BD60A00NUX LED Drivers for LCD Backlights White Backlight LED Drivers for Small to Medium LCD Panels (Switching Regulator Type) BD60A00NUX, BD60A60NUX No.11040EAT42 ●Description This IC is boost DC/DC converter that can drive white LED with constant current. More stabled white LED lighting can be achieved by direct current connection without electric tolerance and High-speed response by current mode. Moreover, separating IC power supply (2.7V~5.5V) and coil power supply (2.3V~20V) makes it possible to widen input range, which will be helpful to be applied to various kinds of applications. Over voltage setting can be selected corresponding to the number of LED lightings. BD60A00NUX is for max 11 lightings, BD60A60NUX is for max 6 lightings. ●Features 1) Boost DC/DC converter 2) Drive LED 11 lightings (VOUT=3.6V×11+0.7V=40.3V <Vf MAX=3.7V>) BD60A00NUX 3) Brightness control by outside PWM signal (PWM frequency =100Hz~30kHz, 25kHz 1% dimming application) 4) Brightness control by DC input 5) Soft start function (1ms typ.) 6) Over voltage protection 42V typ. ( BD60A00NUX), 28Vtyp.( BD60A60NUX) 7) SBD open protection and output short protection 8) Over current protection 9) LED terminal over voltage protection 10) UVLO 11) VSON008x2030 package (2.0mm × 3.0mm × 0.6mm MAX) ●Applications Digital video cameras, digital single-lens reflexes, digital still cameras, digital photo frames, personal navigations (PND), mobile phones, smart phones, MID, PDA, hand-held computers, MP3 players, GPS, digital media players, etc. ●Absolute maximum ratings Parameter Symbol Ratings Unit Maximum applied voltage 1 VMAX1 7 V Maximum applied voltage 2 VMAX2 45 V Maximum applied voltage 2 VMAX3 31 V Operating temperature range Topr -40 ~ +85 ℃ Storage temperature range Tstg -55 ~ +150 ℃ Power dissipation 1 Pd1 2000 mW *1 Condition Vin, EN, PWM, ISET terminals FB, SW, Vout terminals BD60A00NUX FB, SW, Vout terminals BD60A60NUX *1 4 layer (ROHM Standard board) has been mounted. When it’s used by more than Ta=25℃, it’s reduced by 20mW/˚C. ●Recommended operating range (Ta=-40℃ ~ +85℃) Parameter Symbol Ratings Unit Conditions Operating power supply voltage VIN 2.7 ~ 5.5 * V Vin terminal Operating coil voltage Vcoil 2.3 ~ 20 V Coil voltage *When the operating supply voltage is over 4.61V for BD60A00NUX, please refer the application P.17 www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 1/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Electrical characteristics (Unless otherwise specified, Ta=25℃, Vin=3.6V) Limits Parameter Symbol Min. Typ. Max. Quiescent Current Unit Conditions Iq - 0.1 1.0 μA EN=0V IddNB - 1.5 3.0 mA EN=2.8 V, PWM=0V IddB - 2.5 5.0. mA EN=2.8 V, PWM=2.8 V Low Input Voltage range VthL - - 0.5 V High Input Voltage range VthH 1.4 - - V Pull down register Rcnt 65 100 135 kΩ FB Terminal Control Voltage FB 0.56 0.70 0.84 V Switching Frequency fSW - 600 - kHz Max Duty Duty 90 95 - % FB=0V SW Transistor ON Resistor Ronn - 0.5 - Ω Isw=80mA SW Transistor Leak Current IqSW - 0.1 2.0 μA EN=0V Icoil - 750 - mA *1 OVP1 40 42 44 V Detect voltage of VOUT terminal OVP2 26 28 30 V Detect Voltage of VOUT terminal Over Voltage Limit Hysteresis OVPhy - 1 - V VOUT Terminal Leak Current IqVOUT - 0.1 1.0 μA EN=0V Sop - 0.2 - V Detect Voltage of VOUT terminal LEDOVP 4.4 5.9 6.4 V PWM=2.8V UVLO - 2.2 - V Vin falling edge LED Maximum Current ILMAX - - 30 mA LED Current Accuracy ILACCU - - ±3.0 % LED Current Limit ILOCP - 0 0.1 mA Current Limit Value at ISET Resistor 1kΩ Setting LED Leak Current IqLED - 0.1 2.0 μA EN=0V Iset - 0.6 - V Current Consumption (No Boost) Current Consumption (Boost) [EN, PWM Terminal] [Switching Regulator] [Protection] Over Current Limit Over Voltage Limit BD60A00NUX Over Voltage Limit BD60A60NUX Shot key Diode Open Protection LED Terminal Over Voltage Protection Detect Voltage of Low Voltage [Current Driver] ISET Terminal Voltage *1 VIN=4V, Cout=1µF ILED=20mA This parameter is tested with DC measurement. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 2/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Block Diagram and Application L1 10μH Coil Power 2.3V to 20V 11 LEDs Cout 2.2.