TC110 PFM/PWM Step-Up DC/DC Controller FEATURES GENERAL DESCRIPTION The TC110 is a step-up (Boost) switching controller that furnishes output currents as high as 300 mA while delivering a typical efficiency of 84%. The TC110 normally operates in pulse width modulation mode (PWM), but automatically switches to pulse frequency modulation (PFM) at low output loads for greater efficiency. Supply current draw for the 100 KHz version is typically only 50 A, and is reduced to less than 0.5 A when the SHDN input is brought low. Regulator operation is suspended during shutdown. Housed in a tiny 5-pin SOT-23A package, the TC110 occupies minimum board space, and uses tiny external components (the 300 KHz version allows for less than 5 mm surface-mount magnetics). The TC110 accepts input voltages from 2.0V to 10.0V, with a guaranteed start-up voltage of 0.9V. Space-Saving 5-Pin SOT-23A Package Guaranteed Start-Up at 0.9V 50 A (Typ) Supply Current (fOSC = 100 KHz) 300 mA Output Current @ VIN 2.7V 0.5 A Shutdown Mode 100 KHz and 300 KHz Switching Frequency Options Programmable Soft-Start 84% Efficiency TYPICAL APPLICATIONS Palmtops Battery Powered Systems Positive LCD Bias Generators Portable Communicators ORDERING INFORMATION TYPICAL OPERATING CIRCUIT Part Number Battery 3V 10 F + 47 H D1 IN5817 VOUT Si9410DY 47 F Tantalum 5 4 EXT GND + Output Voltage* (V) Package TC110501ECT TC110331ECT TC110301ECT TC110503ECT TC110333ECT TC110303ECT 5.0 3.3 3.0 5.0 3.3 3.0 5-Pin SOT-23A 5-Pin SOT-23A 5-Pin SOT-23A 5-Pin SOT-23A 5-Pin SOT-23A 5-Pin SOT-23A Osc. Operating Freq. Temp. (KHz) Range 100 100 100 300 300 300 -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C -40 to +85C NOTE: *Other output voltages available. Please contact Microchip Technology for details. TC110 VOUT 1 PIN CONFIGURATION VDD SHDN/SS 2 3 5-Pin SOT-23A R OFF ON 5 C 4 *RC Optional TC110 3V to 5V Supply 1 (c) 2001 Microchip Technology Inc. DS21355A 2 3 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 *Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability. ABSOLUTE MAXIMUM RATINGS* Voltage on VDD, VOUT, SHDN Pins ............ -0.3V to +12V EXT Output Current ............................................ 100 mA Voltage on EXT Pin ............................ -0.3V to VDD +0.3V Power Dissipation ................................................150 mW Operating Temperature ............................ -40C to +85C Storage Temperature ............................. -40C to +125C ELECTRICAL CHARACTERISTICS: Note 1, TA = 25C, VIN = 0.6V X VR, VDD = VOUT, unless otherwise noted. Symbol Parameter Test Conditions VDD VSTART VHOLD-UP IDD Supply Voltage Start-Up Supply Voltage Oscillator Hold-Up Voltage Boost Mode Supply Current ISTBY Standby Supply Current ISHDN fOSC Shutdown Supply Current Oscillator Frequency VOUT Output Voltage Note 2 IOUT = 1mA IOUT = 1mA VOUT = SHDN = (0.95 x VR); fOSC = 300 KHz; VR = 3.0V VR = 3.3V VR = 5.0V fOSC = 100 KHz; VR = 3.0V VR = 3.3V VR = 5.0V VOUT = SHDN = (VR + 0.5V); fOSC = 300 KHz; VR = 3.0V VR = 3.3V VR = 5.0V fOSC = 100 KHz; VR = 3.0V VR = 3.3V VR = 5.0V SHDN = GND, VO = (VR x 0.95) VOUT = SHDN = (0.95 x VR); fOSC = 300 KHz fOSC = 100 KHz Note 3 DTYMAX Maximum Duty Cycle (PWM Mode) DTYPFM Duty Cycle (PFM Mode) VIH SHDN Input Logic High VIL SHDN Input Logic Low REXTH EXT ON Resistance to VDD REXTL EXT ON Resistance to GND Efficiency VOUT = SHDN = 0.95 x VR IOUT = 0 mA VOUT = (VR x 0.95) VOUT = (VR x 0.95) VOUT = SHDN = (VR x 0.95); VR = 3.0V VR = 3.3V VEXT = (VOUT - 0.4V) VR = 5.0V VOUT = SHDN = (VR x 0.95); VR = 3.0V VR = 3.3V VEXT = 0.4V VR = 5.0V Min Typ Max Unit 2.0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 255 85 VR x 0.975 -- -- -- -- 120 130 180 50 50 70 20 20 22 11 11 11 0.05 300 100 VR V V V A A A A A A A A A A A A A KHz KHz V -- 10.0 0.9 0.7 190 200 280 90 100 120 34 35 38 20 20 22 0.5 345 115 VR x 1.025 92 15 25 35 % 0.65 -- -- -- -- -- -- -- -- -- -- 32 29 20 20 19 13 84 -- 0.20 47 43 29 30 27 19 -- V V % % Notes: 1. For VR = 3.0V, IOUT = 120mA; For VR = 3.3V, IOUT = 130mA; For VR = 5.0V IOUT = 200 mA. 2. See Application Notes "Operating Mode" description for clarification. 