DEMO MANUAL DC195 NO-DESIGN SWITCHER LTC1627 Monolithic Synchronous Step-Down Regulator U DESCRIPTIO Demonstration circuit DC195 is a constant-frequency step-down converter using an LTC(R)1627 monolithic synchronous regulator. It provides low input voltage, high efficiency conversion for cell phones and other portable electronics operating from one or two Li-Ion cells or three to six NiCd cells. Constant 350kHz operation and up to 500mA output capability in an SO-8 package provide a low noise, space-efficient solution for wireless applications. The circuit highlights the capability of the the LTC1627. Designed to work at low voltages, the input voltage (VIN) can range from 2.65V to 8.5V. At input voltages lower than U W PARAMETER VIN Input Voltage Range VOUT Output Voltage IQ , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. WW PERFOR A CE SU SYMBOL 4.5V, a charge pump bootstrapped to the SW node can be enabled via a jumper to produce a negative supply. This supply is used by the top driver to increase the gate overdrive of the top P-channel MOSFET, lowering its RDS(ON) and increasing efficiency. At VIN < 2.5V, the LTC1627 shuts down and draws just a few microamperes, making it ideal for single lithium-ion battery applications. The output voltage is programmable from 1.8V to 3.3V via a second jumper. ARY CONDITIONS JUMPER POSITION VALUE JP1 = " 5V" JP1 = "< 5V" 2.65V to 8.5V 2.65V to 4.5V See Figure 2 JP2 = "1.8V" JP2 = "2.5V" JP2 = "2.9V" JP2 = "3.3V" JP2 = "OPEN" 1.82V 0.043V 2.52V 0.06V 2.94V 0.07V 3.33V 0.079V Note 1 Forced Continuous Supply Current VIN = 5V, SYNC/FCB = 0V, RUN/SS = 2V, IOUT = 0mA Burst ModeTM Enabled Supply Current VIN = 5V, SYNC/FCB = 2V, RUN/SS = 2V, IOUT = 0mA Shutdown Current VIN = 5V, RUN/SS = 0V, IOUT = 0mA JP1 = " 5V," JP2 = "3.3V" JP1 = " 5V," JP2 = "3.3V" JP1 = " 5V," JP2 = "3.3V" 3.5mA 200A 15A U W U TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTOS LTC1627 Efficiency Curve LTC1627 Efficiency Curve 100 JP1 = " 5V" VIN = 5V 90 90 EFFICIENCY (%) EFFICIENCY (%) Demo Board 100 JP1 = "< 5V" 80 70 VIN = 8.5V 80 70 VIN = 3.6V VOUT = 2.5V VOUT = 3.3V JP1 = " 5V" 60 1 10 100 LOAD CURRENT (mA) 1000 195 TPC01 60 1 10 100 LOAD CURRENT (mA) 1000 195 TPC02 1 DEMO MANUAL DC195 NO-DESIGN SWITCHER U DESCRIPTIO At low output currents, the LTC1627 automatically switches to Burst Mode operation to reduce switching losses and maintain high operating efficiencies. In switching-noise sensitive applications, Burst Mode operation can be inhib- ited by grounding the SYNC/FCB pin or synchronizing it with an external clock. Gerber files for this circuit board are available. Call the LTC factory. WW U W PERFOR A CE SU ARY SYMBOL PARAMETER CONDITIONS JUMPER POSITION VALUE IOUT Minimum Output Current VIN = 5V, VOUT = 3.3V VIN = 3V, VOUT = 2.5V JP1= " 5V" JP1= "< 5V" 500mA 500mA fOSC Operating Frequency Unsynchronized Synchronized VRIPPLE Typical Output Ripple IOUT = 500mA, VIN = 5V, VOUT = 3.3V JP1= " 5V" 30mVP-P VOUT Typical Load Regulation 0mA < IOUT < 0.5A, VIN = 5V, VOUT = 3.3V JP1= " 5V" 0.5% VFCB Forced Continuous Threshold Voltage All 0.8V VSYNC Synchronize Threshold Voltage All 1.2V VRUN/SS Minimum Shutdown Threshold Voltage All 0.4V All All 350kHz 385kHz to 525kHz Note 1: Programmable via optional R5. VOUT = 0.8V(1 + 210k/R5) W W U PACKAGE A D SCHE ATIC DIAGRA S TOP VIEW C4 47pF LTC1627CS8 OPTIONAL 8 SYNC/FCB 7 VDR VFB 3 6 VIN GND 4 5 SW CC1 CSS, 0.1F 1 2 ITH SYNC/FCB RUN/SS VDR 8 7 4 VFB GND VIN SW 6 5 D1 BAT54S CIN 22F 16V E6 VIN 8.5V L1, 10H C1 0.1F E2 RUN/SS C3 0.1F D2* 10V C2 0.1F LTC1627 3 S8 PACKAGE 8-LEAD PLASTIC SO E1 SYNC/FCB + RC ITH 1 RUN/SS 2 JP1 VIN < 5V JP1 VIN 5V R6 210k + COUT 100F 6.3V R1 165k R2 97.6k R3 78.7k 1.8V 2.5V JP2 2.9V * D2 IS