BD6077GUT ROHM

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Description The BD6077GUT is a white LED driver IC with synchronous rectification that can drive up to 3LEDs. With synchronous rectification (no external schottky 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 rectific ation Boost DC/DC converter 2) No external schottky diode required 3) Driving 3 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 Torchlight and easy flash for camera of mobile phone
Absolute maximum ratings (Ta=25°C) Parameter Symbol Ratings Unit Condition Maximum applied voltage 1 VMAX1 7 * 1 V Vin, EN, VFB, TEST Maximum applied voltage 2 VMAX2 20 * 1 V SW, Vout Power dissipation Pd 750 * 2 mW Operating temperature range Topr -30~+85 ℃ Storage temperature range Tstg -55~+150 ℃ *1 These value are based on GND and GNDA pins. *2 50mm×58mm×1.75mm At glass epoxy board mount ing. When it’s used by more than Ta=25 ℃, it’s reduced by 6.0mW/℃.
Operating conditions (Ta=25°C) Parameter Symbol Ratings Unit Condition Min. Typ. Max. Power supply voltage Vin 2.7 3.6 5.5 V No.11040EAT41

Electrical characteristics Unless otherwise specified Ta =-30℃~+85℃, Vin=3.1~5.5V Parameter Symbol Limits Unit Condition Min. Typ. Max. [ EN terminal ] EN threshold voltage (Low) VthL - - 0.4 V EN threshold voltage (High) VthH 1.4 - - V EN terminal input current Iin - 18.3 30.0 µA EN=5.5V EN terminal output current Iout -2.0 -0.1 - µA EN=0 [ Switching regulator ] Quiescent Current Iq - 0.1 2.0 µA EN=TEST=VFB=0V,SW=open Current Consumption Idd - 1.0 1.5 mA EN=1.4V,TEST=0V,VFB=1.0V, SW=open Feedback voltage Vfb 0.47 0.50 0.53 V EN=1.4V,TEST=0V Inductor current limit Icoil 210 310 410 mA EN=1.2V, TEST=2.9V, Vin=3.6V,VOUT=9V (*1) SW saturation voltage Vsat - 0.245 0.345 V Isw=200mA, Vin=3.6V SW on resistance P Ronp - 5.4 7.2 Ω Isw=200mA, Vout=10V Switching frequency fSW 0.8 1.0 1.2 MHz EN=1.4V,TEST=0V,VFB=0V, VOUT=10V,SW=open Duty cycle limit Duty 82.7 95.0 - % EN=1.4V,TEST=0V,VFB=0V, VOUT=10V,SW=open Over voltage limit Ovl 14.0 14.5 15.0 V EN=1.4V,TEST=0V,VFB=0V, SW=open 1 This parameter is tested with DC measurement.

Test circuit *Test circuit A (for Inductor current limit, Feedback voltage.) 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”. 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 12V to 16V 2. You will find frequency change from around 1MHz to 0Hz 3. Then,you can measur the VOUT voltage as “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”. Fig.2 Test Circuit B *TEST circuit C (for Quiescent current, current comsumption, EN Terminal input/output current, EN threshold voltage(Low/High)) Fig.3 Test Circuit C Icoil VIN SW VOUT EN GNDA TEST GND VFB 22µH 1µF 24Ω VIN RFB A Iout Tall Ton Duty= Tall Ton monitor V 1µF 3.1~5.5V VIN SW VOUT EN GNDA TEST GND VFB 1µF VIN 3.1~5.5V 12V to 16V Tall Ton Duty= Tall Ton monitor 1µF VIN SW VOUTEN GNDA TEST GND IEN 3.1~5.5V TEST A A ICC VFB 1uF 0.0~5.5V 1.0V(current comsumption)

Electrical characteristic curves (Reference data) 1234567 VIN[V] IIN[mA] 0.0 0.2 0.4 0.6 0.8 1.0 1234567 VIN[V] IIN[uA] 0.8 0.9 1.0 1.1 1.2 2 . 533 . 544 . 555 . 5 VIN[V] Frequency [MHz] Fig.4 Current consumption Fig.5 Quiesc ent current Fig.6 Oscillation frequency vs. vs. vs. Power supply voltage Power supply voltage Power supply voltage 450 475 500 525 550 Ta[℃] VFB[mV] 200 250 300 350 400 450 -30 -10 10 30 50 70 Ta [deg] Inductor current [mA] 10 15 20 25 30 35 40 Iout[mA] Efficiency[%] Fig.7 Feedback voltage Fig.8 Inductor curr ent limit Fig.9 Efficiency vs. LED current vs. vs. (4LED=VOUT14V) Power supply voltage Temperature 10 15 20 25 30 35 40 Iout [mA] Efficiency [%] 400 600 800 1000 1200 1400 VIN[V] Output Power[mW] VIN[V] Efficiency[%] Fig.10 Efficiency vs. LED current Fig.11 Output power Fig.12 Efficiency (3LED=VOUT10.5V) vs. vs. coil : TOKO DB3015CK Power supply voltage Power supply voltage coil : TOKO DB3015CK (Load=34mA) coil : TOKO DB3015CK Ta=85℃ Ta=25℃ Ta=-30℃ VIN=5.5VVIN=3.6V VIN=3.1V VIN=3.1V VIN=3.6V VIN=4.2V VIN=5.5V Ta=25℃ TOKO : DB3015CK Murata : LQH32CN53L Ta=-30℃ Ta=25℃ Ta=85℃ Ta=25℃ Ta=-30℃ Ta=85℃ Ta=-30℃ Ta=25℃ Ta=85℃ Ta=25℃ Ta=-30℃ Ta=85℃ Ta=25℃ Ta=-30℃ Ta=85℃

