(oy, was NAGS ae CTC eae 19-4759; Rev 1; 1/99 KIT AT ae MAAS 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters General Description The MAX1700/MAX1701 are high-efficiency, low-noise, step-up DC-DC converters intended for use in battery- powered wireless applications. They use a synchro- nous-rectified pulse-width-modulation (PWM) boost topology to generate 2.5V to 5.5V outputs from battery inputs such as one to three NiCd/NiMH cells or one Li- lon cell. Both devices have an internal 1A, 130mQ N- channel MOSFET switch and a 250mQ P-channel synchronous rectifier. With their internal synchronous rectifier, the MAX1700/ MAX1701 deliver 5% better efficiency than similar non- synchronous converters. They also feature a pulse- frequency-modulation (PFM) standby mode to improve efficiency at light loads, and a 3yA shutdown mode. The MAX1700/MAX1701 come in 16-pin QSOP pack- ages (which occupy the same space as an 8-pin SO). The MAX1701 includes two comparators to generate power-good and low-battery warning outputs. It also contains a gain block that can be used to build a linear regulator using an external P-channel pass device. For higher-power outputs, refer to the MAX1703. For dual outputs (step-up and linear regulator), refer to the MAX1705/MAX1706. For an on-board analog-to-digital converter, refer to the MAX848/MAX849. The MAX1701 evaluation kit is available to speed design time. Applications Personal Communicators Palmtop Computers Hand-Held Instruments Digital Cordless Phones PCS Phones Wireless Handsets Two-Way Pagers ; ; ; Pin Configurations Features ft fthUC OrmhU OCU OU ]HrhUF OH Uh HhUCU SH hh SH Up to 96% Efficiency 1.1 Vin Guaranteed Start-Up 0.7V to 5.5V Input Range Up to 800mA Output Step-Up Output (adjustable from 2.5V to 5.5V) PWM/PFM Synchronous-Rectified Topology External Clock or Internal 300kKHz Oscillator 3pHA Logic-Controlled Shutdown Power-Good Output (MAX1701) Low-Battery Comparator (MAX1701) Uncommitted Gain Block (MAX1701) Ordering Information TOP VIEW icf] ite ic. [2| 45] POUT FF [3]) ~naxaaa [4] ou ciKseL [4] MAXt700 [ia] LX eno [5 | 2] PND ic. [a | i] Fe one [7 | 10] 1. ona [| 9] 1.c. QSOP I.C. = INTERNAL CONNECTION, LEAVE OPEN OR CONNECT TO GND Pin Configurations continued at end of data sheet. PART TEMP. RANGE PIN-PACKAGE MAX1700EEE -40C to +85C 16 QSOP MAX1701EEE -40C to +85C 16 QSOP Typical Operating Circuit INPUT 0.7V TO5.5V OUTPUT MAXIM 3.3V ORADJ ON MAX1700 UP TO 800mA Lor mow LX OFF _ Loy md as PWM oR STLPLFL CLK/SEL ~Loerw sync REF OUT FB. GND PGND POUT - MAXIM Maxim Integrated Products 1 For free samples & the latest literature: http://)www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. LOLLXVW/OOZLXVW1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS ONA, ONB, OUT, AO, POK, LBO to GND... ee -0.3V, +6V Operating Temperature Ranges PGND to GND... eee ceceeeecee cece tees eeaeeeeeeeaeeeeeeaeeeeetaeeseaeeaees +0.3V MAX1700EEE, MAX1701 EEE .........eeeeeeeeeeeeees -40C to +85C LX to PGND.......ecceeseeeeceeceeeeeeeeeeeeeeaeeeeeeeeeneeeaes -0.3V, VpOUT+0.3V JUNCTION TEMPeratUre .......eeseeeccseeceecsesseeseteeerereneeeeeenes +150C CLK/SEL, AIN, REF, FB, LBP, LBN, POUT to GND............ -0.3V, Storage Temperature Range.........:ee 65C to +160C VOUTHOLSY eee eee ee cence teen ee tee eee ee es eeeee ee seaeeseeeeseeneesneneenneeeseeneeaes Lead Temperature (soldering, 10SC) ........ esses +300C Continuous Power Dissipation (TA=+70C) 16-QSOP (Derate 8.30mW/C above +70C) ou... 667mW 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 (CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, VouT = 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF, MAX1700/MAX1701 TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER | CONDITIONS | MIN TYP MAX | UNITS DC-DC CONVERTER Input Voltage Range (Note 1) 0.7 5.5 Vv (Note 2) Start-Up Voltage ILOAD < 1mA, Ta = +25C 0.9 14 Vv Frequency in Start-Up Mode VouT = 1.5V 40 150 300 kHz Output Voltage (Note 3) includes load regulation error aallt Wee OS5A 317 330 3.38 Vv FB Regulation Voltage incldes load regulation errrforOcixcossa | -T210, 1.241.255 |v FB Input Current VrFB = 1.25V 0.01 20 nA Output Voltage Adjust Range 2.5 5.5 Vv Se eS Lockout (Note 4) 20 245 23 V Load Regulation (Note 5) CLK/SEL = OUT, No load to full load -1.6 % Supply Current in Shutdown VONB = 3.6V MAXI700 01 20 HA MAX1701 3 20 Supply Current in Low-Power CLK/SEL = GND (MAX1700) 35 70 A Mode (Note 6) CLK/SEL = GND (MAX1701) 55 110 i. Supply Current in Low-Noise CLK/SEL = OUT (MAX1700) 125 250 Mode (Note 6) CLK/SEL = OUT (MAX1701) 140 300 HA DC-DC SWITCHES POUT Leakage Current VLX = OV, VoUT = 5.5V 0.1 20 HA LX Leakage Current VLX = VONB = VOUT = 5.5V 0.1 20 HA CLK/SEL = GND 0.2 0.45 Switch On-Resistance N-ehannel CLK/SEL = OUT 013. 028 | P-channel 0.25 0.5 . CLK/SEL = OUT 1100 1300 1600 N-Channel Current Limit mA CLK/SEL = GND 250 400 550 P-Channel Turn-Off Current CLK/SEL = GND 20 120 mA 2 MAXUM1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters ELECTRICAL CHARACTERISTICS (continued) (CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, VouT = 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER | CONDITIONS | MIN TYP MAX | UNITS GAIN BLOCK (MAX1701) AIN Reference Voltage IAQ = 20HA 1.237 1.25 1.263 Vv AIN Input Current VAIN = 1.5V -30 30 nA Transconductance 1OPA < IAo = 100HA 5 9 16 mmho AO Output Low Voltage VAIN = 0.7V, lag = 100HA 0.1 0.4 Vv AO Output High Leakage VAIN = 1.5V, VAO = 5.5V 0.01 1 pA POWER GOOD (MAX1701) Internal Trip Level Rising VOUT, VFB < 0.1V 2.93 2.97 3.02 Vv External Trip Level Rising VFB 14 1.12 1.14 Vv POK Low Voltage ISINK = 1mMA, VouT = 3.6V or ISINK = 20HA, VoUT = 1V 0.03 0.4 Vv POK High Leakage Current VouT = VPOK = 5.5V 0.01 1 pA LOW-BATTERY COMPARATOR LBN, LBP Input Offset LBP falling, 15mV hysteresis 5 +0.5 5 mV LBN, LBP Common Mode