FOR PROTECTION AGAINST MISAPPLIED INPUT VOLTAGES WITH JP1 IN THE "< 5V" POSITION. ** SPACE IS PROVIDED FOR AN OPTIONAL RESISTOR TO PROGRAM A CUSTOM OUTPUT VOLTAGE. THE OUTPUT VOLTAGE MUST NOT EXCEED 3.3V. Figure 1. LTC1627 Constant Frequency, High Efficiency Converter 2 E5 VOUT R7 10 E4 VOSENSE R4 66.5k 3.3V R5** OPTIONAL OPEN E3/E7 GND DC195 * SCHEMATIC DEMO MANUAL DC195 NO-DESIGN SWITCHER PARTS LIST REFERENCE DESIGNATOR PART NUMBER DESCRIPTION VENDOR CIN QUANTITY 1 TPSC226M016R0375 22F 16V TPS Tantalum Capacitor AVX (803) 448-9411 COUT 1 TPSC107M006R0150 100F 6V TPS Tantalum Capacitor AVX (803) 448-9411 C1, C2, C3, CSS 4 0603YC104KAT 0.1F 16V X7R Chip Capacitor AVX (803) 946-0362 C4 1 06035A470JAT 47pF 50V NPO Chip Capacitor AVX (803) 946-0362 D1 1 BAT54S Zetex (516) 543-7100 E1 to E6 6 2501-2 Turret, Testpoint Mill-Max (516) 922-6000 JP1 1 3914-04-G2 0.05" Double Row Header COMM CON (818) 301-4200 JP2 1 3914-10-G2 0.05" Double Row Header COMM CON (818) 301-4200 JP1, JP2 2 50633-R 0.05" Center Shunt COMM CON (818) 301-4200 L1 1 CD54-150MC 15H 20% Inductor Sumida (847) 956-0666 D2 1 MMBZ5240B 10V Zener Diode in SOT-23 Motorola (602) 244-3576 R1 1 CR16-1653FM 165k 1% 1/16W Chip Resistor TAD (800) 508-1521 R2 1 CR16-9762FM 97.6k 1% 1/16W Chip Resistor TAD (800) 508-1521 R3 1 CR16-7872FM 78.7k 1% 1/16W Chip Resistor TAD (800) 508-1521 R4 1 CR16-6652FM 66.5k 1% 1/16W Chip Resistor TAD (800) 508-1521 R6 1 CR16-2103FM 210k 1% 1/16W Chip Resistor TAD (800) 508-1521 R7 1 CR16-100JM 10 5% 1/16W Chip Resistor TAD (800) 508-1521 LTC (408) 432-1900 CC1 Optional R5 Dual Schottky Diode in SOT-23 Optional RC U1 TELEPHONE Optional 1 LTC1627CS8 Monolithic Synchronous Step-Down Regulator 3 DEMO MANUAL DC195 NO-DESIGN SWITCHER QUICK START GUIDE This demonstration board is easily set up to evaluate the performance of the LTC1627 IC. Please follow the procedure outlined below for proper operation. * Refer to Figure 6 for proper connection of monitoring equipment to ensure correct measurement. * Connect the input power supply to the VIN and GND terminals on the left-hand side of the board. Do not increase VIN over 10V or the Zener, D2, will be damaged. Select the appropriate position of jumper JP1 for the VIN voltage (position "VIN <5V" for VIN < 4.5V only). Table 1. Maximum Allowable Input Voltage vs Selected Output Voltage and JP1 Position MAXIMUM VIN FOR JP1 POSITION JP2 OUTPUT VOLTAGE " 5V" "< 5V" (Note 1) 1.8V 8.5V 4.5V 2.5V 8.5V 4.5V 2.9V 8.5V 4.5V 3.3V 8.5V 4.5V N/A Note 1: The silkscreen label "< 5V" on the demo board is a simplified notation. The actual voltage should be 4.25V. JP2 * Connect the load between the VOUT and GND terminals on the right side of the board. * The RUN/SS pin can be left unconnected. To shut down the LTC1627, tie this pin to GND. * Set the desired output voltage with jumper JP2, as shown in Figure 2 and Table 1. 1.8V 2.5V 2.9V 3.3V OPEN DC195 * F02 Figure 2. Output Voltage Selection (JP2) (3.3V Position Shown) U OPERATIO The circuit in Figure 1 highlights the capabilities of the LTC1627. The application circuit is set up for a variety of output voltages. Output voltages from 1.8V to 3.3V or user programmable voltages can be obtained by selecting the appropriate jumper position. The LTC1627 is a monolithic synchronous step-down switching regulator using a fixed-frequency architecture. Burst Mode operation provides high efficiency at low load currents. Operating efficiencies typically exceed 90% over two decades of load current range. 100% duty cycle provides low dropout operation, which extends operating time in battery-operated systems. Do not use small spring-clip leads when testing this circuit. Small spring-clip leads are very convenient for small-signal bench testing and voltage measurements, but should not be used with this circuit. Soldered wire connections are required to properly ascertain the performance of the PC board. 