3. VR is the factory output voltage setting. TC110-2 5/24/99 2 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 PIN DESCRIPTION Pin Number Name Description 1 VOUT 2 3 VDD SHDN/SS 4 5 GND EXT Power and Voltage Sense Input. This dual function input provides both feedback voltage sensing and internal chip power. It should be connected to the regulator output. (See Applications section). Power Supply Voltage Input. Shutdown Input. A logic low on this input suspends device operation and reduces supply current to less than 0.5 A. Device operation resumes when SHDN is brought high. An RC circuit connected to this input also determines the soft-start time. Ground Terminal. External Switch Transistor Drive Complimentary Output. This pin drives the external switching transistor. It may be connected to the base of the external bipolar transistor or gate of the external N-channel MOSFET. (See Applications section). 2001 Microchip Technology Inc. DS21355A 3 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 DETAILED DESCRIPTION Soft Start TC110 is a PFM/PWM step-up DC/DC controller for use in systems operating from two or more cells, or in low voltage, line-powered applications. It uses PWM as the primary modulation scheme, but automatically converts to PFM at output duty cycles less than approximately 10%. The conversion to PFM provides reduced supply current, and therefore higher operating efficiency at low loads. The TC110 uses an external switching transistor, allowing construction of switching regulators with maximum output currents of 300 mA. The TC110 consumes only 70 A, typical, of supply current and can be placed in a 0.5 A shutdown mode by bringing SHDN low. The regulator is disabled during shutdown, and resumes normal operation when SHDN is brought high. Other features include start-up at VIN = 0.9V, an externally-programmable soft start time and tiny 5-pin SOT-23A packaging. Soft start allows the output voltage to gradually ramp from 0V to rated output value during start-up. This action minimizes (or eliminates) overshoot, and in general, reduces stress on circuit components. Figure 2 shows the circuit required to implement soft start. Values of 470K and 0.1 F for RSS and CSS are adequate for most applications. Input Bypass Capacitors Using an input bypass capacitor reduces peak current transients drawn from the input supply, and reduces the switching noise generated by the regulator. The source impedance of the input supply determines the size of the capacitor that should be used. Output Capacitor The effective series resistance of the output capacitor directly affects the amplitude of the output voltage ripple. (The product of the peak inductor current and the ESR determines output ripple amplitude.) Therefore, a capacitor with the lowest possible ESR should be selected. Smaller capacitors are acceptable for light loads or in applications where ripple is not a concern. The Sprague 595D series of tantalum capacitors are amongst the smallest of all low ESR surface mount capacitors available. Table 1 lists suggested component numbers and manufacturers. Operating Mode The TC110 is powered by the voltage present on the VDD input. The applications circuits of Figures 1a and 1b show operation in the bootstrapped and non-bootstrapped modes. In bootstrapped mode, the TC110 is powered from the output (start-up voltage is supplied by VIN through the inductor