μF D1 Cbat 4.7μF IC Power 2.7V to 5.5V VOUT SW Thermal Shutdown Vin + - TSD Cin 1μF Over & under Voltage Protect UVLO PWMcomp S Q Q1 ERRAMP + Control R Current Sense + FB + Current OSC ISET Driver Over Current protect EN PWM GND Enable control PWM control Fig.1 Block Diagram and Application ・Pin assignment table PIN No. PIN Name In/Out Function Terminal Diagram 1 EN In Enable Control B 2 VIN In Battery Input C 3 PWM In PWM Input B 4 ISET In LED Current Setting Terminal A 5 FB In Feedback Voltage Input B 6 VOUT In Over Voltage Protection Input B 7 GND - GND C 8 SW Out Switching Terminal B ●Terminal Diagram Vin Vin P IN P IN GND G ND A GND B C Fig.2 Terminal Diagram www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 3/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Main characteristics examples 1) Efficiency ●BD60A60NUX <efficiency – ILED> LED 6series, coil : VLF302512MT-100M ●BD60A00NUX <efficiency – ILED> LED 10series, coil : VLF302512MT-100M coil : VLF302512MT-100M www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 4/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX IC Power=5.0V, Coil Power=4V to 16V ・BD60A00NUX IC Power=5.0V, Coil Power=2.7V to 20V, LED 8serial, LED current =25mA, coil 1094AS-10M(TOKO), SBD RB060M-60TR(ROHM) 95 eff1 eff2 90 efficiency (%) BD60A00NUX Vcoil vs efficiency VIN=5V Ta=25℃ LED 8灯(26V) coil 1094AS-10M(TOKO) SBD RB060M-60TR(ROHM) LED電流設定 25mA PWM=100% 85 eff1=(Vout*ILED)/(Vcoil*Icoil)*100 eff2=(Vout*ILED)/(Vcoil*Icoil+VIN+IVIN)*100 80 75 70 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Vcoil (V) ・BD60A60NUX IC Power=5.0V, Coil Power=2.7V to 20V, LED 6serial, LED current =25mA, coil 1094AS-10M(TOKO), SBD RB521A-40TR(ROHM) 95 BD60A60 Vcoil vs efficiency VIN=5V Ta=25℃ LED 6灯(20V) coil 1094AS-10M(TOKO) SBD RB521S-40(Rohm) for BD60A60 LED電流設定 25mA PWM=100% 90 efficiency (%) eff=(Vout*ILED)/(Vcoil*Icoil+VINI*VIN)*100 85 80 75 70 2 3 4 5 6 7 8 9 10 11 12 13 14 Vcoil (V) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 5/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX 100mV/div VOUT LED current PWM PWM 20kHz Duty 50% 40µs/div 100mV/div VOUT LED current PWM 200ns/div PWM 20kHz Duty 1% www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 6/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ・BD60A00NUX PWM duty – LED current IC Power=5.0V, LED 8serial, LED current =25mA, PWM frequency = 20kHz, Ta=25deg coil 1094AS-10M(TOKO), SBD RB060M-60TR(ROHM) 100.00 BD60A00NUX Vcoil vs efficiency VIN=5V Ta=25℃ LED 8 灯(26V) coil 1094AS-10M(TOKO) SBD RB060M-60TR(ROHM) LED current 25mA PWM frequency 20kHz LED current (mA) 10.00 1.00 0.10 0.01 0.1 1.0 0.4% 10.0 100.0 PWM duty (%) Possible to Duty 0.4% at PWM=20kHz www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 7/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Functional Descriptions 1) PWM current mode DC/DC converter This IC keeps output voltage invariably by setting PWM duty to make FB terminal 0.7V when the power is on. As for the inputs of the PWM comparator as the feature of the PWM current mode, one is overlapped with error components from the error amplifier, and the other is overlapped with a current sense signal that controls the inductor current into Slope waveform to prevent sub harmonic oscillation. This output controls internal Nch Tr via the RS latch. In the period where internal Nch Tr gate is ON, energy is accumulated in the external inductor, and in the period where internal Nch Tr gate is OFF, energy is transferred to the output capacitor via external SBD. This IC has many safety functions, and their detection signals stop switching operation at once. 2) Soft Start This IC has soft start function, which prevents rush current at turning on. After EN and PWM are changed L H, soft start becomes effective within 1ms. Soft start doesn't become effective even if Enable is changed L H, after that. By changing EN and PWM L H, soft start can become effective. Since a soft start function stops working at the time of following PWM=H when EN=H is held with PWM=L After EN=H should input a PWM signal within 10ms. EN EN Soft start time Finish PWM PWM Soft Start OFF Soft Start Reset Within 10ms ON OFF ON OFF OFF OFF Reset ON OFF Reset Fig.3 Soft start www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 8/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Protection ・Over voltage protection At such an error of output open as the output DC/DC and the LED is not connected to IC, the DC/DC boosts too much and the VOUT terminal exceeds the absolute maximum ratings, and may destruct the IC. Therefore, when the VOUT becomes sensing voltage or higher, the over voltage limit protection works, turns off the switching Tr, DC/DC will be stopped, and the output voltage goes down slowly. When output voltage becomes below the hysteresis voltage of Over voltage protection, A boost function works and output voltage reaches detection voltage