4 This demonstration board is intended for the evaluation of the LTC1627 switching regulator IC and was not designed for any other purpose. The operating frequency of this demo circuit is 350kHz, the frequency of the LTC1627's internal oscillator. For higher frequencies, SYNC/FCB (E1) can be synchronized with an external clock. Burst Mode operation is automatically disabled when the SYNC/FCB pin is externally driven. Grounding SYNC/FCB also disables Burst Mode operation, potentially reducing noise and interference. Soft start is provided by an external capacitor, CSS, which can be used to properly sequence supplies. The maximum operating current level is 0.5A. This demo board is optimized for 3.3V outputs and 5V input. Output voltages from 1.8V to 3.3V are available by selecting the appropriate jumper position of JP2. For other output voltages, select the OPEN (E) position and add an DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO BURST DEFEAT Y X Y = "0" WHEN X IS A CONSTANT "1" VIN VIN VIN 1.5A SLOPE COMP SYNC/FCB 0.4V 8 OSC 6 VIN 0.6V - 6 VFB 3 + - EN FREQUENCY SHIFT VIN - + 0.8V REFERENCE 0.8V SLEEP + 0.12V + EA BURST - 2.25A - 1 ITH VIN RUN/ SOFT START RUN/SS 2 UVLO TRIP = 2.5V S Q R Q - SWITCHING LOGIC AND BLANKING CIRCUIT OVDET 0.86V + 0.8V - + ICOMP SHUTDOWN 7 VDR ANTI SHOOT THRU 5 SW + FCB IRCMP + - 4 GND DC195 * FD Figure 3. Functional Block Diagram appropriate resistor value in the space provided. The output voltage must never exceed 3.3V because the output capacitor may be damaged. The input supply can range from 2.65V to 8.5V. Main Control Loop (Refer to Functional Diagram) The LTC1627 uses a constant-frequency, current mode step-down architecture. Both the main and synchronous switches, consisting of top P-channel and bottom N-channel power MOSFETs, are internal. During normal operation, the internal top power MOSFET is turned on during each cycle when the oscillator sets the RS latch, and turned off when the current comparator, ICOMP, resets the RS latch. The peak inductor current at which ICOMP resets the RS latch is controlled by the voltage on the ITH pin, which is the output of error amplifier EA. The VFB pin allows EA to receive an output feedback voltage from an external resistive divider. When the load current increases, it causes a slight decrease in the feedback voltage relative to the 0.8V reference, 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 5 DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO MOSFET is turned on until either the inductor current starts to reverse, as indicated by the current reversal comparator IRCMP, or the next cycle begins. The main control loop is shut down by pulling the RUN/SS pin low. Releasing RUN/SS allows an internal 2.25A current source to charge soft start capacitor CSS. When CSS reaches 0.7V, the main control loop is enabled with the ITH voltage clamped at approximately 5% of its maximum value. As CSS continues to charge, ITH is gradually released, allowing normal operation to resume. Comparator OVDET guards against transient overshoots > 7.5% by turning the main switch off and turning the synchronous switch on. With the synchronous switch turned on, the output is crowbarred. This may cause a large amount of current to flow from VIN if the main switch is damaged, blowing the system fuse. SYNC/FCB Pin Function (Frequency Synchronization and Burst Mode Disable) The LTC1627 can be synchronized with an external TTL/CMOS-compatible clock signal driving the SYNC/FCB pin (E1). The frequency range of this signal must be from 385kHz to 525kHz. DO NOT