and Schottky diode while Q1 is off). In bootstrapped mode, the switching transistor is turned on harder because its gate voltage is higher (due to the boost action of the regulator), resulting in higher output current capacity. The TC110 is powered from the input supply in the nonbootstrapped mode. In this mode, the supply current to the TC110 is minimized. However, the drive applied to the gate of the switching transistor swings from the input supply level to ground, so the transistor's ON resistance increases at low input voltages. Overall efficiency is increased since supply current is reduced, and less energy is consumed charging and discharging the gate of the MOSFET. While the TC110 is guaranteed to start up at 0.9V the device performs to specifications at 2.0V and higher. Inductor Selection Selecting the proper inductor value is a trade-off between physical size and power conversion requirements. Lower value inductors cost less, but result in higher ripple current and core losses. They are also more prone to saturate since the coil current ramps to a higher value. Larger inductor values reduce both ripple current and core losses, but are larger in physical size and tend to increse the start-up time slightly. A 22 H inductor, therefore, is recommended for the 300 KHz versions and a 47H inductor is recommended for the 100KHz versions. Inductors with a ferrite core (or equivalent) also are recommended. For highest efficiency, use an inductor with a series resistance less than 20m. The inductor value directly affects the output ripple voltage. Equation 3 is derived as shown below, and can be used to calculate an inductor value, given the required output ripple voltage and output capacitor series resistance: Low Power Shutdown Mode The TC110 enters a low power shutdown mode when SHDN is brought low. While in shutdown, the oscillator is disabled and the output switch (internal or external) is shut off. Normal regulator operation resumes when SHDN is brought high. SHDN may be tied to the input supply if not used. Note: Because the TC110 uses an external diode, a leakage path between the input voltage and the output node (through the inductor and diode) exists while the regulator is in shutdown. Care must be taken in system design to assure the input supply is isolated from the load during shutdown. TC110-2 5/24/99 4 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 minimum input voltage should be used when calculating the AC inductor current (Equation 9). VRIPPLE ESR(di) Equation 1. V = L(di) dt where ESR is the equivalent series resistance of the output filter capacitor, and VRIPPLE is in volts. Equation 7. Expressing di in terms of switch ON resistance and time: di = ESR [(VIN - VSW)tON] L VRIPPLE Equation 8. Equation 2. di = Solving for L: L V(dt) dt [(VIN(MIN) - VSW)tON] L Equation 9. ESR [(VIN - VSW)tON] VRIPPLE where: VSW = VCESAT of the switch (note if a CMOS switch is used substitute VCESAT for RDSON x IIN) Combining the DC current calculated in Equation 6, with half the peak AC current calculated in Equation 9, the peak inductor current is given by: Equation 3. Care must be taken to ensure the inductor can handle peak switching currents, which can be several times load currents. Exceeding rated peak current will result in core saturation and loss of inductance. The inductor should be selected to withstand currents greater than IPK (Equation 10) without saturating. Calculating the peak inductor current is straightforward. Inductor current consists of an AC (sawtooth) current centered on an average DC current (i.e. input current). Equation 6 calculates the average DC current. Note that minimum input voltage and maximum load current values should be used: IPK = IIN(MAX) + 0.5(di) Equation 10. Output Capacitor