ELM901FxA 1A 2x Charge Pump LED Driver ■General description ELM901FxA is a high current LED driver with internal automatic mode switch pump circuit of pass-through mode (1x mode) and boost charge mode (2x mode) and constant current drive circuit; maximum output current of ELM901 series can reach 1A. ELM901 series is ideally suited for high luminosity white LED electrical applications which are powered by 1-cell lithium-ion/polymer battery. The required external parts of ELM901 series can be limited to the minimum of 3 capacitors and 3 programming resistors. With 4mm x 4mm & 3mm x 3mm QFN package, ELM901 series is possible to be assembled within limited space. The sink current, which can be switched to 3 different kinds by enable signal during operation,of LED pin is set by external programming resistors. For LED protection, it is possible to set high current lighting timer with external resistor; the light will be turned off forcibly by timer (3 options among 0.2 sec. to 1 sec.). Built-in soft-start circuitry makes ELM901 series be able to limit excessive power during start-up and switch of 1x & 2x mode. ■Features ■Application • • • • • • Low voltage operation : 2.6V-4.4V • Camera light supply Low power operation : 300μA(1x), 9mA(2x) • High luminosity LED flashlight Low standby current : Max.1μA Large output current : Max.1A LED protection : high current lightening timer Internal LED constant current circuit : external resistance program • Soft-start : LED current start and switch of 1x & 2x mode • Package : QFN16-4x4, QFN16-3x3(under development) • Thermal shutdown function included ■Maximum absolute ratings Parameter VIN voltage VO voltage EN1,EN2 voltage VO current, LED current Operating temperature Storage temperature Symbol Vin Vo Ven Io, Iled Top Tstg Limit GND-0.3 to 6 GND-0.3 to 6 GND-0.3 to Vin+0.3 1500 * -40 to +85 -40 to +125 Unit V V V mA °C °C * Based on long-term current denslty limitations. Assumes an operating duty cycle of ≤ 10% under absolute maximum conditions for durations less than 10 seconds. Max current for continuous operation is 600mA. ■Selection Guide ELM901FxA-S Symbol a Package b Package type c d Product version Taping direction F: QFN A: QFN16-4x4 B: QFN16-3x3(under development) A S: Refer to PKG file 11 - 1 ELM901 F x A - S ↑↑↑ ↑ abc d ELM901FxA 1A 2x Charge Pump LED Driver ■Pin Configuration QFN16-4x4(TOP VIEW) 12 11 10 QFN16-4x4(BOTTOM VIEW) 9 9 10 11 12 13 8 8 13 14 7 7 14 15 6 6 15 16 5 5 16 1 2 4 3 4 QFN16-3x3(TOP VIEW) 12 11 10 3 2 1 QFN16-3x3(BOTTOM VIEW) 9 9 10 11 12 13 8 8 13 14 7 7 14 15 6 6 15 16 5 5 16 1 2 3 4 4 3 2 Pin no. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Pin name ISET2 ISET1 EN2 EN1 AGND FS VIN PGND1 CM PVIN CP NC VO NC PGND2 LED 1 ■Pin description ISET2 : LED current setting 2 The pin that is for the connection of LED current setting resistor(Rset2) between ISET2-GND. The output becomes 1.22V constantly when EN2 is high. The constant current of LED pin will be 3250x of the one flows to ISET2. (e.g.) when Rset2=6.8kΩ, Iled=1.22/6.8k×3250=583mA. ISET1 : LED current setting 1 The pin that is for the connection of LED current setting resistor(Rset1) between ISET1-GND. The output becomes 1.22V constantly when EN1 is high. The constant current of LED pin will be 3250x of the one flows to ISET1. (e.g.) when Rset1=20kΩ, Iled=1.22/20k×3250=198.3mA. EN2 : on/off control 2 LED output current on/off control pin of set current of ISET2. This pin is pulled down to ground inside the IC and the control logic is high active. The set current of ISET2 sinks from LED pin when this pin is connected to VIN. 11 - 2 ELM901FxA 1A 2x Charge Pump LED Driver EN1 : on/off control 1 LED output current on/off control pin of set current of ISET1. This