attempt to synchronize the LTC1627 below 385kHz as this may cause abnormal operation and an undesired frequency spectrum. The top MOSFET turn-on follows the rising edge of the external source. When the LTC1627 is clocked by an external source, Burst Mode operation is disabled; the LTC1627 then operates in PWM pulse-skipping mode. In this mode, when the output load is very low, current comparator ICOMP remains tripped for more than one cycle and forces the main switch to stay off for the same number of cycles. Increasing the output load slightly allows constant-frequency PWM operation to resume. Frequency synchronization is inhibited when the feedback voltage, VFB, is below 0.6V. This prevents the external clock from interfering with the frequency foldback for short-circuit protection. The LTC1627 is capable of Burst Mode operation, in which the internal power MOSFETs operate intermittently based on load demand. To enable Burst Mode, simply allow the SYNC/FCB pin to float or connect it to a logic high. To disable Burst Mode operation and enable forced continuous mode (continuous switching even at no load), connect the SYNC/FCB pin to GND. The threshold voltage between Burst Mode and forced continuous mode is 0.8V. This provides a means to regulate a flyback winding output. See the LTC1627 data sheet for additional information. VDR C1 0.1F LTC1627 VIN VIN < 4.25V D1 SW L1 C2 0.1F + VOUT COUT 100F D2 DC195 * F03 Figure 4. Using a Charge Pump to Bias VDR 6 DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO When the converter uses Burst Mode operation, the peak current of the inductor is set to approximately 200mA, even though the voltage at the ITH pin indicates a lower value. The voltage at the ITH pin drops when the inductor's average current is greater than the load requirement. As the ITH voltage drops below 0.12V, the BURST comparator trips, causing the internal sleep line to go high and turn off both power MOSFETs. In sleep mode, both power MOSFETs are held off and the internal circuitry is partially turned off, reducing the quiescent current to 200A. The load current is now supplied from the output capacitor. When the output voltage drops, causing ITH to rise above 0.22V, the top MOSFET is again turned on and this process repeats. SHORT-CIRCUIT PROTECTION When the output is shorted to ground, the frequency of the oscillator is reduced to about 35kHz, 1/10 of the nominal frequency. This frequency foldback ensures that the inductor current has more time to decay, thereby preventing runaway. The oscillator's frequency will gradually increase to 350kHz (or the synchronized frequency) when VFB rises above 0.3V. DROPOUT OPERATION When the input supply voltage decreases toward the output voltage, the duty cycle increases toward the maximum on-time. Further reduction of the supply voltage forces the main switch to remain on for more than one cycle until it reaches 100% duty cycle. The output voltage will then be determined by the input voltage minus the voltage drop across the P-channel MOSFET and the inductor. In Burst Mode operation or pulse skipping mode operation (externally synchronized) with the outputs lightly loaded, the LTC1627 transistions through continuous mode as it enters dropout. UNDERVOLTAGE LOCKOUT A precision undervoltage lockout shuts down the LTC1627 when VIN drops below 2.5V, making it ideal for single lithium-ion battery applications. In shutdown, the LTC1627 draws only several microamperes, which is low enough to prevent deep discharge and possible damage to a lithiumion battery nearing its end of charge. A 150mV hysteresis ensures reliable operation with noisy supplies. LOW SUPPLY OPERATION The LTC1627 is designed to operate down to 2.65V supply voltage. At