The effective series resistance of the output capacitor directly affects the amplitude of the output voltage ripple. (The product of the peak inductor current and the ESR determines output ripple amplitude.) Therefore, a capacitor with the lowest possible ESR should be selected. Smaller capacitors are acceptable for light loads or in applications where ripple is not a concern. The Sprague 959D series of tantalum capacitors are amongst the smallest of all low ESR surface mount capacitors available. Table 1 lists suggested component numbers and manufacturers. Input Power = Output Power Efficiency Equation 4. Re-writing in terms of input and output currents and voltages: (VIN(MIN)) (IN(MAX)) = (VOUT(MAX))(IOUT(MAX)) Efficiency Equation 5. Solving for input curent: IIN(MAX) = (VOUT(MAX))(IOUT(MAX)) (Efficiency)(VIN(MAX)) Equation 6. The sawtooth current is centered on the DC current level; swinging equally above and below the DC current calculated in Equation 6. The peak inductor current is the sum of the DC current plus half the AC current. Note that 2001 Microchip Technology Inc. DS21355A 5 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 L1 100 H L1 100 H D1 IN5817 VOUT VOUT n MTP3055EL 5 4 EXT GND n MTP3055EL C2 47 F 5 4 EXT GND C1 33F VOUT VDD 2 VDD SHDN SHDN 1 1 C2 47 F TC110xx TC110xx VOUT D1 IN5817 2 3 3 OFF ON OFF ON VIN VIN C1 33F Figure 1b. Non-Bootstrapped Operation Figure 1a. Bootstrapped Operation TC110xx TC110xx SHDN/SS SHDN/SS 3 3 RSS 470K RSS 470K VIN SHDN CSS 0.1 F CSS 0.1 F Shutdown Not Used Shutdown Used Figure 2. Soft Start/Shutdown Circuit TC110-2 5/24/99 6 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 increase switching time due to over-saturation. For peak efficiency, make RB as large as possible, but still guaranteeing the switching transistor is completely saturated when the minimum value of hFE is used. Board Layout Guidelines As with all inductive switching regulators, the TC110 generates fast switching waveforms which radiate noise. Interconnecting lead lengths should be minimized to keep stray capacitance, trace resistance and radiated noise as low as possible. In addition, the GND pin, input bypass capacitor and output filter capacitor ground leads should be connected to a single point. The input capacitor should be placed as close to power and ground pins of the TC110 as possible. APPLICATIONS Circuit Design Figure 3 shows a TC110 operating as a 100 KHz bootstrapped regulator with soft start. This circuit uses an NPN switching transistor (Zetex FZT690B) that has an hFE of 400 and VCESAT of 100 mV at IC = 1A. Other high beta transistors can be used, but the values of RB and CB may need adjustment if hFE is significantly different from that of the FZT690B. Figure 4 and 5 both utilize an N-Channel switching transistor (Silconix Si9410DY). This transistor is a member of the LittlefootTM family of small outline MOSFETs. The circuit of Figure 4 operates in bootstrapped mode, while the circuit of Figure 5 operates in non-bootstrapped mode. Output Diode For best results, use a Schottky diode such as the MA735, 1N5817, MBR0520L or equivalent. Connect the diode between the FB (or SENSE) input as close to the IC as possible. Do not use ordinary rectifier diodes since the higher threshold voltages reduce efficiency. External Switching Transistor Selection The EXT output is designed to directly drive an Nchannel MOSFET or NPN bipolar transistor. N-channel MOSFETs afford the highest efficiency because they do not draw any gate drive current, but are typically more expensive than bipolar transistors. If using an N-Channel MOSFET, the gate should be connected directly to the EXT output as shown in Figure 1. EXT is a complimentary output with a maximum ON resistances of 43 to VDD when high and 