19-2448; Rev 0; 4/02 Triple-Output Power-Management IC for Microprocessor-Based Systems Features ♦ Three Regulators in One Package Peripherals and I/O Supply: 3.3V at 900mA µP Core Supply: 0.7V to VIN at 400mA Memory Supply: 1.8/2.5/3.3V at 800mA ♦ Supports Intel PXA210 and PXA250 Microprocessors ♦ Power-On Reset with Manual Reset Input ♦ Auto Power-Up Sequencing ♦ 1MHz PWM Switching Allows Small External Components ♦ Low 5µA Shutdown Current ♦ Tiny 6mm ✕ 6mm, 36-Pin QFN Package Ordering Information PART MAX1702BEGX TEMP RANGE PIN-PACKAGE -40°C to +85°C 36 6mm x 6mm QFN Applications N.C. INP3 LX3 PG3 N.C. COMP3 OUT3 FB2 36 35 34 33 32 31 30 29 28 TOP VIEW Third Generation Smart Cell Phones Internet Appliances and Web Books Automotive In-Dash Telematics Systems LBO PDA, Palmtop, and Wireless Handhelds Pin Configuration N.C. 1 27 N.C. LBI 2 26 N.C. DBI 3 25 INP2 ON2 4 24 LX2 MAX1702B PGM3 5 GND 6 22 OUTOK 23 PG2 REF 7 21 COMP2 Typical Operating Circuit appears at end of data sheet. GND 8 20 OUT1 Intel is a registered trademark of Intel Corporation. N.C. 9 15 16 17 18 MR COMP1 N.C. PG1 14 LX1 13 INP1 12 N.C. IN ARM and ARM Powered are registered trademarks of ARM Limited. 11 RSO XScale is a trademark of Intel Corporation. 19 N.C. 10 6mm x 6mm QFN ________________________________________________________________ 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 MAX1702B General Description The MAX1702B power-management IC supports ARM Powered ® devices such as the Intel ® PXA210 and PXA250 microprocessors based on the Intel XScale™ micro-architecture. These devices include PDAs, thirdgeneration smart cellular phones, internet appliances, automotive in-dash Telematics systems, and other applications requiring substantial computing and multimedia capability at low power. The MAX1702B integrates three ultra-high-performance power supplies with associated supervisory and management functions. Included is a step-down DC-DC converter to supply 3.3V I/O and peripherals, a step-down DC-DC converter to supply 0.7V to VIN for the microprocessor core, and a step-down DC-DC converter to supply either 1.8V, 2.5V, or 3.3V to power the memory. Management functions include automatic power-up sequencing, power-on-reset and manual reset with timer, and two levels of low-battery detection. The DC-DC converters use fast 1MHz PWM switching, allowing the use of small external components. They automatically switch from PWM mode under heavy loads to skip mode under light loads to reduce quiescent current and maximize battery life. The input voltage range is from 2.6V to 5.5V, allowing the use of three NiMH cells, a single Li+ cell, or a regulated 5V input. The MAX1702B is available in a tiny 6mm x 6mm, 36-pin QFN package and operates over the -40°C to +85°C temperature range. MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems ABSOLUTE MAXIMUM RATINGS IN, FB2, OUT3, COMP1, COMP2, COMP3, PGM3, ON2, LBO, OUTOK, RSO, MR, LBI, DBI, OUT1 to GND .......................................................-0.3V to +6V REF to GND ...................................................-0.3 to (VIN + 0.3V) INP1, INP2, INP3 to IN...........................................-0.3V to +0.3V PG1, PG2, PG3 to GND.........................................-0.3V to +0.3V LX1, LX2, LX3 Continuous Current .......................-1.5A to +1.5A INP1 to PG1..............................................................-0.3V to +6V INP2 to PG2..............................................................-0.3V to +6V INP3 to PG3..............................................................-0.3V to +6V Output Short-Circuit Duration ............................................Infinite Continuous Power Dissipation (TA =+70°C) 36-Pin QFN (derate 22.7 mW/°C)..............................1818mW Operating Temperature Range.............................40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec) .............................+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 (VINP1 = VINP2 = VINP3 = VIN = 3.6V, VLBI = 1.1V, VDBI = 1.35V, MR = ON2 = IN, PGM3 = GND, circuit of Figure 1, TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS 5.5 V INP1, INP2, INP3, IN Supply Voltage Range INP1, INP2, INP3, IN must be connected together externally 2.6 Undervoltage Lockout Threshold VIN rising 2.25 2.40 2.55 VIN falling 2.2 2.35 2.525 Quiescent Current (IINP1 + IINP2 + IINP3 + IIN) ON2 = IN, no load 485 ON2 = GND, no load 335 VDBI < 1.2 V (shutdown) LX1-3 = GND V µA 5 20 3.366 SYNCHRONOUS BUCK PWM REGULATOR 1 (REG1) OUT1 Voltage Accuracy 3.6V ≤ VINP1 ≤ 5.5V, load = 0 to 900mA 3.234 3.3 OUT1 Input Resistance 200 400 Error-Amp Transconductance 55 95 135 µS Load = 800mA (Note 1) 250 425 mV ILX1 = 180mA 0.25 0.4 ILX1 = 180mA, VINP1 = 2.6V 0.3 0.5 