BD9394EFV-E2

Datasheet LED Drivers for LCD Backlights White LED Driver for large LCD Panels (DCDC Converter type) BD9394FP, BD9394EFV ●General Description BD9394FP, BD9394EFV is a high efficiency driver for white LEDs and designed for large LCDs. This IC is built-in a boost DCDC converters that employ an array of LEDs as the light source. BD9394FP, BD9394EFV has some protect function against fault conditions, such as the over-voltage protection (OVP), the over current limit protection of DCDC (OCP), the short circuit protection (SCP), the open detection of LED string. Therefore BD9394FP, BD9394EFV is available for the fail-safe design over a wide range output voltage. ●Features  4ch LED constant current driver and DC/DC converter  Maximum LED Current: 150mA  LED Feedback Voltage: 0.37V (@NADIM=2.62V), so lower heat. Adjustable Feed Back Voltage by following LED Current setting.  2% LED current accuracy (NADIM=2.62V, when each LED is set to 100mA)  Analog current (Linear) dimming at NADIM pin  LED pin rating 60V  Individual detection and individual LED OFF for both open and short circuits  Built-in ISET pin short-circuit protection circuit  Set Soft-Start time by external capacitor.  FET’s Gate (N pin) is driven by 5.8V swing  Built-in Vout discharge circuit for shutdown  Built-in Vout overvoltage protection (OVP) / reduced voltage protection (SCP) circuit  Adjustable LED Short Protection Voltage by LSP terminal  HSOP20, HTSSOP-B24 package with high heat radiation efficiency ●Key Specification  Operating power supply voltage range: 9.0V to 35.0V  LED minimum current 30mA  LED maximum current: 150mA  Oscillator frequency: 150kHz (RT=100kΩ)  Operating Current: 4.5mA (Typ.) Operating temperature range: -40℃ to +85℃ ●Applications TV, Computer Display, Notebook, LCD Backlighting ●Package HSOP20 HTSSOP-B24 W(Typ.) x D(Typ.) x H(Max.) 14.90mm x 7.80mm x 2.10mm 7.80mm x 7.60mm x 1.00mm ● Typical Application Circuit (4 light with PWM) Fig.1(a) HSOP20 Fig.1(b) HTSSOP-B24 VIN Inductor VIN Diode Connector CIN COUT REG58 FIN1, 2 CREG RN2 FET DN RN1 RCS REG58 STB N VCC LED4 CS RRT GN D ROVP1 ROVP2 COVP RFB CFB1 REG58 RLSP1 CFB2 RLSP2 RT LED3 OVP LED_GND FB LED2 LSP LED1 SS PWM ISET GND CLSP CSS RISET CAUTO NADIM RVCC CVCC DCDC_GND DCDC_GN D ON/OFF CLED4 CLED3 CLED2 CLED1 PWM AUTO NADIM Fig.2 Typical Application Circuit ○Product structure：Silicon monolithic integrated circuit .www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・14・001 ○This product is not designed protection against radioactive rays 1/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Absolute maximum ratings (Ta=25℃) Parameter Symbol Power supply voltage STB, NADIM, OVP, PWM terminal voltage LED1 to 4 terminal voltage AUTO, REG58, CS, N, LSP, ISET, SS, FB, RT terminal voltage Power dissipation 1(HSOP20) Ratings Unit VCC 36 V STB, NADIM, OVP, PWM VCC V LED1~4 AUTO, REG58, CS, N, LSP, ISET, SS, FB, RT Pd1 60 V 7 V 2.18 *1 W Power dissipation 2(HTSSOP-B24) Pd2 4.00 *2 W Operating temperature range Topr -40~+85 ℃ Tstg -55~+150 ℃ Tjmax 150 ℃ Storage temperature range Junction temperature *1 *2 Ta = 25°C or more, diminished at -17.4mW/°C in the case of HSOP20 (when 4-layer / 70.0 mm x 70.0 mm x 1.6 mm board is mounted) Ta = 25°C or more, diminished at -32.0mW/°C in the case of HTSSOP-B24 (when 4-layer / 70.0 mm x 70.0 mm x 1.6 mm board is mounted) ●Operating Ratings (Ta = 25℃) Parameter Symbol VCC supply voltage Limits Unit VCC 9.0~35.0 V Min. output current of LED1 to 4 ILED_MIN 30 Max. output current of LED1 to 4 ILED_MAX 150 mA *1 mA Min. output current of LED1 to 4 VNADIM1 0~5.0 *3 V Max. output current of LED1 to 4 *1,2 VNADIM2 7.0~35.0 V DC/DC oscillation frequency VLSP 0.8～3.0 V DC/DC oscillation frequency Fsw 100~800 kHz PWM_MIN 30 us Min. on-duty time for PWM light modulation *1 *2 *3 The amount of current per channel. If LED makes significant variations in its reference voltage, the