BD6074GUT LED Drivers for LCD Backlights White Backlight LED Drivers for Small to Medium LCD Panels (Switching Regulator Type) No.11040EAT39 BD6074GUT ●Description The BD6074GUT is a white LED driver IC with synchronous rectification that can drive up to 4LEDs. With synchronous rectification (no external shottky diode required) and small package, they can save mount space. And the brightness of LED can be adjusted by using PWM pulse on EN pin. ●Features 1) Synchronous rectification Boost DC/DC converter 2) No external schottky diode required 3) Driving 4 series white LEDs 4) Over voltage protection 5) Protect open and short output 6) Thermal shut down 7) Brightness adjustment by external PWM pulse 8) Small and Thin CSP package in 8pins ●Applications White LED Backlight Torch light and easy flash for camera of mobile phone ●Absolute maximum ratings (Ta=25℃) Parameter Symbol Ratings Maximum applied voltage 1 VMAX1 7* Maximum applied voltage 2 VMAX2 20 *1 Pd 800 * mW Operating temperature range Topr -30~+85 ℃ Storage temperature range Tstg -55~+150 ℃ Power dissipation Unit 1 2 Condition V Vin, EN, VFB, TEST V SW, Vout *1 These value are based on GND and GNDA pins. *2 50mm×58mm×1.75mm At glass epoxy board mounting. When it’s used by more than Ta=25 ℃, it’s reduced by 6.4mW/℃. ●Operating range（Ta=-30℃~+85℃） Parameter Power supply voltage www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. Symbol Vin Ratings Min. Typ. Max. 2.7 3.6 5.5 1/15 Unit Condition V 2011.12 - Rev.A Technical Note BD6074GUT ●Electrical characteristics Unless otherwise specified Ta =-30℃ ~+85℃, Vin=3.1~5.5V Parameter Symbol Limits Min. Typ. Max. Unit Condition [ EN terminal ] EN threshold voltage (Low) VthL - - 0.4 V EN threshold voltage (High) VthH 1.4 - - V Iin - 18.3 30.0 µA EN=5.5V Iout -2.0 -0.1 - µA EN=0 Quiescent Current Iq - 0.1 2.0 µA EN=0V Current Consumption Idd - 1.1 1.5 mA EN=2.6V,VFB=1.0V,VIN=3.6V Feedback voltage Vfb 0.47 0.50 0.53 V Inductor current limit Icoil 310 400 490 mA SW saturation voltage Vsat - 0.10 0.28 V Isw=200mA, Vout=13V SW on resistance P Ronp - 2.1 3.2 Ω Ipch=200mA,Vout=13V Switching frequency fSW 0.8 1.0 1.2 MHz Duty cycle limit Duty 82.7 92.5 - % Output voltage range Vo - - 18.0 V Over voltage limit Ovl 18.0 18.5 19.0 V Start up time Ts - 0.5 1.0 ms EN terminal input current EN terminal output current [ Switching regulator ] Vin=3.6V *1 VFB=0V VFB=0V *1 This parameter is tested with DC measurement. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 2/15 2011.12 - Rev.A Technical Note BD6074GUT ●Test circuit *Test circuit A (for Inductor current limit, Feedback voltage, Start up time.) Procedure ~Inducton current limit~ 1. Start to increase Iout from 0mA gradually. 2. You will find that Vout will start to go down and the duty will be decreased. 3. Then, you can measure the coil current as “inductor current limit” ~VFB voltage~ 1. Supply 0mA to Iout 2. Then, you can measure the VFB voltage as “Feedback voltage”. ~Start up time~ 1. Supply the voltage to VIN 2. Then,you can measure the VFB waveform as “Start up time”. 