19-0593; Rev 0; 11/06 KIT ATION EVALU E L B AVAILA 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power Features The MAX8581/MAX8582 high-frequency step-down converters are optimized for dynamically powering the power amplifier (PA) in CDMA handsets. They integrate a highefficiency PWM step-down converter for medium- and low-power transmission and a 60mΩ (typ) bypass mode to power the PA directly from the battery during highpower transmission. They use an analog input driven by an external DAC to control the output voltage linearly for continuous PA power adjustment. The MAX8581/ MAX8582 use an internal feedback network, and the switching frequency is internally set to 2.5MHz and 1.5MHz, respectively. ♦ 600mA Step-Down Converter Fast switching (up to 2.5MHz) and fast soft-start allow the use of ceramic 2.2µF input and output capacitors while maintaining low voltage ripple. The small 1.5µH to 3.3µH inductor size can be optimized for efficiency. The MAX8581/MAX8582 are available in 10-pin, 3mm x 3mm TDFN packages (0.8mm max height). ♦ 0.1µA Shutdown Mode ♦ 60mΩ (typ) Bypass Mode with Integrated FET ♦ Dynamically Adjustable Output from 0.4V to VIN ♦ 2.5MHz and 1.5MHz Switching Frequency ♦ Small LC Components: 1.5µH to 3.3µH and 2.2µF ♦ Up to 94% Efficiency ♦ Low Output Ripple at All Loads ♦ 2.7V to 5.5V Input ♦ Output Short-Circuit Protection ♦ Thermal Shutdown ♦ 10-Pin, 3mm x 3mm TDFN Packag Applications Ordering Information WCDMA/NCDMA Cell Phones PINPACKAGE PART* Wireless PDAs, Smartphones TOP MARK PKG CODE MAX8581ETB+ 10 TDFN-EP** ACT T1033-1 MAX8582ETB+ 10 TDFN-EP** ACU T1033-1 *All devices are specified in the -40°C to +85°C extended temperature range. **EP = Exposed pad. +Denotes lead-free package. Pin Configuration Typical Operating Circuit OUTPUT 0.4V TO VBATT GND IC REFIN 10 9 8 7 6 OUT 1.5μH OR 3.3μH 2.2μF OUT TOP VIEW OUT IN LX INPUT Li+ BATTERY MAX8581 MAX8582 LX 2.2μF HP FORCED BYPASS + 1 2 3 4 5 HP REFIN SHDN ANALOG CONTROL IN SHDN IN ON/OFF GND MAX8581/ MAX8582 ________________________________________________________________ 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 MAX8581/MAX8582 General Description MAX8581/MAX8582 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power ABSOLUTE MAXIMUM RATINGS IN, SHDN, HP, REFIN to GND ...............................-0.3V to +6.0V LX, OUT, IC to GND.....................................-0.3V to (VIN + 0.3V) OUT Short Circuit to GND ..........................................Continuous LX Current ......................................................................0.7ARMS IN, OUT Current..............................................................2.5ARMS Continuous Power Dissipation (TA = +70°C) 10-Pin 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 (VIN = V SHDN = 3.6V, VREFIN = 0.9V, VHP = VIC = 0V, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V 2.63 2.70 V 10 µA SUPPLY Supply Voltage Range UVLO Threshold VIN UVLO 2.7 VIN rising, 180mV hysteresis 2.55 ILOAD = 0A, switching at 1.5MHz Supply Current IIN 4000 Shutdown, TA = +25°C 0.1 Shutdown, TA = +85°C 1.0 OUT VIN = 4.2V, VREFIN = 1.7V OUT Voltage Accuracy OUT Input Resistance VOUT ROUT VIN = 3.6V VLX = VOUT 3.33 3.40 3.47 VREFIN = 0.9V 1.75 1.80 1.85 VREFIN = 0.4V 0.75 0.80 0.85 MAX8581 360 MAX8582 558 V kΩ REFIN REFIN Common-Mode Range 0 REFIN to OUT Gain REFIN Input Resistance REFIN Dual Mode™ Threshold