MAX8640YELT19+

19-3997; Rev 1; 1/07 KIT ATION EVALU E L B AVAILA Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters The MAX8640Y/MAX8640Z step-down converters are optimized for applications where small size, high efficiency, and low output ripple are priorities. They utilize a proprietary PWM control scheme that optimizes the switching frequency for high efficiency with small external components and maintains low output ripple voltage at all loads. The MAX8640Z switches at up to 4MHz to allow a tiny 1µH inductor and 2.2µF output capacitor. The MAX8640Y switches at up to 2MHz for higher efficiency while still allowing small 2.2µH and 4.7µF components. Output current is guaranteed up to 500mA, while typical quiescent current is 24µA. Factory-preset output voltages from 0.8V to 2.5V eliminate external feedback components. Internal synchronous rectification greatly improves efficiency and replaces the external Schottky diode required in conventional step-down converters. Internal fast soft-start eliminates inrush current so as to reduce input capacitor requirements. The MAX8640Y/MAX8640Z are available in the tiny 6pin, SC70 (2.0mm x 2.1mm) and µDFN (1.5mm x 1.0mm) packages. Both packages are lead-free. Applications Microprocessor/DSP Core Power I/O Power Cell Phones, PDAs, DSCs, MP3s Other Handhelds Where Space Is Limited Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ Tiny SC70 and µDFN Packages 500mA Guaranteed Output Current 4MHz or 2MHz PWM Switching Frequency Tiny External Components: 1µH/2.2µF or 2.2µH/4.7µF 24µA Quiescent Current Factory Preset Outputs from 0.8V to 2.5V ±1% Initial Accuracy Low Output Ripple at All Loads Ultrasonic Skip Mode Down to 1mA Loads Ultra-Fast Line- and Load-Transient Response Fast Soft-Start Eliminates Inrush Current Ordering Information PINPACKAGE PKG CODE TOP MARK MAX8640YEXT08+T 6 SC70-6 X6S-1 ACQ MAX8640YEXT11+T 6 SC70-6 X6S-1 ACR MAX8640YEXT12+T 6 SC70-6 X6S-1 ACS MAX8640YEXT13+T 6 SC70-6 X6S-1 ACG MAX8640YEXT15+T 6 SC70-6 X6S-1 ADD MAX8640YEXT16+T 6 SC70-6 X6S-1 ADB MAX8640YEXT18+T 6 SC70-6 X6S-1 ACI MAX8640YEXT19+T 6 SC70-6 X6S-1 ACH MAX8640YEXT25+T 6 SC70-6 X6S-1 *Contact factory for availability of each version. +Denotes a lead-free package. ACJ PART* Note: All devices are specified over the -40°C to +85°C operating temperature range. Ordering Information continued and Selector Guide appears at end of data sheet. Pin Configurations Typical Operating Circuit TOP VIEW L1 1μH OR 2.2μH INPUT 2.7V TO 4.9V IN C1 2.2μF OUTPUT 0.8V TO 2.5V UP TO 500mA LX 1 GND 2 OUT 3 LX MAX8640Y + + MAX8640Y MAX8640Z 6 IN 5 GND 4 SHDN LX 1 6 IN MAX8640Y GND 2 5 GND OUT 3 4 SHDN GND MAX8640Z OUT ON/OFF SHDN C2 2.2μF OR 4.7μF SC70 2.0mm x 2.1mm μDFN 1.5mm x 1.0mm ________________________________________________________________ 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 MAX8640Y/MAX8640Z General Description MAX8640Y/MAX8640Z Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +6V LX, OUT, SHDN to GND ..............................-0.3V to (VIN + 0.3V) LX Current (Note 1) ........................................................0.8ARMS OUTPUT Short Circuit to GND ...................................Continuous Continuous Power Dissipation (TA = +70°C) 6-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW 6-Pin µDFN (derate 2.1mW/°C above +70°C) ..............167.7mW 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 Note 1: LX has internal clamp diodes to IN and GND. Applications that forward bias these diodes should not exceed the IC’s package power-dissipation limit. 