3.1~5.5V VIN 1µF Icoil 22µH monitor A Tall SW VIN Duty= Ton VOUT Ton Tall VIN 1µF EN Iout TEST GNDA 90% monitor for Start up time VFB GND RFB 24Ω V VFB Start up time Fig.1 Test Circuit A *Test circuit B (for Over voltage limit,Duty cycle limit, Switching frequency) Procedure ~Over voltage limit~ 1. Start to increase VOUT from 9V to 20V 2. You will find frequency change from around 1MHz to 0Hz 3. Then,it is “Over Voltage limit” ~Duty cycle limit, Switching frequency ~ 1. Supply 9V to VOUT terminal 2. Then,you can measure the duty as “Duty cycle limit” and the frequency and “Switching frequency”. monitor 3.1~5.5V VIN Ton SW VIN VOUT 1µF EN TEST GNDA GND Tall 1µF Duty= Ton Tall 9V to 20V VFB Fig.2 Test Circuit B *TEST circuit C (for Quiescent current, current comsumption, EN Terminal input/output current, EN threshold voltage(Low/High)) ICC 3.1~5.5V 1uF A VIN SW A EN VOUT IEN 0.0~5.5V TEST GNDA TEST GND VFB 1.0V(current comsumption) Fig.3 Test Circuit C www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 3/15 2011.12 - Rev.A Technical Note BD6074GUT ●Electrical characteristic curves (Reference data) 1.0 14 12 1.2 0.8 1.1 6 0.6 0.4 Ta=85℃ 4 Ta=85℃ Ta=25℃ 0.2 Ta=-30℃ 2 2 3 4 VIN[V] 5 6 Ta=85℃ 2 3 4 5 VIN[V] 6 7 2.5 Fig.5 Quiescent current vs. Power supply voltage 430 Inductor current [mA] Ta=-30℃ Ta=25℃ 500 490 480 Ta=85℃ 85 VIN=3.1V 390 370 350 VIN=5.5V 330 VIN=3.6V 55 Output Power[mW] VIN=3.1V 60 Ta=25℃ 50 15 20 25 30 Iout [mA] 35 10 40 Fig.10 Efficiency vs. LED current (4LED=VOUT14V) coil : TOKO DB3015CK www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 15 20 25 30 Iout[mA] 35 40 Fig.9 Efficiency vs. LED current (4LED=VOUT14V) 90 Ta=-30℃ 85 Ta=25℃ 1200 80 1000 800 Ta=85℃ 600 75 70 Ta=85℃ 65 400 60 200 55 0 10 50 85 70 Ta=-30℃ 1400 VIN=3.6V 55 30 50 Ta [deg] 1600 VIN=5.5V 75 65 10 Fig.8 Inductor current limit vs. Temperature 80 70 -10 TOKO : DB3015CK 65 60 Efficiency[%] VIN=4.2V 85 5.5 Murata : LQH32CN53L 70 290 Fig.7 Feedback voltage vs. Power supply voltage 90 5 75 310 -30 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 VIN[V] 4 4.5 VIN[V] 80 270 470 3.5 90 410 520 3 Fig.6 Oscillation frequency vs. Power supply voltage Efficiency[%] 530 VFB[mV] 0.9 0.8 1 7 Fig.4 Current consumption vs. Power supply voltage 510 Ta=-30℃ Ta=25℃ 0.0 1 Ta=25℃ 1.0 Ta=-30℃ 0 Efficiency [%] Frequency [MHz] 8 IIN[uA] IIN[mA] 10 Ta=25℃ 50 3.0 3.2 3.4 3.6 3.8 VIN[V] 4.0 4.2 Fig.11 Output power vs. Power supply voltage coil : TOKO DB3015CK 4/15 2.7 3.1 3.5 3.9 4.3 VIN[V] 4.7 5.1 5.5 Fig.12 Efficiency vs. Power supply voltage (Load=34mA) coil : TOKO DB3015CK 2011.12 - Rev.A Technical Note BD6074GUT ●Electrical characteristic curves (Reference data) – Continued 1.EN 1.EN 1.VOUT 2.VOUT Δ=1.66V 5.3ms 2.VOUT 3. VFB 3.VFB Idd=1.5mA (4ms/div) Vin=3.6V Ta=25℃ 1.VOUT 2.IIN 4.IIN 4. IIN 1V/div AC 200mA/div DC 1.EN 2V/div DC 2.VOUT 5V/div DC 3.VFB 500mV/div DC 4.IIN 200mA/div DC Fig.14 LED brightness adjustment Fig.15 Soft Start 50 500 50% 450 300 VIN=3.6V VIN=3.1V 30 250 VIN=5.5V 200 150 100 30% VIN=4.2V VFB voltage variation 350 40% 40 VFB[mV] 400 Vin=3.6V, Vin=3.6V, Ta=25 oCTa=25℃ 4LED, 34mA Load 4LED, 34mA Load (3ms/div) Fig.13 LED Open output voltage VFB[mV] Peak=368mA Peak=204mA 2.IIN VIN=3.9V 20 VIN=2.9V VIN=4.2V 10% 0% -10% VIN=5.2V VIN=3.1V VIN=4.2V VIN=5.2V 20% VIN=3.6V -20% -30% 10 50 VIN=3.1V -40% 0 -50% 0 0 10 20 30 40 50 60 70 80 90 100 Duty[%] Fig.16 LED brightness adjustment for PWM control www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 0 2 4 Duty[%] 6 8 10 Fig.17 LED brightness adjustment for PWM control (Expansion) 5/15 0 2 4 6 Duty[%] 8 10 Fig.18 LED brightness variation for PWM control (comparison of VFB at VIN=3.9V) 2011.12 - Rev.A Technical Note BD6074GUT ●Block diagram and pin configuration L 22µH CIN 1µF VIN SW VOUT over voltage protect Q2 short protect TSD Q1 PWMcomp Q S Q R Current Sence COUT 1µF + - white LED ERRAMP + Control + - + VFB + OSC RFB 24Ω 300kΩ GND GNDA EN TEST Fig.19 Block diagram and recommended circuit diagram C1 C2 B3 B1 A1 C3 A2 A3 Fig.20 Pin location diagram VCSP60N1( 8 pin ) ●Pin assignment table PIN Name In/Out