VREFIN rising, 77mV hysteresis 0.45 x VIN 2.2 V 2.00 V/V 518 kΩ 0.463 x 0.475 x VIN VIN V LOGIC INPUTS Logic Input Level Logic Input Bias Current VIH VIN = 2.7V to 5.5V VIL VIN = 2.7V to 5.5V IIH, IIL VINPUT = 0V or VIN 1.4 0.4 TA = +25°C 0.01 TA = +85°C 0.1 Dual Mode is a trademark of Maxim Integrated Products, Inc. 2 _______________________________________________________________________________________ 1 V µA 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power (VIN = VSHDN = 3.6V, VREFIN = 0.9, VHP = VIC = 0V, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS LX On-Resistance LX Leakage Current RONP p-channel MOSFET switch, ILX = -40mA 0.2 0.4 RONN n-channel MOSFET rectifier, ILX = 40mA 0.18 0.35 ILXLKG VIN = 5.5V, LX = GND TA = +25°C 0.1 5 TA = +85°C 1 Ω µA p-Channel MOSFET Peak Current Limit ILIMP 700 1077 1400 mA n-Channel MOSFET Valley Current Limit ILIMN 790 985 1150 mA tON(MIN) 70 114 150 tOFF(MIN) 70 112 150 0.90 1.02 1.13 0.06 0.1 Minimum On- and Off-Times tON/tOFF Ratio tON(MIN) / tOFF(MIN) ns s/s BYPASS On-Resistance RONBYP p-channel MOSFET bypass, IOUT = -400mA, TA = +25°C p-channel MOSFET bypass, IOUT = -400mA Ω 0.12 Bypass Current Limit 1.0 2.1 Step-Down Current Limit in Bypass 700 1077 A 1400 mA GENERAL Thermal Shutdown Thermal-Shutdown Hysteresis Power-Up Delay °C +160 °C 20 VSHDN rising to VLX rising 50 130 µs Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. _______________________________________________________________________________________ 3 MAX8581/MAX8582 ELECTRICAL CHARACTERISTICS (MAX8582 ONLY) (continued) Typical Operating Characteristics (VIN = 3.6V, VOUT = 1.2V, MAX8582 EV Kit, TA = +25°C, unless otherwise noted.) BYPASS MODE DROPOUT VOLTAGE vs. LOAD CURRENT 90 VOUT = 3.2V 0.04 0.03 90 80 EFFICIENCY (%) 85 80 75 VOUT = 3.6V 0.02 70 0.01 65 0 60 0.2 0.4 0.6 0.8 50 40 20 10 0 0.8 1.0 60 30 RLOAD = 7.5Ω 1.2 1.6 2.0 2.4 2.8 3.2 100 10 OUTPUT VOLTAGE (V) LOAD CURRENT (mA) EFFICIENCY vs. LOAD CURRENT (VOUT = 1.2V) EFFICIENCY vs. LOAD CURRENT (VOUT = 0.6V) NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE 80 70 EFFICIENCY (%) 70 80 60 50 40 30 9 8 7 SUPPLY CURRENT (mA) 90 60 50 40 30 6 5 4 3 20 20 2 10 10 1 0 0 10 100 0 10 1000 1000 100 LOAD CURRENT (mA) 2.5 3.0 LOAD CURRENT (mA) 4.0 OUTPUT VOLTAGE vs. REFIN VOLTAGE 1.190 1.180 1.170 1.160 4.5 VIN = 4.2V 4.0 OUTPUT VOLTAGE VOUT (V) MAX8581/2 toc07 1.200 3.5 3.5 VIN = 3.6V 3.0 VIN = 3.0V 2.5 2.0 1.5 1.0 0.5 RLOAD = 7.5Ω 0 1.150 0 100 200 300 400 LOAD CURRENT (mA) 500 600 4.5 SUPPLY VOLTAGE (V) OUTPUT VOLTAGE vs. LOAD CURRENT 1.210 OUTPUT VOLTAGE (V) MAX8581/2 toc06 90 MAX8581/2 toc04 100 4 1000 LOAD CURRENT (A) MAX8581/2 toc05 0 70 MAX8581/2 toc08 0.05 95 EFFICIENCY (%) 0.06 100 MAX8581/2 toc03 100 MAX8581/2 toc02 0.07 EFFICIENCY vs. LOAD CURRENT (VOUT = 1.8V) EFFICIENCY vs. OUTPUT VOLTAGE MAX8581/2 toc01 DROPOUT VOLTAGE (VIN - VOUT) (V) 0.08 EFFICIENCY (%) MAX8581/MAX8582 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 REFIN VOLTAGE (V) _______________________________________________________________________________________ 5.0 5.5 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power LIGHT-LOAD SWITCHING WAVEFORMS HEAVY-LOAD SWITCHING WAVEFORMS MAX8581/2 toc09 MAX8581/2 toc10 ILOAD = 50mA 600mA ILX 100mA/div ILX 0A 400mA 200mA ILOAD = 500mA VOUT 20mV/div AC-COUPLED 2V/div VLX 20mV/div AC-COUPLED VOUT 2V/div VLX 0V 0V 200ns/div 200ns/div