LT3481HDD Linear Technology, LT3481HDD Datasheet
LT3481HDD
Specifications of LT3481HDD
Available stocks
Related parts for LT3481HDD
LT3481HDD Summary of contents
Page 1
... V output voltage. The LT3481 is available in 10-Pin MSOP and 3mm x 3mm DFN packages with exposed pads for low thermal resistance. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. V OUT 3 ...
Page 2
... LT3481HMSE#PBF LT3481HMSE#TRPBF LEAD BASED FINISH TAPE AND REEL LT3481EDD LT3481EDD#TR LT3481IDD LT3481IDD#TR LT3481HDD LT3481HDD#TR LT3481EMSE LT3481EMSE#TR LT3481IMSE LT3481IMSE#TR LT3481HMSE LT3481HMSE#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: ...
Page 3
ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T noted. (Note 2) PARAMETER Minimum Input Voltage Quiescent Current from V IN Quiescent Current from BIAS Minimum Bias Voltage Feedback Voltage FB Pin Bias Current (Note 3) FB Voltage Line ...
Page 4
LT3481 TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency (V = 5.0V) OUT 100 12V 24V NEC PLC-0745-4R7 10 f: 800kHz 0 0.0001 0.001 0.01 0.1 1 LOAD ...
Page 5
TYPICAL PERFORMANCE CHARACTERISTICS Switch Voltage Drop 700 600 500 400 300 200 100 0 0 500 1000 1500 2000 2500 3000 3500 SWITCH CURRENT (mA) 3481 G10 Switching Frequency 1. 45.3k T 1.15 1.10 1.05 1.00 0.95 0.90 ...
Page 6
LT3481 TYPICAL PERFORMANCE CHARACTERISTICS Error Amp Output Current 100 –20 –40 –60 –80 1.065 1.165 1?.265 1.365 1.465 FB PIN VOLTAGE (V) 3481 G19 V Voltages C 2.50 2.00 CURRENT LIMIT CLAMP 1.50 1.00 SWITCHING ...
Page 7
PIN FUNCTIONS BD (Pin 1): This pin connects to the anode of the boost Schottky diode. BOOST (Pin 2): This pin is used to provide a drive voltage, higher than the input voltage, to the internal bipolar NPN power switch. ...
Page 8
LT3481 OPERATION The LT3481 is a constant frequency, current mode step- down regulator. An oscillator, with frequency set by RT, enables an RS fl ip-fl op, turning on the internal power switch. An amplifi er and comparator monitor the current ...
Page 9
APPLICATIONS INFORMATION FB Resistor Network The output voltage is programmed with a resistor divider between the output and the FB pin. Choose the 1% resis- tors according to: ⎛ ⎞ V OUT = – 1 ⎝ ...
Page 10
LT3481 APPLICATIONS INFORMATION frequency will be necessary to achieve safe operation at high input voltages. If the output is in regulation and no short-circuit or start-up events are expected, then input voltage transients 36V are acceptable regardless ...
Page 11
... For details of maximum output current and discontinuous mode operation, see Linear Technology Application Note 44. Finally, for duty cycles greater than 50% (V 0.5), there is a minimum inductance required to avoid subharmonic oscillations. See AN19. ...
Page 12
LT3481 APPLICATIONS INFORMATION Table 2. Capacitor Vendors VENDOR PHONE Panasonic (714) 373-7366 Kemet (864) 963-6300 Sanyo (408) 749-9714 Murata (408) 436-1300 AVX Taiyo Yuden (864) 963-6300 When choosing a capacitor, look carefully through the data sheet to fi nd out ...
Page 13
APPLICATIONS INFORMATION A fi nal precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LT3481. A ceramic input capacitor combined with trace or cable inductance forms a high quality (under damped) tank circuit. If the LT3481 circuit ...
Page 14
LT3481 APPLICATIONS INFORMATION Burst Mode Operation To enhance effi ciency at light loads, the LT3481 auto- matically switches to Burst Mode operation which keeps the output capacitor charged to the proper voltage while minimizing the input quiescent current. During Burst ...
Page 15
APPLICATIONS INFORMATION may not be fully charged. Because the boost capacitor is charged with the energy stored in the inductor, the circuit will rely on some minimum load current to get the boost circuit running properly. This minimum load will ...
Page 16
LT3481 APPLICATIONS INFORMATION from maximum value given by the following equation: ⎛ OUT = DC 1 – ⎝ ⎜ SYNC MAX + V – where V is the ...
Page 17
... LT3481 circuits. However, these capaci tors can cause problems if the LT3481 is plugged into a RT live supply (see Linear Technology Application Note 88 for a complete discussion). The low loss ceramic capacitor, R combined with stray inductance in series with the power C source, forms an under damped tank circuit, and the ...
Page 18
... The die temperature is calculated by multiplying the LT3481 power dissipation by the thermal resistance from junction to ambient. Other Linear Technology Publications Application Notes 19, 35 and 44 contain more detailed descriptions and design information for buck regulators and other switching regulators. The LT1376 data sheet has a more extensive discussion of output ripple, loop compensation and stability testing ...
Page 19
TYPICAL APPLICATIONS V IN 4.4V TO 34V 4.7μF 330pF D: DIODES INC. DFLS240L L: TAIYO YUDEN NP06DZB4R7M 34V 4.7μF 22.1k 220pF D1: DIODES INC. DFLS240L D2: MBR0540 L: TAIYO YUDEN NP06DZB4R7M V IN 8.6V TO 22V ...
Page 20
LT3481 TYPICAL APPLICATIONS V IN 15V TO 34V 10μF 330pF D: DIODES INC. DFLS240L L: NEC/TOKIN PLC-0755-100 V IN 20V TO 34V 4.7μF NOTE: DO NOT APPLY SYNC SIGNAL UNTIL PGOOD GOES HIGH SYNC IN 3.3V SQ WAVE 300kHz TO ...
Page 21
TYPICAL APPLICATIONS 8V TO 34V 1k SYNC WAVE Hz TO 450kHz 25k Q1 25k 50pF V IN 3.5V TO 27V 4.7μF 330pF D: DIODES INC. DFLS240L L: TAIYO YUDEN NP06DZB3R3M 5V Step-Down Converter with Sync and One-Shot ...
Page 22
LT3481 PACKAGE DESCRIPTION 3.50 0.05 1.65 0.05 2.15 0.05 (2 SIDES) 0.25 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF 22 DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG ...
Page 23
... LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 24
... I <1μA, TSSOP16E Package 1.20V 1mA, I <6μA, MS8E Package 1.20V 3.8mA, I <30μA, TSSOP16E Package 1.20V 2.5mA 25μA, TSSOP16E Package 1.20V 100μA, I <1μA, TSSOP16E Package 1008 REV B • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2006 3481fb ...