Ball number Function GNDA - A1 EN In A2 TEST In A3 VIN In B1 Power supply input VFB In B3 Feedback voltage input VOUT Out C1 Boost output SW In C2 Switching terminal GND - C3 Power GND Analog GND Enable control (pull down by inner resistor) TEST input (pull down by inner resistor) ●Operation BD6074GUT is PWM current mode DC/DC converter with fixed frequency. It adopts synchronous rectification architecture. The feature of the PWM current mode is that input is the combination of error components from the error amplifier, and a current sense signal that controls the inductor current into Slope waveform for sub harmonic oscillation prevention. This output controls Q1 and Q2 via the RS latch. Timing of Q1 and Q2 is precisely adjusted so that they will not turn ON at the same time, thus putting them into non-overlapped relation. In the period when Q1 is ON, energy is accumulated in the external inductor, and in the period when Q1 is OFF, energy is transferred to the capacitor of VOUT via Q2. Further more, BD6074GUT has many safety functions, and their detection signals stop switching operation at once. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 6/15 2011.12 - Rev.A Technical Note BD6074GUT ●Description of Functions 1) Soft start and off status BD6074GUT has soft start function and off status function. The soft start function and the off status function prevent large current from flowing to the IC via coil. The soft start function prevents rush current when turning on and the off status function prevents invalid current when turning off. ・Soft start When VOUT is smaller than Vshort, to decrease charge current PMOS is set to off by PMOS Startup Control (in Term “I”). Vshort means “VOUT short detect voltage”. After VOUT is bigger than Vshort, PMOS is turned on and start switching. In term “II” (Vshort < VOUT < VIN), status of Current Limiter is “soft mode”. So “A” voltage is restricted and “D” duty is kept low. Therefore VOUT voltage goes up slowly and coil current is restricted. In term III (VOUT > VIN), status of Current Limiter is “normal mode”. So “A” voltage goes up suitable voltage, and “D” duty goes up slowly. And then VOUT voltage goes up to required voltage. Operation Current at start Current at PWM Max current 450mA 300mA Vout LED current L ERRAMP PWM comp SW A Soft Current limit B R Q S Q C Soft Reference D PMOS Startup Control Off Status OSC Charge current FB 24ohm Fig. 21 lock diagram of soft start and off status EN I II III VIN Vshort VOUT Normal mode Cu r r en t Limit Soft mode D Fig. 22 timing chart ・Off status The gate voltage of the switching Tr either "H" or "L" at power off depends on the operation conditions at that time. When it is fixed to "H", the switching Tr remains to be ON, and invalid current from the battery is consumed. In order to prevent this, at power off, D is always fixed to L level. So that, it is possible to prevent invalid current at power off. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 7/15 2011.12 - Rev.A Technical Note BD6074GUT 2) Isolation control BD6074GUT has isolation control to prevent LED wrong lighting at power off. The cause of the LED wrong lighting is leak current from VIN to the white LED. Therefore, when BD6074GUT powered off (EN = L), the isolation control cuts the DC path between SW and Vout, so that, it prevents from leak current from VIN to LED. VIN SW White LED Vout VFB Fig.23 Isolation control 3) Short-circuit protection and over voltage protection BD6074GUT has short-circuit protection and over voltage protection. These detect the voltage of VOUT, and at