LTC1265 LINER [Linear Technology], LTC1265 Datasheet
LTC1265
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LTC1265 Summary of contents
Page 1
... Figure 1. High Efficiency Step-Down Converter LTC1265/LTC1265-3.3/LTC1265-5 Step-Down DC/DC Converter DESCRIPTIO ® The LTC DC/DC converter featuring Burst Mode output current. The LTC1265 incorporates a 0.3 switch (V =10V) allowing up to 1.2A of output current. = 10V Under no load condition, the converter draws only 160 A. In shutdown it typically draws a mere 5 A making this converter ideal for current sensitive applications ...
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... DC Switch Current (Pin 14) .................................... 1.2A Peak Switch Current (Pin 14) ................................. 1.6A Switch Voltage (Pin 14) .................................. V Operating Temperature Range LTC1265C ............................................... LTC1265I ........................................ – Junction Temperature (Note 2) ............................. 125 C Storage Temperature Range ....................– 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T ...
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... Shutdown Pin Input Current 10 Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note calculated from the ambient temperature T J dissipation P according to the following formulas: D LTC1265CS, LTC1265CS-3.3, LTC1265CS- • 110 C/ TYPICAL PERFORMANCE CHARACTERISTICS ...
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... SENSE N/C,V (Pin 9): For the LTC1265 adjustable version, this FB pin serves as the feedback pin from an external resistive divider used to set the output voltage. On the LTC1265-3.3 and LTC1265-5 versions, this pin is not used SHDN (Pin 10): Pulling this pin HIGH keeps the internal switch off and puts the LTC1265 in micropower shut- down ...
Page 5
... When the load is heavy, the LTC1265 is in continuous operation. During the switch ON time, current comparator C monitors the voltage between Pins 7 and 8 connected across an external shunt in series with the inductor. When LTC1265/LTC1265-3.3/LTC1265-5 W (Pin 9 connection shown for LTC1265-3.3 and LTC1265-5; change create LTC1265) PWR ...
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... OUT Solving for R the LTC1265 and extended component values yields: R SENSE The LTC1265 is rated with a capability to supply a maximum of 1.2A of output current. Therefore, the minimum value of . The maxi- SENSE R that can be used is 0.083 . A graph for selecting SENSE R versus maximum output is given in Figure 2. ...
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... L: . OUT(MAX) L 5.2(10 Using an inductance smaller than the above value will result in the inductor current being discontinuous. A consequence of this is that the LTC1265 will delay entering . Each time the T Burst Mode operation and efficiency will be degraded at is reset to T low currents. ...
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... Under this condition, the diode must safely handle I at close to 100% duty cycle. Most SC(PK) LTC1265 circuits will be well served by either a 1N5818 or a MBRS130LT3 Schottky diode. An MBRS0520 is a good choice for I 500mA. OUT(MAX) ...
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... The junction temperature is simply given by example, consider the LTC1265 is in dropout at an input voltage of 4V with a load current of 0.5A. From the Typical Performance Characteristics graph of Switch Re- sistance, the ON resistance of the P-channel is 0.55 . Therefore power dissipated by the part is ...
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... LTC1265. These items are also illustrated graphically in the layout diagram of Figure 5. Check the following in your layout: 1. Are the signal and power grounds segregated? The LTC1265 signal ground (Pin 11) must return to the (–) plate The power ground (Pin 12) returns to the OUT anode of the Schottky diode, and the (– ...
Page 11
... LTC1265 is in sleep mode with quiescent current reduced to 160 A. The inductor current should also be monitored. If the circuit is poorly decoupled, the peak inductor current will be haphazard as in Figure 7a. A well decoupled LTC1265 has a clean inductor current as in Figure 7b. pin is a sawtooth T 3 ...
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... OFF L At light loads the peak inductor current is at 25mV/0.125 = 0.2A PEAK Therefore, at load current less than 0.1A the LTC1265 will be in Burst Mode operation. Figure 8 shows the complete circuit and Figure 9 shows the efficiency curve with the above calculated component values ...
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... I SHDN THR 7 8 – + SENSE SENSE 1000pF † L1 †† R SENSE 0.1 OUT 3. OUT 220 F 10V LTC1265 TA02 SHDN 22 F † L1 0.1 F 25V OUT –5V 100k C OUT 100 F + 10V †† R SENSE 0.1 LTC1265 TA03 ** 13 ...
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... F 10V 25k 100pF R ** SENSE 0.162 MBRS130LT3 C OUT * F** + 20V †† L1A 25V MBRS130LT3 4 • 301k †† L1B 34k 100pF R * SENSE 0.162 LTC1265 TA05 V OUT 5V * OUT LTC1265 F09 V OUT –12V * V OUT 12V C * OUT 68 F 20V ...
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... DALE 593D107X0010D2W † IRC LRC2010-01-R15-J †† L1 SELECTION PART NO. MANUFACTURER COILCRAFT DO3316-333 CTX33-4 COILTRONICS LPT4545-330LA DALE CD74-330 SUMIDA ††† 0V 3.3V/5V SHDN OUT = 5V OUT †† L1 45. OUT 100 F + 10V 56.2k 75k † R SENSE 0.15 V OUT 0V/3.3V/5V LTC1265 TA07 700mA 15 ...
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... CTX100-4P COILTRONICS CD105-101 SUMIDA †† L1 30k 100 OUT 100 F + 10V 138k † MBRS130LT3 V OUT 4 NICAD 1A FAST CHARGE 0.1A TRICKLE CHARGE LTC1265 TA08 0.337 – 0.344* (8.560 – 8.738 (3.810 – 3.988 16V IN 20V 400mA, MS8 ...