19-3283; Rev 3; 10/06 High-Performance, Single-Ended, Current-Mode PWM Controllers The MAX5070/MAX5071 BiCMOS, high-performance, current-mode PWM controllers have all the features required for wide input voltage range isolated/nonisolated power supplies. These controllers are used for low- and high-power universal input voltage and telecom power supplies. The MAX5070/MAX5071 contain a fast comparator with only 60ns typical delay from current sense to the output for overcurrent protection. The MAX5070A/MAX5070B have an integrated error amplifier with the output at COMP. Soft-start is achieved by controlling the COMP voltage rise using external components. The frequency is adjustable from 20kHz to 1MHz with an external resistor and capacitor. The timing capacitor discharge current is trimmed allowing for programmable dead time and maximum duty cycle for a given frequency. The available saw-toothed waveform at RTCT can be used for slope compensation when needed. The MAX5071A/MAX5071B include a bidirectional synchronization circuit allowing for multiple controllers to run at the same frequency to avoid beat frequencies. Synchronization is accomplished by simply connecting the SYNC pins of all devices together. When synchronizing with other devices, the MAX5071A/MAX5071B with the highest frequency synchronizes the other devices. Alternatively, the MAX5071A/MAX5071B can be synchronized to an external clock with an opendrain output stage running at a higher frequency. The MAX5071C provides a clock output pulse (ADV_CLK) that leads the driver output (OUT) by 110ns. The advanced clock signal is used to drive the secondary-side synchronous rectifiers. The MAX5070/MAX5071 are available in 8-pin µMAX® and SO packages and operate over the automotive temperature range of -40°C to +125°C. Applications Features ♦ Pin-for-Pin Replacement for UC2842 (MAX5070A) and UC2844 (MAX5070B) ♦ 2A Drive Source and 1A Sink Capability ♦ Up to 1MHz Switching Frequency Operation ♦ Bidirectional Synchronization (MAX5071A/MAX5071B) ♦ Advanced Output Drive for Secondary-Side Synchronous Rectification (MAX5071C) ♦ Fast 60ns Cycle-by-Cycle Current Limit ♦ Trimmed Oscillator Capacitor Discharge Current Sets Maximum Duty Cycle Accurately ♦ Accurate 5% Start and Stop Voltage with 6V Hysteresis ♦ Low 32µA Startup Current ♦ 5V Regulator Output (VREF) with 20mA Capability ♦ Overtemperature Shutdown Ordering Information PART TEMP RANGE PIN-PACKAGE MAX5070AASA -40°C to +125°C 8 SO MAX5070AAUA -40°C to +125°C 8 µMAX MAX5070BASA -40°C to +125°C 8 SO MAX5070BAUA -40°C to +125°C 8 µMAX Specify lead-free by adding the + symbol at the end of the part number when ordering. Ordering Information continued at end of data sheet. Selector Guide appears at end of data sheet. Pin Configurations TOP VIEW Universal Input AC/DC Power Supplies Isolated Telecom Power Supplies Isolated Power-Supply Modules Networking Systems COMP 1 FB 2 3 Computer Systems/Servers CS Industrial Power Conversion RT/CT 4 MAX5070A MAX5070B 8 VREF 7 VCC 6 OUT 5 GND Isolated Keep-Alive Circuits µMAX/SO µMAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configurations continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX5070/MAX5071 General Description MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers ABSOLUTE MAXIMUM RATINGS VCC (Low-Impedance Source) to GND ..................-0.3V to +30V VCC (ICC < 30mA).....................................................Self Limiting OUT to GND ...............................................-0.3V to (VCC + 0.3V) OUT Current.............................................................±1A for 10µs FB, SYNC, COMP, CS, RT/CT, VREF to GND ...........-0.3V to +6V COMP Sink Current (MAX5070)..........................................10mA Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.5mW/°C above +70°C) .............362mW 8-Pin SO (derate 5.9mW/°C above +70°C)...............470.6mW Operating Temperature Range (Automotive) ....