LINE-TRANSIENT WAVEFORMS SOFT-START WAVEFORMS LOAD TRANSIENT MAX8581/2 toc12 MAX8581/2 toc11 MAX8581/2 toc13 RLOAD = 7.5Ω VSHDN 2V 2V/div VOUT 1V/div 0V 4V VIN 3V VOUT IIN 50mV/div AC-COUPLED 100mA/div 0A ILX 50mV/div AC-COUPLED VOUT 500mA/div 0A IOUT 200mA/div ILX 100mA/div 0A 0A 20μs/div 20μs/div 20μs/div REFIN TRANSIENT RESPONSE REFIN TRANSIENT WITH AUTOBYPASS HP TRANSIENT RESPONSE WITH FORCED AUTOBYPASS MAX8581/2 toc14 MAX8581/2 toc15 RLOAD = 7.5Ω VOUT 2V MAX8581/2 toc16 RLOAD = 7.5Ω RLOAD = 7.5Ω VREFIN = 0.6V 2V/div VOUT 2V/div 0V VOUT 1V VREFIN 1V/div 1V VREFIN 0.5V ILX 0V 1V/div VHP 0V ILX 500mA/div 0A 0V ILX 500mA/div 0A 200mA/div 0A 20μs/div 500mA/div 0A IOUT 20μs/div 500mA/div 0A IOUT 20μs/div _______________________________________________________________________________________ 5 MAX8581/MAX8582 Typical Operating Characteristics (continued) (VIN = 3.6V, VOUT = 1.2V, MAX8582 EV Kit, TA = +25°C, unless otherwise noted.) 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power MAX8581/MAX8582 Pin Description PIN NAME 1 GND 2, 3 IN 4 SHDN 5 HP 6 REFIN 7 IC FUNCTION Ground Supply Voltage Input. 2.7V to 5.5V. Bypass with a 2.2µF ceramic capacitor as close as possible to IN and GND. Active-Low Shutdown Input. Connect to IN or logic-high for normal operation. Connect to GND or logic-low for shutdown mode. High-Power Mode Set Input. Drive HP high to invoke bypass mode. Bypass mode connects IN directly to OUT with the internal bypass MOSFET. DAC-Controlled Input. Output regulates to 2 x VREFIN for the MAX8581 and MAX8582. Dual-mode threshold at 0.465 VIN enables bypass mode. Internally Connected. Connect to ground. Output Voltage Connection for Bypass Mode. Internally connected to IN using the internal bypass MOSFET during bypass mode. Connects to the internal feedback network. 8, 9 OUT 10 LX Inductor Connection. Connect inductor to the drains of the internal p-channel and n-channel MOSFETs. Connects to the internal feedback network. — EP Exposed Paddle. Connect to GND. Detailed Description The MAX8581/MAX8582 step-down converters deliver over 600mA to dynamically power the PA in CDMA handsets. The hysteretic PWM control scheme switches with nearly fixed frequency at 1.5MHz (MAX8582) to 2.5MHz (MAX8581), allowing efficiency and tiny external components. A 60mΩ bypass mode connects the PA directly to the battery during high-power transmission. Control Scheme A 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 voltage, the error comparator begins a switching cycle by turning on the high-side switch. This switch remains on until the minimum ontime expires and the output voltage is in regulation or the current-limit threshold is exceeded. Once off, the high-side switch remains off until the minimum off-time expires and the output voltage falls out of regulation. During this period, the low-side synchronous rectifier turns on and remains on until the high-side switch turns on again. The internal synchronous rectifier eliminates the need for an external Schottky diode. 