Dropout Voltage P-Channel On-Resistance V kΩ Ω 0.2 0.35 Ω Current-Sense Transresistance 0.40 0.47 0.54 V/A P-Channel Current-Limit Threshold 1.15 1.275 1.45 A P-Channel Pulse-Skipping Current Threshold 0.115 0.140 0.160 A N-Channel Zero-Crossing Comparator 25 55 75 mA N-Channel On-Resistance OUT1 Maximum Output Current ILX1 = 180mA 2.6V ≤ VINP1 ≤ 5.5V (Note 2) 0.9 LX1 Leakage Current VINP1 = 5.5V, LX1= GND or INP1, VOUT1 = 3.6V -20 LX1 Duty-Cycle Range VINP2 = 4.2V 2 A 0.1 0 _______________________________________________________________________________________ +20 µA 100 % Triple-Output Power-Management IC for Microprocessor-Based Systems (VINP1 = VINP2 = VINP3 = VIN = 3.6V, VLBI = 1.1V, VDBI = 1.35V, MR = ON2 = IN, PGM3 = GND, circuit of Figure 1, TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER OUT1 Discharge Resistance CONDITIONS MIN TYP MAX 300 (Note 3) VOUT1 = 3.3V, VDBI = 1V UNITS Ω SYNCHRONOUS BUCK REGULATOR 2 (REG2) FB2 Regulation Voltage 2.6V ≤ VINP2 ≤ 5.5V, load = 0 to 400mA FB Input Current VFB = 0.7V 0.7 0.714 V 1 150 nA 250 350 µS Load = 400mA (Note 1) 150 250 mV ILX2 = 180mA 0.25 0.4 ILX2 = 180mA, VINP2 = 2.6V 0.3 0.5 Error-Amp Transconductance Dropout Voltage P-Channel On-Resistance 0.686 150 Ω 0.2 0.35 Ω Current-Sense Transresistance 0.40 0.47 0.54 V/A P-Channel Current-Limit Threshold 1.15 1.275 1.45 A P-Channel Pulse-Skipping Current Threshold 0.115 0.140 0.160 mA N-Channel Zero-Crossing Comparator 25 55 75 mA 0.1 +20 µA 100 % N-Channel On-Resistance ILX2 = 180mA OUT2 Maximum Output Current 2.6V ≤ VINP2_ ≤ 5.5V (Note 2) 0.4 LX2 Leakage Current VINP2 = 5.5V, LX2 = GND or INP2, VFB2 = 1V -20 LX2 Duty-Cycle Range VINP_ = 4.2V LX2 Discharge Resistance VLX2 = VDBI = 1V A 0 Ω 300 SYNCHRONOUS BUCK REGULATOR 3 (REG3) OUT3 Voltage Accuracy OUT3 Input Resistance Error-Amp Transconductance Dropout Voltage P-Channel On-Resistance N-Channel On-Resistance PGM3 = GND, 3.6V ≤ VINP3_ ≤ 5.5V, load = 0 to 800mA 1.764 1.8 1.836 PGM3 = REF, 3.6V ≤ VINP3_ ≤ 5.5V, load = 0 to 800mA 2.45 2.5 2.55 PGM3 = IN, 3.6V ≤ VINP3_ ≤ 5.5V, load = 0 to 800mA 3.234 3.3 3.366 PGM3 = GND 340 650 V kΩ PGM3 = REF 200 400 PGM3 = IN 160 320 PGM3 = GND 105 175 PGM3 = REF 75 125 175 PGM3 = IN 55 95 135 Load = 800mA (Note 1) 220 400 ILX3 = 180mA 0.25 0.4 ILX3 = 180mA, VINP3 = 2.6V 0.3 0.5 ILX3 = 180mA 0.2 0.35 245 µS mV Ω Ω _______________________________________________________________________________________ 3 MAX1702B ELECTRICAL CHARACTERISTICS (continued) MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems ELECTRICAL CHARACTERISTICS (continued) (VINP1 = VINP2 = VINP3 = VIN = 3.6V, VLBI = 1.1V, VDBI = 1.35V, MR = ON2 = IN, PGM3 = GND, circuit of Figure 1, TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS Current-Sense Transresistance 0.40 0.47 0.54 V/A P-Channel Current-Limit Threshold 1.15 1.275 1.45 A P-Channel Pulse-Skipping Current Threshold 0.115 0.140 0.160 A N-Channel Zero-Crossing Comparator 25 55 75 mA 0.1 +20 µA 100 % OUT3 Maximum Output Current 2.6V ≤ VINP3_ ≤ 5.5V (Note 2) 0.8 LX3 Leakage Current VINP3 = 5.5V, LX3 = GND or INP3, VOUT3 = 3.6V -20 LX3 Duty-Cycle Range VINP3 = 4.2V OUT3 Discharge Resistance VOUT3 = 3.3V, VDBI = 1V A 0 300 (Note 3) Ω REFERENCE REF Output Voltage 1.25 1.275 V REF Load Regulation 10µA < IREF < 100µA 1.225 2.5 6.25 mV REF Line Regulation 2.6V < VBATT < 5.5V 0.6 5 mV 1 1.15 MHz OSCILLATOR Switching Frequency 0.85 THERMAL SHUTDOWN Thermal Shutdown Temperature TJ rising Thermal Shutdown Hysteresis 160 °C 15 °C SUPERVISORY/MANAGEMENT FUNCTIONS Reset Timeout OUTOK Trip Threshold MR rising to RSO rising 55 65.5 75 VFB2 rising 94 95.5 97.5 VFB2 falling 91 92.5 94 107 126 145 VLBI falling 0.98 1.000 1.02 VLBI rising 1.00 1.020 1.04 0.02 0.1 OUTOK, LBO Minimum Assertion Time LBI Input Threshold LBI Input Bias Current DBI Input Threshold DBI Input Bias Current 4 VLBI = 0.95V VDBI falling, TA = 0°C to +85°C 1.2103 1.235 1.2597 VDBI rising, TA = 0°C to +85°C 1.2345 1.2597 1.2849 VDBI falling, TA = -40°C to +85°C 1.198 1.235 1.273 VDBI rising, TA = -40°C to +85°C 1.221 1.260 1.298 0.01 0.1 VDBI = 1.25V _______________________________________________________________________________________ ms % µs V µA V µA Triple-Output Power-Management IC for Microprocessor-Based Systems (VINP1 = VINP2 = VINP3 = VIN = 3.6V, VLBI = 1.1V, VDBI = 1.35V, MR = ON2 = IN, PGM3 = GND, circuit of Figure 1, TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP 2.6V ≤ VIN_ ≤ 5.5V, sinking 1mA RSO, LBO, OUTOK Output Low Level VIN_= 1V, sinking 100µA RSO, LBO, OUTOK Output High Leakage Current V R SO = V L B O = VOUTOK = 5.5V ON2, MR, Input High Level 2.6V ≤ VIN_ ≤ 5.5V ON2, MR, Input Low Level 2.6V ≤ VIN_ ≤ 5.5V ON2, MR, PGM3, Input Leakage Current VON2 = V MR = VPGM3 = GND, 5.5V REG3 target = 2.5V, IN = 2.6V to 5.5V REG3 target = 3.3V, IN = 2.6V to 5.5V UNITS 0.4 V 0.1 µA 1.6 V -1 REG3 target = 1.8V, IN = 2.6V to 5.5V PGM3 Selection Threshold MAX 0.4 V +1 µA 0.4 1.1 REF 1.4 V VIN_ - 0.25 Note 1: Dropout voltage is not tested. Guaranteed by P-channel switch resistance and assumes a 72mΩ (REG1 and REG3) or 162mΩ (REG2) maximum ESR of inductor. Note 2: The maximum output current is guaranteed by the following equation: VOUT (1 − D) 2 × ƒ ×L IOUT(MAX) = (1 − D) 1 + (RN + RL ) 2 × ƒ ×L ILIM − where: D= VOUT + IOUT(MAX) (RN + RL ) VIN + IOUT(MAX) (RN + RP ) and: RN = N-channel synchronous rectifier RDSON RP = P-channel power switch RDSON RL = external inductor ESR IOUT(MAX) = maximum required load current ƒ = operating frequency minimum L = external inductor value Note 3: Specified resistance is in series with an internal diode to LX2. Note 4: Specifications to -40°C are guaranteed by design and not production tested. _______________________________________________________________________________________ 5 MAX1702B ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) REG3 INCREMENTAL EFFICIENCY vs. LOAD CURRENT 70 60 50 40 NOTE: INCREMENTAL EFFICIENCY IS REG3 OUTPUT POWER OVER ADDITIONAL INPUT POWER. REG1 AND REG3 QUIESCENT CURRENT IS REFLECTED IN REG1’S EFFICIENCY GRAPH. 40 20 20 10 10 0 0 1000 100 90 80 VOUT2 = 1V 60 50 NOTE: INCREMENTAL EFFICIENCY IS REG2 OUTPUT POWER OVER ADDITIONAL INPUT POWER. REG1 AND REG3 QUIESCENT CURRENT IS REFLECTED IN REG1’S EFFICIENCY GRAPH. 40 30 20 10 0 1 10 1000 100 1 10 1000 100 LOAD CURRENT (mA) NO LOAD QUIESECNT CURRENT vs. SUPPLY VOLTAGE REG1 DROPOUT VOLTAGE vs. LOAD CURRENT (VIN = 3.3V) REG3 DROPOUT VOLTAGE vs. LOAD CURRENT (VIN = 3.3V) 0.3 0.2 0.1 250 200 150 100 50 0 4.5 5.0 5.5 OUTPUT VOLTAGE (V) 1.107 TA = +40°C 3.25 3.23 1.105 TA = +85°C 1.101 1.099 TA = 0°C TA = -40°C 1.097 200 300 400 500 LOAD CURRENT (mA) 600 700 3.325 3.315 TA = +85°C 3.305 3.295 3.285 TA = -40°C TA = 0°C TA = +40°C 3.275 1.095 3.21 MAX1702B toc06 REG3 OUTPUT VOLTAGE vs. LOAD CURRENT (VOUT3 = 3.3V) TA = +40°C 1.103 50 100 150 200 250 300 350 400 450 LOAD CURRENT (mA) MAX1702B toc08 MAX1702B toc07 3.29 100 0 REG2 OUTPUT VOLTAGE vs. LOAD CURRENT TA = +85°C TA = 0°C 40 LOAD CURRENT (mA) 3.33 TA = -40°C 60 0 REG1 OUTPUT VOLTAGE vs. LOAD CURRENT 3.27 80 0 100 200 300 400 500 600 700 800 900 1000 6.0 SUPPLY VOLTAGE (V) 3.31 100 MAX1702B toc09 4.0 OUTPUT VOLTAGE (V) 3.5 120 20 0 3.0 VOUT3 = 3.3V 140 DROPOUT VOLTAGE (mV) 300 DROPOUT VOLTAGE (mV) 0.4 160 MAX1702B toc05 350 MAX1702B toc04 0.5 0 70 LOAD CURRENT (mA) 0.6 2.5 VOUT2 = 1.1V VOUT2 = 1.3V LOAD CURRENT (mA) 0.7 6 VOUT3 = 2.5V 50 30 10 VOUT3 = 1.8V 60 30 1 VOUT3 = 3.3V 70 100 MAX1702B toc03 80 EFFICIENCY (%) EFFICIENCY (%) 80 90 EFFICIENCY (%) 90 QUIESCENT CURRENT (mA) 100 MAX1702B toc01 100 REG2 INCREMENTAL EFFICIENCY vs. LOAD CURRENT MAX1702B toc02 REG1 EFFICIENCY vs. LOAD CURRENT OUTPUT VOLTAGE (V) MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems 3.265 0 50 100 150 200 LOAD CURRENT (mA) 250 300 0 50 100 150 200 250 300 350 400 450 LOAD CURRENT (mA) _______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems REG3 OUTPUT VOLTAGE vs. LOAD CURRENT (VOUT3 = 1.8V) REG3 OUTPUT VOLTAGE vs. LOAD CURRENT (VOUT3 = 2.5V) 2.500 2.495 TA = +40°C 2.490 TA = -40°C 2.485 1.807 TA = +85°C 1.802 1.797 TA = +40°C 1.792 TA = -40°C TA = 0°C TA = 0°C 1.787 2.480 1.782 2.475 50 100 150 200 250 300 350 400 450 LOAD CURRENT (mA) LOAD CURRENT (mA) INTERNAL OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE INTERNAL REFERENCE vs. TEMPERATURE 1.30 MAX1702B toc12 1040 1020 0 50 100 150 200 250 300 350 400 450 1.29 REFERENCE VOLTAGE (V) TA = +85°C 1000 980 960 TA = +25°C 940 1.28 1.27 1.26 1.25 1.24 1.23 1.22 TA = -40°C 920 MAX1702B toc13 0 FREQUENCY (kHz) MAX1702B toc11 TA = +85°C OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.510 2.505 1.812 MAX1702B toc10 2.515 1.21 900 1.20 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 SUPPLY VOLTAGE (V) -15 10 35 60 85 TEMPERATURE (°C) REG1 HEAVY-LOAD SWITCHING WAVEFORM LOAD = 800mA, VIN = 4V MAX1702B toc14 REG2 HEAVY-LOAD SWITCHING WAVEFORM LOAD = 400mA, VIN = 4V MAX1702B toc15 VLX1 2V/div VLX2 2V/div 0 0 VOUT1 AC-COUPLED 20mV/div 0 I/O VOUT2 AC-COUPLED 20mV/div 0 IL1 500mA/div IL2 500mA/div CORE 0 0 400ns/div 400ns/div _______________________________________________________________________________________ 7 MAX1702B Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) Triple-Output Power-Management IC for Microprocessor-Based Systems MAX1702B Typical Operating Characteristics (continued) REG3 HEAVY-LOAD SWITCHING WAVEFORM LOAD = 700mA, VIN = 4V REG1 MEDIUM-LOAD SWITCHING WAVEFORM LOAD = 100mA, VIN = 4V MAX1702B toc17 MAX1702B toc16 VLX1 2V/div VLX3 2V/div 0 0 VOUT3 AC-COUPLED 20mV/div 0 