BD1754HFN

LED Drivers for LCD Backlights Constant Current Backlight Driver for LCD Panels (Non-step-up Type) BD1754HFN No.11040EBT25 ●Description The multi-level brightness control LED works as a constant current driver in 64 steps, so that the driving current can be adjusted finely. BD1754HFN is best suited to turn on LEDs that require high-accuracy LED brightness control. ●Features 1) Current regulation for LED up to 4 parallels 2) Adjustable constant current 64 steps 3) High accuracy and matching of each current channel (0.5% Typ) 4) Brightness control via a single-line digital control interface (Uni-Port Interface Control = UPIC) 5) 2.9 mm x 3.0 mm HSON8 Small package ●Applications This driver can be used in various fields such as mobile phones, portable game machines and etc. ●Absolute Maximum Ratings(Ta = 25 ℃) Parameter Maximum applied voltage Power dissipation Operating temperature range Storage temperature range (*1) Symbol VMAX Pd Topr Tstg Ratings 7 630 (*1) -30 ~ -55 ~ +85 +150 Unit V mW ℃ ℃ This value is the measurement value when the driver is mounted on a glass epoxy board (70 mm x 70 mm x 1.6 mm). When using the driver at Ta of 25 ℃ or higher, the power is dissipated by approx. 5.04 mW/℃. ●Recommended Operating Conditions (Ta = -30 ℃ to +85 ℃) Ratings Parameter Symbol Min Typ Operating power supply voltage Driver pin voltage range Vin VDRV 2.7 0.2 3.6 - Max 5.5 Vin-1.4 Unit V V Condition When Current driver power on. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 1/11 2011.06 - Rev.B BD1754HFN ●Electrical Characteristics (Unless otherwise specified, Ta = 25 ℃ and Vin = 3.6 V) Parameter Quiescent current Circuit current [Current driver] Maximum current LED Current accuracy LED Current matching [Logic controller] Low threshold voltage High threshold voltage ‘H’ level input current ‘L’ level input current EN ‘H’ time EN ‘L’ time EN Off time-out VIN supply -> EN active time EN stand-by -> VBAT Off time (*1) Technical Note Symbol Iq IDD Limits Min Typ 0.1 1.2 Max 1 2.0 Unit μA mA EN=0V Condition Except LED current ILED-max ILED-diff ILED-match 29.76 - 32.0 0.5 34.24 7.0 3.0(*1) mA % % RISET = 120kΩ When current 16.5 mA setting RISET = 120kΩ When current 16.5 mA setting RISET = 120kΩ VIL VIH IIH IIL THI TLO TOFF TVINON TVINOFF 1.4 -2 0.05 0.3 1 1 0 0 0 - 0.4 2 100 100 - V V μA μA μsec μsec msec msec msec EN=Vin EN=0V The following formula is used for calculation: ILED-match = {(Imax - Imin) / (Imax + Imin)} x 100 Imax = Current value in a channel with the maximum current value among all channels Imin = Current value in a channel with the minimum current value among all channels www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 2/11 2011.06 - Rev.B BD1754HFN ●Reference Data 1.0 2.0 1.8 Technical Note 1.0 0.8 1.6 1.4 Ta=80 ℃ Ta=25 ℃ 0.8 Ist [µA] IDD [mA] 1.0 0.8 0.6 0.4 Ist [µA] 0.6 1.2 0.6 Ta=-30 ℃ 0.4 0.2 Ta=-30,25,80 ℃ 0.4 0.2 0.2 Ta=-30,25,80 ℃ 0.0 2.5 3.0 3.5 4.0 4.5 VIN [V] 5.0 5.5 0.0 2.5 3.0 3.5 4.0 4.5 VIN [V] 5.0 5.5 0.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VIN [V] Fig. 1 Circuit current (stand-by) Fig. 2 Circuit current Fig. 3 LED off-leakage current 40 40 2.0 1.5 30 ILED(L1) [mA] ILED(L1) [mA] 30 DNL(L1) [LSB] 1.0 Ta=-30,25,80 ℃ 20 0.5 0.0 -0.5 -1.0 -1.5 20 Ta=-30,25,80 ℃ 10 10 Ta=-30,25,80 ℃ 0 0 0.6 1.2 1.8 2.4 3 L1 Terminal Voltage [V] 3.6 0 2.5 - 2.0 3.5 VIN [V] 4.5 5.5 0 10 20 30 40 CODE [DEC] 50 60 Fig. 4 LED output current vs. LED pin voltage Fig. 5 LED output current vs. VIN (Vin = 3.6 V, at 32 mA of LED current) (Vin = 3.6 V, at 32 mA of LED current) 2.0 1.5 1.0 INL(L1) [LSB] 0.5 0.0 -0.5 -1.0 -1.5 - 2.0 0 10 20 30 40 CODE [DEC] 50 60 L1-L4 Current Matching(%) 5.0 4.5 4.0 3.5 Fig. 6 LED current characteristics (Vin = 3.6 V, differential linearity error) 100 80 ILED(L1) [mA] 3.0 2.5 2.0 1.5 1.0 0.5 0.0 64 56 48 40 32 24 Current State Ta=80 ℃ Ta=25 ℃ 60 Ta=25 ℃ Ta=-30 ℃ 40 Ta=-30,25,80 ℃ 20 0 16 8 60 80 100 120 140 RISET [kO] 160 180 200 Fig. 7 LED current characteristics (Vin = 3.6 V, integral linearity error) Fig. 8 LED current relative accuracy Fig. 9 LED current vs. RISET (Vin = 3.6 V) (Vin = 3.6 V, at the maximum current