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DEMO MANUAL DC290

NO-DESIGN SWITCHER

dc290 LT/TP 0500 500 • PRINTED IN USA



LINEAR TECHNOLOGY CORPORATION 2000

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

●

FAX: (408) 434-0507

●

www.linear-tech.com

PC FAB DRAWI G

Paste Mask Top

Solder Side

Solder Mask Bottom

Silkscreen Top

Component Side

Solder Mask Top

PCB LAYOUT A D FIL

NOTES: UNLESS OTHERWISE SPECIFIED

MATERIAL; FR4 OR EQUIVALENT EPOXY, 2 OZ COPPER CLAD
THICKNESS 0.031

0.006 TOTAL OF 2 LAYERS

FINISH: ALL PLATED HOLES 0.001 MIN/0.0015 MAX COPPER PLATE
ELECTRODEPOSITED TIN-LEAD COMPOSITION
BEFORE REFLOW, SOLDER MASK OVER BARE COPPER (SMOBC)

SOLDER MASK; BOTH SIDES USING GREEN PC-401 OR EQUIVALENT

SILKSCREEN; USING WHITE NONCONDUCTIVE EPOXY INK

ALL DIMENSIONS ARE IN INCHES

SCORING:

0.017

2.000

SYMBOL

A
B
C
D

DIAMETER

0.020
0.040
0.072
0.095

NUMBER

OF HOLES

10
14

2
7

PLATED

YES
YES

YES

Содержание LTC1877

Страница 1: ... voltage capa bility is ideally suited for two Li Ion cells or 4 to 6 NiCd NiMH cell applications The exclusive use of low profile surface mount compo nents on this demo board results in a highly efficient application in a small volume The output voltage can be selected from 1 5V 2 5V 3 3V or a user programmable voltage by means of a jumper The frequency is internally set at 550kHz or can be synch...

Страница 2: ... MODE is connected to VIN Alternatively if JP1 or JP2 is in the upper position U then RUN or SYNC MODE is connected to GND If external sources drive RUN or SYNC MODE then JP1 JP2 or both must be removed PERFOR A CE SU ARY U W WW NOTE 2 Programmable via optional R7 VOUT 0 8V 1 887kΩ R7 NOTE 3 With VIN 5V the external feedback resistor contributes 0 24µA with JP3 1 5V selected 0 95µA with JP3 2 5V s...

Страница 3: ... LTC1877 8EMS8 Monolithic Synchronous Step Down Regulator LTC 408 432 1900 C2 Optional R2 R7 Optional PARTS LIST Figure 2 Output Voltage Selection JP3 3 3V Position Shown QUICK START GUIDE JP3 3 3V 2 5V 1 5V OPEN Thisdemonstrationboardiseasilysetuptoevaluatethe performance of the LTC1877 or LTC1878 IC Please follow the procedure outlined below for proper opera tion Refer to Figure 5 for proper con...

Страница 4: ...t causes a slight de crease in the feedback voltage relative to the 0 8V refer ence which in turn causes the ITH voltage to increase until the average inductor current matches the new load current While the top MOSFET is off the bottom MOSFET is turned on until either the inductor current starts to reverse as indicated by the current reversal comparator IRCMP or until the beginning of the next clo...

Страница 5: ...vailable on the LTC1877 andtheLTC1878toallowtheoscillatortobesynchronized to an external source connected to the SYNC MODE pin The output of the phase detector at the PLL LPF pin operates over a 0V to 2 4V range corresponding to 400kHz to 700kHz When locked the PLL aligns the turn on of the MOSFETs to the rising edge of the synchro nizing signal When the LTC1877 or the LTC1878 is clocked by an ext...

Страница 6: ...s in excess of 40 As a result the maximum inductor peak current is reduced for duty cycles 40 See the inductor peak current as a function of duty cycle graph in Figure 4 DUTY CYCLE 0 MAXIMUM INDUCTOR PEAK CURRENT mA 1100 1000 900 800 700 600 80 dc290A F04 20 40 60 100 LTC1877 VIN 5V LTC1878 VIN 3 3V Figure 4 Maximum Inductor Peak Current vs Duty Cycle JP3 VIN SYNC MODE RUN GND GND LTC1877 LTC1878 ...

Страница 7: ...solderedontotheboardbetweenVIN andGND Thisshouldeliminateallringingassociatedwith longVINandGNDleads SpaceisprovidedonthePCboard for this purpose as shown in Figure 6 MANUFACTURER DEVICE PHONE FAX Central Semiconductor Diodes 516 435 1110 516 435 1824 Coilcraft Inductors 847 639 6400 847 639 1469 Coiltronics Inductors 561 241 7876 561 241 9339 Dale Inductors 605 665 9301 605 665 0817 International...

Страница 8: ... FIL U W NOTES UNLESS OTHERWISE SPECIFIED 1 MATERIAL FR4 OR EQUIVALENT EPOXY 2 OZ COPPER CLAD THICKNESS 0 031 0 006 TOTAL OF 2 LAYERS 2 FINISH ALL PLATED HOLES 0 001 MIN 0 0015 MAX COPPER PLATE ELECTRODEPOSITED TIN LEAD COMPOSITION BEFORE REFLOW SOLDER MASK OVER BARE COPPER SMOBC 3 SOLDER MASK BOTH SIDES USING GREEN PC 401 OR EQUIVALENT 4 SILKSCREEN USING WHITE NONCONDUCTIVE EPOXY INK 5 ALL DIMENS...

Страница 9: ...Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery Lifecycle Information Analog Devices Inc DC290A B DC290A A ...

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