27 to ground when low. Peak currents should be kept below 10 mA. When selecting an N-channel MOSFET, there are three important parameters to consider: total gate charge (Qg); ON resistance (rDS(on)) and reverse transfer capacitance (CRSS). Qg is a measure of the total gate capacitance that will ultimately load the EXT output. Too high a Qg can reduce the slew rate of the EXT output sufficiently to grossly lower operating efficiency. Transistors with typical Qg data sheet values of 50 nC or less can be used. For example, the Si9410DY has a Qg(typ) of 17nC @ VGS = 5V. This equates to a gate current of: IGATE(max) = fMAX x Qg = 115 KHZ x 17 nC = 2 mA The two most significant losses in the N-Channel MOSFET are switching loss and I2R loss. To minimize these, a transistor with low rDS(on) and low CRSS should be used. Bipolar NPN transistors can be used, but care must be taken when determining base current drive. Too little current will not fully turn the transistor on, and result in unstable regulator operation and low efficiency. Too high a base drive causes excessive power dissipation in the transistor and 2001 Microchip Technology Inc. DS21355A 7 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 D1 Matsushita MA737 VIN CIN 10F/16V L1 47H Sumida CD75 CB 10nF Ceramic VIN CIN 10uF/16V VOUT Q1 FZT690BCT RB 1K EXT TC110301 1 VDD 4 EXT SHDN/SS 2 VOUT Q1 Silconix Si9410DY 5 GND VOUT L1 22uH Sumida CD54 COUT 47F, 10V Tant. 4 5 D1 Motorola MBR0520L 3 CSS 0.1F Ceramic COUT 47uF/16V Tant. GND TC110303 RSS 470K VOUT 1 VDD 2 SHDN/SS 3 SHUTDOWN (Optional) Figure 3. 100 KHz Bootstrapped Regulator with Soft Start Using a Bipolar Transistor VIN CIN 10uF/16V Figure 4. 300 KHz Bootstrapped, N-Channel Transistor D1 Motorola MBR0520L L1 22uH Sumida CD54 VOUT Q1 Silconix Si9410DY 4 5 EXT COUT 47uF/16V Tant. GND TC110303 VOUT 1 VDD 2 SHDN/SS 3 Figure 5. 300 KHz Non-Bootstrapped, N-Channel Transistor TC110-2 5/24/99 8 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 TC110 DEMO CARD accordance with the component side layout diagram of Figure 6. Jumper blocks J1 and J2 control shutdown and operating mode selection respectively. Shorting J1, terminal X to OFF, places the TC110 in shutdown; normal operation is enabled when J1 terminal X is shorted to ON. Shorting J2, terminal Y to BS, selects bootstrapped operating mode; shorting J2 terminal Y to NB, selects non-bootstrapped operation. The TC110DEMO allows the user to quickly prototype TC110-based circuits. The TC110DEMO consists of a printed circuit board (with TC110 installed on the foil side of the board); with separate Schottky diode, output capacitor and 100 H Coiltronics inductor. The circuit schematic appears in Figure 7. The board is designed to accept either a 100 H or 20 H torroidal inductor. The remaining components install in VOUT TC110-0 VIN TC110-0 L1 COUT CIN G, (B) Q1 S (E) GND D (C) R1 TC110 J1 J2 BS Y NB OFF X ON Full Size Component Side of Board Figure 6. TC110 Demo Board Layout VIN L1 D, (C) D1 VOUT CIN R1 Q1 n G, (B) COUT 4 5 EXT S, (E) GND TC110 VOUT 1 VDD SHDN 2 3 NB Y BS J2 Bootstrap/ Non-Bootstrap ON X OFF J1 Shutdown Control Figure 7. TC110 Demo Schematic 2001 Microchip Technology Inc. DS21355A 9 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 Table 1. Suggested Components and Manufacturers Type Inductors Capacitors Transistors Diodes Surface Mount Sumida CD54 Series (300 KHz) CD75 (100 KHz) Matsuo 267 Series N-channel Silconix Si9410DY Nihon EC10 Series Sprague 595D Series Coiltronics CTX Series Through Hole Sumida RCH855 Series RCH110 Series Nichicon F93 Series Sanyo OS-CON Series Motorola MTP3055EL MTD20N03 NPN Zetex ZTX694B Matshushita MA735 Series Motorola 1N5817 - 1N5822 Nichicon PL Series Renco RL1284-12 MARKINGS represents 1st decimal of voltage and frequency 5-Pin SOT-23A Symbol 100KHz 300KHz 0 A 1 B 2 C 3 D 4 E 5 F 6 H 7 K 8 L 9 M represents product classification; TC110 = M represents 1st integer of voltage and frequency Symbol 100KHz 300KHz B 1 C 2 D 3 E 4 F 5 H 6 TC110-2 5/24/99 Output Voltage 1. 