setting) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 3/11 2011.06 - Rev.B BD1754HFN ●Block Diagram and Recommended Circuit Example Power Supply Technical Note L1 VIN Cin 0.1µF EN UPIC 6 Current DAC L2 L3 L4 ISET R ISET GND 120kΩ (When ILED-max=32mA) Fig.10 ●Terminals No. 1 2 3 4 5 6 7 8 Pin Name EN GND ISET VIN L1 L2 L3 L4 BD1754HFN Block Diagram and Recommended Circuit Example In/ Out In Out Out Out Out Out ESD Diode For Power VIN VIN VIN For GND GND GND GND GND GND GND GND Ground Bias current Functions LED enable and Brightness control signal Power supply voltage input Current sink for LED 1 Current sink for LED 2 Current sink for LED 3 Current sink for LED 4 ●Description of Operations (1) UPIC (= Uni-Port Interface Control) interface BD1754HFN has a single-line digital control interface (UPIC) that can control the power ON/OFF and LED current value through the EN pin. The LED current decreases by one step depending on the number of rising edges. After the number of rising edge is reached to the minimum output current (64 rising edges), the next rising edge changes the output current to the maximum value at startup time. To maintain any output current, the EN pin must be kept at ‘H’ level. To power off, the EN pin must be kept at ‘L’ level for more than 1msec. T HI EN (Internal) T LO TOFF State OFF C64 C63 C62 C62 C61 C60 C2 C1 C64 C63 OFF ILED OFF MAX Current MAX Current OFF MIN Current Fig.11 THI EN Brightness Control Method TLO TOFF Fig.12 www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. UPIC Interface 4/11 2011.06 - Rev.B BD1754HFN By following sequence, UPIC can control current driver for MAX current and OFF state only. Technical Note TOFF EN (Internal) State OFF C 64 OFF C64 TOFF OFF ILED OFF M AX OFF M AX O FF Fig.13 UPIC Interface usage for MAX current or OFF only (2) Current Driver The MAX Current is determined by the ISET resistance and the following formula. ILED-MAX [mA] = 6.4 x 600 [mV] / RISET [kΩ] The LED current state can be changed by the EN control signal. When the state is Cn, the output current (ILED) can be obtained from the following formula (where, n indicates a state number). ILED [mA] = ILED-MAX x n / 64 The following table is the example of LED current, when ISET resistance is 120 [kΩ]. RISET : 120[kΩ] Output current [mA] 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 State C64 C63 C62 C61 C60 C59 C58 C57 C56 C55 C54 C53 C52 C51 C50 C49 Output current [mA] 32.0 31.5 31.0 30.5 30.0 29.5 29.0 28.5 28.0 27.5 27.0 26.5 26.0 25.5 25.0 24.5 State C48 C47 C46 C45 C44 C43 C42 C41 C40 C39 C38 C37 C36 C35 C34 C33 Output current [mA] 24.0 23.5 23.0 22.5 22.0 21.5 21.0 20.5 20.0 19.5 19.0 18.5 18.0 17.5 17.0 16.5 State C32 C31 C30 C29 C28 C27 C26 C25 C24 C23 C22 C21 C20 C19 C18 C17 Output current [mA] 16.0 15.5 15.0 14.5 14.0 13.5 13.0 12.5 12.0 11.5 11.0 10.5 10.0 9.5 9.0 8.5 State C16 C15 C14 C13 C12 C11 C10 C9 C8 C7 C6 C5 C4 C3 C2 C1 When the state is C64 (the maximum value), the output current value can be changed on the ISET resistance value as below. State : C64 Total output current of the four channels (mA) 64.0 128.0 170.8 256.0 ISET resistance value (kΩ) 240 120 90 60 Output current per channel (mA) 16.0 32.0 42.7 64.0 www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 5/11 2011.06 - Rev.B BD1754HFN ●Application Circuit Examples (1) Circuit example when the power supply is separated Power Supply2=5V Technical Note (Ex.) On the assumption that Vf is 3 V The voltage value of L* pin must be VIN-1.4 V at the maximum when the LED is powered ON. (Maximum rating = 7.0 V) Power Supply1 VIN Cin 0.1µF EN UPIC 6 Current DAC L1 L2 L3 L4 ISET RISET GND 120kΩ (When ILED-max=32mA) Fig.14 Circuit example when the power supply is separated This figure shows a circuit example when the power supply for VIN and for LEDs is separated. Apply a voltage of Vf (threshold voltage value of a white LED) or higher to the LED. In this case, please note that when the LED is powered ON, the voltage value of L* pin (each pin of L1 to L4) must be VIN-1.4 V at the maximum. If a voltage of higher than VIN-1.4 V is applied to L* pin, a desired current value cannot be