LTC3454 Linear Technology, LTC3454 Datasheet
LTC3454
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LTC3454 Summary of contents
Page 1
... In shutdown no supply current is drawn. A high constant operating frequency of 1MHz allows the use of small external components. The LTC3454 is offered in a low profi le (0.75mm) thermally enhanced 10-lead (3mm × 3mm) DFN package. ...
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... Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3454 is guaranteed to meet specifi cations from 0°C to 70°C. Specifi cations over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls ...
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... LED Current Programming Ratio 4050 PROGRAMMED I = 500mA LED T = 25°C A 4000 3950 3900 3850 3800 3750 3700 3650 125 2.7 3.1 3.5 3.9 4.3 4.7 V (V) IN LTC3454 www.DataSheet4U.com Enable Thresholds vs V 1200 T = 25°C A 1100 1000 900 800 V 700 600 500 400 300 200 125 2.7 3.1 3.5 3.9 4.3 V ...
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... LTC3454 W U TYPICAL PERFOR A CE CHARACTERISTICS LED IN 60 PROGRAMMED I = 500mA LED 25° 2.7 3.1 3.5 3.9 4.3 4.7 5.1 V (V) IN 3454 G10 Maximum Regulated V OUT vs Programmed LED Current 5. 3. 25°C A 5.30 5.25 5.20 5.15 5.10 5.05 5.00 4.95 4.90 100 200 300 400 500 600 700 800 900 PROGRAMMED I ...
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... LED SW1 (Pin 10): Switching Node. External inductor con- nects between SW1 and SW2. Recommended value is 4.7µH/5µH. Exposed Pad (Pin 11): Ground Pin. Solder to PCB ground for electrical contact and optimal thermal performance. LTC3454 www.DataSheet4U.com CH1, V OUT 1V/DIV CH2, I LED ...
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... LTC3454 W BLOCK DIAGRA 2.7V TO 5.5V UNDERVOLTAGE LOCKOUT OVERTEMP PROTECTION BANDGAP REFERENCE OUT 800mV I SET1 3 R ISET1 800mV I SET2 4 EN1 R ISET2 1 EN2 2 6 OPTIONAL 10 SW1 SWITCH A GATE DRIVERS AND SWITCH B ANTICROSS- CONDUCTION UV FORWARD CURRENT LIMIT + OT – 3.4A 1.23V LOGIC + – ...
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... U OPERATIO Buck-Boost DC-DC Converter The LTC3454 employs an LTC proprietary buck-boost DC/DC converter to generate the output voltage required to drive a high current LED. This architecture permits high- effi ciency, low noise operation at input voltages above, below or equal to the output voltage by properly phasing four internal power switches. The error amp output voltage on the V pin determines the duty cycle of the switches ...
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... With either enable pin pulled high, the buck-boost will regulate the output voltage at the current programmed by R ISET1 With both enable pins pulled to GND, the LTC3454 shutdown and draws zero current. The enable pins are high impedance inputs and should not be fl oated. ...
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... U APPLICATIO S I FOR ATIO COMPONENT SELECTION Inductor Selection The high frequency operation of the LTC3454 allows the use of small surface mount inductors. The inductor cur- rent ripple is typically set to 20% to 40% of the maximum average inductor current. For a given ripple the inductance term in Boost mode is: ...
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... DAC, a current DAC, a simple potentiometer or a PWM input not recommended to control brightness by PWMing the enable pins directly as this will toggle the LTC3454 in and out of shutdown and result in erratic operation. LED Failure Modes If the LED fails as an open circuit, the safety amplifi er takes ...
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... TOP AND BOTTOM OF PACKAGE LTC3454 www.DataSheet4U.com OUT ENx LTC3454 I LED SETx I = 3850 • IDAC LED 0.8V IDAC ≤ R MIN (3b OUT ENx LTC3454 I LED SETx 0.8V – V PWM ≥ 3850 R LED SET MIN R SET V PWM 0.8V – (DC% • 3850 R SET DV CC ≥ 10kHz f ...
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... SW1 SW2 V 4.7 F OUT SWD LED LED SWC EN2 1MHz I SET1 BUCK-BOOST R I ISET1 SET2 6.19k LTC3454 1% GND (EXPOSED PAD) COMMENTS V : 1.6V to 18V MS10 Package/EDD Package V : 2.6V to 16V ThinSOT Package 10V ThinSOT Package V : 2.5V to 10V ThinSOT Package/SC70 Package ...