this voltage the converter is most likely to be running at high duty cycles or in dropout, where the main switch is on continuously. Hence, the I2R loss is due mainly to the RDS(ON) of the P-channel MOSFET. See the LTC1627 data sheet for additional information. When VIN is low (< 4.5V), the RDS(ON) of the P-channel MOSFET can be lowered by driving its gate below ground. The top P-channel MOSFET driver makes use of a floating return pin, VDR, to allow biasing below GND. A simple charge pump bootstrapped to the SW pin realizes a negative voltage at the VDR pin, as shown in Figure 4. This charge pump can be enabled via jumper JP1 for VIN < 4.5V. For VIN 4.5V, do not enable the charge pump to ensure that VIN - VDR does not exceed its absolute maximum voltage. A 10V Zener clamp (Z3) prevents VIN - VDR from exceeding 10V even if VIN 5V is inadvertently applied. When VIN decreases to a voltage close to VOUT, the loop may enter dropout and attempt to turn on the P-channel MOSFET continuously. When the VDR charge pump is enabled, a dropout detector counts the number of oscillator cycles that the P-channel MOSFET remains on and periodically forces a brief off period to allow C1 to recharge. 100% duty cycle is allowed when VDR is grounded. SLOPE COMPENSATION AND PEAK INDUCTOR CURRENT Slope compensation provides stability by preventing subharmonic oscillations. It works by internally adding a ramp to the inductor current signal at duty cycles in excess of 40%. As a result, the maximum inductor peak current is lower for VOUT/VIN > 0.4 than when VOUT/VIN < 0.4. See the maximum inductor peak current vs duty cycle graph in Figure 5. 7 DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO The graph labeled "With External Clock" shows the worstcase peak current reduction obtained when the oscillator is synchronized at its minimum frequency, that is, to a clock just above the oscillator's free-running frequency. HOW TO MEASURE VOLTAGE REGULATION MAXIMUM INDUCTOR PEAK CURRENT (mA) When trying to measure voltage regulation, remember that all measurements must be taken at the point of regulation. This point is where the LTC1627's control loop looks for the information to keep the output voltage constant. In this demonstration board, this information point occurs between Pin 4, the GND of the LTC1627, and the output side of R6. These points correspond to the GND (E7) and VOSENSE (E4) terminals of the board. Output voltage test leads should be attached directly to these terminals. The load should be placed between VOUT (E5) and GND (E7). Measurements should not be taken at the end of test leads at the load. Refer to Figure 6 for the proper monitoring equipment configuration. This applies to line regulation (input-to-output voltage regulation) as well as load regulation tests. In doing the line regulation tests, always look at the input voltage across the input terminals. 950 900 850 800 WITH EXTERNAL CLOCK 750 700 WITHOUT EXTERNAL CLOCK 650 600 550 500 0 20 60 40 DUTY CYCLE (%) 80 100 DC195 * F04 Figure 5. Maximum Inductor Peak Current Vs Duty Cycle IIN + A + VIN + MONOLITHIC SYNCHRONOUS STEP-DOWN REGULATOR LTC1627CS8 VIN VOUT JP1 E6 E5 A V VIN < 5V VIN 5V JP2 LOAD + E4 VOSENSE V OPEN 3.3V 2.9V 2.5V 1.8V GND E3 + 10 SYNC/FCB E1 RUN/SS E2 IOUT VOUT GND E7 DEMO CIRCUIT DC195 (408) 432-1900 DC195 * F05 Figure 6. Proper Measurement Setup 8 DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO For the purposes of these tests, the demonstration circuit should be powered from a regulated DC bench supply, so that variations on the DC input do not add errors to the regulation measurements. REMOTE OUTPUT-VOLTAGE SENSING Remote output-voltage sensing can be accomplished by modifying the PC board. A small PC trace connecting VOUT to VOSENSE must be cut, as shown in Figure 7. An external connection from VOSENSE directly to the load must be made. To prevent uncertainty, there is a 10 resistor placed across the VOUT and VOSENSE terminals. Never, under any circumstance, allow VOSENSE to float! 