LTC1771 LINER [Linear Technology], LTC1771 Datasheet
LTC1771
Available stocks
Related parts for LTC1771
LTC1771 Summary of contents
Page 1
... LTC1771 ideal for a wide variety of battery-powered appli- cations where maximizing battery life is important. The LTC1771’s availability in both 8-lead MSOP and SO packages provides for a minimum area solution. , LTC and LT are registered trademarks of Linear Technology Corporation. ...
Page 2
... Switch Off Time OFF V Mode Pin Threshold MODE 2 U (Note 1) Junction Temperature (Note 2) ............................ 125 C Operating Temperature Range (Note 3) + 0.3V) LTC1771E ......................................... – LTC1771I ......................................... – Storage Temperature Range ................. – 150 C + 0.3V) Lead Temperature (Soldering, 10 sec).................. 300 0.3V ORDER PART ...
Page 3
... LOAD Note 4: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See Applications Information. Note 5: The LTC1771 is tested in a feedback loop that servos V and power A balance point for the error amplifier (V Note 6: No-load supply current consists of sleep mode current (9 A typical) plus a small switching component necessary to overcome Schottky diode leakage and feedback resistor current ...
Page 4
... LTC1771 U U FUNCTIONAL BLOCK DIAGRA RUN/SS 1 MODE (BURST ENABLE 1.23V ON EA – 10% CURRENT V OUT * GND – MODE * OPTIONAL FOR FOLDBACK CURRENT LIMITING 4 W READY REFERENCE SOFT-START SLEEP READY ON TRIGGER 1-SHOT 3.5 s STRETCH 1.23V ...
Page 5
... EA to full power along with the other necessary circuitry. This scheme (patent pending) allows the reduced to such a low operating current during sleep mode without adding unacceptable delay to wake up the LTC1771 due to the compensation capacitor on I normal operation. . When ...
Page 6
... LTC1771 APPLICATIO S I FOR ATIO The basic LTC1771 application circuit is shown in Figure 1 on the first page. External component selection is driven by the load requirement and begins with the selection Once R is known, L can be chosen. Next, the SENSE SENSE MOSFET and D1 are selected. The inductor is chosen based largely on the desired amount of ripple current and for Burst Mode operation ...
Page 7
... MOSFET (R guaranteed 2.5V) is required for applications that GS work close to this voltage. When these MOSFETs are used, make sure that the input supply to the LTC1771 is less than the absolute maximum V rating (typically 12V), as the GS MOSFET gate will see the full supply voltage. ...
Page 8
... Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in the LTC1771 circuits: the LTC1771 DC bias current, MOSFET gate charge current, I catch diode losses. 1. The DC bias current load and increases proportionally with load constant 150 A during continuous mode ...
Page 9
... SENSE Run/Soft-Start Function The RUN/SS pin is a dual purpose pin that provides the soft- start function and a means to shut down the LTC1771. Soft-start reduces the input surge current from V gradually increasing the internal current limit. Power supply sequencing can also be accomplished using this pin ...
Page 10
... Minimum On-Time Considerations Minimum on-time t is the smallest amount of time ON(MIN) that the LTC1771 is capable of turning the top MOSFET on and off again determined by internal timing delays and the amount of gate charge required to turn on the P-channel MOSFET. Low duty cycle applications may ...
Page 11
... RUN/SS MODE MODE C ITH R ITH SENSE TH LTC1771 GND PGATE C 0 BOLD LINES INDICATE HIGH CURRENT PATHS Figure 3. LTC1771 Layout Diagram LTC1771 DS(ON 130 . GS(MAX (i.e., short circuit) at maximum OUT ...
Page 12
... I SENSE TH 1000pF LTC1771 GND PGATE R Si3443DV 1.02M 1% 5pF UPS5817 5V/2A Regulator with Burst Mode Operation Disabled 8 RUN/SS MODE 7 I SENSE TH 1000pF LTC1771 GND PGATE R 0.05 Si6447DQ 22 H 3.09M 1% 5pF UPS5817 SENSE TO 12V IN 0 25V OUT 2 ...
Page 13
... Zeta Converter 1 8 RUN/SS MODE MODE SENSE TH 1000pF LTC1771 GND PGATE Si6435DQ 8.66M 1% 5pF • 20V LTC1771 + C Li-Ion IN SENSE 22 F 3.3V TO 4.2V 25V OUT OUT 150 F 6.3V 1771 TA02 18V IN SENSE 22 F 0.025 ...
Page 14
... MODE MODE 7 SENSE 1000pF LTC1771 PGATE + R SENSE 0.1 1.02M 5pF 4-NiCd Battery Charger 8 MODE MODE 7 SENSE 1000pF LTC1771 PGATE R SENSE 0.1 Si6447DQ 47 H 4.69M 1% 5pF UPS5817 12V 25V 1N4148 OUT 2 ...
Page 15
... TYP 0.016 – 0.050 0.014 – 0.019 (0.406 – 1.270) (0.355 – 0.483) TYP LTC1771 0.118 0.004** (3.00 0.102 0.034 0.004 (0.86 0.102) 0.006 0.004 (0.15 0.102) MSOP (MS8) 1098 (0 ...
Page 16
... Low Noise, LDO Micropower Regulators LTC1772 Constant Frequency Step-Down DC/DC Controller Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com 5V/1A Zeta Converter 8 RUN/SS MODE MODE 7 I SENSE TH 1000pF LTC1771 GND PGATE R SENSE 0.025 Si3443DV 3.09M 1% 5pF • ...