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| BD6155FVM Communication ICs DC/DC converter for LCD back light BD6155FVM BD6155FVM is an ideal IC to drive white LED used for the LCD back light of cellular phones, and PDA etc. This IC incorporates charging pump step-up circuit to drive white LED with high VF. It also integrates a driver to drive white LED with 4-step constant current. Only one external resistor can set the current value. !Applications Small portable appliances, such as cellular phones, PHS, PDA Battery-powered equipments using the white LED. !Features 1) Built-in charging pump step-up circuit. 2) Built-in constant current driver for LED. (Current value : 4 steps variable) 3) Ultra small MSOP8 package. (Height 0.9mm Max.) !Absolute maximum ratings (Ta=25C) Parameter Maximum supply voltage Maximum input voltage Power dissipation Symbol VBAT VIN Pd Topr Tstg Limits -0.3~+6.0 -0.3~+6.0 350 -25~+75 -55~+125 Unit V V mW C C Operating temperature Storage temperature Reduce to 3.5mW/C when Ta=25C or above. !Recommended operating conditions (Ta=25C) Parameter Power supply Symbol VBAT Min. 2.9 Typ. - Max. 5.5 Unit V 1/7 BD6155FVM Communication ICs !Block diagram CURRENT1 1 CURRENT CONT 8 CHARGE PUMP DRIVER 7 VBAT CURRENT2 2 C STBY 3 6 GND LEDS 4 5 LED !Pin descriptions Pin No. 1 2 3 4 5 6 7 8 Pin Name CURRENT1 CURRENT2 STBY LEDS LED GND C VBAT Function Fixed current setup pin1. Fixed current setup pin2. Stand-by pin (High:Operation, Low:No operation) LED driver current pin (Fixed current sink pin) LED cathode connection pin for charge pump Ground Capacitor connection pin for charge pump Power supply voltage input pin 2/7 BD6155FVM Communication ICs !Electrical characteristics (unless otherwise noted, Ta=25C, VBAT=3.6V, STBY=3.6V) Parameter This product is not designed for protection against radioactive rays. !Measurement circuit 1F 1 V1 A AM1 CURRENT1 VBAT 8 SWD1 OPEN D1 2 7 A AM8 V8 7 SW7 1 C1 ON OPEN 1 AM72 A V72 SW72 2 V F 2 V2 A AM2 CURRENT2 C+ 7 3 IS72 VM72 FM72 D2 SWD2 OPEN AM3 5 3 V3 A STBY GND 6 ON OPEN 1 A SW52 2 V SW4 1 2 3 1 4 LEDS LED 5 SW5 2 5 SWO1 OPEN C2 ON OPEN SWO3 SWO2 ISO1 V AM52 V52 IS52 VM52 R=2.7 R=20K 3 ON V SW4B ON AM4 V V VM4 VO1 VA01 Fig.1 3/7 BD6155FVM Communication ICs !Circuit operation 1) Charge pump driver Charge pump is consisted capacitor pin (pin7), external schotky diodes and capacitors. Output voltage at no loading is 2VBAT-2VF. (VF is as same as schotky's VF ) Output voltage at loading is referred Fig2. As standard example, however it depends on external components. Shotky diodes RB521-S30 15 Charge pump output (V) 12 VBAT=5.5V 1F VBAT 1F OUTPUT VOLTAGE : 9 VBAT=3.6V LED C (Pin7) 6 3 VBAT=2.9V 0 0 20 40 60 80 (mA) 100 OUTPUT LOAD : Fig.2 Charge pump loading characteristics (Typical operating characteristics) 2) Fixed current driver LED driver fixed current is determined by resistor value between LEDS pin (pin4) and GND. At current control set up voltage1 (Current1, 2=High) resistor value between LEDS-GND is set as 2.7. 205mV / 2.7 = 75.9mA (2 expressions) The above current is loaded to LED as fixied current. LED LED (5Pin) + - LEDS (4Pin) CURRENT1 CURRENT2 RSENSE * LED drive current fix example LEDS pin voltage (mV) Current control setup voltage 1 (Current 1=High Current 2=High) Current control setup voltage 2 (Current 1=Low Current 2=High) Current control setup voltage 3 (Current 1=High Current 2=Low) Current control setup voltage 4 (Current 1=Low Current 2=Low) 205.0 155.0 105.0 55.0 LED drive current (mA) RSENSE=2.7 RSENSE=5.1 75.9 57.4 38.9 20.4 40.2 30.4 20.6 10.8 The less RSENSE, the bigger fixed current for LED drive. Resistors value should be determined with confirmation of charge pump loading characteristics (Fig.2) and LED's I-V characteristics. 4/7 BD6155FVM Communication ICs !Design information 1. The maximum of power loss of this IC is controlled by the output transistor M1 in regulator driver. Relations of the power supply voltage are signified in 2 expressions with this loss. V = VOUT - (VF2 + ILED x R1 + VLED) The loss in M1, V x ILED = ILED x {2VBAT- (2VF1 + VF2 + ILED x R1 + VLED)} (2 expressions) V ; The voltage between LED-LEDS VF1 ; Shotky's Di VF VF2 ; LED's VF VOUT ; Charge pump output voltage (Fig.2) VLED ; The voltage across RSENSE (examples at 205mV calculation) ILED ; Drive current. ILED VF1 VF1 VOUT VBAT VF2 LED R1 LED LEDS M1 RSENS 0.2V V Room temperature power dissipation (350mW) Pd-VBAT 300 Loss Pd : (mW) 200 IO=50mA 100 IO=80mA VF1=0.5V VF2=3.4V R1=0 0 2 3 4 5 6 Power supply voltage VBAT (V) 2) Power supply voltage The thermal shutdown circuit turn on, and output electric current declines when chip temperature is about 125 degrees due to low electric current driver. 