To maintain input offset < t5mV (at least one input must Range be within this range) 0.5 1s V LBO Output Low Voltage ISINK = 1mMA, VouT = 3.6V or ISINK = 20HA, VoUT = 1V 0.03 0.4 Vv LBO High Leakage VouT = VLBO = 5V 0.01 1 pA LBN, LBP Input Current VLBP = VLBN = 1.5V 20 nA REFERENCE Reference Output Voltage IREF = 0 1.237 1.250 1.263 Vv REF Load Regulation -1pA < IREF < 5OHA 5 15 mV REF Supply Rejection 2.5V < VouT < 5V 0.2 5 mV LOGIC AND CONTROL INPUTS Input Low Voltage (Note 7) 1.2V < VouT < 5.5V, ONA and ONB 0.2VOUT V 2.5V < VouT < 5.5V, CLK/SEL 0.2VOUT input High Voltage (Note 7) 1.2V < VouT < 5.5V, ONA and ONB 0.8VoUT V 2.5V < VouT < 5.5V, CLK/SEL 0.8VOUT Logic Input Current ONA, ONB, and CLK/SEL -1 1 HA Internal Oscillator Frequency CLK/SEL = OUT 260 300 340 kHz Oscillator Maximum Duty Cycle 80 86 90 % Range, Clock Frequency 200 400 kHz Minimum CLK/SEL Pulse Width 200 ns Maximum CLK/SEL Rise/Fall Time 100 ns MAXLAA 3 LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters ELECTRICAL CHARACTERISTICS (continued) (CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, Vout = 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF, TA = -40C to +85C, unless otherwise noted.) (Note 8) PARAMETER | CONDITIONS MIN TYP MAX | UNITS DC-DC CONVERTER Output Voltage (Note 3) segulation orror for OA hax.c aan = 2M, Includes load | 4 47 338 | Vv FB Regulation Votage includes load regulation error for OA SLX <0.55A. 120 17 |v Se eS Lockout (Note 4) 2.0 2.3 V Supply Current in Shutdown VONB = 3.6V 20 HA Supply Current in Low-Power CLK/SEL = GND (MAX1700) 70 A Mode (Note 6) CLK/SEL = GND (MAX1701) 110 i. Supply Current in Low-Noise CLK/SEL = OUT (MAX1700) 250 Mode (Note 6) CLK/SEL = OUT (MAX1701) 300 HA DC-DC SWITCHES N-channel CLK/SEL = GND 0.45 Switch On-Resistance CLK/SEL = OUT 0.28 Q P-channel 0.5 CLK/SEL = OUT 1100 1800 N-Channel Current Limit mA CLK/SEL = GND 250 600 GAIN BLOCK (MAX1701) AIN Reference Voltage IAQ = 20pA 1.23 1.27 Vv Transconductance 1OpA < lao < 100pA 5 16 mmho POWER-GOOD (MAX1701) Internal Trip Level Rising VOUT, VFB < 0.1V 2.92 3.03 Vv External Trip Level Rising VFB 14 1.14 Vv LOW-BATTERY COMPARATOR (MAX1701) LBN, LBP Input Offset LBP falling, 15mV hysteresis 5 5 mV LBN, LBP Common Mode To maintain input offset < t5mV (at least one input must Range be within this range) 0.5 1s V REFERENCE Reference Output Voltage IREF = 0 1.23 1.27 Vv MAXLA1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters ELECTRICAL CHARACTERISTICS (continued) (CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, VouT = 3.6V, MAX1701: AIN = LBN = GND, LBP = REF, TA = -40C to +85C, unless otherwise noted.) (Note 8) PARAMETER | CONDITIONS MIN TYP MAX | UNITS LOGIC AND CONTROL INPUTS 1.2V < Vout < 5.5V, ONA and ONB 0.2VouT Input Low Voltage (Note 7) Vv 2.5V < VouT < 5.5V, CLK/SEL 0.2VOUT 12V<V 5.5V, ONA and ONB 0.8V Input High Voltage (Note 7) SCOUTS OUT V 2.5V < VouT < 5.5V, CLK/SEL 