-40°C to +125°C Maximum 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 = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.950 5.000 5.050 V 0.4 4 mV 25 mV REFERENCE Output Voltage VVREF TA = +25°C, IVREF = 1mA Line Regulation ∆VLINE 12V < VCC < 25V, IVREF = 1mA Load Regulation ∆VLOAD 1mA < IVREF < 20mA Total Output Variation VREFT 1mA < IVREF < 20mA, 12V < VCC < 25V Reference Output-Noise Voltage VNOISE 10Hz < f < 10kHz, TA = +25°C Reference Output Short Circuit IS_SC 6 4.9 5.1 50 V µV VVREF = 0V -30 -100 -180 mA Initial Accuracy TA = +25°C 51 54 57 kHz Voltage Stability 12V < VCC < 25V 0.2 0.5 Temp Stability -40°C < TA < +85°C 0.5 % 1.7 V OSCILLATOR RT/CT Voltage Ramp (P-P) RT/CT Voltage Ramp Valley VRAMP VRAMP_VALLEY Discharge Current IDIS Frequency Range fOSC 1.1 VRT/CT = 2V, TA = +25°C 7.9 8.3 20 % V 8.7 mA 1000 kHz ERROR AMPLIFIER (MAX5070A/MAX5070B) FB Input Voltage VFB FB shorted to COMP 2.465 2.5 2.535 V -0.01 -0.1 µA FB Input Bias Current IB(FB) Open-Loop Voltage Gain AVOL Unity-Gain Bandwidth fGBW Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V (Note 2) 60 80 dB COMP Sink Current ISINK VFB = 2.7V, VCOMP = 1.1V 2 6 mA -0.5 -1.2 5 5.8 2V ≤ VCOMP ≤ 4V COMP Source Current ISOURCE VFB = 2.3V, VCOMP = 5V COMP Output High Voltage VCOMPH VFB = 2.3V, RCOMP = 15kΩ to GND COMP Output Low Voltage VCOMPL VFB = 2.7V, RCOMP = 15kΩ to VREF 100 dB 1 MHz -1.8 mA V 0.1 0.5 V V/V CURRENT-SENSE AMPLIFIER Gain Maximum Current-Sense Signal 2 ACS VCS_MAX (Notes 3, 4) 2.85 3 3.26 MAX5070A/B (Note 3) 0.95 1 1.05 VCOMP = 5V, MAX5071_ 0.95 1 1.05 _______________________________________________________________________________________ V High-Performance, Single-Ended, Current-Mode PWM Controllers (VCC = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER Power-Supply Rejection Ratio SYMBOL MIN TYP MAX UNITS 12V ≤ VCC ≤ 25V 70 VCOMP = 0V -1 tCS_DELAY 50mV overdrive 60 OUT Low-Side On-Resistance VRDS_ONL ISINK = 200mA 4.5 10 Ω OUT High-Side On-Resistance VRDS_ONH ISOURCE = 100mA 3.5 7 Ω Input Bias Current PSRR CONDITIONS ICS Delay From CS to OUT dB -2.5 µA ns MOSFET DRIVER ISOURCE (Peak) ISOURCE COUT = 10nF 2 ISINK COUT = 10nF 1 A Rise Time tr COUT = 1nF 15 ns Fall Time tf COUT = 1nF 22 ns ISINK (Peak) A UNDERVOLTAGE LOCKOUT/STARTUP Startup Voltage Threshold VCC_START 15.2 16 16.8 V Minimum Operating Voltage After Turn-On VCC_MIN 9.2 10 10.8 V Undervoltage-Lockout Hysteresis UVLOHYST 6 V PWM Maximum Duty Cycle DMAX Minimum Duty Cycle DMIN MAX5070A/MAX5071A MAX5070B/MAX5071B/MAX5071C 94.5 96 97.5 48 49.8 50 0 % % SUPPLY CURRENT Startup Supply Current ISTART Operating Supply Current ICC VFB = VCS = 0V Zener Bias Voltage at VCC VZ ICC = 25mA 24 32 65 µA 3 5 mA 26.5 V THERMAL SHUTDOWN Thermal Shutdown TSHDN +150 °C Thermal-Shutdown Hysteresis THYST 4 °C SYNCHRONIZATION (MAX5071A/MAX5071B only) (Note 5) SYNC Frequency Range fSYNC 20 SYNC Clock Input High Threshold VSYNCINH 3.5 SYNC Clock Input Low Threshold VSYNCINL SYNC Clock Input Minimum Pulse Width tPW_SYNCIN 200 VSYNCOH 1mA external pulldown SYNC Clock Output Low Level VSYNCOL RSYNC = 5kΩ ISYNC VSYNC = 0V 4.0 kHz V 0.8 SYNC Clock Output High Level SYNC Leakage Current 1000 V ns 4.7 V 0 0.1 V 0.01 0.1 µA _______________________________________________________________________________________ 3 MAX5070/MAX5071 ELECTRICAL CHARACTERISTICS (continued) MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers ELECTRICAL CHARACTERISTICS (continued) (VCC = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP 2.4 3 MAX UNITS ADV_CLK (MAX5071C only) ADV_CLK High Voltage VADV_CLKH IADV_CLK = 10mA source ADV_CLK Low Voltage VADV_CLKL IADV_CLK = 10mA sink V 0.4 V ADV_CLK Output Pulse Width tPULSE 85 ns ADV_CLK Rising Edge to OUT Rising Edge tADV_CLK 110 ns ADV_CLK Source and Sink Current IADV_CLK 10 mA ELECTRICAL CHARACTERISTICS (VCC = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.950 5.000 5.050 V 0.4 4 mV 6 25 mV REFERENCE Output Voltage VVREF TA = +25°C, IVREF = 1mA Line Regulation ∆VLINE 12V < VCC < 25V, IVREF = 1mA Load Regulation ∆VLOAD 1mA < IVREF < 20mA Total Output Variation VREFT 1mA < IVREF < 20mA, 12V < VCC < 25V Reference Output Noise Voltage VNOISE 10Hz < f < 10kHz, TA = +25°C Reference Output Short Circuit IS_SC 4.9 5.1 50 V µV VVREF = 0V -30 -100 -180 mA Initial Accuracy TA = +25°C 51 54 57 kHz Voltage Stability 12V < VCC < 25V 0.2 0.5 Temp Stability -40°C < TA < +125°C OSCILLATOR RT/CT Voltage Ramp (P-P) RT/CT Voltage Ramp Valley VRAMP VRAMP_VALLEY Discharge Current IDIS Frequency Range fOSC % 1.7 V 1.1 VRT/CT = 2V, TA = +25°C 7.9 % 1 8.3 20 V 8.7 mA 1000 kHz ERROR AMPLIFIER (MAX5070A/MAX5070B) FB Input Voltage VFB FB shorted to COMP FB Input Bias Current IB(FB) Open-Loop Voltage Gain AVOL Unity-Gain Bandwidth fGBW Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V (Note 2) ISINK VFB = 2.7V, VCOMP = 1.1V COMP Sink Current 2V ≤ VCOMP ≤ 4V COMP Source Current ISOURCE VFB = 2.3V, VCOMP = 5V COMP Output High Voltage VCOMPH VFB = 2.3V, RCOMP =15kΩ to GND COMP Output Low Voltage VCOMPL VFB = 2.7V, RCOMP = 15kΩ to VREF 4 2.465 60 2.5 2.535 V -0.01 -0.1 µA 100 dB 1 MHz 80 dB 2 6 -0.5 -1.2 5 5.8 0.1 _______________________________________________________________________________________ mA -1.8 mA V 0.5 V High-Performance, Single-Ended, Current-Mode PWM Controllers (VCC = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS (Notes 3, 4) 2.85 3 3.26 V/V MAX5070A/B (Note 3) 0.95 1 1.05 VCOMP = 5V, MAX5071_ 0.95 1 1.05 CURRENT-SENSE AMPLIFIER Gain ACS Maximum Current-Sense Signal Power-Supply Rejection Ratio Input Bias Current VCS_MAX PSRR 12V ≤ VCC ≤ 25V 70 ICS Delay From CS to OUT -1 V dB -2.5 60 µA tCS_DELAY 50mV overdrive ns OUT Low-Side On-Resistance VRDS_ONL ISINK = 200mA 4.5 12 Ω OUT High-Side On-Resistance VRDS_ONH ISOURCE = 100mA 3.5 9 Ω MOSFET DRIVER ISOURCE (Peak) ISOURCE COUT = 10nF 2 ISINK COUT = 10nF 1 A Rise Time tr COUT = 1nF 15 ns Fall Time tf COUT = 1nF 22 ns ISINK (Peak) A UNDERVOLTAGE LOCKOUT/STARTUP Startup Voltage Threshold VCC_START 15.2 16 16.8 V Minimum Operating Voltage After Turn-On VCC_MIN 9.2 10 10.8 V Undervoltage-Lockout Hysteresis UVLOHYST 6 V PWM Maximum Duty Cycle DMAX Minimum Duty Cycle DMIN MAX5070A/MAX5071A MAX5070B/MAX5071B/MAX5071C 94.5 96 97.5 48 49.8 50 0 % % SUPPLY CURRENT Startup Supply Current ISTART Operating Supply Current ICC VFB = VCS = 0V Zener Bias Voltage at VCC VZ ICC = 25mA 24 32 65 µA 3 5 mA 26.5 V THERMAL SHUTDOWN Thermal Shutdown TSHDN +150 °C Thermal-Shutdown Hysteresis THYST 4 °C SYNCHRONIZATION (MAX5071A/MAX5071B only, Note 5) SYNC Frequency Range fSYNC 20 SYNC Clock Input High Threshold VSYNCINH 3.5 SYNC Clock Input Low Threshold VSYNCINL SYNC Clock Input Minimum Pulse Width 1000 V 0.8 tPW_SYNCIN 200 SYNC Clock Output High Level VSYNCOH 1mA external pulldown SYNC Clock Output Low Level VSYNCOL RSYNC = 5kΩ 4.0 kHz V ns 4.7 0 V 0.1 V _______________________________________________________________________________________ 5 MAX5070/MAX5071 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VCC = +15V, RT = 10kΩ, CT = 3.3nF, VVREF = OPEN, CVREF = 0.1µF, COMP = OPEN, VFB = 2V, CS = GND, TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL SYNC Leakage Current CONDITIONS ISYNC MIN VSYNC = 0V TYP MAX UNITS 0.01 0.1 µA ADV_CLK (MAX5071C only) ADV_CLK High Voltage VADV_CLKH IADV_CLK = 10mA source ADV_CLK Low Voltage VADV_CLKL IADV_CLK = 10mA sink 2.4 3 V 0.4 V ADV_CLK Output Pulse Width tPULSE 85 ns ADV_CLK Rising Edge to OUT Rising Edge tADV_CLK 110 ns ADV_CLK Source and Sink Current IADV_CLK Note 1: Note 2: Note 3: Note 4: Note 5: 10 mA All devices are 100% tested at +25°C. All limits over temperature are guaranteed by design, not production tested. Guaranteed by design, not production tested. Parameter measured at trip point of latch with VFB = 0V (MAX5070A/MAX5070B only). Gain is defined as A = ∆VCOMP/∆VCS, 0 ≤ VCS ≤ 0.8V. Output Frequency equals oscillator frequency for MAX5070A/MAX5071A. Output frequency is one-half oscillator frequency for MAX5070B/MAX5071B/MAX5071C. Typical Operating Characteristics (VCC = 15V, TA = +25°C, unless otherwise noted.) VCC FALLING 7 6 5 6 HYSTERESIS MAX5070 toc02 6.0 38 37 36 35 34 33 32 31 CT = 100pF 5.5 SUPPLY CURRENT (mA) 13 12 11 10 9 8 STARTUP CURRENT (µA) 15 14 STARTUP CURRENT vs. TEMPERATURE 40 39 MAX5070 toc01 VCC RISING OPERATING SUPPLY CURRENT (ICC) vs. TEMPERATURE AFTER STARTUP (fOSC = fSW = 250kHz) MAX5070 toc03 BOOTSTRAP UVLO vs. TEMPERATURE 17 16 VCC (V) MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers 5.0 4.5 4.0 3.5 3.0 30 29 28 2.5 2.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) _______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers 5.3 5.20 5.15 5.0 4.90 4.7 4.85 4.6 4.80 4.5 4.995 4.75 4.990 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 30 10 45 12 14 16 18 20 22 IREF (mA) VCC (V) OSCILLATOR FREQUENCY (fOSC) vs. TEMPERATURE OSCILLATOR RT/CT DISCHARGE CURRENT vs. TEMPERATURE MAXIMUM DUTY CYCLE vs. TEMPERATURE 510 500 490 480 470 460 450 8.35 8.30 8.25 8.20 8.15 MAX5070A/MAX5071A 80 8.45 8.40 RT = 3.01kΩ CT = 1nF 90 DUTY CYCLE (%) 520 VRT/CT = 2V 8.55 8.50 24 100 MAX5070 toc08 530 8.60 RT/CT DISCHARGE CURRENT (mA) MAX5070 toc07 RT = 3.01kΩ CT = 1nF 26 70 60 MAX5070B/MAX5071B/MAX5071C 50 40 30 20 8.10 8.05 8.00 10 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) MAX5070A/MAX5071A MAXIMUM DUTY CYCLE vs. FREQUENCY 70 CT = 220pF 60 50 CT = 1nF 40 CT = 560pF MAX5070 toc11 80 1.10 1.08 1.06 CS THRESHOLD (V) CT = 100pF 90 CURRENT-SENSE (CS) TRIP THRESHOLD vs. TEMPERATURE MAX5070 toc10 100 DUTY CYCLE (%) OSCILLATOR FREQUENCY (kHz) 15 TEMPERATURE (°C) 550 540 5.000 4.95 IREF = 20mA 4.8 5.00 MAX5070 toc09 4.9 5.05 VVREF (V) IREF = 1mA 5.1 IREF = 1mA 5.005 5.10 VVREF (V) VVREF (V) 5.2 5.010 MAX5070 toc06 5.4 MAX5070 toc05 5.25 MAX5070 toc04 