SEMICONDUCTOR TECHNICAL DATA KIB3402F KIB3402F. Figure1. 4Series White LED Driver in Thin TS6. White LED Step-Up Converter

Transcription

1 SEMICONDUCTOR TECHNICAL DATA KIBF BICD LINEAR INTEGRATED CIRCUIT White LED StepUp Converter The KIBF is a monolithic stepup DC/DC converter specifically designed to drive white LEDs with a constant current from Liion cell. Relative large mv feedback voltage & it s high accuracy help you setting LED current with a external resistor. KIBF is available in a extremely low profile & small TS package. A.7 H inductor is sufficient for most application. FEATURES Inherently Matched LED Current. High Efficiency : 8% (max.) Built in a open circuits protection for the LEDs fail. Drives Up to four LEDs without external zener diode. Drives Up to six LEDs with external zener diode. Built in a Nchannel MOSFET Switch. Fast.MHz(typ.) Switching Frequency. Uses Tiny mm Tall Inductors. Bulit in Thermal protection. Wide Dimming control range : %~%. Extremely low height & small Packaging. A C F L G G E K B K J I H J TS D DIM MILLIMETERS A.9 _. B. _. C.7 _. D. _. E.8 _.7 F.9 _. G.9 H. _. I. _. J MIN. K. _.7 L. APPLICATIONS Celluars Phones PDAs Digital Cameras MP Players, Color Displays Marking Type Name Lot No. TYPICAL APPLICATION L.7 µ H~ µ H D 87. CONVERSION EFFICIENCY OFF ON Shutdown and Dimming control KIBF LED LED LED R.Ω C EFFICIENCY (%) Vin.V 77..V.V 7., C : XR OR X7R DIELECTRIC D : KEC KDR7E/KDR7E (Low V F ) L : MURATA LQHCNKL OR EQUIVALENT LOAD CURRENT (ma) Figure. Series White LED Driver in Thin TS.. Revision No : /

2 KIBF One Shot One Shot OUT Vth _ OUT VRef _ OUT BLOCK DIAGRAM mv ADC (Rsense) figure. KIBF Block Diagram MAXIMUM RATINGS (Ta= ) CHARATERISTICS SYMBOL RATING UNIT Input Voltage. ~. V Switching pin Voltage V. ~ V pin Voltage V. ~ V Operating temperature range Topr ~ 8 Storage temperature range Tstg ~ Maximum Junction temperature Tj RECOMMENDED OPERATING CONDITIONS (T opr =~8 ) CHARATERISTICS SYMBOL CONDITION MIN. TYP. MAX. UNIT Input Voltage.8. V pin voltage for full LED current V H.7 V =.V pin voltage to shutdown chip V L. V pin input pulse width t PW() Both Positive and Negative pulse LED Current Response Delay (When Power ON.) IF =.V, R SENSE =, Topr =, Four LED T pd.. Revision No : /

3 KIBF ELECTRICAL CHARACTERISTIC (Topr=~8, =.8~.V, R SENSE =, unless otherwise noted.) CHARATERISTICS SYMBOL CONDITION MIN. TYP. MAX. UNIT Input Voltage.8. V Supply Current I CC =.V, V =.V.9. V = V. Feedback Voltage V =V =.V, T opr =, L = H 9 Pin Bias Current I =.V, V =.V Switching Frequency f OSC V =.V.77.. Switching Pin Current I O() Switch RDS(ON) R ON I O().7. Switch Leak Current I OZ(). Pin Voltage V V Pin Leak Current I OZ(). Thermal Shutdown TSD 8 Switching Pin OVP V O() V pin voltage for Full LED Current V H.7 V =.V pin voltage to shutdown Chip V L. V Feedback Bias Current I. Maximum Duty Cycle D max 8 9 % PIN FUNCTIONS NO. SYMBOL FUNCTION AND CONNECTION. Control pin : Shutdown or dimming control. Connect external enable or dimming circuits. Shutdown mode (IF = ) : V <.V Dimming control mode : (IF = % ~ %, depend on V ).V < V <.V, when V is above.v IF keep its maximum value(%). Filtered PWM signal, above us of pulse width, can be used for dimming control. Over output voltage detect pin. Connect cathode of schottky diode and anode of highest LED. Switch pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI. Feedback pin. Reference voltage is mv. Connect cathode of lowest LED and resistor here. Ground pin. Connect directly to local ground plane, Input supply pin. Must be locally bypassed... Revision No : /