driver will increase power dissipation, resulting in a rise in package temperature. To avoid this problem, design the board with thorough consideration given to heat radiation measures. The range which the LED current changes with linearity is from 1.5V to 5V. ●Pin Configuration HSOP20 1 AUTO VCC 20 NADIM 19 2 REG58 3 CS RT 18 4 N FB 17 5 DCDC_GND SS 16 6 LSP ISET 15 7 OVP PWM 14 8 LED1 LED4 13 9 LED2 LED3 12 10 LED_GND STB HTSSOP-B24 11 Fig.3 Pin Configuration www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 2/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Marking diagram and physical dimension HSOP20 HTSSOP-B24 LOT No. BD9394FP D9394EFV LOT No. Fig.4 Physical Dimension o ●Electrical Characteristics (Unless otherwise noted, Ta = 25 C, VCC=24V) Limit Parameter Symbol Unit Min. Typ. Max. Condition [Whole Device] Circuit current while in operation ICC - 4.5 9 mA STB=3V,PWM=3V,RT=100kΩ Circuit current while in standby ISTB - 40 80 μA STB=0V REG58 Output Voltage REG58 5.742 5.8 5.858 V IO=0mA Soft start completion voltage IREG58 15 - - mA UVLO release voltage VUVLO_VCC 6.5 7.5 8.5 V UVLO hysteresis voltage VUHYS_VCC 150 300 600 mV VLED 0.35 0.37 0.39 V fsw 142.5 150.0 157.5 kHz RT=100kohm Max. duty cycle per output of N pin DMAX 83 90 97 % RT=100kohm On resistance on N pin source side RONH - 4 8 Ω ION=-10mA On resistance on N pin sink side RONL - 3 6 Ω ION=10mA SS pin source current ISSSO -4 -2 -1 uA VSS=2V VSS_END 3.3 3.7 4.1 V SS=SWEEP UP IFBSINK 50 100 150 μA LED=2.0V, VFB=1.0V IFBSOURCE -150 -100 -50 μA LED=0V, VFB=1.0V VCS 0.40 0.45 0.50 V CS=SWEEP UP [REG58 Block] [UVLO Block] VCC=SWEEP UP VCC=SWEEP DOWN [DC/DC Block] Error amp. Reference voltage Oscillation frequency Soft start completion voltage FB sink current FB source current Over current detection voltage www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 3/28 ISET=75kΩ, NADIM=2.62V TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Electrical Characteristics (Unless otherwise noted, Ta = 25oC, VCC=24V) Limit Parameter Symbol Unit Condition Min. Typ. Max. VOVP 2.7 3.00 3.3 V VOVP_HYS 50 100 200 mV VOVP=SWEEP DOWN VSCP 0.04 0.10 0.25 V VOVP=SWEEP DOWN LED pin current accuracy 1 dILED1 -2 - 2 % ILED=100mA, (VNADIM=2.62V,RISET=75kΩ) LED pin current accuracy 2 dILED2 -3 - 3 % ILED=100mA, (VNADIM=7V,RISET=75kΩ) LED pin Leakage Current ILLED -2.5 - 2.5 uA VLED=60V LED open detection voltage VOPEN 0.05 0.2 0.285 V VLED=SWEEP DOWN LED short detection voltage VSHORT 4 5 6 V RULSP 1000 2000 3000 kΩ VLSP=0V RDLSP 500 1000 1500 kΩ VLSP=3V ILNADIM -2.5 - 2.5 uA VNADIM=5V STB pin high-level voltage STBH 2 - 35 V STB=SWEEP UP STB pin low-level voltage STBL -0.3 - 0.8 V STB=SWEEP DOWN STB pin pull-down resistance RSTB 500 1000 1500 kΩ VSTB=3.0V PWM pin high-level voltage PWMH 2 - 35 V PWM=SWEEP UP PWM pin low-level voltage PWML -0.3 - 0.8 V PWM= SWEEP DOWN PWM pin pull-down resistance RPWM 180 300 420 kΩ PWM=3.0V [DC/DC Protection Block] Overvoltage protection detection voltage Overvoltage protection detection hysteresis voltage Short circuit protection detection voltage VOVP=SWEEP UP [LED Driver Block] LSP pin resistive divider upper side resistance LSP pin resistive divider lower side resistance NADIM pin Input Current VLED=SWEEP UP, VLSP=OPEN [STB Block] [PWM Block] [Failure Indication Block (Open Drain)] AUTO pin source current IAUTO -2 -1 -0.5 μA VAUTO=2V AUTO pin Detection Voltage VAUTO 3.6 4.0 4.4 V VAUTO=SWEEP UP Abnormal Detection Timer tCP www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 20 4/28 ms RT=75kΩ TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Pin Descriptions (BD9394FP) Pin No Pin Name In/Out Function Rating [V] 1 AUTO Out -0.3 ~ 7 2 REG58 Out Power supply for N pin -0.3 ~ 7 3 CS In DC/DC output current detection and OCP detection pin -0.3 ~ 7 4 N In DC/DC switching output pin -0.3 ~ 7 Auto-restart time setting pin 5 DCDC_GND - Power GND