pin is pulled down to ground inside the IC and the control logic is high active. The set current of ISET1 sinks from LED pin when this pin is connected to VIN. AGND : internal analog circuit ground This pin should be connected to GND of internal analog circuit and is connected in short circuit with internal circuit on back pad. The connection to PGND1 & PGND2 is required and should be designed according to the external wiring. FS : fail safe setting When EN1=EN2=1 continues for a period of time, fail safe function will turn down LED current forcibly. This function aims for thermal protection of LED, and it is possible to be turned off. There are 3 timer options according to the resistor connected between FS and GND since EN1=EN2=1 until LED current is off: (1)1s when the resistor is short, (2)0.2s when the resistor is 20kΩ, and (3)0.5s when the resistor is 51kΩ. This fail safe function becomes ineffective when it is short between FS and VIN or FS is open. VIN : internal circuit power This pin should be connected to the power pin of internal circuit. The connection to PVIN is required and should be designed according to the external wiring; GND-connected ceramic capacitor( above 2.2μF) is also necessary. PGND1 : charge pump circuit ground This pin should be connected to GND of charge pump circuit. The connection to AGND & PGND2 is required and should be designed according to the external wiring. CM : step-up capacitor connection( low potential) This pin should be connected to the low potential of step-up capacitor. The wiring of step-up capacitor should be connected between CM and CP as closely as possible; ELM recommends using 2.2μF capacitor. PVIN : charge pump power This pin is power supply of charge pump circuit. This pin should be connected to VIN according to the external wiring. CP : step-up capacitor connection( high potential) This pin should be connected to the high potential of step-up capacitor. The wiring of step-up capacitor should be connected between CM and CP as close as possible; ELM recommends using 2.2μF capacitor. VO : step-up output The output voltage is almost the same as VIN under 1x mode, while it becomes 5.5V under step-up mode. This pin should be connected to LED anode. PGND2 : LED current drive circuit ground This pin should be connected to the GND of LED current drive circuit. The connection to AGND & PGND1 is required and should be designed according to the external wiring. LED : constant current sink To sink the output current which is set by ISET1 & ISET2. This pin should be connected to LED cathode. 11 - 3 ELM901FxA 1A 2x Charge Pump LED Driver ■Standard circuit C2 12 NC 11 CP 10 PVIN 9 CM 13 ● 8 Charge pump VO C1 14 7 NC LED PGND1 15 PGND2 ● C3 6 FS CC Control 16 ● VIN 900kHz OSC Timer Rfs 5 LED AGND 1 ISET2 2 ISET1 3 Rset1 Rset2 PVIN CP EN2 4 EN1 ● ■Block diagram VIN x1/x2 charge pump ▲ Thermal protection CM ▲ ▲▲▲ ▲ ▲ ▲ VO ▲ Step-up circuit Vref 900kHz oscillator EN2 PGND1 x1/x2 switch Control logic Short protection ▲ ▲ Drop out detection Current sense control ISET1 LED ▲ ▲ EN1 Vref(soft) Fail safe circuit ▲ FS AGND ISET2 11 - 4 PGND2 ELM901FxA 1A 2x Charge Pump LED Driver ■Operation ELM901 is designed to drive high luminosity LED which is powered by 1 lithium-ion/polymer battery with constant current. When the battery voltage is much higher than LED forward voltage, LED is lit by connecting directly to the battery; output voltage is stepped up to 5.5V by internal charge pump circuit to light LED when voltage drops. LED current is driven by the constant current circuit which is set by external programming resistors. With 2 types of LED current programming resistors, 3 current-driving options can be designed by different combinations of enable