4 KIBF APPLICATION INFORMATION Inductor Selection A.7 H inductor is sufficient for most application. The efficiency comprison of different value inductors help you design your application circuits. EFFICIENCY (%) Vin=.V, LED Inductor=Murata 7..7uH 7. uh 7. LOAD CURRENT (ma) Figure. Efficiency Comaprison of different value inductors Capacitor Selection A input capacitor and output capacitor above are sufficient for most KIBF application. Diode Selection For Diode Selection, both forward voltage drop and diode capacitance need to be considered. Shottky diodes with higher current ratings usually have lower forward voltage and larger diode capacitance, which can cause significant switching losses. A schottky diode rated at to is sufficient for most KIBF applications. Part No. Reverse Voltage (V) Forward Current (ma) KDR7E ma KDR7E ma KDR ma Voltage Drop (V).V (max) at ma.v(max) at ma.v(max) at ma Table. Recommended Schottky Diodes LED Current Control The LED current is controlled by the feedback resistor(r SENSE in Figure ). The feedback reference is. The LED current is /R SENSE. The tolerance of LED Current is depends on tolerance of R SENSE and feedback reference. OpenCircuits Protection In the case of output open circuit, when LEDs are disconnected from the circuit or the LEDs fail, the feedback voltage will be zero Package The KIBF will then switch at a high duty cycle resulting in a high output voltage, but Internal Over Voltage Protection Circuits prevent output voltage ascending over pin voltage( V ~ V see Fig. ). This circuits is valid when driving up to LEDs in series. But, when driving more than LEDs in series, Normal output voltage could be over pin voltage. In this case, zener diode can be used to limit output voltage, but check connection of pin to VCC.(see Fig.) L.7 µ H~ µ H KIBF Figure. LEDs driver with Opencircuit protection. L.7 µ H~ µ H KIBF Figure. LEDs driver with Opencircuit protection. D D DZ LED LED LED LED LED LED LED LED Dimming Control There are different type of dimming control circuits:. Using a DC Voltage to pin. V Table pin Voltage vs I LED.Ω R Ω C C Description V~.V UNIT V~.V V >.V Rate Of the LED Current ~ % Example : R SENSE = ~ ma.. Revision No : /

5 KIBF DC L.7 µ H~ µ H KIBF Figure. Using a DC Signal to pin..ω C. Using a PWM Signal to pin. With the PWM signal applied to the pin, the KIBF is turned on or off by the signal. Typical frequency range of the PWM signal is khz to khz. The switching waveforms of the pin PWM control are shown in Figure 7(A) and 7(B) D LED LED LED Vsw V/Div V V/Div (A) khz (ms/div) Figure 7. Using a PWM Signal to pin.. Using a DC Voltage to pin. The dimming control using a DC control voltage to pin of the KIBF is shown in Figure. The LED current can be varied applying a DC voltage to the pin. The voltage can come from a filtered PWM signal. It can be used to replace the variable DC Voltage source in dimming control. L D PWM L.7 µ H~ µ H D KIBF LED LED LED.Ω C KIBF LED LED LED R R DC C Figure8. Using DC Voltage to pin. Vsw V/Div. Using a Logic Signal to pin. For applications that need to adjust the LED current in discret steps, a logic signal can be used as shown in Figure 9. L D V V/Div (A) khz (ms/div) uf KIBF LED LED LED Rdim KTKV LOGIC C uf Figure9. Using a Logic Signal to pin... Revision No : /

6 KIBF V vs V Efficicncy vs Temperature V (mv) V EFFICICNCY (%) Vin=.V Vin=.V Vin=.V 9 V (V) Temperature ( C) Frequency vs Vcc Switching Frequency vs Temperature FREQUENCY (MHz) ITCHING FREQUENCY (MHz) Vcc (V) Temperature ( C) Quiescent Current vs Temperature Thermal Shut Down Icc (µa) Vin=.V Vin=.V Vin=.7V V (mv) TEMP ( C) TEMP ( C).. Revision No : /