MAX1553

19-2875; Rev 0; 6/03 KIT ATION EVALU BLE AVAILA High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs General Description Features o Constant-Current Regulation for Even LED Illumination o Internal 40V MOSFET Switch Capable of Driving 10 LEDs o Small, Low-Profile External Components o 2.7V to 5.5V Input Range o Up to 88% Efficiency Driving 6 LEDs o Up to 82% Efficiency Driving 9 LEDs (20mA, VCC = 3.6V) o Analog or PWM Control of LED Intensity o Optimized for Low Input Ripple o Soft-Start to Minimize Inrush Current o 3mm x 3mm 8-Pin TDFN Package MAX1553/MAX1554 The MAX1553/MAX1554 drive white LEDs in series with a constant current to provide efficient display backlighting in cellular phones, PDAs, and other hand-held devices. The step-up converter includes an internal 40V, low RDSON, N-channel MOSFET switch for high efficiency and maximum battery life. The MAX1553 has a current limit of 480mA for driving two to six white LEDs, while the MAX1554 has a current limit of 970mA for driving up to 10 white LEDs. A single analog/PWM Dual Mode input provides two simple means of brightness adjustment. A separate enable input provides on/off control. Soft-start minimizes inrush current during startup. The MAX1553/MAX1554 are available in space-saving 8-pin TDFN 3mm x 3mm packages. Applications Cellular Phones PDA, Palmtop, and Wireless Handhelds Color Display Backlight PART MAX1553ETA MAX1554ETA Ordering Information TEMP RANGE -40°C to +85°C -40°C to +85°C PIN-PACKAGE 8 TDFN 3mm x 3mm 8 TDFN 3mm x 3mm Dual Mode is a trademark of Maxim Integrated Products, Inc. Typical Operating Circuit TOP VIEW 2.7V TO 5.5V INPUT VCC ON OFF EN LX OV WHITE LEDS Pin Configuration GND VCC 1 2 3 4 8 7 LX 0V SS PWM OR DC CONTROL MAX1553 MAX1554 BRT SS FB GND EN BRT MAX1553 MAX1554 6 5 FB TDFN 3mm x 3mm ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 ABSOLUTE MAXIMUM RATINGS VCC, FB, OV to GND..............................................-0.3V to +6.0V LX to GND ..............................................................-0.3V to +45V EN, BRT, SS to GND...................................-0.3V to (VCC + 0.3V) ILX ...................................................................................0.9ARMS Continuous Power Dissipation (TA = +70°C) 8-Pin 3mm x 3mm TDFN (derate 24.4mW/°C above +70°C) .............................1951mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond 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 beyond 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. ELECTRICAL CHARACTERISTICS (VCC = 3.3V, VOV = 0V, COUT = 1µF, RSENSE = 10Ω, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Supply Voltage Undervoltage Lockout Threshold Quiescent Current Shutdown Supply Current OV Threshold OV Input Bias Current BRT Input Resistance TIMING CONTROL Maximum On-Time On-Time Constant (K) Minimum Off-Time ERROR AMPLIFIER FB Threshold FB Input Bias Current N-CHANNEL SWITCH LX On-Resistance 0.8 1.4 Ω VBRT = 1.25V VBRT = 3.3V VFB = 1.0V TA = +25°C TA = +85°C 192 203 280 15 100 200 212 mV nA VCC = 3.3V tON = K / VCC 150 2.0 3.4 6.3 250 350 4.8 µs µs-V ns MAX1553 MAX1554 VCC rising or falling, 35mV hysteresis typical Not switching Switching VEN = 0V Rising edge VOV = 1V TA = +25°C TA = +85°C 200 TA = +25°C TA = +85°C 1.18 CONDITIONS MIN 2.7 3.15 2.35 2.5 0.33 0.44 0.1 1 1.25 1 10 400 600 1.33 200 TYP MAX 5.5 5.50 2.65 0.65 0.9 1 UNITS V V mA µA V nA kΩ 0 < VBRT < 1.5V, EN = VCC 2 _______________________________________________________________________________________ High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs ELECTRICAL CHARACTERISTICS (continued) (VCC = 3.3V, VOV = 0V, COUT = 1µF, RSENSE = 10Ω, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER LX Current Limit LX Leakage Current SHUTDOWN CONTROL EN Logic-Level High EN Logic-Level Low EN Input Current VEN = 0V or 5.5V TA = +25°C TA = +85°C 0.01 0.1 