circuit. ELM901A is capable of supplying output current up to 1A and thus able to provide high luminosity. To avoid LED burnout caused by longtime lighting by large current, the internal lighting timer of ELM901A can shut down current forcibly. The timer only operates when maximum setting current is on and can be set to 3 options-0.2s, 0.5s, 1s by external resistors connected to FS. This timer can be turned off when it is short between FS and VIN or FS is open. Operation right after power is supplied ELM901 becomes standby operation when EN1=EN2=0 or open(standby); unde this operation, high resistance PMOS switch between VIN and VO becomes ON. PMOS switch (=switch 4) between CP and VO and NMOS switch (=switch 1) between CM and PGND1 also become on. Hence, output capacitor Co and flying capacitor C1 are gradually charged through high resistance PMOS switch; it takes 5ms to fullcharge after the power is on. Rush current may happen when operation starts within 5ms after power is on. Standby mode In this mode, output capacitor Co and flying capacitor become fully charged, and through individual high resistance PMOS switch, VIN is turned to be output mode. With maintenance of fully-charged mode during standby situation, it is possible to avoid rush current when operation begins and lighten LED rapidly. Start-up mode During start-up, ELM901 detects VO short first; the low resistance switch between VIN-VO becomes on and operates in 1x mode if short is not detected. When short is detected, Vo maintains the same condition as in standby mode, the output of LED also remains off while other internal circuits are operated normally. 1x mode is operated right after short is solved. It takes 30ms(typ.) from start-up to 1x mode output. Vo=Vin under normal operation, and inrush current does not occur due to the charge of capacitor. When abnormality (Vo>0.7V) such as short between VO and GND which is resulted from resistance of 10~1KΩ, inrush current occurs due to the charge of capacitor. LED current becomes ON after 130μs(typ.) after starpup; it takes less than 100us since LED current becomes ON until the set current flows. 1x mode When dropout of LED pin is detected under 1x mode, the operation switches to 2x mode automatically. When LED current works under “low” current mode, the operation remains 1x mode for around 150ms even if the dropout of LED pin is detected; if dropout is dissolved during this period of time, timer is reset and 1x mode continues. When the operation is by “high” or “low+high” current, it becomes 2x mode after 2ms; if dropout is dissolved during this period of time, timer is reset and 1x mode continues. Dropout detection voltage is in proportion to Iled when it is above 240mA(typ.) and the voltage is regulated to 100mV when Iled is small. 11 - 5 ELM901FxA 1A 2x Charge Pump LED Driver Soft step-up The operation becomes soft step-up by charge pump operation right after 2x mode starts. Rush current is decreased by soft step-up which increases Vo straight. The current is controlled when Iled becomes 1/2 of the setting during soft step-up. Iled is limited under 350mA(typ.) forcibly to avoid abrupt change of Iled within 10us after step-up operation starts. Iled control current returns to the setting after step-up is finished. 