LT3476 LINER [Linear Technology], LT3476 Datasheet
LT3476
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LT3476 Summary of contents
Page 1
... A frequency adjust pin allows the user to program switching frequency between 200kHz and 2MHz to optimize effi ciency and external component size. The LT3476 senses output current at the high side of the LED. High side current sensing is the most fl exible scheme for driving LEDs, allowing buck, boost or buck- boost confi ...
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... LT3476EUHF#TRPBF LEAD BASED FINISH TAPE AND REEL LT3476EUHF LT3476EUHF#TR Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ELECTRICAL CHARACTERISTICS temperature range, (Note 3) otherwise specifi ...
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... SW SHDN = 0V PWM1-4 < 0.4V, CAP = LED = 5V CAP = LED = 5V Note 3: The LT3476E is guaranteed to meet specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. LT3476 ...
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... LT3476 W U TYPICAL PERFOR A CE CHARACTERISTICS V(CAP-LED) Threshold vs V ADJ 150 T = 25°C A 120 0.3 0.6 0.9 1.2 V (V) ADJ 3476 G01 V(CAP-LED) Threshold vs Temperature ADJ REF 108 107 106 105 104 103 102 –45 – TEMPERATURE (°C) 3476 G04 Reference Voltage 1 ...
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... Pad directly to ground plane. The Exposed Pad metal of the package provides both electrical contract to ground and good thermal contact to the printed circuit board. It must be soldered to the circuit board for proper pin ADJ operation. pin ADJ LT3476 pin for the channel to become high C 3476fa 5 ...
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... U OPERATIO The LT3476 is a constant-frequency, current mode regula- tor with an internal power switch. Operation can be best understood by referring to the Block Diagram. At the start of each oscillator cycle, the SR latch is set, which turns on the Q1 power switch. A voltage proportional to the switch current is added to a stabilizing ramp and the resulting sum is fed into the positive terminal of the PWM comparator, A2 ...
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... I(SW) 1A/DIV 0A Figure 1. LED Disconnect Transient Setting the Switching Frequency The switching frequency of the LT3476 is set by an ex- ternal resistor connected between the R supply not leave this pin open. Also, do not load this pin with a capacitor. A resistor must always be connected for proper operation. See Table 1 below or see the Oscil- ...
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... PWM pin is sampled only during a narrow time slot at the beginning of each switch period. Inductor Selection The inductors used with the LT3476 should have a satura- tion current rating of 2.5A or greater. For best loop stability results, the inductor value selected should provide a ripple current of 350mA or more. For buck (step-down) or boost (step-up) confi ...
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... LED current large input supply range is expected. At low duty cycles (T less than 350ns) and low ON average inductor current (less than 500mA), the LT3476 may start to skip switching pulses to maintain output regulation. Pulse-skipping mode is usually less desirable because it leads to increased ripple current in the LED. ...
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... U Dimming Control There are two methods to control the current source for dimming using the LT3476. The fi rst method, popular with LED applications, uses the PWM pin to modulate the current source between zero and full current to achieve a precisely programmed average current. To make this ...
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... SIDES) PIN 1 TOP MARK (SEE NOTE 6) 7.00 ± 0.10 (2 SIDES) 0.75 ± 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE M0-220 VARIATION WHKD 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS LT3476 350mA 10μH LED3 LED4 300mΩ 300mΩ CAP3 CAP4 2.2μF SW4 1.05V REF VADJ1-4 ...
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... FAX: (408) 434-0507 ● × Quad Boost 100mA 8LED Driver 4.7μH 2.2μF CAP1 CAP2 1Ω 2.2μF 2.2μF LED2 100mA SW1 SW2 CAP1-4 LED1-4 LT3476 V IN PWM1-4 SHDN GND COMMENTS 18V, V IN(MIN) IN(MAX) Package V = 2.7V 5.5V, V IN(MIN) IN(MAX) DFN-10 Package ...