5/7 BD6155FVM Communication ICs !Application example CURRENT1 1 CURRENT CONT 8 CHARGE PUMP DRIVER VBAT C1 1F C C2 1F D2 (RB521S30) D1 (RB521S30) CURRENT2 2 7 STBY 3 6 GND C3 1F LEDS RSENS 2.7 LED 4 5 VOUT !Attached components (1) We recommend capacitor with lower ESR. (2) We recommend capacitor with is good characteristics to temperature. (3) Mount all capacitor as close together as possible. !Operation notes (1) The notes in power supply turning on. Turn STBY pin (pin3) in the low state with power supply. From this sequence, current flowing to the LED terminal is prevented. (2) Patern layout Make wiring for power supply, GND and - GND short and thick. Take into considerations the power supply ripple. A coupling capacitor, which lowers power supply impedance will make it decline. (3) Though this product is carefully checked for quality assurance, however if it exceeds the absolute maximum rating such as applied voltage and operating temperature range, this IC may be deteriorated or damaged. One this IC is damaged, short-circuits and open modes can not be identified. If the usage of the devices involves operations which will exceed the absolute maximum rating, then it is necessary to take safety measures such as a fuse to protect the device. (4) GND Electric potential as the GND pin must be minimum in any operating condition. Keep the electric potential of the GND pin below that of the other pins except GND pin in consideration of transient phenomenon. (5) Thermal design Be careful to ensure adequate margins for thermal design in consideration of power dissipation (Pd) in actual operating mode. (6) Misplacement and short-circuit between pins When you put the IC on the print-circuit board, please be careful of the direction and correct placement of the IC. If the IC is placed wrongly, IC may be damaged. And also, the IC may be damaged if an alien substance is mixed into the line (output-output or output-GND) to be short. 6/7 BD6155FVM Communication ICs (7) Operation in the strong electromagnetic field Please be careful that this IC may be miss operated in the strong electromagnetic field. !Electrical characteristic curves 1.0 CIRCUIT CURRENT : IQ1 (mA) 100 12 VOUT OUTPUT VOLTAGE : VDC (%) 0.8 EFFENCIENCY : (%) 80 10 RSENSE=5.1 8 6 4 BAT 0.6 60 BSENSE=2.7 0.4 40 0.2 20 2 0 0 0.0 0 1 2 3 4 5 6 0 0 10 20 30 40 50 60 70 80 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE : VBAT (V) SUPPLY VOLTAGE : VBAT (V) CHAGE PUMP OUTPUT CURRENT : IO (mA) Fig.4 Circuit current-power supply voltage Fig.5 Effenciency-load current (note1) note1 : Charge pump's characteristic Fig.6 Charge pump outputpower supply voltage 250 0.7 0.6 0.5 0.4 0.3 0.2 0.1 RSENSE=0 250 LEDS OUTPUT VOLTAGE : VLED (mV) LEDS OUTPUT VOLTAGE : VLED (mV) LED OUTPUT VOLTAGE : VLED (V) 200 200 150 150 100 100 50 50 0 0 1 2 3 4 5 6 0 0 50 100 150 200 0 0 2 4 6 STBY PIN CONTROL VOLTAGE : VSTBY (V) LED INPUT CURRENT : ILED (mA) SUPPLY VOLTAGE : VBAT (V) Fig.7 LEDS output voltageSTBY terminal voltage Fig.8 LED output voltageLED power supply Fig.9 LEDS output voltagepower supply voltage !External dimensions (Units: mm) 2.90.1 8 5 4.00.2 2.80.1 1 4 0.475 0.9Max. 0.750.05 0.080.05 0.22 0.65 +0.05 -0.04 0.290.15 0.60.2 +0.05 0.145-0.03 0.08 M 0.08 S MSOP8 7/7 Appendix Notes No technical content pages of this document may be reproduced in any form or transmitted by any means without prior permission of ROHM CO.,LTD. The contents described herein are subject to change without notice. The specifications for the product described in this document are for reference only. Upon actual use, therefore, please request that specifications to be separately delivered. Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. Any data, including, but not limited to application circuit diagrams information, described herein are intended only as illustrations of such devices and not as the specifications for such devices. ROHM CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any third party's intellectual property rights or other proprietary rights, and further, assumes no liability of whatsoever nature in the event of any such infringement, or arising from or connected with or related to the use of such devices. Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or otherwise dispose of the same, no express or implied right or license to practice or commercially exploit any intellectual property rights or other proprietary rights owned or controlled by ROHM CO., LTD. is granted to any such buyer. Products listed in this document use silicon as a basic material. Products listed in this document are no antiradiation design. The products listed in this document are designed to be used with ordinary electronic equipment or devices (such as audio visual equipment, office-automation equipment, communications devices, electrical appliances and electronic toys). Should you intend to use these products with equipment or devices which require an extremely high level of reliability and the malfunction of with would directly endanger human life (such as medical instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other safety devices), please be sure to consult with our sales representative in advance. About Export Control Order in Japan Products described herein are the objects of controlled goods in Annex 1 (Item 16) of Export Trade Control Order in Japan. In case of export from Japan, please confirm if it applies to "objective" criteria or an "informed" (by MITI clause) on the basis of "catch all controls for Non-Proliferation of Weapons of Mass Destruction. Appendix1-Rev1.0 |
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