LT3491 LINER [Linear Technology], LT3491 Datasheet
LT3491
Available stocks
Related parts for LT3491
LT3491 Summary of contents
Page 1
... Schottky diode are all contained inside the tiny SC70 and 2mm × 2mm DFN packages. With such a high level of integration, the LT3491 provides a high efficiency LED driver solution in the smallest of spaces. , LTC, LT and LTM are registered trademarks of Linear Technology Corporation. ...
Page 2
... Operating Temperature Range (Note 2) .. – 40°C to 85°C Maximum Junction Temperature ......................... 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10sec, SC-70) ......... 300° CTRL LED CAP = 20° ORDER PART NUMBER LCHJ LT3491ESC8 CONDITIONS V = 30V CAP V = 16V 16V CAP LED V = 16V 15V, CTRL = 3V ...
Page 3
... V = 3.6V 200ns/DIV IN FRONT PAGE APPLICATION CIRCUIT Note 2: The LT3491E is guaranteed to meet performance specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. ) Schottky Forward Voltage Drop 400 ...
Page 4
... LT3491 W U TYPICAL PERFOR A CE CHARACTERISTICS Quiescent Current (V = 3V) CTRL 3.0 2.5 2.0 1.5 1.0 0 (V) IN 3491 G09 Open-Circuit Output Clamp Voltage vs Temperature 125 –50 – 100 TEMPERATURE (°C) 3491 G12 Sense Voltage (V – CAP LED vs V CTRL 240 ...
Page 5
... PCB ground to achieve the rated thermal performance. IN PWM COMP – Σ RAMP GENERATOR OSCILLATOR – Figure 1. Block Diagram LT3491 200 mV R SENSE 1 SW CAP 8 DRIVER Q1 OVERVOLTAGE PROTECTION + R A3 – 6.25 LED – 7 GND CTRL PINS ...
Page 6
... CTRL is pulled lower than 50mV. 50mA/DIV 6 Minimum Output Current The LT3491 can drive a 3-LED string at 2mA LED current without pulse skipping using the same external compo- nents shown in the application circuit on the front page of this data sheet. As current is further reduced, the device will begin skipping pulses ...
Page 7
... INRUSH CURRENT The LT3491 has a built-in Schottky diode. When supply voltage is applied to the V through the inductor and the Schottky diode and charges up the CAP voltage. The Schottky diode inside the LT3491 can sustain a maximum current of 1A. Taiyo Yuden (800) 368-2496 www.t-yuden.com ...
Page 8
... LT3491 U U APPLICATIO S I FOR ATIO For low DCR inductors, which is usually the case for this application, the peak inrush current can be simplified as follows: α π ⎛ ⎞ V – ⎝ ⎜ ⎠ ⎟ I • exp – • PK ω ω L • ...
Page 9
... Si2302 MOSFET can be used since its source is connected to ground. The PWM signal is applied to the CTRL pin of the LT3491 and the gate of the MOSFET. The PWM signal should traverse between 0V to 2.5V, to ensure proper turn on and off of the driver and the NMOS transistor Q1 ...
Page 10
... PWM DIMMING RANGE 3491 F08 Figure 8. Dimming Range Comparison of Three PWM Frequencies IN L1 10µ CAP C1 R SENSE 1µF LT3491 10Ω GND LED CTRL PWM FREQ 2. Si2302 100k 3491 F09 Figure 9. Li-Ion to Four White LEDs with Both PWM Dimming and Analog Dimming C2 1µ ...
Page 11
... APPLICATIO S I FOR ATIO LOW INPUT VOLTAGE APPLICATIONS The LT3491 can be used in low input voltage applications. The input supply voltage to the LT3491 must be 2.5V or higher. However, the inductor can be run off a lower battery voltage. This technique allows the LEDs to be powered off two alkaline cells. Most portable devices have a 3 ...
Page 12
... CTRL DIMMING CONTROL 3491 TA07a R SENSE 10Ω CAP SHUTDOWN AND CTRL DIMMING CONTROL 3491 TA08a C2 4.7µF R SENSE 1Ω D1 CAP LED 10µH LT3491 CTRL SW GND 3491 TA09a Efficiency 3. LED CURRENT (mA) ...
Page 13
... CONTROL GND C1, C3: TAIYO YUDEN LMK212BJ105MD C2: TAIYO YUDEN LMK316BJ475ML D1: LUXEON EMITTER LXHL-BWO2 L1: MURATA LQH32CN150 C2 4.7µF D1 LED L1 15µH SW 3491 TA02a 15µH SW 3491 TA03a LT3491 Efficiency 100 120 140 160 180 200 LED CURRENT (mA) ...
Page 14
... GND C1: TAIYO YUDEN LMK212BJ105MD C2: TAIYO YUDEN GMK316BJ105ML L1: MURATA LQH32CN100 Li-Ion Driver for Five White LEDs SHUTDOWN AND DIMMING CONTROL CTRL CAP LT3491 10µH SW LED C1 1µF GND C1: TAIYO YUDEN LMK212BJ105MD C2: TAIYO YUDEN GMK316BJ105ML L1: MURATA LQH32CN100 LEDs ...
Page 15
... DFN (2mm × 2mm) (Reference LTC DWG # 05-08-1703) 0.675 ±0.05 PIN 1 BAR PACKAGE TOP MARK OUTLINE (SEE NOTE 6) 0.25 ± 0.05 0.75 ±0.05 0.200 REF 0.50 BSC LT3491 1.80 – 2.20 (NOTE 4) PIN 8 INDEX AREA (NOTE 6) PIN 1 0.15 – 0.27 0.50 BSC 8 PLCS (NOTE 3) 0.00 – 0.10 REF SC8 SC70 0905 REV Ø ...
Page 16
... LT3491 U TYPICAL APPLICATIO Li-Ion Driver for Six White LEDs SHUTDOWN AND DIMMING CONTROL CTRL CAP LT3491 10µH SW LED GND C1 1µF C1: TAIYO YUDEN LMK212BJ105MD C2: TAIYO YUDEN GMK316BJ105ML L1: MURATA LQH32CN100 RELATED PARTS PART NUMBER DESCRIPTION LT1618 Constant Current, Constant Voltage 1.24MHz, High Efficiency ...