obtained. Also, please pay attention to the voltage application procedure at start-up. Be sure to power the current driver ON using the UPIC after applying power supply voltages to the VIN and the LED-anode pins. If the current driver is powered ON prior to applying power supply voltages to the LED, a rush current occurs in the LED. Determine the resistance value with which the LED current value is maximized and then connect such resistor between the ISET and the GND pins. The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format. (2) Circuit example when using only two LEDs Connect to the GND pin. L1 VIN Cin 0.1µF EN UPIC 6 Current DAC L2 L3 L4 ISET RISET GND 120kΩ (When ILED-max=32mA) Fig.15 Circuit example when using only two LEDs This figure shows a circuit example when none of L3 and L4 LEDs are used. Connect both of the unused L3 and L4 pins to the GND pin.Likewise, it is possible to make the L1 and/or the L2 pins unused, which allows the back lights to be used with the one or three LED(s) turned on.In all cases, connect the unused L* pin to the GND pin. Determine the resistance value with which the LED current value is maximized and then connect such resistor between the ISET and the GND pins.The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 6/11 2011.06 - Rev.B BD1754HFN (3) Circuit example when the EN pin is powered on at all times Technical Note L1 VIN Cin 0.1µF Rs EN Cs 6 Current DAC L2 L3 L4 UPIC ISET RISET GND 120kΩ (When ILED-max=32mA) Fig.16 Circuit example when the EN pin is powered on at all times This figure shows a circuit example when the EN pin is powered on at all times. To prevent a rush current from occurring in the driver, it is necessary to apply voltages to the VIN pin and the LEDs prior to powering the current driver ON. Mount an RC filter between the VIN and the EN pins to delay the EN pin rising against the power-supply voltage rising. Determine the resistance value with which the LED current value is maximized and then connect such resistor between the ISET and the GND pins. (4) Circuit example when performing a PWM brightness control L1 VIN Cin 0.1µF EN UPIC 6 Current DAC L2 L3 L4 ISET RISET GND 1MΩ PWM 120kΩ Fig.17 Circuit example when performing a PWM brightness control This figure shows a circuit example when performing a PWM brightness control. Through switching the ISET resistance value by the PWM input signal, the LED current is outputted under a PWM mode. The EN signal is controlled by an applied voltage level.In the circuit example shown above, the LED current value is changed to 3.43 mA in 0 % of the PWM duty cycle, 17.72 mA in 50 % of that and 32 mA in 100 % of that. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 7/11 2011.06 - Rev.B BD1754HFN (5) Circuit example when driving a large current with only one LED powered on. Technical Note ILED=128mA L1 VIN Cin 0.1µF EN UPIC 6 Current DAC L2 L3 L4 ISET RISET GND 120kΩ (When ILED-max=32mA) Fig.18 Circuit example when driving a large current with only one LED powered on. This figure shows a circuit example when driving a large current through all of four channels with only one LED powered on. By shorting out all the LED driver pins, in the example of using 120 kΩ RISET, a current up to 128 mA (32 mA x 4) can be driven. In this example, the brightness can be adjusted in 64 gradations with 2 mA step (0.5 mA step/channel x 4 channels). For higher current values, using 60 kΩ RISET allows a current up to 256 mA to be driven into one of the LEDs. The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format. (6) Circuit example when making the eight LEDs available by connecting the two BD1754HFN drivers ILED=32mA ILED=32mA L1 VIN Cin 0.1µF EN UPIC 6 L2 L3 L4 L1 VIN Cin 0.1µF EN UPIC 6 Current DAC L2 L3 L4 ISET RISET GND 120kΩ (When ILED-max=32mA) Current DAC ISET RISET GND 120kΩ (When ILED-max=32mA) Fig.19 Circuit example when making the eight LEDs available by connecting the two BD1754HFN drivers This figure shows a circuit example when making eight LEDs available by connecting two BD1754HFN drivers. By connecting the control signals to the EN pins in parallel, the eight LED channels can