VOUT1 AC-COUPLED 20mV/div 0 IL1 500mA/div IL3 500mA/div 0 0 400ns/div 400ns/div REG3 MEDIUM-LOAD SWITCHING WAVEFORM LOAD = 100mA, VIN = 4V REG1 LIGHT-LOAD SWITCHING WAVEFORM LOAD = 10mA, VIN = 4V MAX1702B toc18 MAX1702B toc19 VLX3 2V/div 0 VLX1 2V/div 0 VOUT3 AC-COUPLED 20mV/div 0 VOUT1 AC-COUPLED 20mV/div 0 IL3 500mA/div 0 IL1 500mA/div 0 2µs/div 10µs/div REG2 LIGHT-LOAD SWITCHING WAVEFORM LOAD = 10mA, VIN = 4V MAX1702B toc20 REG3 LIGHT-LOAD SWITCHING WAVEFORM LOAD = 10mA, VIN = 4V MAX1702B toc21 VLX2 2V/div 0 VLX3 2V/div 0 VOUT2 AC-COUPLED 20mV/div 0 VOUT3 AC-COUPLED 20mV/div 0 IL2 500mA/div 0 0 10µs/div 8 IL3 500mA/div 10µs/div _______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems TURN-ON SEQUENCE FROM POWER APPLICATION ILOAD1 = 250mA, ILOAD2 = 100mA, ILOAD3 = 200mA MAX1702B toc22 0 0 0 0 TURN-OFF SEQUENCE ILOAD1 = 250mA, ILOAD2 = 100mA, ILOAD3 = 200mA MAX1702B toc23 VIN 5V/div VOUT1 5V/div 0 VOUT3 5V/div VOUT2 2V/div 0 0 0 IIN 500mA/div 0 VIN 5V/div VOUT1 5V/div VOUT3 5V/div VOUT2 2V/div 0 IIN 500mA/div 0 VRSO 5V/div VRSO 5V/div 0 20ms/div 200µs/div REG1 LOAD TRANSIENT WAVEFORM LOAD = 100mA TO 500mA, VIN = 4V TURN-ON DELAY ILOAD1 = 250mA, ILOAD2 = 100mA, ILOAD3 = 200mA MAX1702B toc25 MAX1702B toc24 VON2 2V/div VOUT1 AC-COUPLED 200mV/div 0 VOUT2 1V/div 0 0 ILX1 500mA/div 0 ILOAD1 500mA/div IIN 200mA/div 0 40µs/div 40µs/div _______________________________________________________________________________________ 9 MAX1702B Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) REG3 LOAD TRANSIENT WAVEFORM LOAD = 75mA TO 400mA, VIN = 4V REG2 LOAD TRANSIENT WAVEFORM LOAD = 20mA TO 200mA, VIN = 4V MAX1702B toc27 MAX1702B toc26 VOUT2 AC-COUPLED 100mV/div 0 VOUT3 AC-COUPLED 200mV/div 0 ILX3 200mA/div ILX2 200mA/div 0 0 ILOAD3 200mA/div ILOAD2 100mA/div 0 0 40µs/div 40µs/div LINE TRANSIENT RESPONSE WAVEFORM VIN = 4V TO 5V, ILOAD1 = 250mA, ILOAD2 = 100mA, ILOAD3 = 200mA ENTERING AND EXITING DROPOUT WAVEFORM VIN = 2.75V TO 4V, ILOAD1 = 250mA, ILOAD2 = 100mA, ILOAD3 = 200mA MAX1702B toc28 MAX1702B toc29 VIN 2V/div 0 VIN AC-COUPLED 500mV/div 0 VOUT1 AC-COUPLED 500mV/div 0 VOUT3 AC-COUPLED 500mV/div 0 VOUT1 AC-COUPLED 50mV/div 0 VOUT2 AC-COUPLED 50mV/div VOUT3 AC-COUPLED 20mV/div 0 0 400µs/div 10 20ms/div ______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems PIN NAME FUNCTION 1, 9, 13, 18, 19, 26, 27, 31, 35 N.C. No Connection. These pins are not internally connected. 2 LBI Low-Battery Input. Connect a resistive voltage-divider from the battery voltage to LBI to set the lowbattery threshold. LBI threshold voltage is 1.235V. 3 DBI Dead-Battery Input. Connect a resistive voltage-divider from the battery voltage to DBI to set the dead-battery voltage threshold. When the voltage at DBI is below the 1.25V threshold, the MAX1702B is turned off and draws only 5µA from the battery. 4 ON2 REG2 On/Off Input. Drive ON2 high to turn on REG2, drive it low to turn it off. When enabled, the MAX1702B soft-starts REG2, when disabled, the output of REG2 is internally discharged to PG2. 5 PGM3 REG3 Regulation Voltage-Control Input. Connect PGM3 to IN, REF, or GND to set the REG3 output regulation voltage. Connect PGM3 to GND for 1.8V, REF for 2.5V, and IN for 3.3V. 6 GND Connect Pin 6 to Pin 8 7 REF Reference Output. Output of the 1.25V reference. Bypass REF to GND with a 0.1µF or greater capacitor. 8 GND Analog Ground. Connect GND to a local analog ground plane with no high-current paths. GND should be connected to the main ground plane at a single point as close to the IC and the IN bypass capacitor as possible. Connect the ground of the low-noise components, such as resistive voltagedividers and reference bypass capacitor to the analog ground plane. 10 IN Analog Supply Input. Bypass IN to GND with a 1µF or greater low-ESR capacitor. 11 RSO Reset Output. RSO is low (sinks current to GND) during initial startup or while the manual reset input, MR, is asserted. RSO remains low for 65.5ms after all regulators are in regulation or after MR is deasserted. RSO is an open-drain output. RSO remains high when REG2 is turned off. The RSO line maintains a valid low output for IN as low as 1V. 12 PG1 REG1 Power Ground. Connect PG1 directly to a power ground plane. Connect PG1, PG2, PG3 and GND together at a single point as close to the IC as possible. 14 LX1 REG1 Power-Switching Node. Connect the external inductor of the REG1 output LC filter from LX1 to OUT1 (see the Inductor Selection section). 15 INP1 REG1 Power Input. Bypass INP1 to PG1 with a 1.0µF or greater low-ESR capacitor. INP1, INP2, INP3, and IN must be connected together externally. A single 4.7µF capacitor can be used for INP1, INP2, and INP3. 16 MR Manual Reset Input. A momentary low on MR forces RSO to go low. RSO remains low as long as MR is low, and returns high 65.5ms after MR returns high and all output voltages are in regulation. 