1.8 0.4 1 V V µA MAX1553 MAX1554, VCC = 4.2V VLX = 38V, VEN = 0V TA = +25°C TA = +85°C CONDITIONS MIN 300 600 TYP 480 970 0.1 1 MAX 600 1200 5 UNITS mA µA MAX1553/MAX1554 ELECTRICAL CHARACTERISTICS (VCC = 3.3V, VOV = 0V, COUT = 1µF, RSENSE = 10Ω, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER Supply Voltage Undervoltage Lockout Threshold Quiescent Current OV Threshold BRT Input Resistance TIMING CONTROL Maximum On-Time Minimum Off-Time ERROR AMPLIFIER FB Threshold N-CHANNEL SWITCH LX On-Resistance LX Current Limit SHUTDOWN CONTROL EN Logic-Level High EN Logic-Level Low 1.8 0.4 V V MAX1553 MAX1554, VCC = 4.2V 300 600 1.4 600 1200 Ω mA VBRT = 1.25V 192 217 mV VCC = 3.3V 2.0 150 4.8 350 µs ns MAX1553 MAX1554 VCC rising or falling, 35mV hysteresis typical Not switching Switching Rising edge 0 < VBRT < 1.5V, EN = VCC 1.18 200 CONDITIONS MIN 2.7 3.15 2.35 MAX 5.5 5.50 2.65 0.65 0.9 1.33 600 UNITS V V mA V kΩ Note 1: Specifications to -40°C are guaranteed by design, not production tested. _______________________________________________________________________________________ 3 High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 Typical Operating Characteristics (MAX1553 driving six white LEDs, VCC = VEN = 3.6V, Circuit of Figure 1, TA = +25°C, unless otherwise noted.) EFFICIENCY vs. LOAD CURRENT DRIVING 6 WHITE LEDS MAX1553/54 toc01 EFFICIENCY vs. LOAD CURRENT DRIVING 6 WHITE LEDS MAX1553/54 toc02 EFFICIENCY vs. LOAD CURRENT DRIVING 6 WHITE LEDS VCC = 4V 90 EFFICIENCY (%) VCC = 5V MAX1553/54 toc03 100 VCC = 5V 90 EFFICIENCY (%) VCC = 4V 100 VCC = 4V 90 EFFICIENCY (%) VCC = 5V 100 80 VCC = 3.6V 80 VCC = 3.6V VCC = 3V 70 80 VCC = 3.6V 70 VCC = 3V 70 VCC = 3V 60 L1 = 22µH NO CAPACITOR ACROSS LEDs 0 5 10 LOAD CURRENT (mA) 15 20 60 L1 = 33µH 4700pF ACROSS LEDs 0 5 10 LOAD CURRENT (mA) 15 20 60 L1 = 47µH 4700pF ACROSS LEDs 0 5 10 LOAD CURRENT (mA) 15 20 50 50 50 EFFICIENCY vs. LOAD CURRENT WITH MAX1554 DRIVING 9 WHITE LEDS VCC = 5V MAX1553/54 toc04 LED CURRENT vs. INPUT VOLTAGE MAX1553/54 toc05 LED CURRENT vs. INPUT VOLTAGE MAX1553/54 toc06 100 VCC = 4V 26 L1 = 22µH, NO CAPACITOR ACROSS LEDs 26 90 EFFICIENCY (%) 23 LED CURRENT (mA) 23 LED CURRENT (mA) L1 = 22µH, NO CAPACITOR ACROSS LEDs 80 VCC = 3.6V 20 L1 = 47µH, 4700pF ACROSS LEDs L1 = 33µH, 4700pF ACROSS LEDs R1 = 10Ω, VBRT = 1.25V 11 20 L1 = 47µH, 4700pF ACROSS LEDs L1 = 33µH, 4700pF ACROSS LEDs R1 = 14Ω, VBRT = 3.3V 11 70 17 17 60 CIRCUIT OF FIGURE 3 50 0 5 10 LOAD CURRENT (mA) 15 20 14 14 2.5 3.0 3.5 4.0 4.5 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) LED CURRENT vs. INPUT VOLTAGE WITH MAX1554 DRIVING 9 LEDS MAX1553/54 toc07 LED CURRENT vs. BRT VOLTAGE MAX1553/54 toc08 LED CURRENT vs. BRT DUTY CYCLE MAX1553/54 toc09 26 35 30 LED CURRENT (mA) 25 20 15 10 30 25 LED CURRENT (mA) 20 15 10 5 0 23 LED CURRENT (mA) 20 17 14 5 CIRCUIT OF FIGURE 3 11 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) 0 0 0.6 1.2 1.8 2.4 3.0 3.6 BRT VOLTAGE (V) 0 20 40 60 80 100 BRT DUTY CYCLE (%) 4 _______________________________________________________________________________________ High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs Typical Operating Characteristics (continued) (MAX1553 driving six white LEDs, VCC = VEN = 3.6V, Circuit of Figure 1, TA = +25°C, unless otherwise noted.) SWITCHING WAVEFORMS (CONTINUOUS OPERATION, 3.75V Li+ BATTERY, 18mA OUTPUT) MAX1553/54 toc10 MAX1553/MAX1554 SWITCHING WAVEFORMS (DISCONTINUOUS OPERATION, 3.75V Li+ BATTERY, 10mA OUTPUT) MAX1553/54 toc11 VLX 10V/div VLX 10V/div VOUT 200mV/div VOUT 200mV/div IL 200mA/div IL 200mA/div 2µs/div L1 = 47µH, 4700pF CAPACITOR ACROSS LEDs 2µs/div L1 = 47µH, 4700pF CAPACITOR ACROSS LEDs STARTUP/SHUTDOWN WAVEFORMS MAX1553/54 toc12 BRT STEP RESPONSE MAX1553/54 toc13 VEN 5V/div VBRT 1V/div VFB 200mV/div VFB 200mV/div VOUT VOUT 10V/div 2V/div 40ms/div L1 = 22µH 20ms/div L1 = 22µH, VBRT = 0.5V TO 1.25V TO O.5V _______________________________________________________________________________________ 5 High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 Pin Description PIN 1 2 3 4 NAME GND VCC EN BRT Ground Voltage-Supply Input. 