0.7V, the LTC1627 begins operating. As the voltage on RUN/SS continues to increase from 0.7V to 1.8V, the internal current limit also increases at a proportional linear rate. The current limit begins at 25mA (at VRUN/SS 0.7V) and ends at the Figure 5 value (VRUN/SS 1.8V). The output current thus increases slowly, charging the output capacitor. If RUN/SS has been pulled all the way to ground, there is a delay before starting of approximately 310ms/F, followed by an additional 490ms/F to reach full current. CSS = 0.1F on this PC board. Pulling the RUN/SS pin below 0.7V (0.4V min) puts the LTC1627 into a low quiescent current shutdown mode (IQ < 15A). See the LTC1627 data sheet for further information. RUN/SOFT START FUNCTION The RUN/SS pin (E2) is a dual-purpose pin that provides the soft start function and a means to shut down the LTC1627. Soft start reduces surge currents from VIN by gradually increasing the internal current limit. Power supply sequencing can also be accomplished using this pin. An internal 2.25A current source charges an external capacitor, CSS. When the voltage on RUN/SS reaches COMPONENT MANUFACTURERS Table 2 is a partial list of manufacturers of components that can be used in LTC1627 applications. Using components other than the ones supplied on the demonstration board will require careful analysis to verify that all component specifications are not exceeded. Finally, recharacterizing the circuit for efficiency is necessary. CUT THIS TRACE IIN + A + VIN + MONOLITHIC SYNCHRONOUS STEP-DOWN REGULATOR LTC1627CS8 VIN VOUT JP1 E6 E5 A E4 VOSENSE V + VIN < 5V VIN 5V JP2 OPEN 3.3V 2.9V 2.5V 1.8V GND E3 + 10 SYNC/FCB E1 RUN/SS E2 IOUT V VOUT LOAD GND E7 DEMO CIRCUIT DC195 (408) 432-1900 DC195 * F06 Figure 7. Remote Output Voltage Sense 9 DEMO MANUAL DC195 NO-DESIGN SWITCHER U OPERATIO Table 2. List of Alternative Component Manufacturers MANUFACTURER DEVICE PHONE FAX AVX Capacitors (803) 448-9411 (803) 448-1943 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 COMM CON Connectors (818) 301-4200 (818) 301-4212 Dale Inductors (605) 665-9301 (605) 665-0817 International Rectifier Diodes (310) 322-3331 (310) 322-3332 Motorola Diodes (602) 244-3576 (602) 244-4015 Murata-Erie Capacitors (814) 237-1431 (814) 238-0490 Sanyo Capacitors (619) 661-6835 (81) 0952-82-3959 (619) 661-1055 (81) 0952-82-4655 Sprague Capacitors (603) 224-1961 (603) 224-1430 Sumida Inductors (847) 956-0666 (81) 03-3607-5111 (847) 956-0702 (81) 03-3607-5114 TDK Inductors (847) 803-6100 (847) 803-6294 TAD Resistors (714) 255-9123 (714) 255-9291 Zetex Diodes (516) 543-7100 (516) 864-7630 10 DEMO MANUAL DC195 NO-DESIGN SWITCHER W U PCB LAYOUT A D FIL Component Side Silkscreen Component Side Component Side Solder Mask Solder Side Pastemask Solder Side Solder Mask 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 DEMO MANUAL DC195 NO-DESIGN SWITCHER U PC FAB DRAWI G 2.00 C D B A A A A D A A A A A D A D D A 2.00 A B D D C SYMBOL A B C D DIAMETER 0.020 0.023 0.072 0.095 NUMBER OF HOLES 14 14 2 7 NOTES: UNLESS OTHERWISE SPECIFIED 1. MATERIAL: FR4 OR EQUIVALENT EPOXY, 2 OZ COPPER CLAD THICKNESS 0.062 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 SR1020 OR EQUIVALENT 4. SILKSCREEN: USING WHITE NONCONDUCTIVE EPOXY INK 5. ALL DIMENSIONS ARE IN INCHES 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 FAX: (408) 434-0507 www.linear-tech.com dc195f LT/TP 0898 500 * PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1998