5.5 REFERENCE VOLTAGE (VREF) vs. VCC VOLTAGE REFERENCE VOLTAGE (VREF) vs. REFERENCE LOAD CURRENT REFERENCE VOLTAGE (VREF) vs. TEMPERATURE 1.04 1.02 1.00 0.98 30 0.96 20 0.94 10 0.92 0.90 0 0 400 800 1200 1600 OSCILLATOR FREQUENCY (kHz) 2000 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) _______________________________________________________________________________________ 7 MAX5070/MAX5071 Typical Operating Characteristics (continued) (VCC = 15V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = 15V, TA = +25°C, unless otherwise noted.) OUT IMPEDANCE vs. TEMPERATURE (RDS_ON PMOS DRIVER) 10 1 CT = 10nF CT = 4.7nF CT = 3.3nF CT = 2.2nF 0.1 ISOURCE = 100mA 9.0 8.5 ISINK = 200mA 8.0 7.5 RDS_ON (Ω) 100 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 MAX5070 toc13 MAX5070 toc12 CT = 1nF CT = 560pF CT = 220pF CT = 100pF RDS_ON (Ω) 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) PROPAGATION DELAY FROM CURRENT-LIMIT COMPARATOR TO OUT vs. TEMPERATURE ERROR-AMPLIFIER OPEN-LOOP GAIN AND PHASE vs. FREQUENCY COMP VOLTAGE LEVEL TO TURN OFF DEVICE vs. TEMPERATURE 100k 1M 10M MAX5070 toc16 90 80 70 GAIN (dB) 60 50 40 2.5 140 10 120 -15 2.3 100 -40 2.2 GAIN -65 80 PHASE 60 -90 2.4 VCOMP (V) MAX5070 toc15 100 2.1 2.0 1.9 40 -115 20 20 -140 10 0 -165 1.6 0 -20 -190 10k 100k 1M 10M 100M 1.5 30 -40 -25 -10 5 20 35 50 65 80 95 110 125 0.01 1 TEMPERATURE (°C) 10 100 1k 10V < VCC < 18V 1.8 1.7 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) FREQUENCY (Hz) ADV_CLK RISING EDGE TO OUT RISING EDGE PROPAGATION DELAY vs. TEMPERATURE ADV_CLK AND OUT WAVEFORMS PROPAGATION DELAY (ns) MAX5070 toc18 MAX5070 toc19 114 112 110 108 106 104 102 100 98 96 94 92 90 MAX5071C VCC = 15V MAX5071C ADV_CLK 5V/div 10kΩ LOAD OUT 10V/div -40 -25 -10 5 20 35 50 65 80 95 110 125 20ns/div TEMPERATURE (°C) 8 MAX5070 toc17 -40 -25 -10 5 20 35 50 65 80 95 110 125 FREQUENCY (Hz) 10k PHASE (DEGREES) RT RESISTANCE (kΩ) 1000 OUT IMPEDANCE vs. TEMPERATURE (RDS_ON NMOS DRIVER) MAX5070 toc14 TIMING RESISTANCE (RT) vs. OSCILLATOR FREQUENCY PROPAGATION DELAY (ns) MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers _______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers IOUT 2A/div SUPPLY CURRENT (mA) 90 80 8 TA = +125°C 7 6 MAX5070 toc22 9 VOUT 10V/div 100 MAX5070 toc21 10 TA = +85°C TA = +25°C 5 DUTY CYCLE (%) MAX5070 toc20 VCC = 15V COUT = 10nF MAX5070A/MAX5071A MAXIMUM DUTY CYCLE vs. RT SUPPLY CURRENT (ICC) vs. OSCILLATOR FREQUENCY (CT = 100pF) OUT SOURCE AND SINK CURRENTS CT = 1nF CT = 560pF CT = 220pF CT = 100pF 70 60 50 40 4 TA = -40°C 30 3 20 2 20 120 220 320 420 520 620 720 820 920 1020 20Ons/div FREQUENCY (kHz) 100 1k 10k 100k RT (Ω) Pin Descriptions MAX5070A/MAX5070B PIN NAME FUNCTION 1 COMP 2 FB Error-Amplifier Inverting Input 3 CS Input to the PWM Comparator and Overcurrent Protection Comparator. The current-sense signal is compared to a signal proportional to the error-amplifier output voltage. 4 RT/CT Timing Resistor and Capacitor Connection. A resistor RT from RT/CT to VREF and capacitor CT from RT/CT to GND set the oscillator frequency. 5 GND Power-Supply Ground. Place the VCC and VREF bypass capacitors close to the IC to minimize ground loops. 6 OUT MOSFET Driver Output. OUT connects to the gate of the external n-channel MOSFET. 7 VCC Power-Supply Input for MAX5070. Bypass VCC to GND with a 0.1µF ceramic capacitor or a parallel combination of a 0.1µF and a higher value ceramic capacitor. 8 VREF 5V Reference Output. Bypass VREF to GND with a 0.1µF ceramic capacitor or a parallel combination of a 0.1µF and a higher value ceramic capacitor. Error-Amplifier Output. COMP can be used for soft-start. _______________________________________________________________________________________ 9 MAX5070/MAX5071 Typical Operating Characteristics (continued) (VCC = 15V, TA = +25°C, unless otherwise noted.) MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers Pin Descriptions (continued) MAX5071A/MAX5071B/MAX5071C PIN NAME FUNCTION 1 COMP COMP is level-shifted and connected to the inverting input of the PWM comparator. Pull up COMP to VREF through a resistor and connect an optocoupler from COMP to GND for proper operation. 2 — SYNC Bidirectional Synchronization Input. When synchronizing with other MAX5071A/MAX5071Bs, the higher frequency part synchronizes all other devices. — 2 ADV_CLK 3 3 CS 4 4 RT/CT Timing Resistor and Capacitor Connection. A resistor RT from RT/CT to VREF and capacitor CT from RT/CT to GND set the oscillator frequency. 5 5 GND Power-Supply Ground. Place the VCC and VREF bypass capacitors close to the IC to minimize ground loops. 