17 COMP1 REG1 Compensation Node. Connect a series resistor and capacitor from COMP1 to GND in parallel with a 33pF capacitor to compensate REG1 (see the Compensation and Stability section). ______________________________________________________________________________________ 11 MAX1702B Pin Description Triple-Output Power-Management IC for Microprocessor-Based Systems MAX1702B Pin Description (continued) 12 PIN NAME FUNCTION 20 OUT1 21 COMP2 REG2 Compensation Node. Connect a series resistor and capacitor from COMP2 to GND in parallel with a 33pF capacitor to compensate REG2 (see the Compensation and Stability section). 22 OUTOK Output-OK Output. OUTOK sinks current to GND when the voltage at REG2 is below the regulation threshold. When the output is in regulation, OUTOK is high impedance. OUTOK is used by the processor to indicate when it is safe for the processor to exit sleep mode. OUTOK is an open-drain output. OUTOK maintains a valid low output for IN as low as 1V. 23 PG2 REG2 Power Ground. Connect PG2 directly to a power ground plane. Connect PG1, PG2, PG3, and GND together at a single point as close to the IC as possible. 24 LX2 REG2 Power-Switching Node. Connect the external inductor of the REG2 output LC filter from LX2 to OUT2. LX2 discharges OUT2 when REG2 is disabled (see the Inductor Selection section). 25 INP2 REG2 Power Input. Bypass INP2 to PG2 with a 1.0µF or greater low-ESR capacitor. INP1, INP2, INP3, and IN must be connected together externally. A single 4.7µF capacitor can be used for INP1, INP2, and INP3. 28 FB2 REG2 Feedback-Sense Input. Set the REG2 output voltage with a resistive voltage-divider from the REG2 output voltage to FB2. The FB2 regulation threshold is 0.7V. Connect FB2 directly to OUT2 for an output voltage of 0.7V. 29 OUT3 REG3 Output-Voltage Sense Input. Bypass OUT3 to GND with a 10µF or greater low-ESR capacitor (see the Output Capacitor Selection section). 30 COMP3 REG3 Compensation Node. Connect a series resistor and capacitor from COMP3 to GND in parallel with a 33pF capacitor to compensate REG3 (see the Compensation and Stability section). 32 PG3 REG3 Power Ground. Connect PG3 directly to a power ground plane. Connect PG1, PG2, PG3, and GND together at a single point as close to the IC as possible. 33 LX3 REG3 Power-Switching Node. Connect the external inductor of the REG3 output LC filter from LX3 to OUT3 (see the Inductor Selection section). 34 INP3 REG3 Power Input. Bypass INP3 to PG3 with a 1.0µF or greater low-ESR capacitor. INP1, INP2, INP3, and IN must be connected together externally. A single 4.7µF capacitor can be used for INP1, INP2, and INP3. 36 LBO Low-Battery Output. LBO sinks current to GND when the voltage at LBI is below the LBI threshold voltage; LBO is high impedance when LBI is above the threshold. LBO is an open-drain output. LBO maintains a valid low output level for IN as low as 1V. REG1 Output-Voltage Sense Input. Bypass OUT1 to PG1 with a 10µF or greater low-ESR capacitor (see the Output Capacitor Selection section). ______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems IN REG1 MAX1702B DBI DEADBATTERY DETECTOR INP1 DBO LX1 LBI LBO EN LOWBATTERY DETECTOR REF PG1 DC-DC BUCK WITH SKIP 1MHz PWM REG2 OUTOK ON2 OUT1 COMP1 INP2 POK ON/OFF CONTROL LOGIC EN LX2 REF PG2 DC-DC BUCK WITH SKIP 1MHz PWM REG3 RSO MR FB2 COMP2 INP3 EN RESET TIMER LX3 REF PG3 DC-DC BUCK WITH SKIP 1MHz PWM BANDGAP REFERENCE OUT3 COMP3 PGM3 GND REF Detailed Description The MAX1702B triple-output step-down DC-DC converter is ideal for powering PDA, palmtop, and subnotebook computers. Normally, these devices require separate power supplies for the processor core, memory, and the peripheral circuitry. The MAX1702B’s REG1 provides a fixed 3.3V output designed to power the microprocessor I/O and other peripheral circuitry. REG1 delivers up to 900mA output current. The microprocessor core is powered from REG2, which has an adjustable 0.7V to VIN output, providing up to 400mA output current. The third output, REG3, is designed to power memory. REG3 output voltage is set to one of 3 voltages; 3.3V (PGM3 = IN), 2.5V (PGM3 = REF), or 1.8V (PGM3 = GND) and delivers up to 800mA of output current. All three regulators utilize a proprietary regulation scheme allowing PWM operation at medium to heavy loads, and automatically switch to pulse skipping at light loads for improved efficiency. Under low-battery conditions, the MAX1702B issues a warning (LBO output). The MAX1702B employs PWM control at medium and heavy loads, and skip mode at light loads (below approximately 80mA) to improve efficiency and reduce quiescent current to 485µA. During skip operation, the MAX1702B switches