Linear Technology LTC1872 Manual Download Page 13

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LTC1872

1872fa

For more information

www.linear.com/LTC1872

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.

revision hisTory

REV

DATE

DESCRIPTION

PAGE NUMBER

09/15

Revised package drawing

Summary of Contents for LTC1872

Page 1: ...ieved n n Wide VIN Range 2 5V to 9 8V n n VOUT Limited Only by External Components n n Constant Frequency 550kHz Operation n n Burst Mode Operation at Light Load n n Current Mode Operation for Excelle...

Page 2: ...N Falling VIN Rising l 1 55 1 85 2 00 2 10 2 35 2 40 V V Shutdown Threshold at ITH RUN l 0 15 0 35 0 55 V Start Up Current Source VITH RUN 0V 0 25 0 5 0 85 A Regulated Feedback Voltage 0 C to 70 C Not...

Page 3: ...DUTY CYCLE 20 30 V IN V SENSE mV 100 1872 G04 40 50 60 70 80 90 130 120 110 100 90 80 70 60 50 VIN 4 2V TA 25 C TEMPERATURE C 55 200 I TH RUN VOLTAGE mV 240 320 360 400 600 480 15 25 45 125 1872 G05...

Page 4: ...BLANKING CIRCUIT 0 15V 0 5 A 0 3V SLEEP OVP BURST CMP SHDN 1 2V UV 1872FD VREF 60mV VREF 0 8V VIN RS VOLTAGE REFERENCE SLOPE COMP ICMP R S Q FREQ FOLDBACK OSC SENSE VIN 5 2 4 4 EAMP VFB 3 NGATE VIN 6...

Page 5: ...age drops below approximately 2 0V the N channel MOSFET andallcircuitryisturnedoffexcepttheundervoltageblock which draws only several microamperes Overvoltage Protection The overvoltage comparator in...

Page 6: ...of current Using the scaling factor SF in in Figure 2 the value of RSENSE is RSENSE SF 10 IOUT 100 VIN VOUT VD Applications Information Inductor Value Calculation The operating frequency and inductor...

Page 7: ...ycle of the LTC1872 Output Diode Selection Under normal load conditions the average current con ducted by the diode in a boost converter is equal to the output load current ID avg IOUT It is important...

Page 8: ...d dry tantalum capacitors are both available in surface mount configurations An excellent choice of tantalum capacitors is the AVX TPS and KEMET T510 series of surface mount tantalum capacitors Also c...

Page 9: ...rrents VIN currentresultsinasmallloss which increases with VIN 2 MOSFET gate charge current results from switching the gate capacitance of the power MOSFET Each time a MOSFET gate is switched from low...

Page 10: ...inductor 3 The input decoupling capacitor 0 1 F should be connected closely between VIN Pin 5 and ground Pin 2 4 Connect the end of RSENSE as close to VIN Pin 5 as possible The VIN pin is the SENSE o...

Page 11: ...E C1 10 F 10V VIN 3V TO 9 8V VOUT 12V C2 47 F 16V M1 D1 LTC1872 12V 500mA Boost Converter ITH RUN LTC1872 10k R1 0 27 53 6 L1 150 H 220pF C1 TAIYO YUDEN CERAMIC EMK325BJ106MNT C2 AVX TPSD156M035R0300...

Page 12: ...BSC 0 80 0 90 1 00 MAX 0 01 0 10 0 20 BSC 0 30 0 50 REF PIN ONE ID NOTE 1 DIMENSIONS ARE IN MILLIMETERS 2 DRAWING NOT TO SCALE 3 DIMENSIONS ARE INCLUSIVE OF PLATING 4 DIMENSIONS ARE EXCLUSIVE OF MOLD...

Page 13: ...believed to be accurate and reliable However noresponsibilityisassumedforitsuse LinearTechnologyCorporationmakesnorepresenta tion that the interconnection of its circuits as described herein will not...

Page 14: ...nt Current VIN Down to 1V LTC1700 No RSENSE Synchronous Current Mode DC DC Step Up Controller 95 Efficient 0 9V VIN 5V 550kHz Operation LTC1772 Constant Frequency Current Mode Step Down DC DC Controll...