6 6 OUT MOSFET Driver Output. OUT connects to the gate of the external n-channel MOSFET. MAX5071A/ MAX5071B MAX5071C 1 10 ADV_CLK is an 85ns clock output pulse preceding the rising edge of OUT (see Figure 4). Use the pulse to drive the secondary-side synchronous rectifiers through a pulse transformer or an optocoupler (see Figure 8). Input to the PWM Comparator and Overcurrent Protection Comparator. The currentsense signal is compared to the voltage at COMP. 7 7 VCC Power-Supply Input for MAX5071. Bypass VCC to GND with a 0.1µF ceramic capacitor or a parallel combination of a 0.1µF and a higher value ceramic capacitor. 8 8 VREF 5V Reference Output. Bypass VREF to GND with a 0.1µF ceramic capacitor or a parallel combination of a 0.1µF and a higher value ceramic capacitor. ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers UVLO 2.5V REFERENCE 2.5V 16V/10V PREREGULATOR 5V VOLTAGEDIVIDER 2.5V 7 VCC THERMAL SHUTDOWN EN-REF 26.5V VDD BG 5V REGULATOR SNS EN-DRV-BAR REG_OK 8 VREF VP DELAY VOLTAGEDIVIDER 1V ILIM S 6 OUT Q CLK R CS 3 CPWM GND 5 OSC Q 4 RT/CT 2R VEA FB 2 COMP 1 R 100% MAX DUTY CYCLE (MAX5070A) 50% MAX DUTY CYCLE (MAX5070B) Figure 1. MAX5070A/MAX5070B Functional Diagram Detailed Description The MAX5070/MAX5071 current-mode PWM controllers are designed for use as the control and regulation core of flyback or forward topology switching power supplies. These devices incorporate an integrated low-side driver, adjustable oscillator, error amplifier (MAX5070A/ MAX5070B only), current-sense amplifier, 5V reference, and external synchronization capability (MAX5071A/ MAX5071B only). An internal +26.5V current-limited VCC clamp prevents overvoltage during startup. Five different versions of the MAX5070/MAX5071 are available. The MAX5070A/MAX5070B are the standard versions with a feedback input (FB) and internal error amplifier. The MAX5071A/MAX5071B include bidirectional synchronization (SYNC). This enables multiple MAX5071A/MAX5071Bs to be connected and synchronized to the device with the highest frequency. The MAX5071C includes an ADV_CLK output, which precedes the MAX5071C’s drive output (OUT) by 110ns. Figures 1, 2, and 3 show the internal functional diagrams of the MAX5070A/MAX5070B, MAX5071A/MAX5071B, and MAX5071C, respectively. The MAX5070A/ MAX5071A are capable of 100% maximum duty cycle. The MAX5070B/MAX5071B/MAX5071C are designed to limit the maximum duty cycle to 50%. ______________________________________________________________________________________ 11 MAX5070/MAX5071 VP MAX5070A/MAX5070B MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers VP MAX5071A/MAX5071B UVLO 2.5V 1V REFERENCE 2.5V 16V/10V PREREGULATOR 5V VOLTAGEDIVIDER 2.5V 7 VCC THERMAL SHUTDOWN EN-REF 26.5V VDD BG 5V REGULATOR SNS EN-DRV-BAR REG_OK 8 VREF VP DELAY VOLTAGEDIVIDER 1V ILIM S Q 6 OUT CLK R CS 3 CPWM GND 5 OSC Q 100% MAX DUTY CYCLE (MAX5071A) 50% MAX DUTY CYCLE (MAX5071B) 2R COMP 1 4 RT/CT R SYNC 2 BIDIRECTIONAL SYNC Figure 2. MAX5071A/MAX5071B Functional Diagram Current-Mode Control Loop The advantages of current-mode control over voltagemode control are twofold. First, there is the feed-forward characteristic brought on by the controller’s ability to adjust for variations in the input voltage on a cycle-bycycle basis. Secondly, the stability requirements of the current-mode controller are reduced to that of a singlepole system unlike the double pole in the voltage-mode control scheme. 12 The MAX5070/MAX5071 use a current-mode control loop where the output of the error amplifier is compared to the current-sense voltage (VCS). When the current-sense signal is lower than the noninverting input of the PWM comparator, the output of the CPWM comparator is low and the switch is turned on at each clock pulse. When the current-sense signal is higher than the inverting input of the CPWM, the output of the CPWM comparator is high and the switch is turned off. ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers MAX5070/MAX5071 VP MAX5071C UVLO 2.5V 1V REFERENCE 2.5V 16V/10V PREREGULATOR 5V 2.5V 7 VCC THERMAL SHUTDOWN EN-REF 26.5V VDD BG 5V REGULATOR SNS EN-DRV-BAR REG_OK VOLTAGEDIVIDER 8 VREF VP DELAY VOLTAGEDIVIDER 1V ILIM S Q 6 OUT CLK R CS 3 CPWM GND 5 OSC Q 50% MAX DUTY CYCLE 2R 4 RT/CT COMP 1 R ADV_CLK 2 Figure 3. MAX5071C Functional Diagram VCC and Startup In normal operation, VCC is derived from a tertiary winding of the transformer. However, at startup there is no energy delivered through the transformer, thus a resistor must be connected from VCC to the input power source (see RST and CST in Figures 5 to 8). During startup, CST charges up through RST. The 5V reference generator, comparator, error amplifier, oscillator, and drive circuit remain off during UVLO to reduce startup current below 65µA. When V CC reaches the undervoltage-lockout threshold of 16V, the output driver begins to switch and the tertiary winding will supply power to VCC. VCC has an internal 26.5V current-limited clamp at its input to protect the device from overvoltage during startup. Size the startup resistor, RST, to supply both the maximum startup bias (ISTART) of the device (65µA max) and the charging current for CST. The startup capacitor CST must charge to 16V within the desired time period t ST (for example, 500ms). The size of the startup capacitor depends on: 1) IC operating supply current at a programmed oscillator frequency (fOSC). 2) The time required for the bias voltage, derived from a bias winding, to go from 0 to 11V. 3) The MOSFET total gate charge. 4) The operating frequency of the converter (fSW). ______________________________________________________________________________________ 13 MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers To calculate the capacitance required, use the following formula: ⎡ ⎛V − 13V ⎞ ⎤ ⎢ICC + IG − ⎜ INMIN ⎟ ⎥(t SS ) RST ⎝ ⎠ ⎥⎦ ⎢⎣ CST = VHYST where: IG = QG fSW ICC is the MAX5070/MAX5071s’ maximum internal supply current after startup (see the Typical Operating Characteristics to find the IIN at a given fOSC). QG is the total gate charge for the MOSFET, fSW is the converter switching frequency, VHYST is the bootstrap UVLO hysteresis (6V), and tSS is the soft-start time, which is set by external circuitry. Size the resistor RST according to the desired startup time period, tST, for the calculated CST. Use the following equations to calculate the average charging current (ICST) and the startup resistor (RST). V × CST ICST = SUVR t ST VSUVR ⎞ ⎛ ⎜ VINMIN − ⎟ ⎝ 2 ⎠ RST ≅ ICST + ISTART Where VINMIN is the minimum input supply voltage for the application (36V for telecom), VSUVR is the bootstrap UVLO wake-up level (16V), and ISTART is the VIN supply current at startup (65µA, max). Choose a higher value for RST than the one calculated above if longer startup times can be tolerated in order to minimize power loss in RST. The above startup method is applicable to circuits where the tertiary winding has the same phase as the output windings. Thus, the voltage on the tertiary winding at any given time is proportional to the output voltage and goes through the same soft-start period as the output voltage. The minimum discharge time of CST from 16V to 10V must be greater than the soft-start time (tSS). Undervoltage Lockout (UVLO) The minimum turn-on supply voltage for the MAX5070/MAX5071 is 16V. Once VCC reaches 16V, the reference powers up. There is 6V of hysteresis from the minimum turn-on voltage to the UVLO threshold. Once VCC reaches 16V, the MAX5070/MAX5071 will operate with VCC down to 10V. Once VCC goes below 10V the device is in UVLO. When in UVLO, the quiescent supply current into VCC falls back to 37µA (typ), and OUT and VREF are pulled low. MOSFET Driver OUT drives an external n-channel MOSFET and swings from GND to VCC. Ensure that VCC remains below the absolute maximum VGS rating of the external MOSFET. OUT is a push-pull output with the on-resistance of the PMOS typically 3.5Ω and the on-resistance of the NMOS typically 4.5Ω. The driver can source 2A typically and sink 1A typically. This allows for the MAX5070/MAX5071 to quickly turn on and off high gate-charge MOSFETs. Bypass VCC with one or more 0.1µF ceramic capacitors to GND, placed close to the MAX5070/MAX5071. The average current sourced to drive the external MOSFET depends on the total gate charge (QG) and operating frequency of the converter. The power dissipation in the MAX5070/MAX5071 is a function of the average output drive current (IDRIVE). Use the following equation to calculate the power dissipation in the device due to IDRIVE: IDRIVE = QG x fSW PD = (IDRIVE + ICC) x VCC where I CC is the operating supply current. See the Typical Operating Characteristics for the operating supply current at a given frequency. Error Amplifier (MAX5070A/MAX5070B) The MAX5070 includes an internal error amplifier. The inverting input is at FB and the noninverting input is internally connected to a 2.5V reference. The internal error amplifier is useful for nonisolated converter design (see Figure 6) and isolated design with primary-side regulation through a bias winding (see Figure 5). In the case of a nonisolated power supply, the output voltage will be: R1 ⎞ ⎛ VOUT = ⎜1 + ⎟ × 2.5V ⎝ R2 ⎠ where R1 and R2 are from Figure 6. 