2.7V to 5.5V. The IC is powered from VCC. Enable Input. Drive high or connect to VCC to enable the IC. Drive EN low for shutdown. Brightness-Control Input. Either an analog or PWM control signal can be used. The LED current can be controlled over a 10 to 1 range. The PWM signal must be between 100Hz and 10kHz, and must have an amplitude greater than 1.72V. Feedback Input. Connect to the cathode of the LED string and connect a resistor from FB to GND to set the LED current. Soft-Start Timing-Control Input. Connect a capacitor from SS to GND to control soft-start timing. See the SoftStart section for information on selecting the soft-start capacitor. SS is pulled to ground with an internal 200Ω switch when EN is low. Overvoltage Sense. Connect to a resistor-divider from the anode of the LED string to set the overvoltage threshold. See Figures 1, 2, and 3. Inductor Connection. Connect to the inductor and diode. LX is high impedance when EN is low. Exposed Pad. Connect to GND. FUNCTION 5 FB 6 SS 7 8 — OV LX EP Detailed Description Control Scheme The MAX1553/MAX1554 utilize a minimum off-time, current-limited control scheme. If the voltage at FB drops below the regulation threshold, the internal low-side MOSFET turns on and the inductor current ramps up to the current limit. Once the current-limit comparator trips, the low-side MOSFET turns off for the minimum off-time (250ns). After 250ns, if the voltage at FB is above the regulation threshold, the low-side MOSFET stays off. If the voltage at FB is below the regulation point, the low-side MOSFET turns back on and the cycle repeats. By using a regulation control scheme that is not fixed frequency and that can skip pulses, the MAX1553/MAX1554 operate with very high efficiency. Shutdown The MAX1553/MAX1554 feature a low-current shutdown feature. When EN is low, the IC turns off, reducing its supply current to approximately 0.1µA. For normal operation, drive EN high or connect to VCC. Overvoltage Protection The MAX1553/MAX1554 have an adjustable overvoltageprotection circuit. When the voltage at OV reaches the overvoltage threshold (1.25V typ), the protection circuitry prevents the internal MOSFET from switching, allowing the output voltage to decay. The peak output voltage in an overvoltage-protection event is set with a resistor-divider from the output connected to OV (R2 and R3 in Figures 1, 2, and 3). Select a value for R3 (10kΩ is recommended), then solve for R2 using the following equation: V  R2 = R3 x  OUT(PEAK) − 1   VOV where VOV is the overvoltage threshold (1.25V typ), and VOUT(PEAK) is the desired peak output voltage. Soft-Start Soft-start is provided on the MAX1553/MAX1554 to minimize inrush current. The soft-start time is set with an external capacitor, C3 (Figures 1, 2, and 3). Use the following equation to solve for C3: C3 = tSS 2 x 105 where tSS is the soft-start time. A value of 0.1µF provides a soft-start time of 20ms. 6 _______________________________________________________________________________________ High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 Functional Diagram VCC LX EN ENABLE CONTROL CIRCUITRY CONTROL LOGIC DRIVER CURRENT LIMIT GND UVLO VLIM REF 1.25V BANDGAP REFERENCE MINIMUM tOFF ONE-SHOT MINIMUM tON ONE-SHOT BIAS GENERATOR ERROR COMPARATOR FB OV OV COMPARATOR 67kΩ 128kΩ BRT 206kΩ SS REF MAX1553 MAX1554 1.72V 2.7V TO 5.5V INPUT C1 4.7µF ON OFF L1 47µH TOKO A920CY-470M D1 CMDSH2-3 C2 0.47µF 25V VCC EN LX OV R2 200kΩ C4 4700pF R3 10kΩ 2.7V TO 5.5V INPUT C1 10µF ON OFF L1 4.7µH MURATA LQH32C D1 CMDSH1-60M C2 0.47µF 50V VCC EN LX OV R2 330kΩ C4 3300pF R3 10kΩ D2–D10 WHITE LEDs MAX1553 PWM OR DC CONTROL C3 0.1µF