again. This operation is repeated unless the abnormalities in application are recovered. ・Schottky Diode open protection In the case of external SBD is not connected to IC, or VOUT is shorted to GND, the coil or internal Tr may be destructed. Therefore, at such an error as VOUT becoming 0.2V or below, turns off the output Tr, and prevents the coil and the IC from being destructed. And the IC changes from activation into non-activation, and current does not flow to the coil (0mA). ・Thermal shut down This IC has thermal shut down function. The thermal shut down works at 175C or higher, and the IC changes from activation into non-activation. ・Over Current Protection Over current flows the current detection resistor that is connected to between internal switching transistor source and GND. Current sense voltage turns more than detection voltage, over current protection is operating and it is prevented from flowing more than detection current by reducing ON duty of switching Tr without stopping boost. As over current detector of This IC is detected peak current, current more than over current setting value does not flow. SW + - < The estimate of the current value which need for the normal operation> As over current detector of This IC is detected the peak current, it has to estimate peak current to flow to the coil by operating condition. In case of, ○ Switching frequency = fsw Typ=0.6MHz ○ Supply voltage of coil = VIN ○ Inductance value of coil = L ○ Output voltage = VOUT ○ Total LED current = IOUT ○ Average current of coil = Iave ○ Peak current of coil = Ipeak ○ Efficiency = eff ○ ON time of switching transistor = Ton Ipeak = (VIN / L) × (1 / fsw) × (1-(VIN / VOUT)) Iave=(VOUT × IOUT / VIN) / eff 1/2 Ton=(Iave × (1-VIN/VOUT) × (1/fsw) × (L/VIN) × 2) As peak current varies according to whether there is the direct current superposed, the next is decided. (1-VIN/VOUT) × (1/fsw) < Ton peak current = Ipeak /2 + Iave (continuous mode CCM) (1-VIN/VOUT) × (1/fsw) > Ton peak current = (VIN / L)×Ton (discontinuous mode DCM) (Example 1) In case of, VIN=6.0V, L=10µH, fsw=0.6MHz, VOUT=32.5V, IOUT=25mA, current =85% Ipeak = (6.0V / 10µH) × (1 / 0.6MHz) × (1-(6.0V / 32.5V)) =0.82 A Iave = (32.5V × 25mA / 6.0V) / 85% = 0.16A Ton = (0.16A × (1-6.0V / 32.5V) × (1 / 0.75MHz) × (10µH /6.0V) × 2)1/2 = 0.85µs (1- VIN/VOUT) × (1/fsw)=1.36µs > Ton peak current = (6.0V / 10µH)×0.85µs =0.51A www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 9/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ・LED terminal over voltage protection When FB terminal becomes higher than 5.9V(typ), IC senses the situation trouble after 100us and then stops constant current driver and DC/DC. Therefore IC becomes never heated, even if output and FB are both shorted. Moreover, if FB terminal becomes lower than 5.9V(typ), IC senses normal condition and activates constant current driver. FB 5.9 V 0V Current Driver DC/DC Active reset Active Active Active Active ・Prevention of LED terminal over voltage protection malfunction As the below diagrams show, voltage drop of FB terminal becomes slow when PWM operates by connecting capacitor on a parallel with LED and decreasing LED current. At that time, LED terminal voltage protection works after condition of FB terminal > 5.9V keeps more than 100us. LED terminal voltage protection might stop current driver and DC/DC and also turns off LEDs, so that please set up coil selection and LED current setting less than 100us until FB terminal < 5.9V. FB 100us VOUT Current Driver DC/DC 5.9 V reset Active reset reset Active reset FB PWM H L EN H L ・Low voltage detect protection (UVLO) Supply voltage(VIN) becomes lower than low voltage detect voltage 2.2V(typ), IC stops DC/DC and constant current driver. Moreover, this function can be off by boosting supply voltage up to more than hysteresis voltage. VIN 5% 2.20 V 2.32 V 0V DC/DC Current Driver Active www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. reset 10/22 Active 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Operating of the application deficiency 1) When 1 LED or 1string OPEN during the operating Since FB terminal is set to 0V when set to OPEN, Output boosts up to the over voltage protection voltage. When over voltage is detected, the boosting operation stops and then output voltage goes down slowly. Later, if output voltage becomes less than hysteresis of over current protection, output voltage keeps boosting up to over voltage protection voltage again. Vout Hysteresis voltage FB voltage FB LED connection