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 (VIN = 3.6V, SHDN = IN, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 2) PARAMETER Supply Range UVLO Threshold SYMBOL CONDITIONS VIN UVLO MIN VIN rising, 100mV hysteresis 2.44 No load, no switching Supply Current Output Voltage Range ICC VOUT Output Voltage Accuracy (Falling Edge) Output Load Regulation (Voltage Positioning) TYP 2.7 SHDN = GND 2.6 MAX UNITS 4.9 V 2.70 V 24 48 TA = +25°C 0.01 0.1 µA TA = +85°C 0.1 2.5 V Factory preset 0.8 ILOAD = 0mA, TA = +25°C -1 ILOAD = 0mA, TA = -40°C to +85°C -2 Equal to inductor DC resistance 0 +1 +2 RL % V/A VIH VIN = 2.7V to 4.9V VIL VIN = 2.7V to 4.9V IIH,IL VIN = 4.9V, SHDN = GND or IN Peak Current Limit ILIMP pFET switch 590 770 1400 mA Valley Current Limit ILIMN nFET rectifier 450 650 1300 mA ILXOFF nFET rectifier 10 40 70 mA RONP pFET switch, ILX = -40mA 0.6 1.2 RONN nFET rectifier, ILX = 40mA 0.35 0.7 ILXLKG VIN = 4.9V, LX = GND to IN, SHDN = GND TA = +25°C 0.1 1 TA = +85°C 1 SHDN Logic Input Level SHDN Logic Input Bias Current Rectifier Off-Current Threshold On-Resistance LX Leakage Current Minimum On and Off Times Thermal Shutdown Thermal-Shutdown Hysteresis 1.4 0.4 TA = +25°C 0.001 TA = +85°C 0.01 tON(MIN) 95 tOFF(MIN) 95 1 V µA Ω µA ns +160 °C 20 °C Note 2: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. 2 _______________________________________________________________________________________ Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX8640YEXT18 30 SUPPLY CURRENT (μA) 80 70 60 50 40 30 20 25 20 MAX8640ZEXT15 15 10 10 MAX8640ZEXT15 1 MAX8640YEXT18 10 5 0 1 10 100 LOAD CURRENT (mA) 0.1 2.9 1000 3.3 3.7 4.1 SUPPLY VOLTAGE (V) 4.5 4.9 0 100 200 300 400 LOAD CURRENT (mA) 500 LIGHT-LOAD SWITCHING WAVEFORMS (IOUT = 1mA) OUTPUT VOLTAGE vs. LOAD CURRENT (VOLTAGE POSITIONING) MAX8640Y/Z toc05 1.55 MAX8640ZEXT15 1.50 MAX8640Y/Z toc04 0.1 OUTPUT VOLTAGE (V) EFFICIENCY (%) 35 MAX8640Y/Z toc03 MAX8640YEXT18 MAX8640Y/Z toc02 90 MAX8640Y/Z toc01 100 SWITCHING FREQUENCY vs. LOAD CURRENT SWITCHING FREQUENCY (MHz) EFFICIENCY vs. LOAD CURRENT 1.8V OUTPUT 20mV/div (AC-COUPLED) VOUT 1.45 VLX 2V/div 1.40 1.35 ILX 200mA/div 1.30 0 100 200 300 400 LOAD CURRENT (mA) 500 10μs/div MEDIUM-LOAD SWITCHING WAVEFORMS (IOUT = 40mA) HEAVY-LOAD SWITCHING WAVEFORMS (IOUT = 300mA) MAX8640Y/Z toc06 MAX8640Y/Z toc07 20mV/div (AC-COUPLED) VOUT 20mV/div (AC-COUPLED) VOUT 2V/div VLX VLX 0V 2V/div 0V 200mA/div ILX 200mA/div ILX 0mA 0mA 200ns/div 200ns/div _______________________________________________________________________________________ 3 MAX8640Y/MAX8640Z Typical Operating Characteristics (VIN = 3.6V, VOUT = 1.5V, MAX8640Z, L = Murata LQH32CN series, TA = +25°C, unless otherwise noted.) MAX8640Y/MAX8640Z Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters Typical Operating Characteristics (continued) (VIN = 3.6V, VOUT = 1.5V, MAX8640Z, L = Murata LQH32CN series, TA = +25°C, unless otherwise noted.) LIGHT-LOAD STARTUP WAVEFORM (100Ω LOAD) HEAVY-LOAD STARTUP WAVEFORM (5Ω LOAD) MAX8640Y/Z toc08 MAX8640Y/Z toc09 5V/div VSHDN 5V/div VSHDN 1V/div 1V/div VOUT 0V VOUT 0V 100mA/div 100mA/div 0mA IIN IIN 0mA ILX 500mA/div 500mA/div ILX 0mA 0mA 20μs/div 20μs/div LOAD-TRANSIENT RESPONSE (5mA TO 250mA TO 5mA) LINE-TRANSIENT RESPONSE (4V TO 3.5V TO 4V) MAX8640Y/Z toc11 MAX8640Y/Z toc10 1V/div 4V VIN VOUT 50m/div AC-COUPLED VOUT 500mA/div ILX 20mV/div AC-COUPLED 200mA/div IOUT 200mA/div ILX 0mA 0mA 40μs/div 20μs/div LOAD-TRANSIENT RESPONSE (10mA TO 500mA TO 10mA) MAX8640Y/Z toc12 100mV/div AC-COUPLED VOUT 500mA/div ILX 0V IOUT 200mA/div 40μs/div 4 _______________________________________________________________________________________ Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters PIN NAME FUNCTION 1 LX 2, 5 GND Ground. Connect these pins together directly under the IC. 3 OUT Output Sense Input. Bypass with a ceramic capacitor as close as possible to pin 3 (OUT) and pin 2 (GND). OUT is internally connected to the internal feedback network. 