error, they stop the output Tr. Details are as shown below. ・Short-circuit protection In the case of short-circuit of the DC/DC output (VOUT) to GND, the coil or the IC may be destroyed. Therefore, in a case of error as VOUT becomes 0.7V or lower, the Under Detector shown in the figure works, and turns off the output Tr, and prevent the coil and the IC from being destroyed. And the IC turns into non operation condition from operation condition, and current does not flow to the coil (0mA). ・Over voltage protection In a case of error as the IC and the LED being cut off, over voltage causes the SW terminal and the VOUT terminal exceed the absolute maximum ratings, and may destroy the IC. Therefore, when VOUT becomes 18.5V or higher, the over voltage limits works, and turns off the output Tr, and prevents the SW terminal and the VOUT terminal from exceeding the absolute maximum ratings. At this moment, turns into non operation condition from operation condition, and the output voltage goes down slowly. And, when the output voltage becomes the hysteresis of the over voltage limit or below, the output voltage goes on up to 18.5V once again. This protection action is shown in Fig.24. Cout SW Vout OVER Detector OVER VOLTAGE REF driver UNDER Detector UNDER VOLTAGE REF Control Fig.24 Block diagram of short-circuit protection and over voltage 4) Thermal shut down BD6074GUT has thermal shut down function. The thermal shut down works at 175C or higher, and while holding the setting of EN control from the outside, turns into non operation condition from operation condition. And at 175C or below, the IC gets back to its normal operation. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 8/15 2011.12 - Rev.A Technical Note BD6074GUT ●Start control and brightness control BD6074GUT can control the start conditions by its EN terminal, and power off at 0.4V or below, and power on at 1.4V or higher. And by changing the duty of power on and off by PWM control, the LED brightness can be adjusted. Two techniques are available for the brightness adjustment. One is PWM adjustment, and the other is analog adjustment. (1) PWM brightness adjustment is done by giving PWM signal to EN as shown in Fig.25. The BD6074GUT is powered on/off by the PWM signal. By this method, LED current is controlled from 0 to the maximum current. The average LED current increases with proportion to the duty cycle of PWM signal. While in PWM off-cycle mode, the IC and LED both consume no currents, thus providing a high-efficiency operation. The recommended PWM frequency is 100Hz ~ 300Hz. 22µH VIN SW VIN VOUT PWM 1µF EN TEST GNDA GND VFB 24Ω Fig.25 The brightness adjustment example of EN terminal by PWM (fPWM = 100 ~ 300Hz) (2-1) Analog brightness adjustment is made by giving DC control voltage to VFB pin of BD6074GUT via a series resistor as shown in Fig.26. LED brightness (current) changes by giving DC voltage to VFB directly. DC voltage is given from filtered one of DAC signal, or PWM signal shown in Fig.28. The advantage of this approach is that the PWM signal to be used to control the LED brightness can be set to a high frequency (1kHz or higher). LED current (ILED) is approximated by the following equation. ILED = [[(VFB-DAC) / R1] * R2 + VFB ] / RFB 3030 22µH VIN 2525 SW 2020 VOUT 1µF EN ILED TEST GNDA GND 22kΩ R2 R1 1515 1010 55 4.7kΩ VFB ILED [mA] VIN 00 24Ω RFB -5-5 00 0.5 0.5 11 DAC 22µH 3.5 3.5 4 20 SW 1µF ILED [mA] VOUT ILED GND 33 25 EN GNDA 2.5 2.5 Fig.27 DAC adjustment VIN TEST 22 DAC [V] (VFB=500mV) Fig.26 The brightness adjustment example by DAC VIN 1.5 1.5 VFB 5 100kΩ 