normal Open LED current 20mA 0mA Fig. 8 LED open detect 2) When LED short-circuited in the plural Even if one LED short-circuits during boost operation, it usually passes along LED and it is turned on. By making LED shorted, FB terminal voltage increases by LED VF. Therefore output voltage becomes lower by LED VF, and the condition turns to be normal. VOUT output VF of LED LED short 0.7V+VF of LED FB FB 0.7V LED current VF of LED 20mA Fig. 9 One LED shorted VOUT VOUT VIN LED short 5.9V FB 0.7V FB 0.1mA LED current 20mA 100uS Fig.10 FB terminal – VOUT terminal shorted www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 11/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX 3) When Schottky diode(SBD) remove In the situation that connection is opened and also DC/DC is activated, SW terminal voltage becomes more than rated voltage due to a lack of parts that can accept the current accumulated inside the coil. Consequently IC might be destroyed. To prevent the IC destruction, SBD open protection is functioned. SW terminal is never destroyed as boosting operation is stopped after VOUT terminal detects less than 0.2V. 4) When resistance linked to an ISET terminal short-circuits Since Resistor connected to ISET terminal becomes 0Ω, LED current setting value becomes more than rating. In order to avoid this trouble, this IC has LED current limit protection. By using this function, setting current of rating current driver becomes 0mA, and the current flow of LED is almost same as leak current. ●Control signal input timing 2.2V ① VIN VIN ② Min. 100µs ③ EN EN PWM PWM DC/DC VOUT DC/DC VOUT Min. 10ms Fig.11 Control signal input timing When input control signals such as Enable and PWM without completing the standup of supply voltage (VIN), be careful of the following points. ① Input each control signal after VIN exceeds 2.2V and UVLO is off. ② When input Enable and PWM, the standup time should be placed as Min.100µs from 2.2V to stable voltage for VIN. ③ Since a soft start function stops working at the time of following PWM=H when EN=H is held with PWM=L. After EN=H should input a PWM signal within 10ms. ●Start control (EN) and select LED current driver (PWM) This IC can control the IC system by EN terminal and also turns off compulsorily by setting “L” level input voltage 0.4V or below. It also powers on when EN becomes more than “H” level input voltage 1.4V. In the case of EN=H, LED current fixed by ISET resistor with PWM=H flows. When it is selected at PWM=L, LED current stop to flow. EN L H L H PWM L L H H IC Off On Off On LED current Off Off Off Current fixed by ISET ●LED current setting range LED current sets up normal current by resister (RISET) connected to ISET voltage. Each setting current is shown as below. Normal current = 600/RISET [A] Normal current setting range is 10mA~30mA, and also LED current at off setting is MAX 2µA of leak current. ISET Normal current setting example RISET 20.0kΩ (E96) 24.0kΩ (E24) 30.0kΩ (E24) 56.0kΩ (E24) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. LED current 30.0mA 25.0mA 20.0mA 10.7mA 12/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Brightness control There are two dimming method available; the first method is analog dimming that applies analog voltage to ISET terminal, and the second method is digital dimming that inputs PWM to PWM terminal. Since each method has the different merits, please choose a suitable method for the application of use. Current driver PWM control is controlled by providing PWM signal to PWM, as it is shown Fig.12. The current set up with ISET is chosen as the H section of PWM and the current is off as the L section. Therefore, the average LED current increases in proportion to duty cycle of PWM signal. This method that internal circuit and DC/DC work, because it becomes to switch the driver, the current tolerance is a few when the PWM brightness is adjusted, so it makes it possible to brightness control until 0.4µs (MIN1% at 25kHz). And, don't use for the brightness control, because effect of ISET changeover is big under 0.4µs ON time and under 3µs OFF time. Typical PWM frequency is 100Hz~25kHz. L1 10μH Vin 2.7V to 4.6V 30 Cout 2.2μF Cin 4.7μF 25 Vin PWM Input SW Vout 25mA PWM RESET EN FB ISET R1 24kΩ GND LED Current [mA] 1) 20 15 10 5 PWM ON OFF LED current ON OFF Coil current ON OFF 0 0 20 40 60 80 PWM Hi duty [%] 100 ON IC’s active current Fig.12 PWM sequence Analog dimming can be operated by applying voltage to ISET terminal via resistor as the below figure shows. ISET terminal voltage