pin - FIN1 GND - Analog GND pin - 6 LSP In LED Short detection voltage setting resistor connection pin -0.3 ~ 7 7 OVP In Overvoltage protection detection pin -0.3 ~ 36 8 LED1 Out Output pin 1 for LED -0.3 ~ 60 9 LED2 Out Output pin 2 for LED -0.3 ~ 60 10 LED_GND - Ground pin for LED 11 STB In Enable pin -0.3 ~ 36 12 LED3 Out Output pin 3 for LED -0.3 ~ 60 13 LED4 Out 14 PWM In 15 ISET Out FIN2 GND - 16 SS Out 17 FB In/Out 18 RT Out 19 NADIM In 20 VCC In ●Pin Descriptions (BD9394EFV) Pin No Pin Name In/Out - Output pin 4 for LED -0.3 ~ 60 External PWM light modulation signal input pin for LED1-4 -0.3 ~ 36 LED current setting resistor connection pin -0.3 ~ 7 - Analog GND pin Soft start pin / LED protection masking time setting pin. -0.3 ~ 7 Error amp output pin -0.3 ~ 7 DC/DC drive frequency setting resistor connection pin. -0.3 ~ 7 Analog dimming DC voltage input pin -0.3 ~ 36 Power supply pin -0.3 ~ 36 Function Rating [V] 1 AUTO Out Auto-restart time setting pin -0.3 ~ 7 2 REG58 Out Power supply for N pin -0.3 ~ 7 3 CS In DC/DC output current detection and OCP detection pin -0.3 ~ 7 4 N In DC/DC switching output pin -0.3 ~ 7 5 DCDC_GND - Power GND pin 6 LSP In LED Short detection voltage setting resistor connection pin -0.3 ~ 7 7 OVP In Overvoltage protection detection pin -0.3 ~ 36 8 LED1 Out Output pin 1 for LED -0.3 ~ 60 Output pin 2 for LED -0.3 ~ 60 - 9 LED2 Out 10 N.C. - Unconnected pin. - 11 LED_GND - Ground pin for LED - 12 N.C. - Overvoltage protection detection pin. 13 STB In Enable pin -0.3 ~ 36 14 LED3 Out Output pin 3 for LED -0.3 ~ 60 15 N.C. - 16 LED4 Out 17 PWM In 18 ISET Out 19 GND - 20 SS Out 21 FB In/Out 22 RT Out 23 NADIM 24 GND - DC/DC switching output pin. - Output pin 4 for LED -0.3 ~ 60 External PWM light modulation signal input pin for LED1-4 -0.3 ~ 36 LED current setting resistor connection pin -0.3 ~ 7 - Analog GND pin Soft start pin / LED protection masking time setting pin. -0.3 ~ 7 Error amp output pin -0.3 ~ 7 DC/DC drive frequency setting resistor connection pin. -0.3 ~ 7 In Analog dimming DC voltage input pin -0.3 ~ 36 - Ground pin for analog block. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 5/28 - TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Pin ESD Type REG58 / N / DCDC_GND / CS NADIM FB FB LED1~4, LED_GND RT SS ISET LSP LED1-4 LED_GND PWM 3V 1.8M LSP 100k 5V OVP 1.2M STB AUTO AUTO STB 100k 5V 1M Fig. 5 Pin ESD Type www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 6/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Block Diagram Fig. 6 Block Diagram www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 7/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Typical Performance Curve 10 1000 9 fSW [ kHz ] ICC[mA] 8 7 6 100 5 4 3 10 9 14 19 24 VCC[V] 29 34 10 100 RRT[kohm] 1000 Fig.8 N Frequency [MHz] vs. R_RT [MΩ] Fig.7 Operating Current (ICC) [mA] vs. VCC[V] 110 140 108 120 106 100 102 ILED[mA] ILED[mA] 104 100 98 96 80 60 40 94 VCC=24V ISET=75kΩ 20 92 90 0 -40 -20 0 20 40 Temp[℃] 60 80 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 NADIM[V] Fig.9 LED Current (ILED) [mA] vs. Temp [℃] www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 Fig.10 LED Current (ILED) [mA] vs. NADIM [V] 8/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Pin Function ○AUTO (HSOP20:1pin / HTSSOP-B24：1pin) This sets up time till auto-restart time from the point of abnormal detection. Having 1uA constant current charge at external capacitor connected to AUTO pin, it will start again when it becomes over 4.0V (The auto pin is shorted to GND, this IC’s protection function operates latched off mode). ○Auto-restart period vs. AUTO capacitance (Ideal) T AUTO  4 .0[V ]  C AUTO  4 .0  10 6  C AUTO [sec] 6 1 .0  10 [ A ] ○REG58 (HSOP20:2pin / HTSSOP-B24：2pin) The REG58 pin is used in the DC/DC converter driver block to output 5.8V power. The maximum operating current is 15mA. Using the REG58 pin at