be controlled concurrently. This parallel connection scheme can increase the number of the LED channels further as necessary (such as twelve, sixteen, or more). Determine the resistance value with which the LED current value is maximized and then connect such resistor between the ISET and the GND pins. The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 8/11 2011.06 - Rev.B BD1754HFN (7) Circuit example when connecting the two LEDs to each of the channels in series Power Supply2=6.2~7V Technical Note (Ex.) On the assumption that Vf is 3 V The voltage value of L* pin must be VIN-1.4 V at the maximum when the LED is powered ON. L1 L2 L3 L4 (Maximum rating = 7.0 V) Power Supply1 VIN 0.1µF EN UPIC 6 Current DAC ISET 120kΩ GND (When ILED-max=32mA) Fig.20 Circuit example when connecting the two LEDs to each of the channels in series This figure shows a circuit example when making 8 (2 x 4) LEDs available by connecting two LEDs to each of the channels in series. In this example, when Vf is set to approx. 3 V in order to ensure the voltage to L1 through L4 pins, it is necessary to apply a voltage of 6.2 V (3 V x 2 LEDs in series + 0.2 V of the minimum voltage value of the driver pin) or higher to the LED anode pin as its power supply voltage. Pay attention that the voltage should not exceed the 7.0-V maximum rating of the L1 through L4 pins. Determine the resistance value with which the LED current value is maximized and then connect such resistor between the ISET and the GND pins. The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format. ●Application Component Selection Symbol Recommended value Cin Symbol RISET 0.1µF Recommended value 120kΩ Recommended component GRM188B31H104KA92B Recommended component MCR10PZHZF1203 Manufacturer MURATA Manufacturer ROHM ●Recommended PCB Layout Design PCB pattern to provide low impedance for the wiring to the power supply line. Also, provide a bypass capacitor if needed. LED_PWR L ED_PWR L4 L3 L2 L1 Connect Cin input-bypass capacitor in close proximity between the VIN and GND pins. Connect the RISET resistor in close proximity to the ISET pin. Cin RISET EN GND VIN RISET EN GND Cin VIN EN GND ISET VIN Fig.21 Layout image of the application components (Top View) Fig.22 Surface (Top View) www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 9/11 2011.06 - Rev.B BD1754HFN Technical Note ●Notes for Use (1) Absolute Maximum Ratings An excess in the absolute maximum ratings, such as applied voltage, temperature range of operating conditions, 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) Recommended 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. The voltage and temperature characteristics are also shown under the conditions in respect of electrical ones. (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 that 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 that no terminal is operated 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 cause a malfunction. (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 that applied to 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) Thermal design Perform thermal design in which there are adequate margins by taking into account the permissible dissipation (Pd) in actual states of use. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 10/11 2011.06 - Rev.B BD1754HFN ●Ordering part number Technical Note B D 1 Part No. 1754 7 5 4 H F N - T R Part No. Package HFN=HSON8 Packaging and forming specification TR: Embossed tape and reel HSON8 2.9 ± 0.1 (MAX 3.1 include BURR) (0.2) (2.2) (0.05) Tape Quantity Embossed carrier tape 3000pcs TR The direction is the 1pin of product is at the upper right when you hold 0.475 3.0 ± 0.2 2.8 ± 0.1 8 765 (0.15) (0.3) 5678 (0.45) (0.2) (1.8) Direction of feed +0.1 0.13 –0.05 ( reel on the left hand and you pull out the tape on the right hand 1pin ) 1234 4321 1PIN MARK 0.6MAX S +0.03 0.02 –0.02 0.1 0.65 0.32±0.1 S 0.08 M Direction of feed (Unit : mm) Reel ∗ Order quantity needs to be multiple of the minimum quantity. www.rohm.com © 2011 ROHM Co., Ltd. All rights reserved. 11/11 2011.06 - Rev.B 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