works to become 0.6V regardless of the connected resistor. LED current increases ISET terminal current 600 times, so that LED current can be minimized by decreasing flow current into ISET terminal using external DC input Vin 2.7V to 4.6V L1 10μH Cout 2.2μF Cin 4.7μF 30 Vin LED ON/OFF RESET 25 EN FB ISET R1 470kΩ Vout PWM R2 22kΩ DC SW LED Current [mA] 2) GND 20 15 10 5 1000 1000 x 0.6V + 0.6V - DAC output LED current = 22kΩ 470kΩ 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 DC Voltage [V] www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 13/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX 3) The brightness control to set large current over IC max setting current is made by giving DC control voltage to VFB pin of IC via a series resistor as shown in under figure. LED luminance (current) changed by giving DC voltage to VFB directly. DC voltage is given from filtered one of DAC signal, or PWM signal shown in under figure. LED current (ILED) is next expression. ILED = [[(FB-DC) / R1] * R2 + FB ] / RFB L1 10μH BD60A60NUX 3LEDx7pararel Cout 2.2μF Cin 4.7μF Vin 3s7p Vout SW PWM RESET R2 6.8kΩ EN FB ISET R1 22kΩ GND RFB 6.49Ω ILED total (mA) Vin 2.7V to 4.6V DC DC (V) Vin 2.7V to 4.6V L1 10μH Cout 2.2μF Cin 4.7μF Vin 3s7p Vout SW PWM RESET EN 33kΩ FB ISET 47kΩ GND 5Ω 100kΩ PWM 0 - 3.3V www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 47nF 14/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●The coil selection The DC/DC is designed by more than 4.7µH. When L value sets to a lower value, it is possibility that the specific sub-harmonic oscillation of current mode DC / DC will be happened. Please do not let L value to 3.3µH or below. And, L value increases, the phase margin of DC / DC becomes to zero. Please enlarge the output capacitor value when you increase L value. ●Output capacitor selection Output Capacitor smoothly keeps output voltage and supplies LED current. If LED current is set more than 20mA with Vcoil=2.3V～5.5V, please make output capacitor more than 2.2µF. Otherwise phase margin of DC/DC decreases and might oscillate. Output Voltage consists of Charge (FET ON) and Discharge (LED current). So Output voltage has Output ripple Voltage every FET switching. Output ripple voltage is calculated as following. Output ripple Voltage - Switching cycle = T - Total LED current = ILED - Switching ON duty = D - Output ripple Voltage = Vripple - Output Capacitor (real value) = Creal - Output Capacitor = COUT - Decreasing ratio of Capacitor = Cerror (Capacitor value is decreased by Bias, so) Creal = COUT × Cerror Creal = ILED × (1-D) × T / Vripple COUT = ILED × (1-D) × T / Vripple / Cerror (Example 1) In case of, VIN=5.0V, fsw = 0.6MHz, VOUT =32.5V, ILED =20mA, COUT = 2.2µF, Cerror = 50% T = 1 / 0.6MHz D = 1 – VIN / VOUT = 1 – 5/32.5 Vripple = ILED × (1-D) × T / (COUT×Cerror) = 20mA × (5/32.5) ×(1 / 0.6MHz) / (2.2µF×0.5) = 4.7mV Cout Capa [µF] Creal 0V 35V 50V Output voltage ●LED selection Please select LED VF that input voltage is smaller than output voltage (VOUT). www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 15/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●The separation of the IC power supply and coil power supply This IC can work in separating the power source in both IC power supply and coil power supply. With this application, it can obtain that decrease of IC power consumption, and the applied voltage exceeds IC rating 5.5V. That application is shown in below Fig.14. The coil power supply is connected to high voltage source applied from adapters. Then the IC power supply is connected to the power supply that should be different from the coil power supply. 2,3cell Battery Coil Power 2.3V to 20V L1 10μH IC Power 2.7V to 4.6V Step down DC/DC Ccoil 4.7μF Cout 2.2μF Cin 1μF Vin PWM Input SW Vout 25mA PWM RESET EN FB ISET R1 24kΩ GND Fig.14 Application at the time of power supply separation １cell Battery L1 10μH IC Power 2.3V to 4.6V Cout 2.2μF Cin 4.7μF Vin PWM Input SW Vout 25mA PWM RESET EN FB ISET R1 24kΩ GND Fig.15 Application at the time of power supply common The number of available LEDs by each power supply voltage condition ＰＷＭ dimming（LED current setting＝25mA) ２セル １セル VIN LEDs 2.7V 3V 3セル ４V 5V 6V 7V 2 C、S C、S C、S C、S × × 3 C、S C、S C、S C、S S S 4 C、S C、S C、S C、S S S 5 C、S C、S C、S C、S S S 6 C、S C、S C、S C、S S S 7 C、S C、S C、S C、S S S 8 C、S C、S C、S C、S S S 9 C、S C、S C、S C、S S S 10 C、S C、S C、S C、S S S ※ C・・・Vcoil-Vin common power supply S・・・Vcoil-Vin separated power supply ×・・・No use due to LED terminal over voltage