D2–D7 WHITE LEDs PWM OR DC CONTROL MAX1553 BRT SS FB GND R1 10Ω BRT C3 0.1µF SS FB GND R1 10Ω Figure 1. Circuit with the MAX1553 Driving Six White LEDs Figure 2. Circuit with the MAX1553 Driving Nine White LEDs at Up to 15mA _______________________________________________________________________________________ 7 High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 Adjusting the LED Current Adjusting the output current changes the brightness of the LEDs. The LED current is set by the voltage at BRT (VBRT) and the sense resistor (R1) at FB. The VBRT range for adjusting output current is 0 to 1.25V. Over this range, the LED current is found from the following equation: ILED = VBRT + 0.17 6.67 x R1 3.15V TO 5.5V INPUT C1 10µF ON OFF L1 22µH A915BY-220M D1 CMDSH1-60M C2 0.47µF 50V VCC EN LX OV R2 330kΩ C4 3300pF R3 10kΩ D2–D11 WHITE LEDs MAX1554 PWM OR DC CONTROL C3 0.1µF BRT SS FB GND R1 10Ω BRT can be overdriven; however, applying a V BRT greater than 1.72V does not increase the output current above the level at 1.72V. See the LED Current vs. BRT Voltage graph in the Typical Operating Characteristics section. To set the maximum LED current, calculate R1 when VBRT is at its maximum, as follows: R1 = VBRT(MAX) + 0.17 6.67 x ILED(MAX) Figure 3. Circuit with the MAX1554 Driving 10 White LEDs Inductor Selection The MAX1553 has a 480mA inductor current limit and can drive up to six LEDs at 20mA or nine LEDs at 15mA. Inductor values from 4.7µH to 47µH work satisfactorily. Larger values provide the best efficiency while small inductor values allow the smallest inductor size. A good choice for best efficiency is the TOKO D62 or D62L series at 47µH. For smallest size, the Murata LQH32C at 4.7µH works well. The MAX1554 has a 970mA inductor current limit and can drive up to 10 LEDs at 20mA. Inductor values from 4.7µH to 22µH work satisfactorily. A good choice for high efficiency and small size when driving 9 or 10 LEDs is the TOKO D62 series at 22µH. When large inductor values are used to optimize efficiency, the MAX1553/MAX1554 operate with continuous inductor current. With large inductor values (typically greater than 10µH), stability, input, and output ripple are improved by connecting a capacitor in parallel with the LEDs (C4 in Figures 1, 2, and 3). To prevent saturation, use an inductor with a current rating that matches the device ’ s LX current limit. However, if size is particularly important, it is sometimes acceptable to operate the inductor 10% into saturation. For best efficiency, the inductor’s DC resistance should also be as low as possible. where VBRT(MAX) is 1.72V if BRT is connected to any value greater than 1.72V, such as V CC . Otherwise, VBRT(MAX) is the maximum applied BRT control voltage. Power dissipation in R1 is typically less than 5mW; therefore, power dissipation in a standard chip resistor is not a concern. PWM Dimming Control The BRT input is also used as a digital input allowing LED brightness control with a logic-level PWM signal applied directly to BRT. The frequency range is from 100Hz to 10kHz, and the duty cycle range is 0 to 100%. A 0% duty cycle corresponds to the minimum current, and a 100% duty cycle corresponds to full current. See the LED Current vs. BRT Duty Cycle graph in the Typical Operating Characteristics section. The BRT resistor and SS capacitor form a lowpass filter, so PWM dimming results in DC current to the LEDs without the need for additional RC filters. Capacitor Selection A 0.47µF ceramic output capacitor (C2) is recommended for most applications. For circuits driving six or fewer LEDs, use a 4.7µF ceramic input capacitor (C1). For circuits driving more than six LEDs, use a 10µF input capacitor (C1). For best stability over a wide temperature range, use capacitors with an X5R, X7R, or better dielectric. Diode Selection The MAX1553/MAX1554s ’ h igh switching frequency demands a