2x mode After switching to normal 2x mode, operation remains this mode until standby mode(EN1=EN2=GND) starts. To work under 1x mode again, it is necessary to restart after switching to standby mode. ■Protection function Thermal protection When junction temperature becomes over 150°C, Vo output is turned to be OFF (only high resistance PMOS switch is ON)thermal shutdown circuit and LED output is shut down by thermal shutdown circuit. To shut down thermal protection, it is necessary to restart operation after returning to standby mode. ISET1/ISET2 short protection When EN1=0→1 during start-up, if Rset which is connected to ISET1 is under 3.9kΩ(setting current of Iled is above 1A),LED current which is the same with[low] current is shut down. If ISET2 is under normal operation under this situation, LED current which is the same with[high] current is flowed. When it is short between ISET1 and GND under the operation that EN1=1, LED current limit is detected by 1.5A and shut down without flowing to EN logic. When EN2=0→1 during start-up, if Rset which is connected to ISET2 is under 3.9kΩ( setting current of Iled is above 1A), LED current which is the same with[high] current is shut down. If ISET1 is under normal operation under this situation, LED current which is the same with[low] current is flowed. When it is short between ISET2 and GND under the operation that EN2=1, LED current limit is detected by 1.5A and shut down without flowing to EN logic. LED current becomes 0 when [low]+[high]current reaches 1.5A under EN1=EN2=1 under the above-mentioned 2 situations. VO short protection When VO lowers to around 0.7V during operation, device shuts down the outputs of both Vo and LED; Vin and Vo become connected by high resistance PMOS switch(standby output) under this situation. After VO short is dissolved and Vo rises above 0.7V, outputs of Vo and LED restart. When VO short is detected under 2x mode, the operation switches to standby mode. Fail safe function Fail safe function refers to the function that the output of LED is turned to be OFF automatically when “low+high” current(EN1=EN2=1) continues for certain period of time. To dissolve the function that LED output is turned to be OFF forcibly, it is necessary to switch EN1=EN2=1 to other modes. 3 options are available for FS time; FS time is set by external resistors (Rfs). This function can be turned off by setting short between FS and VIN pins or FS to be open. 11 - 6 ELM901FxA 1A 2x Charge Pump LED Driver ■Electrical characteristics When conditions are not mentioned specifically, Vin=3.6V, Cin=C1=2.2μF, Co=4.7μF, Ta=25°C Parameter Symbol Condition Min. Typ. Max. Unit Input voltage range Vin 2.6 4.4 V current consumption under Iqs1 1x mode, Iled=0mA 300 550 μA still condition 1 current consumption under Iqs2 2x mode, Iled=0mA 9 16 mA still condition 2 Standby current Isd EN1=EN2=0V 0.1 1.0 μA LED current LED current ratio1 typ.× typ.× Iled1 Vin=3.8V, Iled=200mA, Vf=3.3V 3250 mA/mA (Iled/Iset1/2) 0.96 1.04 LED current ratio2 Vin=3.3 to 4.4V, typ.× typ.× Iled2 3250 mA/mA (Iled/Iset1/2) Iled=200 to 800mA 0.90 1.10 Vled1 Mode switch threshold voltage, Iled dropout voltage1 125 225 mV (Min.) Iled=300mA Vled2 Mode switch threshold voltage, Iled dropout voltage2 80 100 120 mV (Min.) Iled=150mA Mode switch delay time1 Td1 EN1=High, EN2=Low 100 150 200 ms Mode switch delay time2 Td2 EN1=Low or High, EN2=High 1 2 3 ms since EN is ON until LED current LED current on time LED(on) 50 130 250 μs starts Iled Vin=3.3V, EN1=EN2=High, set Current capability 900 mA (Max.) Iled=1A, VF=4.6V LED current stablize time1 TIled1 Iled=0mA→200mA 40 μs LED current stablize time2 TIled2 Iled=200mA→700mA 60 μs LED current during soft Iled set Iled=700mA 250 350 450 mA step-up (soft) Charge pump Soft step-up Tsoft Iled=700mA, Vo=3.7V→5.2V 75 150 300 μs 1x mode output voltage Vo(x1) Iled=0mA Vin V typ.× typ.