protection www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 8V 9V 10V 11V 12V 13V 14V 15V 16V 17V 18V 19V 20V × × S S S S S S S × × S S S S S S S × × S S S S S S S × × × S S S S S S × × × S S S S S S × × × × S S S S S × × × × S S S S S × × × × × S S S S × × × × × S S S S × × × × × × S S S × × × × × × × S S × × × × × × × S S × × × × × × × × S 16/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●About the order of a power supply injection at the time of power supply separation Even if the IC power supply is 0V, leak channel is blocked as pull down resistor for power off is placed inside the IC. The resistor intercepts leak channel from coil power supply. Additionally, there is no order for standing up and down of coil and IC power supply. At the time of starting It doesn’t matter whether coil Power or IC Power becomes activated first. ・ At the time of power supply OFF Please turn off after make EN terminal “L”. If power supply voltage of coil power becomes low, coil current increases due to high boosting, which leads to over current limit. In order to avoid this state, before turning off a power supply it is necessary to surely set EN to L. ・ Coil Power Free IC Power EN PWM VOUT ●Input voltage 5V（BD60A00NUX） The GND noise become big by impedance of PCB boards, so that wake up characteristics might become unstable. To select input voltage to 5V(input voltage 4.61V over), we recommend under application to insert 4.7Ω between input voltage line and Vin terminal L1 10μH Vin 2.7V to 5.5V Cin 4.7μF PWM Input Cout 2.2μF 4.7Ω Vin SW Vout 25mA PWM RESET EN FB RISET 24kΩ www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. ISET GND 17/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●PCB Layout In order to make the most of the performance of this IC, its PCB layout is very important. Characteristics such as efficiency and ripple and the likes change greatly with PCB layout, which please note carefully Vin 2.7V to 4.6V L1 10μH Cout 2.2μF Cin 4.7μF PWM Input Vin SW Vout 25mA PWM RESET EN FB RISET 24kΩ ISET GND <Input capacitor Cin (1μF) for coil> Connect input capacitor Cin (1μF) as close as possible between coil L1 and GND. <Schottky barrier diode SBD> Connect schottky barrier diode SBD as close as possible between coils L1and SW pin. <Output capacitor Cout> Connect output capacitor Cout between cathode of SBD and GND. Make both GND sides of Cin and Cout as close as possible. <LED current setting resistor RISET(24kΩ)>> Connect LED current setting resistor RISET(24kΩ) as close as possible between ISET pin and GND. There is possibility to oscillate when capacity is added to ISET terminal, So pay attention that capacity isn’t added. <Heat radiation of back side PAD> PAD is used for improving the efficiency of IC heat radiation. Solder PAD to GND pin. Moreover, connect ground plane of board using via as shown in the patterns of next page. The efficiency of heat radiation improves according to the area of ground plane. <Others> When those pins are not connected directly near the chip, influence is give to the performance of BD60A00NUX, and may limit the current drive performance. As for the wire to the inductor, make its resistance component small so as to reduce electric power consumption and increase the entire efficiency. The PCB layout in consideration of these is shown in the next page. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 18/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ● Recommended PCB layout www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 19/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Selection of external parts Recommended external parts are as shown below. When to use other parts than these, select the following equivalent parts. L1: This coil is for boosting. Recommended capacity value is 10uH. Please use the coil with adequate direct current capacity and also low direct current resistor. Value Manufacturer Product number 10µH 10µH 10µH 10µH TDK TDK TOKO TOKO VLF4012AT-100MR79 VLF302512MT-100M 1094AS-100M 1229AS-H-100M Vertical 4.0 3.0 3.5 3.5 Size Horizontal 3.8 2.5 3.7 3.7 Height 1.2 1.2 1.2 1.2 DC current (mA) 800 690 760 750 DCR (Ω) 0.30 0.25 0.18 0.24 Cin: This is bypath capacitor for power supply, which removes power supply noise occurred instantly and provides stable power supply for IC. In order to obtain better quality, please use low ESR products such as ceramic capacitors. Recommended capacity value is more than 1µF. C0: This is output smoothing capacitor. Recommended capacity value is 2.2µF. When choosing capacitors such as Cin and C0, please be careful of pressure. The base line of pressure is about 2 times of actual applying voltage. If pressure margin decreases, it might be happened that capacity value becomes almost a half of nominal value. Pressur Manufactur Product number e e [ Cin : Power supply voltage capacitor] 1.0µF 10V. MURATA GRM185B31A105 [ C0 : Output capacitor ] 1.0µF 50V MURATA GRM31MB31H105 2.2µF 50V MURATA GRM31CB31H225 Value Vertical Size Horizontal Height 1.6. 