14 ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers The MAX5071A/MAX5071B/MAX5071C are designed to be used with either an external error amplifier when designed into a nonisolated converter or an error amplifier and optocoupler when designed into an isolated power supply. The COMP input is level-shifted and connected to the inverting terminal of the PWM comparator (CPWM). Connect the COMP pin to the output of the external error amplifier for nonisolated design. Pull COMP high externally to at least 5V (or VREF) and connect the optocoupler transistor as shown in Figures 7 and 8. COMP can be used for soft-start and also as a shutdown. See the Typical Operating Characteristics to find the turn-off COMP voltage at different temperatures. If the maximum external COMP voltage is below 4.9V, it may reduce the PWM current-limit threshold below 1V. Use the following equation to calculate minimum COMP voltage (VCOMP) required for a guaranteed peak primary current (IP-P): VCOMP = (3 x IP-P x RCS) + 1.95V where RCS is a current-sense resistor. Oscillator The oscillator frequency is adjusted by adding an external capacitor and resistor at RT/CT (see RT and CT in the Typical Application Circuits). RT is connected from RT/CT to the 5V reference (VREF) and CT is connected from RT/CT to GND. VREF charges CT through RT until its voltage reaches 2.8V. CT then discharges through an 8.3mA internal current sink until CT’s voltage reaches 1.1V, at which time C T is allowed to charge through RT again. The oscillator’s period will be the sum of the charge and discharge times of CT. Calculate the charge time as: tC = 0.57 x RT x CT The discharge time is then: tD = RT × CT × 103 4.88 × RT − 1.8 × 103 The oscillator frequency will then be: fOSC = 1 tC + tD Reference Output VREF is a 5V reference output that can source 20mA. Bypass VREF to GND with a 0.1µF capacitor. Current Limit The MAX5070/MAX5071 include a fast current-limit comparator to terminate the ON cycle during an overload or a fault condition. The current-sense resistor (RCS), connected between the source of the MOSFET and GND, sets the current limit. The CS input has a voltage trip level (VCS) of 1V. Use the following equation to calculate RCS: V RCS = CS IP − P IP-P is the peak current in the primary that flows through the MOSFET. When the voltage produced by this current (through the current-sense resistor) exceeds the currentlimit comparator threshold, the MOSFET driver (OUT) will turn the switch off within 60ns. In most cases, a small RC filter is required to filter out the leading-edge spike on the sense waveform. Set the time constant of the RC filter at 50ns. Use a current transformer to limit the losses in the current-sense resistor and achieve higher efficiency especially at low input-voltage operation. Synchronization (MAX5071A/MAX5071B) SYNC SYNC is a bidirectional input/output that outputs a synchronizing pulse and accepts a synchronizing pulse from other MAX5071A/MAX5071Bs (see Figures 7 and 9). As an output, SYNC is an open-drain p-channel MOSFET driven from the internal oscillator and requires an external pulldown resistor (RSYNC) from between 500Ω and 5kΩ. As an input, SYNC accepts the output pulses from other MAX5071A/MAX5071Bs. Synchronize multiple MAX5071A/MAX5071Bs by connecting their SYNC pins together. All devices connected together will synchronize to the one operating at the highest frequency. The rising edge of SYNC will precede the rising edge of OUT by approximately the discharge time (tD) of the oscillator (see the Oscillator section). The pulse width of the SYNC output is equal to the time required to discharge the stray capacitance at SYNC through RSYNC plus the CT discharge time tD. Adjust RT/CT such that the minimum discharge time tD is 200ns. For the MAX5070A/MAX5071A, the converter output switching frequency (fSW) is the same as the oscillator frequency (f OSC ). For the MAX5070B/MAX5071B/ MAX5071C, the output switching frequency is 1/2 the oscillator frequency. ______________________________________________________________________________________ 15 MAX5070/MAX5071 MAX5071A/MAX5071B/MAX5071C Feedback MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers Advance Clock Output (ADV_CLK) (MAX5071C) ADV_CLK is an advanced pulse output provided to facilitate the easy implementation of secondary-side synchronous rectification using the MAX5071C. The ADV_CLK pulse width is 85ns (typically) with its rising edge leading the rising