifier along with the drop of input voltage. The slope compensation signal would reduce the peak inductor current to avoid sub-harmonic oscillations when duty cycles is larger than 50%; on the contrary, it would increase the peak inductor current when duty cycle is decreased, as which is shown in the graph. 10 - 6 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter ■Typical characteristics • ELM600LA(Adj.version) : Unless otherwise noted Vout=1.8V, Cin=10µF, Cout=22µF, L=2.2µH, R1=22kΩ, R2=11kΩ, Top=25°C • V=1.8V(AdJ.) Vout-Vin 2.4 EFFICIENCY (%) Iout=1mA 1.2 100mA 0.8 0.4 0 1 2 3 Vin (V) 5 60 40 20 0 0.1 6 1 10 100 1000 Iout (mA) Start Response Vout-Iout Vout (V) 1.9 Vout (V) 4 Vin=5V 80 Ven=Vin=5V, No load 2 1 0 5 4 Vin=5V 1.8 3 2 Ven (V) Vout (V) 2.0 1.6 EFFICIENCY-Iout 100 1 0 1 10 100 0 1000 Iout (mA) Vin=5V, Iout=10mA�600mA Time (ms) 1.5 2 Vin=5V, Iout=100mA�600mA Vout (V) 2.5 2 1.5 2 2 1.5 1 0 0 0.5 1 1.5 2 2.5 Time (ms) 3 3.5 1 Iout (A) Vout (V) 2 1 Load Transient Response Load Transient Response 2.5 0.5 0 0 4 10 - 7 0.5 1 1.5 2 2.5 Time (ms) 3 3.5 Iout (A) 1.7 4 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter • ELM600LA(Adj.version) : Unless otherwise noted Vout=3.3V, Cin=10µF, Cout=22µF, L=2.2µH, R1=47kΩ, R2=10.4kΩ, Top=25°C • V=3.3V(AdJ.) Vout-Vin 4.0 3.5 Iout=1mA EFFICIENCY (%) Vout (V) 3.0 2.5 2.0 100mA 1.5 EFFICIENCY-Iout 100 1.0 Vin=5V 80 60 40 20 0.5 0 1 2 3 4 Vin (V) 5 0 0.1 6 100 1000 Start Response Vout (V) 3.4 Ven=Vin=5V, No load 3.5 3 2 1 0 5 3.3 4 3 Vin=5V 3.2 2 Ven (V) Vout (V) 10 Iout (mA) Vout-Iout 3.5 1 1 0 1 10 100 Iout (mA) 0 1000 1.5 2 Load Transient Response Vin=5V, Iout=10mA�600mA Vout (V) 3.5 Vin=5V, Iout=100mA�600mA 4 2 3 3.5 2 3 1 0 0 0.5 1 Time (ms) 1.5 1 Iout (A) Vout (V) 1 Time (ms) Load Transient Response 4 0.5 0 0 2 10 - 8 0.5 1 Time (ms) 1.5 Iout (A) 3.1 2 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter • ELM600LA-12(Fixed version) : Unless otherwise noted Vout=1.2V, Cin=10µF, Cout=22µF, L=2.2µH, Top=25°C • V=1.2V(Fixed) EFFICIENCY-Iout Vout-Vin 100 1.4 EFFICIENCY (%) 1.2 Vout (V) 1.0 Iout=1mA 0.8 0.6 100mA 0.4 Vin=5V 80 60 40 20 0.2 0 1 2 3 4 Vin (V) 5 0 0.1 6 1 10 100 Iout (mA) 1000 Start Response Vout-Iout Vout (V) 1.3 1.25 Ven=Vin=5V, No load 2 1 0 4 1.2 3 Vin=5V 2 1.15 Ven (V) Vout (V) 5 1 0 1 10 100 0 1000 Iout (mA) Load Transient Response Vin=5V, Iout=10mA�600mA 0 2 4 6 Time (ms) 8 10 0.8 1 Vin=5V, Iout=100mA �600mA 2 Vout (V) 2 2 1.5 1 1 0 0.6 Time (s) Load Transient Response 1.5 1 0.4 1 Iout (A) Vout (V) 2 0.2 0 0 12 10 - 9 2 4 6 Time (ms) 8 10 Iout (A) 1.1 12 Rev.1.1 ELM600LA 800mA 1.4MHz high efficiency synchronous PWM step down DC/DC converter • ELM600LA-18(Fixed version) : Unless otherwise noted Vout=1.8V, Cin=10µF, Cout=22µF, L=2.2µH, Top=25°C • V=1.8V(Fixed) EFFICIENCY-Iout Vout-Vin 100 2.4 Vin=5V 80 1.6 EFFICIENCY (%) 100mA Iout=1mA 1.2 0.8 0.4 0 1 2 3 Vin (V) 4 5 60 40 20 0 0.1 6 1 100 1000 Start Response Vout-Iout Ven=Vin=5V, No load Vout (V) 1.9 1.85 Vout (V) 10 Iout (mA) 2 1 0 5 4 1.8 3 2 Vin=5V 1.75 Ven (V) Vout (V) 2.0 1 0 1 10 100 0 1000 Iout (mA) Load Transient Response 0.6 0.8 Time (s) 1 Vin=5V, Iout=100mA�600mA Vout (V) 2.5 2 1.5 2 2 1.5 1 0 0 2 4 6 Time (ms) 8 10 1 Iout (A) Vout (V) 2 0.4 Load Transient Response Vin=5V, Iout=10mA�600mA 2.5 0.2 0 0 12 10 - 10 2 4 6 Time (ms) 8 10 Iout (A) 1.7 12 Rev.1.1