0.8. 0.5. 3.2 3.2 1.6 1.6 1.15 1.6 R1: LED current ILED should be decided when activated. Value Tolerance Manufacturer Product number [ R1 : Resistor used for deciding LED current] 20kΩ ±0.5% ROHM MCR03PZPZD2002 24kΩ ±0.5% ROHM MCR03PZPZD2402 30kΩ ±0.5% ROHM MCR03PZPZD3002 56kΩ ±0.5% ROHM MCR03PZPZD5602 Vertical Size Horizontal Height 1.6 1.6 1.6 1.6 0.8 0.8 0.8 0.8 0.45 0.45 0.45 0.45 ILED (mA) 30 25 20 10.7 D1: This schottky diode (SBD) is for output rectification. In order to obtain higher switching efficiency, please use low Vf, low reverse leak, and high current capacity. Size Pressure Manufacturer Product Number Vertical Horizontal Height 60V ROHM RB160M-60 3.5 1.6 0.8 40V ROHM RB521S-40 1.6 0.8 0.6 60V ROHM RB060M-60 3.5 1.6 0.8 www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 20/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Cautions on use (1) Absolute Maximum Ratings An excess in the absolute maximum ratings, such as supply voltage (Vin), temperature range of operating conditions (Topr), etc., can break down devices, thus making impossible to identify breaking mode such as a short circuit or an open circuit. If any special mode exceeding the absolute maximum ratings is assumed, consideration should be given to take physical safety measures including the use of fuses, etc. (2) Operating conditions These conditions represent a range within which characteristics can be provided approximately as expected. The electrical characteristics are guaranteed under the conditions of each parameter. (3) Reverse connection of power supply connector The reverse connection of power supply connector can break down ICs. Take protective measures against the breakdown due to the reverse connection, such as mounting an external diode between the power supply and the IC’s power supply terminal. (4) Power supply line Design PCB pattern to provide low impedance for the wiring between the power supply and the GND lines. Furthermore, for all power supply terminals to ICs, mount a capacitor between the power supply and the GND terminal. At the same time, in order to use an electrolytic capacitor, thoroughly check to be sure the characteristics of the capacitor to be used present no problem including the occurrence of capacity dropout at a low temperature, thus determining the constant. (5) GND voltage Make setting of the potential of the GND terminal so that it will be maintained at the minimum in any operating state. Furthermore, check to be sure no terminals are at a potential lower than the GND voltage including an actual electric transient. (6) Short circuit between terminals and erroneous mounting In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting can break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or between the terminal and the power supply or the GND terminal, the ICs can break down. (7) Operation in strong electromagnetic field Be noted that using ICs in the strong electromagnetic field can malfunction them. (8) Inspection with set PCB On the inspection with the set PCB, if a capacitor is connected to a low-impedance IC terminal, the IC can suffer stress. Therefore, be sure to discharge from the set PCB by each process. Furthermore, in order to mount or dismount the set PCB to/from the jig for the inspection process, be sure to turn OFF the power supply and then mount the set PCB to the jig. After the completion of the inspection, be sure to turn OFF the power supply and then dismount it from the jig. In addition, for protection against static electricity, establish a ground for the assembly process and pay thorough attention to the transportation and the storage of the set PCB. (9) Input terminals In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the parasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the input terminal. Therefore, pay thorough attention not to handle the input terminals, such as to apply to the input terminals a voltage lower than the GND respectively, so that any parasitic element will operate. Furthermore, do not apply a