a current higher than 15mA can affect the N pin output pulse, causing the IC to malfunction and leading to heat generation of the IC itself. To avoid this problem, it is recommended to make load setting to the minimum level. Please place the ceramic capacitor connected to REG58 pin (2.2uF～10uF) closest to REG58-GND pin. ○CS (HSOP20:3pin / HTSSOP-B24：3pin) The CS pin has the following two functions: 1. DC/DC current mode current feedback function Current flowing through the inductor is converted into voltage by the current sensing resistor RCS connected to the CS pin and this voltage is compared with voltage set with the error amplifier to control the DC/DC output voltage. 2. Inductor current limit function The CS pin also incorporates the over current protection (OCP) function. If the CS pin voltage reaches 0.45V (Typ.) or more, switching operation will be forcedly stopped. ○N (HSOP20:4pin / HTSSOP-B24：4pin) The N pin is used to output power to the external NMOS gate driver for the DC/DC converter in the amplitude range of approx. 0 to REG58. ON resistances is 4.0Ω(typ.) in sorrce (H side), 3.0Ω(typ.) in sink (L side). Frequency setting can be made with a resistor connected to the RT pin. For details of frequency setting, refer to the description of the RT pin. ○DCDC_GND (HSOP20:5pin / HTSSOP-B24：5pin) The PGND pin is a power ground pin for the driver block of the output pin N. ○GND (HSOP20:FIN1, FIN2 / HTSSOP-B24：19pin) The GND pin is an internal analog circuit ground of the IC. ○LSP (HSOP20:6pin / HTSSOP-B24：6pin) Terminal which sets LED SHORT detection voltage; the SHORT detection voltage is in a proportional relationship to LSP set voltage and is set by the following equation: LED SHORT  5  VLSP [ V ] LEDSHORT：LED detection voltage、VLSP：LSP setting voltage LSP setting voltage should be made in the range of 0.8 to 3.0V. Set at 5 V (typ.) when LSP = OPEN. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 9/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ○OVP (HSOP20:7pin / HTSSOP-B24：7pin) The OVP pin is an input pin for over-voltage protection and short circuit protection of DC/DC output voltage. If over-voltage is detected, the OVP pin will stop the DC/DC converter conducting step-up operation. When the short circuit protection (SCP) function is activated, the DC/DC converter will stop operation, and then the timer will start counting. When the timer completes counting the preset period of time, the LED drivers are stopped. The OVP pin is of the high impedance type and involves no pull-down resistor, resulting in unstable potential in the open-circuited state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider or otherwise. ○LED1 – LED4 (HSOP20:8,9,12,13pin / HTSSOP-B24：8,9,14,16pin) The LED1 to 4 pins are used to output constant current to LED drivers. Current value setting can be made by connecting a resistor to the ISET pin. For the current value setting procedure, refer to the description of “ISET pin”. If any of the LED pins is put in an erroneous state (e.g. short circuit mode, open circuit mode, or ground short circuit mode), the relevant protection function will be activated. ○LED_GND (HSOP20:10pin / HTSSOP-B24：11pin) The LED_GND pin is a power ground pin used for the LED driver block. ○STB (HSOP20:11pin / HTSSOP-B24：13pin) The STB pin is used to make setting of turning ON and OFF the IC and allowed for use to reset the IC from shutdown. Note: The IC state is switched (i.e., the IC is switched between ON and OFF state) according to voltages input in the STB pin. Avoid using the STB pin between two states (0.8 to 2.0V). ○PWM (HSOP20:14pin / HTSSOP-B24：17pin) The PWM pin is used to turn ON and OFF LED drivers. Light can be modulated by changing the duty cycle through the direct input of a PWM light modulation signal The high and low voltage levels of PWM pin is as listed in the table below: State PWM Voltage LED ON 状態 