30Ω 0 0 47nF 10 20 30 40 50 60 70 80 90 100 HI Duty [%] Fig.28 The brightness adjustment example of VFB terminal by PWM (fPWM = 10kHz) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 10 33kΩ 47kΩ PWM 10kHz 0~2.85V 15 9/15 Fig.29 VFB PWM Control 2011.12 - Rev.A Technical Note BD6074GUT 2-2) The below the brightness adjustment is done in adjusting of R2 ON time at Duty cycle of R1 and PWM. The minimum value of the LED current is decided by VFB / R1 at the PWM 0%, the maximum value of the LED current is decided by VFB / R2 at the PWM 100%. ILED is given as shown below. ILED=VFB / R1 + VFB / R2 x HI Duty 22µH 25 VIN SW VIN 20 VOUT 1µF ILED [mA] EN TEST GNDA VFB GND R2 47Ω R1 47Ω 15 10 5 0 PWM 1kHz 0 10 20 30 40 50 60 70 80 90 100 HI Duty [%] Fig.30he brightness adjustment example of VFB terminal by PWM (fPWM=100~1kHz) ●Setting range of LED current LED current is determined by the voltage of VFB and the resistor connected to VFB terminal. ILED is given as shown below. ILED=VFB/RFB The current in the standard application is as shown below. VFB=0.5V, RFB=24Ω ILED=20.8mA Reference The maximum value of RFB is 30Kohm and minimum current of ILED is 16uA. Fig.31FB PWM Control 22µH VIN 1μF SW VIN VOUT PWM 1µF EN ILED TEST GNDA GND VFB RFB 24Ω Fig.32 standard application The shaded portion in the figure below is the setting range of LED current to become the standard. Depending on coils and white LEDs to be used, however, some ICs may not be used at desired currents. Consequently, for the proper setting of LED current, thoroughly check it for the suitability under use conditions including applicable power supply voltage and temperature. 80 70 ILED[mA] 60 50 40 30 20 10 Min 16uA 0 7 8 9 10 11 12 13 14 15 16 17 18 VOUT[V] Fig.33 Setting range of LED current www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 10/15 2011.12 - Rev.A Technical Note BD6074GUT ●Selection of external parts Recommended external parts are listed as below. When to use other parts than these, select the following equivalent components. ・Coil Value Tolerance Manufacturer Product number Vertical size Size Horizontal size 22µH ±10% MURATA LQH32CN220K53 2.5 22µH ±20% TDK VLF3012AT220MR33 22µH ±20% Coil Craft 22µH ±20% TDK Height DCR (Ω) 3.2 1.55 0.71 2.6 2.8 1.2 0.66 DO1608 4.45 6.6 2.92 0.37 VLF3010AT220MR33 2.6 2.8 1.0 1.30 Please refer to the reference data of p.4 for the change in the efficiency when the coil is changed. ・Capacitor Value Manufacturer Product number Vertical size Size Horizontal size MURATA GRM188B11A105K 1.6 MURATA GRM188B11E105K 1.6 Height Temperature range 0.8 0.8 -25℃~+85℃ 0.8 0.8 -25℃~+85℃ 【 CIN 】 1µF 【 COUT 】 1µF ・Resistor Value Tolerance Manufacturer Product number Vertical size Size Horizontal size ±1% ROHM MCR006YZPF24R0 0.6 0.3 Height 【 RFB 】 24Ω 0.23 The coil is the component that is most influential to efficiency. Select the coil which direct current resistor (DCR) and current - inductance characteristic are excellent. The BD6074GUT are designed for the inductance value of 22µH. Please do not use other inductance value. Select a capacitor of ceramic type with excellent frequency and temperature characteristics. Further, select Capacitor to be used for CIN/COUT with small direct current resistance, and pay much attention to the PCB layout shown in the next page. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 11/15 2011.12 - Rev.A Technical Note BD6074GUT ●PCB layout In order to make the most of the performance of this IC, PCB layout is very important. Please note that characteristics such as efficiency and ripple will likely to change greatly depending on PCB layout. To battery power source CIN GNDA EN TEST VIN VOUT VFB SW RLED GND To battery GND COUT L1 Fig.34 PCB layout Connect the input bypath capacitor CIN between VIN and GNDA pin closely, as shown in the upper diagram. Thereby, the input voltage ripple of the IC can be reduced. And, connect the output capacitor COUT between VOUT and GND pin closely. Thereby, the output voltage ripple of the IC can be reduced. Connect the current setting RLED FB pin closely. Connect the GND closely connection side of RLED directly to GND pin. Connect the GNDA pin directly to GND pin. When those pins are not connected directly near the chip, the performance of BD6074GUT shall be influenced and may limit the current drive performance. As for the wire to the inductor, make its resistance component small to reduce electric power consumption and increase the entire efficiency. Please keep away which are subject to be influenced like FB pin in wire connection with SW. The layout pattern in consideration of these is shown in the next page. 112mVpp VOUT (VBAT=3.6V, Ta=25 oC, VOUT=14V. 20mA Load) Fig.35 Output noise www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 12/15 2011.12 - Rev.A Technical Note BD6074GUT ●Recommended layout pattern FB EN GNDA LED Cin RFB １ １V １ ２G LED Cout SW L1 VOUT LED VBAT GND Fig.36 Front surface (TOP VIEW) VOUT GND １ １V １ ２G SW VOUT VOUT Fig.37 Rear surface (TOP VIEW) ●Attention point for PCB layout For PCB design, the wire of power supply line should be low Impedance, and put bypass capacitor if necessary. Especially the wiring impedance must be low around DC/DC converter. ●About heat loss For heat design, operate DC/DC converter in the following condition. (The following temperature is a guaranteed temperature, margin will be needed.) 1. Periphery temperature Ta must be less than 85℃. 2. The loss of IC must be less than dissipation Pd. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 13/15 2011.12 - Rev.A Technical Note BD6074GUT ●Notes for use 1) Absolute Maximum Ratings An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, 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. In this regard, for the digital block power supply and the analog block power supply, even though these power supplies has the same level of potential, separate the power supply pattern for the digital block from that for the analog block, thus suppressing the diffraction of digital noises to the analog block power supply resulting from impedance common to the wiring patterns. For the GND line, give consideration to design the patterns in a similar manner. 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°C (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. 14/15 2011.12 - Rev.A Technical Note BD6074GUT ●Ordering part number B D 6 Part No. 0 7 4 G Part No. 6074 U T Package GUT : VCSP60N1 - E 2 Packaging and forming specification E2: Embossed tape and reel VCSP60N1 (BD6074GUT) (BD6069GUT) <Tape and Reel information> 1.68±0.05 1.68±0.05 0.21±0.05 0.6±0.08 1PIN MARK (φ0.15)INDEX POST A C B B A 1 0.34±0.05 2 3000pcs E2 The direction is the 1pin of product is at the upper left when you hold ( reel on the left hand and you pull out the tape on the right hand ) P=0.5×2 0.34±0.05 0.08 S Embossed carrier tape Quantity Direction of feed S 8-φ0.3±0.05 0.05 A B Tape 3 1pin P=0.5×2 (Unit : mm) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. Reel 15/15 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. 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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