4 SHDN 6 IN Inductor Connection to the Internal Drains of the p-channel and n-channel MOSFETs. High impedance during shutdown. Active-Low Shutdown Input. Connect to IN or logic-high for normal operation. Connect to GND or logic-low for shutdown mode. Supply Voltage Input. Input voltage range is 2.7V to 4.9V. Bypass with a ceramic capacitor as close as possible to pin 6 (IN) and pin 5 (GND). Detailed Description The MAX8640Y/MAX8640Z step-down converters deliver over 500mA to outputs from 0.8V to 2.5V. They utilize a proprietary hysteretic PWM control scheme that switches at up to 4MHz (MAX8640Z) or 2MHz (MAX8640Y), allowing some trade-off between efficiency and size of external components. At loads below 100mA, the MAX8640Y/MAX8640Z automatically switch to pulse-skipping mode to minimize the typical quiescent current (24µA). Output ripple remains low at all loads, while the skip-mode switching frequency remains ultrasonic down to 1mA (typ) loads. Figure 1 is the simplified functional diagram. IN SHDN PWM LOGIC GND OUT 0.6V Control Scheme A proprietary hysteretic PWM control scheme ensures high efficiency, fast switching, fast transient response, low output ripple, and physically tiny external components. This control scheme is simple: when the output voltage is below the regulation threshold, the error comparator begins a switching cycle by turning on the high-side switch. This switch remains on until the minimum on-time expires and the output voltage is above the regulation threshold or the inductor current is above the current-limit threshold. Once off, the high-side switch remains off until the minimum off-time expires and the output voltage falls again below the regulation threshold. During the off period, the low-side synchronous rectifier turns on and remains on until either the high-side switch turns on again or the inductor current approaches zero. The internal synchronous rectifier eliminates the need for an external Schottky diode. Voltage-Positioning Load Regulation The MAX8640Y/MAX8640Z utilize a unique feedback network. By taking DC feedback from the LX node, the usual phase lag due to the output capacitor is removed, making the loop exceedingly stable and LX MAX8640Y MAX8640Z Figure 1. Simplified Functional Diagram allowing the use of very small ceramic output capacitors. This configuration yields load regulation equal to the inductor’s series resistance multiplied by the load current. This voltage-positioning load regulation greatly reduces overshoot during load transients, effectively halving the peak-to-peak output-voltage excursions compared to traditional step-down converters. See the Load-Transient Response in the Typical Operating Characteristics. Shutdown Mode Connecting SHDN to GND or logic low places the MAX8640Y/MAX8640Z in shutdown mode and reduces supply current to 0.1µA (typ). In shutdown, the control circuitry and internal MOSFET switches turn off and LX becomes high impedance. Connect SHDN to IN or logic high for normal operation. _______________________________________________________________________________________ 5 MAX8640Y/MAX8640Z Pin Description MAX8640Y/MAX8640Z Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters Soft-Start The MAX8640Y/MAX8640Z are optimized for use with a tiny inductor and small ceramic capacitors. The correct selection of