only as needed to service the load, reducing the switching frequency and associated losses in the internal switch, the synchronous rectifier, and the external inductor. There are three steady-state operating conditions for the MAX1702B. The device performs in continuous conduction for heavy loads. The inductor current becomes discontinuous at light loads, requiring the synchronous rectifier to be turned off before the end of a cycle as the inductor current reaches zero. The device enters into skip mode when the converter output voltage exceeds its regulation limit before the inductor current reaches the pulse-skip threshold. During skip mode, a switching cycle initiates when the output voltage drops below the regulation voltage. The P-channel MOSFET switch turns on and conducts current to the output-filter capacitor and load until the inductor current reaches the pulse-skip current threshold. Then the main switch turns off, and the current flows through the synchronous rectifier to the output-filter capacitor and the load. The synchronous rectifier is turned off when the inductor current approaches zero. The MAX1702B waits until the output voltage drops below the regulation voltage again to initiate the next cycle. 100% Duty-Cycle Operation If the inductor current does not rise sufficiently to supply the load during the on-time, the switch remains on, allowing operation up to 100% duty cycle. This allows the output voltage to maintain regulation while the input voltage approaches the regulation voltage. Dropout voltage is the output current multiplied by the on-resistance of the internal switch and inductor, approximately 220mV for an 800mA load for REG1 and REG3 and 150mV for a 400mA load on REG2. Near dropout, the on-time may exceed one PWM clock cycle; therefore, small amplitude subharmonic ripple can occur in the output voltage. During dropout, the ______________________________________________________________________________________ 13 MAX1702B Functional Diagram MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems high-side P-channel MOSFET turns on, and the controller enters a low-current consumption mode. The device remains in this mode until the MAX1702B is no longer in dropout. Synchronous Rectification An N-channel synchronous rectifier eliminates the need for an external Schottky diode and improves efficiency. The synchronous rectifier turns on during the second half of each cycle (off-time). During this time, the voltage across the inductor is reversed, and the inductor current falls. The synchronous rectifier is turned off at the end of the cycle (at which time another on-time begins) or when the inductor current approaches zero. Battery Monitoring and Undervoltage Lockout The MAX1702B does not operate with input voltages below the undervoltage lockout (UVLO) threshold of 2.35V (typ). The inputs remain high impedance until the supply voltage exceeds the UVLO threshold, reducing battery load under this condition. The MAX1702B provides a low-battery comparator that compares the voltage on LBI to the reference voltage. An open-drain output (LBO) goes low when the LBI voltage is below 1V. Use a resistive voltage-divider network as shown in Figure 1 to set the trip voltage to the desired level. LBO is high impedance in shutdown mode. The MAX1702B also provides a dead-battery comparator that turns off the IC when the battery has excessively discharged. When the voltage at DBI is below the 1.235V threshold, the MAX1702B is turned off and draws only 5µA from the battery. Use a resistive voltage-divider network as shown in Figure 1 to set the trip voltage to the desired level. Power-On Sequencing The MAX1702B starts when the input voltage rises above the UVLO threshold and the voltage at DBI is greater than the DBI threshold. When power is initially applied, REG1 starts in soft-start mode. Once OUT1 reaches its regulation voltage, REG3 ramps to its target in soft-start mode. Finally, once OUT3 reaches its regulation voltage, REG2 ramps to its target in soft-start mode. The RSO output holds low during this time and remains low until 65.5ms after REG2 reaches its target output voltage. Once all the regulators are running, ON2 turns REG2 on and off. During startup (before the end of the reset period) REG2 is enabled and can only be turned off once the RSO output goes high. When turned off, the REG2 output voltage is discharged to PG2 through LX2. REG1 and REG3 Step-Down Converters REG1 and REG3 are 1MHz PWM, current-mode stepdown converters and generate 3.3V at up to 900mA (REG1), and 3.3V, 2.5V, or 1.8V at up to 800mA (REG3). Internal switches and synchronous rectifiers are integrated for small size and improved efficiency. Both regulators remain on while the input voltage is above the