× 2x mode output voltage Vo(x2) Iled=0mA 5.5 V 0.95 1.05 1x mode output impedance Ro(x1) Vin=3.4V 0.25 0.37 Ω (2Vin-Vo)/Io, Vin=3.2V, 2x mode output impedance Ro(x2) 1.70 2.55 Ω Vo=5.1V Oscillation frequency Fosc 0.72 0.90 1.08 MHz EN1, EN2 Output on control voltage Vc(ON) Vin=2.9 to 4.4V, each pin 0.95 V Output off control voltage Vc(OFF) Vin=2.9 to 4.4V, each pin 0.45 V EN bias current Ic(ON) Ven=3.6V, each pin 20 50 μA ISET1, ISET2 Reference voltage Vref Iset=50μA, each pin 1.202 1.220 1.238 V ISET set current Iset each pin 310 μA 11 - 7 ELM901FxA Parameter Short protection circuit 1A 2x Charge Pump LED Driver Symbol Condition Min. ISET1&2 turn Iled to be OFF Iled Iled limit when ISET is short for short protection, Vin=3.9V, (short) Vled=1.0V, 2x operation VO short protection detection Vo Iled is OFF when short protection 0.45 voltage (short) is activated VO short current Ishort Vin=3.6V Thermal protection circuit Iled is OFF when thermal Thermal protection circuit OHP protection circuit is activated Fail safe circuit Tfs Fail safe set range 0.2 (range) Fail safe function is OFF when Fail safe time1 Tfs1 * 0.80 FS-VIN is short or open. Fail safe time2 Tfs2 0.16 Fail safe time3 Tfs3 0.40 Fail safe current Ifs 10 FS threshold voltage1 Vfs1 0.120 FS threshold voltage2 Vfs2 0.405 FS threshold voltage3 Vfs3 1.080 Parameter EN logic & LED current EN logic Standby(output OFF) Low current High current Low+High current Typ. Max. Unit 1.5 0.60 A 0.95 V 30 mA 150 °C 1.00 0.20 0.50 15 0.150 0.450 1.220 1.0 s 1.20 0.24 0.60 20 0.180 0.495 1.360 s s s μA V V V Condition EN1 0 1 0 1 EN2 0 0 1 1 * EN1 & EN2 will be in standby mode when being pulled down to be open. ■Marking • QFN16-4x4 package : ELM901FAA • QFN16-3x3 package : ELM901FBA ELM 901FAA a bc ELM 901FBA a bc Mark ELM901FAA abc (000 to 999) Content Name Mark ELM901FBA abc (000 to 999) Assembly lot No. 11 - 8 Content Name Assembly lot No. ELM901FxA 1A 2x Charge Pump LED Driver ■Typical characteristics EFFICIENCY-Vin ILED= 200mA 400mA 600mA 80 Dropout Voltage (V) EFFICIENCY (%) 90 70 60 50 Dropout Voltage-Iled 0.5 LED = LUMILEDS LXHL-LW3C 100 800mA 40 30 20 0.4 0.3 0.2 0.1 10 0 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 Iled-Rset 1000 Iled (mA) 900 900 800 500 400 500 200 200 100 100 0 0 20 40 60 80 100 120 140 160 180 200 Rset (k�) 100mA 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 2x Mode Output Resistance - Top 1x Mode Output Resistance - Top Vin=3.2V, Vo=4.8V 2.5 Vin=3.3V 0.2 0.15 Vin=3.6V Vin=3.9V 0.1 0.05 0 -40 200mA Vled (V) 2x Mode Output Resistance (�) 1x Mode Output Resistance (�) 0.25 400mA 400 300 0 600mA 600 300 -20 0 20 40 Top (�) 60 1000 Iled=800mA 700 Iled (mA) Iled (mA) 700 600 800 Iled-Vled 1000 800 600 400 200 Vin (V) 2 1.5 1 0.5 0 -40 80 11 - 9 -20 0 20 40 Top (�) 60 80 ELM901FxA Isd-Vin 0.1 Frequency (kHz) Top=85� 0.06 0.04 Top=25� 0.02 Vref-Top Iled/Iset Ratio-Top 3280 Iled/Iset Ratio Vref (V) 1.21 3260 3240 3220 -20 0 20 40 Top (�) 60 3200 -40 80 EN Pin Input Current-Top 0.9 EN Thereshold Voltage (V) EN Pin Input Current (uA) Top= -40� 3300 1.22 25 20 15 10 -40 860 Vin (V) 1.23 30 880 820 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 Vin (V) 1.24 Top=85� Top=25� 900 840 Top=��40� 0 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 1.2 -40 Frequency - Vin 940 920 0.08 Isd (�A) 1A 2x Charge Pump LED Driver -20 0 20 40 Top (�) 60 11 - 10 0 20 40 Top (�) 60 80 EN Threshold Voltage-Top 0.8 0.7 0.6 0.5 -40 80 -20 -20 0 20 40 Top (�) 60 80 ELM901FxA 1A 2x Charge Pump LED Driver Iled Start Response Iled/Iset Ratio-Iled 3350 Vin=3.6V, Iled=0mA�200mA 300 200 Top=85� Iled (mA) 3250 Top=25� 0 V(EN1) : 0V � 3.6V Top= -40� 3200 3150 100 0 200 400 Iled (mA) 600 800 0 40 Iled 0 Vo Vo, V(EN2) (2V/Div) 240 Time (us) 320 400 Vin=3.6V, Iled=800mA Iled (mA) Iled (mA) Vin=3.6V, Iled=200mA�800mA 400 160 Iled, Vo Ripple Voltage 1x to 2x Mode Switch Response 800 80 Iled A/C Coulpled 20 0 -20 -40 200 Vo A/C Coulpled V(EN2) : 0V � 3.6V 100 0 -100 0 0.8 1.6 2.4 Time (ms) 3.2 4 0 11 - 11 2 4 6 Time (us) 8 -200 10 Vo (mV) Iled/Iset Ratio 3300