external components ensures high efficiency, low output ripple, and fast transient response. It is acceptable to use a 1.5µH inductor with either the MAX8640Y or MAX8640Z, but efficiency and ripple should be verified. Similarly, it is acceptable to use a 3.3µH inductor with the MAX8640Y, but performance should be verified. For optimum voltage positioning of load transients, choose an inductor with DC series resistance in the 75mΩ to 150mΩ range. For higher efficiency at heavy loads (above 200mA) or minimal load regulation (but some transient overshoot), the resistance should be kept as low as possible. For light-load applications up to 200mA, higher resistance is acceptable with very little impact on performance. Inductor Selection Capacitor Selection The MAX8640Y/MAX8640Z include internal soft-start circuitry that eliminates inrush current at startup, reducing transients on the input source. Soft-start is particularly useful for higher impedance input sources, such as Li+ and alkaline cells. See the Soft-Start Response in the Typical Operating Characteristics. Applications Information A 1µH inductor is recommended for use with the MAX8640Z, and 2.2µH is recommended for the MAX8640Y. A 1µH inductor is physically smaller but requires faster switching, resulting in some efficiency loss. Table 1 lists several recommended inductors. Output Capacitor The output capacitor, C2, is required to keep the output voltage ripple small and to ensure regulation loop stability. C2 must have low impedance at the switching frequency. Ceramic capacitors are recommended due to Table 1. Suggested Inductors MANUFACTURER SERIES MIPFT2520D FDK Murata Sumida Taiyo Yuden MIPF2520D LQM31P CDRH2D09 CKP3216T GLF201208T TDK GLF2012T GLF251812T MDT2520-CR TOKO D2812C 6 INDUCTANCE (µH) DC RESISTANCE (Ω typ) CURRENT RATING (mA) DIMENSIONS L x W x H (mm) 2.5 x 2.0 x 0.5 2.0 0.16 900 1.5 0.07 1500 2.2 0.08 1300 3.3 0.10 1200 1.0 0.12 1200 1.5 0.16 1000 2.2 0.22 900 1.2 0.08 590 1.5 0.09 520 2.2 0.12 440 1.0 0.11 1100 1.5 0.13 1000 2.2 0.14 900 1.0 0.15 460 2.2 0.36 300 1.0 0.07 400 2.2 0.10 300 1.0 0.10 800 2.2 0.20 600 1.0 0.05 1000 2.2 0.08 700 1.0 0.07 1100 2.2 0.14 770 2.5 x 2.0 x 1.0 3.2 x 1.6 x 0.95 3.0 x 3.0 x 1.0 3.2 x 1.6 x 0.9 2.0 x 1.25 x 0.9 2.0 x 1.25 x 1.35 _______________________________________________________________________________________ 2.5 x 1.8 x 1.35 2.5 x 2.0 x 1.0 2.8 x 2.8 x 1.2 Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters Input Capacitor The input capacitor, C1, reduces the current peaks drawn from the battery or input power source and reduces switching noise in the IC. The impedance of C1 at the switching frequency should be kept very low. Ceramic capacitors are recommended due to their small size and low ESR. Make sure the capacitor maintains its capacitance over temperature and DC bias. Capacitors with X5R or X7R temperature characteristics typically perform well. Due to the MAX8640Y/ MAX8640Z soft-start, the input capacitance can be very low. For optimum noise immunity and low input ripple, choose a capacitor value in µF that is equal to or larger than the inductor’s value in µH. PCB Layout and Routing High switching frequencies and large peak currents make PCB layout a very important part of design. Good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. Connect the inductor, input capacitor, and output capacitor as close together as possible, and keep their traces short, direct, and wide. Connect the two GND pins under the IC and directly to the grounds of the input and output capacitors. Keep noisy traces, such as the LX node, as short as possible. Refer to