6 Voltage-Positioning Load Regulation The MAX8581/MAX8582 utilize a unique feedback network. By taking feedback from the LX node, the usual phase lag due to the output capacitor is removed, making the loop exceedingly stable and allowing the use of very small ceramic output capacitors. This configuration yields load regulation equal to half the inductor’s series resistance multiplied by the load current. This voltage-positioning load regulation greatly reduces overshoot during load transients or when changing VOUT from one voltage to another. However, when calculating REFIN voltage, the load regulation should be considered. Because inductor resistance is typically well specified and the typical PA is a resistive load, the VREFIN to VOUT gain is slightly less than 2V/V for the MAX8581/MAX8582. Bypass Mode During high-power transmission, the bypass mode’s low on-resistance provides low dropout, long battery life, and high output-current capability. Bypass mode connects IN directly to OUT with the internal 60mΩ (typ) bypass FET, while the step-down converter is forced into 100% duty-cycle operation to slightly lower total on-resistance to less than 60mΩ (typ). _______________________________________________________________________________________ 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power The MAX8581/MAX8582 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. VIN = 3.2V TO 3.66V 200mV/div Setting the Output Voltage The MAX8581/MAX8582 output voltages are set by the voltage applied to REFIN. The output voltage is 2 VREFIN minus half the IR voltage drop caused by the inductor’s DC resistance for the MAX8581/MAX8582. VOUT = 3V 200mV/div Inductor Selection 5ms/div Figure 1. VIN and VOUT with Automatic Entry/Exit into Bypass Mode Forced and Automatic Bypass Mode Invoke forced-bypass mode by driving HP high or invoke automatic bypass by applying a high voltage to REFIN (VREFIN > 2.1V with a Li-ion (Li+) battery at IN). To prevent excessive output ripple as the step-down converter approaches dropout, the MAX8581/MAX8582 preemptively enter bypass mode automatically when VREFIN > 0.465 VIN (see Figure 1). Shutdown Mode Connect SHDN to GND or logic-low to place the MAX8581/MAX8582 in shutdown mode and reduce supply current to 0.1µA. In shutdown, the control circuitry, internal switching MOSFET, and synchronous rectifier turn off and LX becomes high impedance. Connect SHDN to IN or logic-high for normal operation. Fast Soft-Start The MAX8581/MAX8582 have internal fast soft-start circuitry that limits inrush current at startup, reducing transients on the input source. Soft-start is particularly useful for supplies with high output impedance such as Li+ and alkaline cells. See the Soft-Start Waveforms in the Typical Operating Characteristics. Analog REFIN Control The MAX8581/MAX8582 use REFIN to set the output voltage and to switch to bypass mode. The output voltage is two times the voltage applied at REFIN minus half the IR voltage drop caused by the inductor’s DC resistance for the MAX8581/MAX8582. This allows the converter to operate in applications where dynamic voltage control is required. The MAX8581/MAX8582 use 1.5µH and 3.3µH, respectively. Low inductance values are physically smaller but require faster switching, which results in some efficiency loss (see the Typical Operating Characteristics for efficiency). The inductor’s DC current rating only needs to match the maximum load of the application because the MAX8581/MAX8582 feature zero current overshoot during startup and load transients. For optimum transient response and high efficiency, choose an inductor with DC series resistance in the 50mΩ to 150mΩ range. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. Due to the unique feedback network, the output capacitance can be very low. In most applications, 2.2µF works well. For optimum load-transient performance and very low output ripple, the output capacitor value can be increased. Input Capacitor Selection The input capacitor reduces the current peaks drawn from the battery or input power source and reduces switching noise in the MAX8581/MAX8582. The impedance of the input capacitor at the switching frequency should be kept very low. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. Due to the MAX8581/MAX8582s’ fast soft-start, the input capacitance can be very low. In most applications, 2.2µF works well. For optimum noise immunity and low input ripple, the input capacitor value can be increased. _______________________________________________________________________________________ 7 MAX8581/MAX8582 Applications Information MAX8581/MAX8582 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power Table 1. Suggested Inductors MANUFACTURER SERIES Coilcraft LP03310 SD3110 Cooper SD3112 FDK MIPF2520D Panasonic ELC3FN Sumida Taiyo Yuden ESR (Ω) CURRENT RATING (mA) 1.5 0.10 1400 3.3 0.16 950 1.5 0.11 970 1.5 0.10 1090 3.3 0.17 840 1.5 0.07 1500 3.3 0.10 1200 2.2 0.12 1000 CDRH2D09 1.5 0.05 680 CDRH2D11 3.3 0.10 450 DIMENSIONS 3.3 x 3.3 x 1.0 = 11mm3 3.1 x 3.1 x 1.05 = 10mm3 3.1 x 3.1 x 1.2 = 12mm3 2.5 x 2.0 x 1.0 = 5mm3 3.2 x 3.2 x 1.2 = 12mm3 3.2 x 3.2 x 1.2 = 12mm3 CB2016 2.2 0.13 510 CBC2016 2.2 0.20 750 CB2518 2.2 0.09 510 2.0 x 1.6 x 1.8 = 5.8mm3 CBC2518 2.2 0.13 890 2.5 x 1.8 x 2.0 = 9mm3 1.5 0.08 1200 3.3 0.14 840 2.2 0.08 700 1.5 0.11 900 1.3 0.17 730 NR3010 MDT2520-CR TOKO INDUCTANCE (µH) D2812C 2.0 x 1.25 x 1.45 = 3.6mm3 3.2 x 3.2 x 1.2 = 12mm3 2.5 x 2.0 x 1.0 = 5mm3 2.8 x 2.8 x 1.2 = 9.4mm3 PCB Layout Checklist High switching frequencies and relatively large peak currents make the 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 input capacitor close to IN and GND. Connect the inductor and output capacitor as close to the IC as possible and keep their traces short, direct, and wide. Keep noisy traces, such as the LX node, as short as possible. Connect GND to the exposed paddle directly under the IC. Figure 2 illustrates an example PCB layout and routing scheme. L1 = FDK MIPF2520 SERIES 1.5μH FOR MAX8581 3.3μH FOR MAX8582 C1, C2 = TAIYO YUDEN JMK105BJ225MV-B L1 GND C1 IN C2 SHDN HP REFIN Chip Information PROCESS: BiCMOS Figure 2. Example PCB Layout and Routing Scheme 8 _______________________________________________________________________________________ OUT GND 2.5MHz/1.5MHz Step-Down Converters with 60mΩ Bypass in TDFN for CDMA PA Power 6, 8, &10L, DFN THIN.EPS PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm 21-0137 COMMON DIMENSIONS MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b A 0.70 0.80 T633-1 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF E 2.90 3.10 T833-1 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF 0.00 0.05 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF L 0.20 0.40 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF A2 0.20 REF. 2 [(N/2)-1] x e A1 0.25 MIN. 1 PACKAGE VARIATIONS SYMBOL k H T1033-2 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 21-0137 H 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 _____________________ 9 © 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX8581/MAX8582 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.)