voltage to the input terminals when no power supply voltage is applied to the IC. In addition, even if the power supply voltage is applied, apply to the input terminals a voltage lower than the power supply voltage or within the guaranteed value of electrical characteristics. (10) Ground wiring pattern If small-signal GND and large-current GND are provided, It will be recommended to separate the large-current GND pattern from the small-signal GND pattern and establish a single ground at the reference point of the set PCB so that resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well. (11) External capacitor In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a degradation in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc. (12) Thermal shutdown circuit (TSD) When junction temperatures become 175℃ (typ) or higher, the thermal shutdown circuit operates and turns a switch OFF. The thermal shutdown circuit, which is aimed at isolating the LSI from thermal runaway as much as possible, is not aimed at the protection or guarantee of the LSI. Therefore, do not continuously use the LSI with this circuit operating or use the LSI assuming its operation. (13) Thermal design Perform thermal design in which there are adequate margins by taking into account the permissible dissipation (Pd) in actual states of use. (14) Selection of coil Select the low DCR inductors to decrease power loss for DC/DC converter. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 21/22 2011.12 - Rev.A Technical Note BD60A00NUX, BD60A60NUX ●Ordering part number B D 6 ROHM type name 0 A 0 0 N U X - Package NUX: VSON008X2030 Part No. BD60A00:60A00 BD60A60:60A60 T R Packaging and forming specification TR: Embossed tape and reel VSON008X2030 <Tape and Reel information> 3.0±0.1 2.0±0.1 0.6MAX 1PIN MARK 0.25 TR The direction is the 1pin of product is at the upper right when you hold ( reel on the left hand and you pull out the tape on the right hand ) (0.12) +0.03 0.02 −0.02 1.5±0.1 4000pcs 0.5 1 4 8 5 1.4±0.1 0.3±0.1 C0.25 Embossed carrier tape Quantity Direction of feed S 0.08 S Tape 1pin +0.05 0.25 −0.04 Reel (Unit : mm) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 22/22 Direction of feed ∗ Order quantity needs to be multiple of the minimum quantity. 2011.12 - Rev.A Notice Notes No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. The content specified herein is subject to change for improvement without notice. The content specified herein is for the purpose of introducing ROHM's products (hereinafter "Products"). If you wish to use any such Product, please be sure to refer to the specifications, which can be obtained from ROHM upon request. Examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the Products. The peripheral conditions must be taken into account when designing circuits for mass production. Great care was taken in ensuring the accuracy of the information specified in this document. However, should you incur any damage arising from any inaccuracy or misprint of such information, ROHM shall bear no responsibility for such damage. The technical information specified herein is intended only to show the typical functions of and examples of application circuits for the Products. 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Please be sure to implement in your equipment using the Products safety measures to guard against the possibility of physical injury, fire or any other damage caused in the event of the failure of any Product, such as derating, redundancy, fire control and fail-safe designs. ROHM shall bear no responsibility whatsoever for your use of any Product outside of the prescribed scope or not in accordance with the instruction manual. The Products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuelcontroller or other safety device). ROHM shall bear no responsibility in any way for use of any of the Products for the above special purposes. If a Product is intended to be used for any such special purpose, please contact a ROHM sales representative before purchasing. If you intend to export or ship overseas any Product or technology specified herein that may be controlled under the Foreign Exchange and the Foreign Trade Law, you will be required to obtain a license or permit under the Law. Thank you for your accessing to ROHM product informations. More detail product informations and catalogs are available, please contact us. ROHM Customer Support System http://www.rohm.com/contact/ www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. R1120A