the MAX8640Z evaluation kit for an example PCB layout and routing scheme. Selector Guide PART OUTPUT VOLTAGE (V) FREQUENCY (MHz) MAX8640YEXT08 0.8 1.2 RECOMMENDED COMPONENTS L1 (µH) C2 (µF) TOP MARK 2.2 10 ACQ ACR MAX8640YEXT11 1.1 1.7 2.2 4.7 MAX8640YEXT12 1.2 1.8 2.2 4.7 ACS MAX8640YEXT13 1.3 1.9 2.2 4.7 ACG MAX8640YEXT15 1.5 2.0 2.2 4.7 ADD MAX8640YEXT16 1.6 2.0 2.2 4.7 ADB MAX8640YEXT18 1.8 2.0 2.2 4.7 ACI ACH MAX8640YEXT19 1.9 2.0 2.2 4.7 MAX8640YEXT25 MAX8640YELT08 2.5 0.8 1.7 1.2 2.2 2.2 4.7 10 ACJ NB MAX8640YELT11 1.1 1.7 2.2 4.7 NC MAX8640YELT12 1.2 1.8 2.2 4.7 ND MAX8640YELT13 1.3 1.9 2.2 4.7 NE MAX8640YELT15 1.5 2.0 2.2 4.7 NF MAX8640YELT16 1.6 2.0 2.2 4.7 NG MAX8640YELT18 1.8 2.0 2.2 4.7 NH MAX8640YELT19 1.9 2.0 2.2 4.7 NI MAX8640YELT25 2.5 1.7 2.2 4.7 NJ MAX8640ZEXT08 0.8 2.4 1 4.7 ACL MAX8640ZEXT11 1.1 3.4 1 2.2 ACM MAX8640ZEXT12 1.2 3.6 1 2.2 ACN MAX8640ZEXT13 1.3 3.7 1 2.2 ACO MAX8640ZEXT15 1.5 3.9 1 2.2 ACP MAX8640ZEXT18 1.8 4.0 1 2.2 ACU _______________________________________________________________________________________ 7 MAX8640Y/MAX8640Z their small size and low ESR. Make sure the capacitor maintains its capacitance over temperature and DC bias. Capacitors with X5R or X7R temperature characteristics typically perform well. The output capacitance can be very low; see the Selector Guide for recommended capacitance values. For optimum load-transient performance and very low output ripple, the output capacitor value in µF should be equal to or larger than the inductor value in µH. Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters MAX8640Y/MAX8640Z Ordering Information (continued) PART* PINPACKAGE PKG CODE TOP MARK MAX8640YELT08+T 6 µDFN-6 L611-1 NB MAX8640YELT11+T 6 µDFN-6 L611-1 NC MAX8640YELT12+T 6 µDFN-6 L611-1 ND MAX8640YELT13+T 6 µDFN-6 L611-1 NE MAX8640YELT15+T 6 µDFN-6 L611-1 NF MAX8640YELT16+T 6 µDFN-6 L611-1 NG MAX8640YELT18+T 6 µDFN-6 L611-1 NH MAX8640YELT19+T 6 µDFN-6 L611-1 NI MAX8640YELT25+T 6 µDFN-6 L611-1 NJ MAX8640ZEXT08+T 6 SC70-6 X6S-1 ACL MAX8640ZEXT11+T 6 SC70-6 X6S-1 ACM MAX8640ZEXT12+T 6 SC70-6 X6S-1 ACN MAX8640ZEXT13+T 6 SC70-6 X6S-1 ACO MAX8640ZEXT15+T 6 SC70-6 X6S-1 ACP Chip Information PROCESS: BiCMOS Revision History Pages changed at Rev 1: 1–11 ACU MAX8640ZEXT18+T 6 SC70-6 X6S-1 *Contact factory for availability of each version. Note: All devices are specified over the -40°C to +85°C operating temperature range. 8 _______________________________________________________________________________________ Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters SC70, 6L.EPS PACKAGE OUTLINE, 6L SC70 21-0077 E 1 1 _______________________________________________________________________________________ 9 MAX8640Y/MAX8640Z 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.) 6L UDFN.EPS MAX8640Y/MAX8640Z Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters 10 ______________________________________________________________________________________ Tiny 500mA, 4MHz/2MHz Synchronous Step-Down DC-DC Converters TABLE 1 Translation Table for Calendar Year Code Calendar Year Legend: TABLE 2 2005 2006 Marked with bar 2007 2008 2009 2010 2011 2012 2013 42-47 48-51 52-05 2014 Blank space - no bar required Translation Table for Payweek Binary Coding Payweek Legend: 06-11 12-17 Marked with bar 18-23 24-29 30-35 36-41 Blank space - no bar required TITLE: PACKAGE OUTLINE, 6L uDFN, 1.5x1.0x0.8mm APPROVAL -DRAWING NOT TO SCALE- DOCUMENT CONTROL NO. 21-0147 REV. D 2 2 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 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX8640Y/MAX8640Z 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.)