UVLO threshold and DBI is above the DBI threshold. REG1 and REG3 cannot be independently turned on or off. To turn both regulators off, pull DBI below the DBI threshold (1.235V typ). The REG3 output voltage is set through the PGM3 pin. Connect PGM3 to IN to set the output voltage to 3.3V, connect it to REF to set it to 2.5V, and connect it to GND to set the voltage to 1.8V. REG2 Step-Down Converter REG2 is a 1MHz, current-mode step-down converter and generates a 0.7V to VIN output delivering up to 400mA. An internal switch and synchronous rectifier are used for small size and improved efficiency. REG2 is turned on and off through the ON2 input. Drive ON2 low to turn off the regulator, and high to turn it on. OUTOK goes low when the REG2 output voltage drops below 92.5% of the regulation voltage. OUTOK is an open-drain output. OUTOK can be used to signal the processor that the REG2 voltage is in, allowing the processor to exit from sleep mode into run mode. Reset Output MAX1702B features an active-low, open-drain reset output (RSO), RSO holds low during startup or when the manual reset input MR is held low. RSO goes high impedance 65.5ms after REG2 reaches its target value and the MR input goes high. (see the Power-On Sequencing section). Note that RSO remains high when REG2 is turned off. Applications Information Setting the Output Voltages The REG1 output voltage is fixed at 3.3V and cannot be changed. The REG3 output voltage can be set by the PGM3 input to either 3.3V (connect PGM3 to IN), 2.5V (connect PGM3 to REF), or 1.8V (connect PGM3 to GND). The REG2 output voltage is set between 0.70V and VIN through a resistive voltage-divider from the REG2 output voltage to FB2 (Figure 1). Select feedback resistor R5 to be less than 14kΩ. R4 is then given by: V R4 = R5 OUT − 1 VFB2 where VFB2 = 0.70V and VOUT is the REG2 output voltage. 14 ______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems This resistor and capacitor set a compensation zero that defines the system’s transient response. The load pole is a dynamic pole, shifting frequency with changes in load. As the load decreases, the pole frequency shifts lower. System stability requires that the compensation zero must be placed properly to ensure adequate phase margin (at least 30°). The following is a design procedure for the compensation network: 1) Select an appropriate converter bandwidth (fC) to stabilize the system while maximizing transient response. This bandwidth should not exceed 1/5 of the switching frequency. Use 100kHz as a reasonable starting point. 2) Calculate the compensation capacitor, COMP_, based on this bandwidth. Calculate COMP1 and COMP3 with the following equation: VOUT(MAX) 1 1 CCOMP1/ 3 = 2 × π × f gm I R OUT(MAX) CS where RCS is the regulator’s current-sense transresistance and gm is the regulators error amplifier transconductance. Calculate COMP2 with the following equation: VOUT(MAX) 1 1 R5 CCOMP2 = gm × R4 + R5 IOUT(MAX) RCS 2 × π × f where RCS is REG2’s current-sense transresistance and gm is REG2’s error-amplifier transconductance. Calculate the equivalent load impedance, RL, by: RL = VOUT(MIN) IOUT(MAX) where VOUT(MIN) equals the minimum output voltage. IOUT(MAX) equals the maximum load current. Choose the output capacitor, COUT (see the Output Capacitor Selection section). Calculate the compensation resistance (RC) value to cancel out the dominant pole created by the output load and the output capacitance: 1 1 = 2 × π × RL × COUT 2 × π × RC × CCOMP_ Solving for RC gives: R × COUT RC = L CCOMP _ To find CCOMPHF_, calculate the high-frequency compensation pole to cancel the zero created by the output capacitor’s equivalent series resistance (ESR): 1 1 = 2 × π × RESR × COUT 2 × π × RC × CCOMPHF_ Solving for CCOMPHF_ gives: R × COUT CCOMPHF _ = ESR , but not less than 33pF RC If low-ESR ceramic capacitors are used, the CCOMPHF_ equation can yield a very small capacitance value. In such cases, do not use less than 33pF to maintain noise immunity. Inductor Selection A 4.7µH inductor with a saturation current of at least 1.5A is recommended for most applications. For best efficiency, use an inductor with low ESR. See Table 1 for recommended inductors and manufacturers. For most designs, a reasonable inductor value (LIDEAL) can be derived from the following equation: LIDEAL = VOUT (VIN − VOUT ) VIN × LIR × IOUT(MAX) × fOSC where LIR is the inductor current ripple as a percentage of the load current. LIR should be kept between 20% and 40% of the maximum load current for best performance and stability. The maximum inductor current is: LIR ILMAX = 1 + IOUT(MAX) 2 ______________________________________________________________________________________ 15 MAX1702B Compensation and Stability Compensate each regulator by