PWM= 2.0V~35V LED OFF 状態 PWM= －0.3V～0.8V ○ISET (HSOP20:15pin / HTSSOP-B24：18pin) The ISET pin is an output current setting resistor. Output current ILED varies in inverse proportion to resistance. The relation between output current ILED and the resistance of ISET pin connection resistor RISET is given by the following equation: I LED [ mA]  7.12  V NADIM [V ] 5000  RISET [ kΩ] 3 I LED [mA]  7500 RISET [ kΩ] (NADIM=0~5V) (NADIM>7V~35V) Output current setting should be made in the range of 30 to 150mA. It prepares automatically to suitable LED feedback voltage that can output LED current set by ISET pin. In short LED feedback voltage is dropped when the LED current is small and the IC heating is held automatically. In case of a large current is needed, raise the LED pin feedback voltage. And it adjusts automatically to LED pin voltage that can be flow large LED current. The calculation is as below. VLED  3.7  I LED [ A] [V ] 　 The LED feedback voltage (VLED) is clamped to 0.3V (typ.) when the LED current (ILED) is less than 81.1mA. NADIM input range is from 0V to 5V. And the range which the LED currents change with linearity is from 1.5V to 5.0V. When it reaches under VISET×0.90V(typ), the LED current is off to prevent from passing a large current to the LED pin when the RISET is shorted and the ISET pin is shorted to the GND. And as the ISET pin returns to a normal state, the LED current returns. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 10/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ○SS (HSOP20:16pin / HTSSOP-B24：20pin) The SS pin is used to make setting of soft start time and duty for soft start. It performs constant current charge of 2.0 uA to the external capacitor connected with SS terminal, which enables soft-start of DC/DC converter. Since the LED protection function (OPEN/SHORT detection) works when the SS terminal voltage reaches 3.7 V (typ.) or higher, it must be set to bring stability to conditions such as DC/DC output voltage and LED constant current drive operation, etc. before the voltage of 3.7 V is detected. ○FB (HSOP20:17pin / HTSSOP-B24：21pin) The FB pin is an output pin used for DC/DC current mode control error amplifier. In other words, the FB pin detects the voltages of LED pins (1 to 4) and controls inductor current so that the pin voltage of the LED located in the row with the highest Vf will come to 0.37V (NADIM=(2.62)V, ILED=100mA). As a result, the pin voltages of other LEDs become higher by Vf variation. After completion of soft start, the FB pin is put into the high-impedance state with the PWM signal being in the low state, thus maintaining the FB voltage. ○RT (HSOP20:18pin / HTSSOP-B24：22pin) The RT pin is used to connect a DC/DC frequency setting resistor. DC/DC drive frequency is determined by connecting the RT resistor. Drive frequency vs. RT resistance (Ideal) R RT  15000 f SW [ kHz ] [ k ] When RT is 100kΩ, Fsw is 150kHz(typ.). However, drive frequency setting should be made in the range of 100 kHz to 800 kHz. ○NADIM (HSOP20:19pin / HTSSOP-B24：23pin) NADIM pin is for analog dimming. Output current is proportionality with input voltage (negative). Basically, NADIM pin assumes the voltage inputted externally using high accuracy of resistive divider and etc., IC internally is in OPEN (High impedance) condition. Please be sure to apply externally for Resistive divider and etc. from REG58 output. Cannot use in an OPEN condition. ○VCC (HSOP20:20pin / HTSSOP-B24：24pin) The VCC pin is used to supply power for the IC in the range of 9 to 35V. If the VCC pin voltage reaches 7.5V (Typ.) or more, the IC will initiate operation. If it reaches 7.2V (Typ.) or less, the IC will be shut down. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 11/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●Startup operation and soft start (SS) capacitance setting The following section describes the sequence for the startup of this IC. 5V SS SLOPE VOUT Q D PWM SS COMP N DRIVER Css SS=FB Circuit OSC LED LED_OK FB 0.8V PWM LED_DRIVER Description of startup sequence (1) Set the STB and PWM pin to “ON”. (2) Set sll systems to “ON”, SS charge will be initiated. At this time, a circuit in which SS pin voltage for soft start becomes equal to FB pin voltage operates to equalize the FB pin and SS pin voltages regardless of whether the PWM pin is et to Low or High level. (3) Since the FB pin and SS pin reach the lower limit of the internal sawtooth wave of the IC, the DC/DC converter operates to start VOUT voltage rising. (4) The Vout voltage continues rising to reach a voltage at which LED current starts flowing. (5) When the LED current reaches the set amount of current, isolate the FB circuit from the SS circuit. With this, the startup operation is completed. (6) After that, conduct normal operation following the feedback operation sequence with the LED pins. If the SS pin voltage reaches 3.7V or more, the LED protection function will be activated to forcedly end the SS and FB equalizing circuit. SS capacitance setting procedure As aforementioned, this IC stops DC/DC converter when the PWM pin is set to Low level and conducts step-up operation only in the section in which the PWM pin is maintained at High level. Consequently, setting the PWM duty cycle to the minimum will extend the startup time. The startup time also varies with application settings of output capacitance, LED current, output voltage, and others. Startup time at minimum duty cycle can be approximated according to the following method: Make maeasurement of VOUT startup time with a 100% duty cycle, first. Take this value as “Trise100”. The startup time “Trise_min” for the relevant application with the minimum duty cycle is given by the following equation. Trise _ min  Trise _100[Sec] Min _ Duty [ratio] [Sec] However, since this calculation method is just for approximation, use it only as a guide. Make setting of time during which the SS pin voltage reaches the FB pin voltage longer than this startup time. Assuming that the FB pin voltage is VFB, the time is given by the following equation: Tss  Css [ F ] VFB[V ] 2[A] [Sec] As a result, it is recommended to make SS capacitance setting so that “Tss” will be greater than “Trise_min” www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 12/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ｛  About unused LED terminal automatic detecting function This IC is detected automatically that it is an unused channel by asssuming the LED terminal to be OPEN at starting. It explains the sequence. Sequence; ① STB=ON ② All systems are ON at initial timing of PWM=H. SS starts charging. ③ When the output voltage is boosted enough, and enough current flows through the LED, LED_OK signal is switched in the IC. PWM=L from the Rise timing of this signal for about 20us ④ During this PWM=L period, LED pins with LED connections' output voltage becomes 0.2V and above, where as unused LED pins are below 0.2V. ⑤ During this time, determination on whether the LED pins are 0.2V above/below is done. ⑥ After the determination, unused LED pins are pulled up to 5V. ⑦The AUTO signal remains “L” level. In addition, automatic determination of the OPEN decision will only be in SS range, therefore, please set the application so that the step-up/boost be completed before SS> 3.7V. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 13/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●LED current setting Setting of LED output current “ILED” can be made by connecting a resistor RISET to the ISET pin. RISET vs. ILED current relation equation R ISET  7500 [ k] 　 I LED [ mA] (NADIM=7~35V) However, LED current setting should be made in the range of 30mA to 150mA. [Setting example] To set ILED current to 100mA, RISET resistance is given by the following equation: R ISET  7500 7500   75 [k] 　 I LED [mA] 100[ mA] ●DC/DC converter drive frequency setting DC/DC converter drive frequency is determined by making RT resistance setting. Drive frequency vs. RT resistance (ideal) relation equation R RT  15000 f SW [ kHz ] [ k ] where fsw  DC/DC converter oscillation frequency [kHz] This equation has become an ideal equation without any correction item included. For accurate frequency settings, thorough verification should be performed on practical sets. [Setting example] To set DC/DC drive frequency “fsw” to 200 kHz, RRT is given by the following equation: RRT  15000 15000   75 [ k] 　 f sw [ kHz ] 200[ kHz ] www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 14/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●LSP setting procedure Making a change to the LSP pin input voltage will allow the threshold for LED short circuit protection to be changed. The LED short circuit detection voltage is set to 6V (Typ.) with the LSP pin being in the open-circuited state.LSP pin input voltage setting should be made in the range of 0.8V to 3V. The relation between the LSP pin voltage and the LED short circuit protection detection voltage is given by the following equation. LED SHORT  5  VLSP [ V ] Since the LSP pin divides 3V within the IC using resistive dividers (see the circuit diagram shown below), connecting an external resistor to the LSP pin will produce resistance combined with the internal IC resistance. Consequently, to make LSP pin voltage setting using external resistive dividers, it is recommended to connect them having resistance little affected by the internal resistance. (Smaller resistance makes the LSP pin increasingly less likely to be affected by the internal resistance, but this results in more power consumption. Careful attention should be paid to this matter.) LSP detection voltage setting equation If the setting of LSP detection voltage VLSP is made by dividing the REG58 voltage by the use of resistive dividers R1 and R2, VLSP will be given by the following equation:   R2[k]   5 [V ]　 LEDSHORT   REG58[V ]   (1) ( R1[k]  R2[k]   However, this equation includes no internal IC resistance. If internal resistance is taken into account, the detection voltage VLSP will be given by the following equation:   R2[k]  R4[k]  REG58[V ]  R3  REF[V ]  R1[k]   5 [V ]　 LEDSHORT   (2)  ( R1[k]  R3[k]  R2  R4  R2[k]  R4[k]  R1[k]  R3[k]  Make setting of R1 and R2 resistance so that a difference between resistance values found by Equations (1) and (2) will come to approximately 2% or less as a guide. [Setting example] Assuming that LSP is approximated by Equation (1) in order to set LSP detection voltage to 6V, R1 comes to 38.3k and R2 comes to 10k. When calculating LSP detection voltage taking into account internal IC resistance by Equation (2), it will be given as:   10[k]  1000[k]  5.8[V ]  2000[k]  3[V ]  38.3[k]   5  5.992[V ] VLSP    (38.3[k]  2000[k]  10[k]  1000[k]  10[k]  1000[k]  38.3[k]  2000[k]  The difference is given as: 5.992[V ]  6[V ] / 6[V ]  100  0.13% As a result, this setting will be little affected by internal impedance. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 15/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV ●OVP/SCP Settings OVP pin is DC/DC output voltage’s over voltage protection and short circuit protection input pin. OVP pin is a high impedance pin with no pull down resistor. Thus, at OPEN state please set the voltage input settings using voltage dividing resistor and such. Respective OVP pin protection conditions are as below Protection Name Detection Pin Detection Condition Cancellation Condition Timer Operations Protection Type OVP OVP OVP>3.0V OVP0.45 it stops the DCDC. Thus, RCS resistor value need to be checked after the peak current flow through the inductor is calculated. Furthermore, DCDC external components’ current capacity needs to be greater than peak current flowing