edge of OUT by 110ns. Use this leading pulse to turn off the secondary-side synchronous-rectifier MOSFET (QS) before the voltage appears on the secondary (see Figure 8). Turning off the secondary-side synchronous MOSFET earlier avoids the shorting of the secondary in the forward converter. The ADV_CLK pulse can be propagated to the secondary side using a pulse transformer or highspeed optocoupler. The 85ns pulse, with 3V drive voltage (10mA source), significantly reduces the volt-second requirement of the pulse transformer and the advanced pulse alleviates the need for a highspeed optocoupler. RT/CT OUT tADV_CLK = 110ns ADV_CLK tPULSE = 85ns Thermal Shutdown Figure 4. ADV_CLK When the MAX5070/MAX5071s’ die temperature goes above +150°C, the thermal-shutdown circuitry will shut down the 5V reference and pull OUT low. Typical Application Circuits VIN RST VOUT CST 1 R1 2 R2 RT 3 4 COMP VREF FB MAX5070A VCC MAX5070B CS OUT RT/CT GND 8 7 6 N 5 CT RCS Figure 5. MAX5070A/MAX5070B Typical Application Circuit (Isolated Flyback with Primary-Side Regulation) 16 ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers VIN RST VOUT CST 1 R1 2 R2 3 RT 4 COMP VREF FB MAX5070A VCC MAX5070B CS OUT RT/CT GND 8 7 6 N 5 CT RCS Figure 6. MAX5070A/MAX5070B Typical Application Circuit (Non-Isolated Flyback) VIN RST SYNC INPUT/OUTPUT VOUT CST RSYNC 1 2 RT 3 4 COMP VREF SYNC MAX5071A VCC MAX5071B CS OUT RT/CT GND 8 7 6 N 5 CT RCS Figure 7. MAX5071A/MAX5071B Typical Application Circuit (Isolated Flyback) ______________________________________________________________________________________ 17 MAX5070/MAX5071 Typical Application Circuits (continued) High-Performance, Single-Ended, Current-Mode PWM Controllers MAX5070/MAX5071 Typical Application Circuits (continued) VD VIN VOUT RST N QS CST N QR VD VCC VREF RT N OUT MAX5071C RT/CT CS CT RCS COMP ADV_CLK MAX5078 GND 0.5V/µs PULSE TRANSFORMER Figure 8. MAX5071C Typical Application Circuit (Isolated Forward with Secondary-Side Synchronous Rectification) 18 ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers VIN VIN VCC VREF RT VCC OUT VREF RT MAX5071A MAX5071B RT/CT N VCC OUT N N MAX5071A MAX5071B CS CT SYNC GND OUT RT/CT CS CT SYNC VREF RT MAX5071A MAX5071B RT/CT CS CT MAX5070/MAX5071 VIN SYNC GND GND TO OTHER MAX5071A/Bs RSYNC Figure 9. Synchronization of MAX5071s ______________________________________________________________________________________ 19 MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers Selector Guide PART FEEDBACK/ ADVANCED CLOCK MAXIMUM DUTY CYCLE (%) PIN-PACKAGE PIN COMPATIBLE MAX5070AASA Feedback 100 8 SO UC2842/UCC2842 MAX5070AAUA Feedback 100 8 µMAX UC2842/UCC2842 MAX5070BASA Feedback 50 8 SO UC2844/UCC2844 MAX5070BAUA Feedback 50 8 µMAX UC2844/UCC2844 MAX5071AASA Sync. 100 8 SO — MAX5071AAUA Sync. 100 8 µMAX — MAX5071BASA Sync. 50 8 SO — MAX5071BAUA Sync. 50 8 µMAX — MAX5071CASA ADV_CLK 50 8 SO — MAX5071CAUA ADV_CLK 50 8 µMAX — Pin Configurations (continued) TOP VIEW COMP 1 SYNC 2 CS 3 MAX5071A MAX5071B RT/CT 4 8 VREF 7 VCC -40°C to +125°C 8 SO MAX5071AAUA -40°C to +125°C 8 µMAX MAX5071BASA -40°C to +125°C 8 SO MAX5071BAUA -40°C to +125°C 8 µMAX MAX5071CASA -40°C to +125°C 8 SO MAX5071CAUA -40°C to +125°C 8 µMAX 7 VCC MAX5071C CS 3 6 OUT 5 GND RT/CT 4 5 GND PIN-PACKAGE MAX5071AASA VREF OUT Ordering Information (continued) TEMP RANGE ADV_CLK 2 8 6 µMAX/SO PART COMP 1 µMAX/SO Chip Information TRANSISTOR COUNT: 1987 PROCESS: BiCMOS Specify lead-free by adding the + symbol at the end of the part number when ordering. 20 ______________________________________________________________________________________ High-Performance, Single-Ended, Current-Mode PWM Controllers N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0∞-8∞ A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 ______________________________________________________________________________________ 21 MAX5070/MAX5071 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.) 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.) 4X S 8 E Ø0.50±0.1 8 INCHES DIM A A1 A2 b H c D e E H 0.6±0.1 1 L 1 α 0.6±0.1 S BOTTOM VIEW D MIN 0.002 0.030 MAX 0.043 0.006 0.037 0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6° 0° 0.0207 BSC 8LUMAXD.EPS MAX5070/MAX5071 High-Performance, Single-Ended, Current-Mode PWM Controllers MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0° 6° 0.5250 BSC TOP VIEW A1 A2 e A c b FRONT VIEW α L SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 REV. J 1 1 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. 22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.