placing a resistor and a capacitor in series, from COMP_ to GND and connect a 33pF capacitor from COMP_ to GND for improved noise immunity (Figure 1). The capacitor integrates the current from the transconductance amplifier, averaging output-voltage ripple. This sets the device speed for transient responses and allows the use of small ceramic output capacitors. The resistor sets the proportional gain of the output error voltage by a factor gm ✕ RC. Increasing this resistor also increases the sensitivity of the control loop to the output-voltage ripple. MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems Table 1. Suggested Inductors PART NUMBER INDUCTANCE (µH) ESR (mW) SATURATION CURRENT (A) DIMENSIONS (mm) DO1606 4.7 120 1.2 5.3 x 5.3 x 2 Coilcraft LPT1606-472 4.7 240 (max) 1.2 6.5 x 5.3 x 2.0 Sumida CDRH4D28-4R7 4.7 56 1.32 4.6 x 5 x 3 Sumida CDRH5D18-4R1 4.1 57 1.95 5.5 x 5.5 x 2 Sumida CR43 4.7 108.7 1.15 4.5 x 4 x 3.5 MANUFACTURER Coilcraft The inductor current becomes discontinuous if IOUT decreases to LIR/2 from the output current value used to determine LIDEAL. Input Capacitor Selection The input capacitor reduces the current peaks drawn from the battery or input power source and reduces switching noise in the IC. The impedance of the input capacitor at the switching frequency should be less than that of the input source so high-frequency switching currents do not pass through the input source but instead are shunted through the input capacitor. The input capacitor must meet the ripple-current requirement (IRMS) imposed by the switching currents. The input capacitor RMS current is: IRMS = ILOAD VOUT (VIN −VOUT ) VIN Output Capacitor Selection The output capacitor is required to keep the output-voltage ripple small and to ensure regulation control-loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors are recommended. The output ripple is approximately: 1 VRIPPLE ≈ LIR × IOUT(MAX) × ESR + 2 × fOSC × COUT See the Compensation and Stability section for a discussion of the influence of output capacitance and ESR on regulation control-loop stability. The capacitor voltage rating must exceed the maximum applied capacitor voltage. Consult the manufacturer’s specifications for proper capacitor derating. Avoid Y5V and Z5U dielectric types due to their huge voltage and temperature coefficients of capacitance and ESR. X7R and X5R dielectric types are recommended. 16 Setting the Battery Detectors The low-battery and dead-battery detector trip points can be set by adjusting the resistor values of the divider string (R1, R2, and R3) in Figure 1 according to the following: 1) Choose R3 to be less than 250kΩ 2) R1 = R3 ✕ VBL ✕ (1 - VTH/VBD) 3) R2 = R3 ✕ (VTH ✕ VBL/VBD - 1) where VBL is the low-battery voltage, VBD is the deadbattery voltage, and VTH = 1.235V. PC Board Layout and Routing High switching frequencies and large peak currents make PC board 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 filter capacitor, and output filter capacitor as close together as possible, and keep their traces short, direct, and wide. Connect their ground pins to a single common power ground plane. The external voltage-feedback network should be very close to the FB pin, within 0.2in (5mm). Keep noisy traces (from the LX pin, for example) away from the voltage-feedback network; also, keep them separate, using grounded copper. Connect GND and PG_ pins together at a single point, as close as possible to the MAX1702B. Refer to the MAX1702B evaluation kit for a PC board layout example. Chip Information TRANSISTOR COUNT: 10,890 PROCESS: BiCMOS ______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems INPUT 2.6V TO 5.5V 4.7µF 4.7µF IN INP1 INP2 INP3 VOUT1 3.3V AT 900mA 4.7µH LX1 R1 162kΩ COUT1 10µF PG1 DBI OUT1 R2 53.6kΩ CCOMP1 RCOMP1 1000pF 33kΩ COMP1 LBI CCOMPHF1 33pF R3 86.6kΩ MAX1702B OUT1 VOUT2 1.1V AT 400mA 4.7µH LBO LX2 COUT2 10µF 8.06kΩ 100kΩ PG2 FB2 CCOMP2 RCOMP2 14kΩ 680pF 18kΩ 100kΩ COMP2 CCOMPHF2 33pF OUTOK OUT1 ON2 4.7µH VOUT3 3.3V/2.5V/1.8V AT 800mA LX3 100kΩ COUT3 10µF PG3 RSO OUT3 CCOMP3 RCOMP3 1000pF 22kΩ MR COMP3 CCOMPHF3 33pF PGM3 GND REF Figure 1. Typical Operating Circuit ______________________________________________________________________________________ 17 MAX1702B Typical Operating Circuit 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.) 36L,40L, QFN.EPS MAX1702B Triple-Output Power-Management IC for Microprocessor-Based Systems 18 ______________________________________________________________________________________ Triple-Output Power-Management IC for Microprocessor-Based Systems 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 ____________________ 19 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX1702B 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.)