high-speed rectification diode (D1) for optimum efficiency. A Schottky diode is recommended due to its fast recovery time and low forward-voltage drop. 8 _______________________________________________________________________________________ High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs Table 1. Component Suppliers SUPPLIER Central Semiconductor Kamaya Murata Nichia Panasonic Sumida Taiyo Yuden TDK TOKO PHONE 631-435-1110 260-489-1533 814-237-1431 248-352-6575 714-373-7939 847-956-0666 408-573-4150 847-803-6100 847-297-0070 WEBSITE www.centralsemi.com www.kamaya.com www.murata.com www.nichia.com www.panasonic.com www.sumida.com www.t-yuden.com www.component.tdk.com www.toko.com C3 0.1µF BATTERY INPUT C1 4.7µF L1 3.3V LOGIC C4 0.1µF ON OFF D1 C2 0.47µF MAX1553/MAX1554 VCC LX R2 EN OV R3 WHITE LEDs MAX1553 MAX1554 BRT SS FB GND R1 Ensure the diode’s average and peak current ratings exceed the average output current and peak inductor current. In addition, the diode’s reverse breakdown voltage must exceed VOUT. Figure 4. The MAX1553/MAX1554 can drive LEDs from battery voltages that are lower than the device operating voltage range by powering VCC from a logic supply and connecting the boost inductor to the battery. Applications Information Low Input-Voltage Applications The MAX1553/MAX1554 have minimum input voltages of 2.7V (MAX1553) and 3.15V (MAX1554). However, lower battery voltages can still be boosted for LED drive as long as V CC remains within the operating range. Since most systems have a 3.3V system supply active when the display is active and backlit, that logic supply can be used to supply VCC, while the battery power connects directly to the boost inductor. No battery current is drawn when EN is low (Figure 4). When laying out a board, minimize trace lengths between the IC and the inductor, diode, input capacitor, output capacitor, and R1. Keep traces short, direct, and wide. Keep noisy traces, such as the LX node trace, away from FB. Place the VCC bypass capacitor (C1) as close to the IC as possible. The ground connections of C1 and C2 should be as close together as possible. Star connect the grounds for R1, R3, C3, and the BRT voltage supply as close to the IC as possible. The traces from VCC to C1, from C2 to the LEDs, and from the LEDs to R1 can be longer if required. PC Board Layout Due to fast-switching waveforms and high-current paths, careful PC board layout is required. An evaluation kit (MAX1553EVKIT) is available as an example of a proper layout. TRANSISTOR COUNT: 740 PROCESS: BiCMOS Chip Information _______________________________________________________________________________________ 9 High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs MAX1553/MAX1554 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages. 6, 8, &10L, QFN THIN.EPS 1 2 L D A A2 PIN 1 ID D2 1 N 1 b PIN 1 INDEX AREA C0.35 [(N/2)-1] x e REF. e E DETAIL A E2 A1 k C L C L L e A e L SEMICONDUCTOR PROPRIETARY INFORMATION TITLE: DALLAS PACKAGE OUTLINE, 6, 8 & 10L, TDFN, EXPOSED PAD, 3x3x0.80 mm NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY APPROVAL DOCUMENT CONTROL NO. REV. 21-0137 D 10 ______________________________________________________________________________________ High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages. MAX1553/MAX1554 COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40 0.25 MIN. 0.20 REF. PACKAGE VARIATIONS PKG. CODE T633-1 T833-1 T1033-1 N 6 8 10 D2 1.50–0.10 1.50–0.10 1.50–0.10 E2 2.30–0.10 2.30–0.10 2.30–0.10 e 0.95 BSC 0.65 BSC 0.50 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEED-3 b 0.40–0.05 0.30–0.05 0.25–0.05 [(N/2)-1] x e 1.90 REF 1.95 REF 2.00 REF SEMICONDUCTOR PROPRIETARY INFORMATION TITLE: DALLAS PACKAGE OUTLINE, 6, 8 & 10L, TDFN, EXPOSED PAD, 3x3x0.80 mm APPROVAL DOCUMENT CONTROL NO. REV. 2 2 21-0137 D Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.