through this inductor. （Inductor peak current Ipeak calculation method） Firstly, ripple voltage which occurs at the CS pin is decided depending on the DCDC application conditions. The conditions when made as below; Output voltage=VOUT[V] LED total current=IOUT[A] DCDC input voltage=VIN[V] DCDC efficiency =η[%] Total required average input current IIN: VOUT [V ]  I OUT [ A] [ A] VINwhich [V ] occurs [%] at inductor L[H] during Inductor ripple current IL[A] I IN  DCDC drive operation with switching frequency=fsw[Hz] is as follows (VOUT [V ]  V IN [V ])  V IN [V ] [ A] [ H ]  VIpeak ]  be f SWcalculated [ Hz ] Therefore, IL’s peak L current can using below equation OUT [V Δ IL  Ipeak  I IN [ A]  IL[ A] 2 [ A] (1) (Resistor RCS connected to CS pin selection method) This Ipeak flows in RCS and generates voltage. (refer to time chart diagram on the right). This voltage value, VCSpeak can be calculated as below VCS peak  Rcs  Ipeak [V ] This VCSpeak when reach 0.45V, will stop the DCDC output. Thus when selecting RCS value, below condition needs to be met. Rcs [ ]  Ipeak [ A]  0.45[V ] (DCDC Components’ Current Capacity Selection Method) When OCP reach detection voltage CS=0.45V, Iocp current I OCP  0.45[V ] [ A]  ( 2 ) Rcs[ ] Ipeak current (1)、IOCP current (2)、and components’ MAX current capacity needs to satisfy the following I peak  I OCP  Rated current of components Above condition needs to be satisfied when selecting DCDC application parts eg. FET, inductor, diode etc. Furthermore, continuous mode is recommended for normal DCDC applications. Inductor’s ripple current MIN limit value, lmin becoming Im in  I IN [ A]  IL[ A] [ A]  0 2 Is a condition to be met. If this is not met, it is called discontinuous mode. www.rohm.com © 2012 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 18/28 TSZ02201-0F1F0C100180-1-2 09.May.2014 Rev.003 Datasheet BD9394FP, BD9394EFV 【Setting Example】 Output voltage=VOUT[V]=56V LED total current=IOUT[A]=100mA×4ch=0.40A DCDC input voltage=VIN[V]=14V DCDC efficiency=η[%]=90% Total required average input current IIN: I IN [ A]  VOUT [V ]  I OUT [ A] 56[V ]  0.40[ A] 　   1.78 [ A] VIN [V ] [%] 14[V ]  90[%] When, DCDC switching frequency =fsw[Hz]=200kHz Inductor L[H]=33uH, Inductor ripple current ΔIL[A]: Δ IL  (VOUT [V ]  V IN [V ])  V IN [V ] (56[V ]  14[V ])  14[V ] 　  1.59 [ A]  L[ H ]  VOUT [V ]  f SW [ Hz ] 33  10  6 [ H ]  56[V ]  200  10 3 [ Hz ] Thus, IL peak current Ipeak becomes Ipeak  I IN [ A]  IL[ A] 1.59[ A] [　 A]  1.78[ A]   2.58 [ A] 2 2 …Peak current calculation result RCS resistor value when set at 0.1ohm VCS peak  Rcs  Ipeak  0 . 10 [  ]  2 . 58 [ A ]  0 . 258 [V ]  0 . 45V …RCS resistor consideration and satisfy the condition. In addition、OCP detection current IOCP at this time is I OCP  0.45[V ]  4 . 5 [ A] 0.1[ ] If parts used (FET,INDUCTOR、DIODE etc)’s current capacity3.7V LEDx > 0.2V Immediately Auto-Restart after detection (Judge periodically whether normal or not) LEDSHORT LEDｘ H SS>3.7V ISET GND SHORT ISET - - REG58 UVLO REG58 REG582.6V Auto-Restart VCC UVLO VCC VCC7.5V Auto-Restart OVP OVP OVP>3.0V - - OVP 5V (LSP=OPEN) (LSP=OPEN) Immediately Auto-Restart after detection (Judge periodically whether normal or not) Above Under ISET×90% Auto-Restart ISET×90% SCP OVP OVP0.1V FB OVER SHOOT FB FB>4V - - FB0.45V - - - Auto-Restart Immediately Auto-Restart after detection (Judge periodically whether normal or not) Immediately Auto-Restart after detection (Judge periodically whether normal or not) Pulse-by-Pulse To clear the latch type, STB should be set to “L” once, and then to “H”. Operation after the protection function detected Protection Function LED Driver DC/DC Soft-start LED OPEN Continue to operate LEDSHORT Continue to operate ISET GND SHORT Stop immediately Only detects LED, stops after CP count Only detects LED, stops after CP count Stop immediately STB Stop immediately Stop(and when REG58