Electrical characteristic curves (Reference data) – Continued VOUT delta=1.68V Fig.13 LED Open output voltage Fig.14 LED brightness adjustment Fig.15 Soft Start 02468 1 0 Duty[%] VFB[mV] Fig.16 LED brightness adjustment for PWM control VIN=3.6V VIN=3.9V VIN=3.1V VIN=4.2V VIN=5.2V Fig.17 LED brightness adjustment for PWM control (Expansion) -20% -15% -10% -5% 10% 15% 20% 0 2 04 06 08 0 1 0 0 Duty[%] VFB voltage variationVIN=3.1V VIN=4.2V VIN=5.2V VIN=3.6V Fig.18 LED brightness variation for PWM control (comparison of VFB at VIN=3.9V) Peak=160m EN Iin VFB VOUT Peak=208mA EN Iin VFB VOUT Vin=3.6V, Ta=25oC 3LED, 34mA Load 100 200 300 400 500 0 2 04 06 08 0 1 0 0 Duty[%] VFB[mV] VIN=3.6V VIN=3.9V VIN=3.1V VIN=4.2V VIN=5.2V

Block diagram and pin configuration Fig.19 Block diagram and recommended circuit diagram Fig.20 Pin location diagram VCSP60N1( 8 pin )
Pin assignment table PIN Name In/Out Ball number Function GNDA - A1 Analog GND EN In A2 Enable control (pull down by inner resistor) TEST In A3 TEST input (pull down by inner resistor) 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
Operation BD6077GUT is PWM current mode DC/DC conv erter with fixed frequency. It adopts sy nchronous rectification architecture. The feature of the PWM current mode is that input is the combination of erro r components from the error amplifier, and a current sense signal that contro ls 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 ad justed 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, BD6077GUT has many safety functions, and their detection signals stop switching operation at once. OSC Control Current Sence Q 24Ω S Q R TSD VIN CIN SW VOUT VFB TESTENGNDA GND 1µF L 22µH COUT 1µF RFB white LED over voltage protect short protect PWMcomp ERRAMP A1 A2 A3 C3C2

Functional descriptions 1) Soft start and off status BD6077GUT 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 VO UT 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 restrict ed. 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 Max current Current at start 380mA Current at PWM 270mA Fig. 21 lock diagram of soft start and off status 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 inva lid 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. LED current 24ohm FB Vout Charge current A DR S Q Q SW L C PWM comp OSC B Off Status ERRAMP Soft Reference Soft Current limit PMOS Startup Control Soft mode DD CCuurrrreenntt LLiimmiitt Normal mode VVOOUUTT Vshort VIN II IIII IIIIII EENN LED VF=3.2V@20mA, COUT : 1µF@16V X5R

www.rohm.com 2011.12 - Rev. A © 2011 ROHM Co., Ltd. All rights reserved. 2) Isolation control BD6077GUT 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 BD6077GUT 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. Fig.23 Isolation control 3) Short-circuit protection and over voltage protection BD6077GUT 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 prevents 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 14.5V 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 op eration condition, and the output voltage goes down slowly. And, when the output voltage becom es the hysteresis of the over voltage limit or below, the output voltage goes on up to 14.5V once again. This protection action is shown in Fig.24. Fig.24 Block diagram of short-circuit protection and over voltage 4) Thermal shut down BD6077GUT has thermal shut down function. The thermal shut down works at 175°C or higher, and while holdi ng the setting of EN control from the outside, turns into non operation condition from operation condition. And at 175°C or below, the IC gets back to its normal operation. VIN SW Vout VFB White LED Vout OVER Detector Control UNDER Detector OVER VOLTAGE REF UNDER VOLTAGE REF driver SW Cout

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BD6077GUT ROHM

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