2. 3. 4. 5. 6. Output Voltage .0 .1 .2 .3 .4 .5 .6 .7 .8 .9 represents lot ID number 10 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 TAPING FORMS Component Taping Orientation for 5-Pin SOT-23A (EIAJ SC-74A) Devices PIN 1 User Direction of Feed User Direction of Feed Device Marking Device Marking W PIN 1 P Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up) Reverse Reel Component Orientation RT Suffix Device (Mark Upside Down) Carrier Tape, Number of Components Per Reel and Reel Size Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 8 mm 4 mm 3000 7 in 5-Pin SOT-23A Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 8 mm 4 mm 3000 7 5-Pin SOT-23A TYPICAL CHARACTERISTICS CURVES OUTPUT VOLTAGE vs. OUTPUT CURRENT EFFICIENCY vs. OUTPUT CURRENT TC110 (300KHz, 3.3V) TC110 (300KHz, 3.3V) L = 22H, CL = 94 F (Tantalum) L = 22H, CL = 94 F (Tantalum) 100 80 2.7V 3.4 1.2V 1.8V EFFICIENCY (%) OUTPUT VOLTAGE (VOUT) (V) 3.5 3.3 VIN = 0.9V 3.2 1.5V 2.0V 2.7V 3.1 1.2V 60 1.5V 2.0V 1.8V 40 20 VIN = 0.9V 0 0.1 3.0 0.1 1 10 100 1000 OUTPUT CURRENT (IOUT) (mA) 2001 Microchip Technology Inc. DS21355A 1 10 100 1000 OUTPUT CURRENT (IOUT) (mA) 11 TC110-2 5/24/99 PFM/PWM Step-Up DC/DC Controller TC110 PACKAGE DIMENSIONS 5-Pin SOT-23A (EIAJ SC-74A) .075 (1.90) REF. .071 (1.80) .059 (1.50) .122 (3.10) .098 (2.50) .020 (0.50) .012 (0.30) PIN 1 .037 (0.95) REF. .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .010 (0.25) .004 (0.09) 10 MAX. .006 (0.15) .000 (0.00) .024 (0.60) .004 (0.10) Dimensions: inches (mm) TC110-2 5/24/99 12 2001 Microchip Technology Inc. DS21355A PFM/PWM Step-Up DC/DC Controller TC110 WORLDWIDE SALES AND SERVICE AMERICAS New York ASIA/PACIFIC (continued) Corporate Office 150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 631-273-5305 Fax: 631-273-5335 Singapore 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com Rocky Mountain 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7966 Fax: 480-792-7456 San Jose Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-334-8870 Fax: 65-334-8850 Taiwan Atlanta 6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509 500 Sugar Mill Road, Suite 200B Atlanta, GA 30350 Tel: 770-640-0034 Fax: 770-640-0307 Microchip Technology Taiwan 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139 ASIA/PACIFIC Austin EUROPE China - Beijing Australia Analog Product Sales 8303 MoPac Expressway North Suite A-201 Austin, TX 78759 Tel: 512-345-2030 Fax: 512-345-6085 Boston 2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821 Boston Analog Product Sales Unit A-8-1 Millbrook Tarry Condominium 97 Lowell Road Concord, MA 01742 Tel: 978-371-6400 Fax: 978-371-0050 Toronto Microchip Technology Beijing Office Unit 915 New China Hong Kong Manhattan Bldg. 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Le Colleoni 1 20041 Agrate Brianza Milan, Italy Tel: 39-039-65791-1 Fax: 39-039-6899883 United Kingdom Arizona Microchip Technology Ltd. 505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44 118 921 5869 Fax: 44-118 921-5820 Printed on recycled paper. 01/09/01 Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchipis products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, except as maybe explicitly expressed herein, under any intellectual property rights. The Microchip logo and name are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries. All rights reserved. All other trademarks mentioned herein are the property of their respective companies. 2001 Microchip Technology Inc. DS21355A 13 TC110-2 5/24/99