0.8VOUT Logic Input Current ONA, ONB, and CLK/SEL -1 1 HA Internal Oscillator Frequency CLK/SEL = OUT 260 340 kHz Oscillator Maximum Duty Cycle 80 92 % External Clock Frequency 200 400 kHz Range Note 1: Operating voltage. Since the regulator is bootstrapped to the output, once started it will operate down to 0.7V input. Note 2: Start-up is tested with the circuit of Figure 2. Note 3: In low-power mode (CLK/SEL = GND), the output voltage regulates 1% higher than low-noise mode (CLK/SEL = OUT or synchronized). Note 4: The regulator is in start-up mode until this voltage is reached. Do not apply full load current. Note 5: Load regulation is measured from no-load to full load where full load is determined by the N-channel switch current limit. Note 6: Supply current from the 3.30V output is measured between the 3.30V output and the OUT pin. This current correlates directly to the actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. Set VoUT = 3.6V to keep the internal switch open when measuring the current into the device. Note 7: ONA and ONB have hysteresis of approximately 0.15xVoUT. Note 8: Specifications to -40C are guaranteed by design and not production tested. Typical Operating Characteristics (Ta = +25C, unless otherwise noted.) MAX1701 EFFICIENCY vs. LOAD CURRENT EFFICIENCY vs. LOAD CURRENT SHUTDOWN CURRENT (VouT = 3.3V) (Vout = 5V) vs. INPUT VOLTAGE (V) . 3 7.0 8 g =38V E & 2 2 60 8 = _ = B 5.0 = = cf 40 a z 3 3 z = 3.0 Hi io e Zz 20 wy PPM === 1.0 PWM PWMw 0 04 i 10 100 4000 04 1 10 100 1000 0 1 2 3 4 5 8 LOAD CURRENT (mA) LOAD CURRENT (mA) INPUT VOLTAGE (V) MAXKLM 5 LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters Typical Operating Characteristics (continued) (Ta = +25C, unless otherwise noted.) REFERENCE VOLTAGE REFERENCE VOLTAGE vs. TEMPERATURE vs. REFERENCE CURRENT FREQUENCY vs. TEMPERATURE 1.254 a 4.254 2 325 3 5 E320 5 = = Vout =5V = ; 4.252 s 4.252 s 315 lu lu => oO go - 310 F 1.250 F 4.250 = S 2 8 305 pL 9 S| 3 NO 3 300 1.248 y 1.248 < fd Hy | Hh h 295 fe aa PA. 1.246 1.246 eS 200 285 1.244 4.244 280 -40 -20 0 20 40 60 80 100 0 10 2 30 40 50 60 70 80 40-20 0 20 40 60 80 100 120 140 TEMPERATURE (C) REFERENCE CURRENT (1A) TEMPERATURE (C) START-UP INPUT VOLTAGE PEAK INDUCTOR CURRENT vs. OUTPUT CURRENT vs. OUTPUT VOLTAGE 23 1 1 a 1.6 g NO-LOAD START-UP: 8 g 21 T 10VAT-40C g 14 g S 19 L 0.79AT+25C __] E wy 0.64V AT +85C = 1.2 = 1.7 | CONSTANT-CURRENT LOAD = 3 Vout =3.3 = en = 10 z D1 =MBRO520L & Z 13-5 re 08 a = 14 i 5 3 pee Co w 09 NT, = 425C 0.7 Leen t 0.4 Ta = 485C | 05 0.2 001 O41 1 10 100 1000 25 680CiiC KH OSC QL! KOC OUTPUT CURRENT (mA) QUTPUT VOLTAGE (V) HEAVY-LOAD SWITCHING WAVEFORM S (VouT = 3.3V) LINE- TRANSIENT RESPONSE MAX1700-08. MAX1700-09 Vout A OV rs ey ee B ov OA Cc B ius/div 5ms/div Vin =1.1V, lout = 200mA, Vour = 3.3V lout = OmA, Vout = 3.3V A =LX VOLTAGE, 2W/div A=Vin, 1.1V TO2.1V, 1Wdiv B = INDUCTOR CURRENT, 0.5A/div B= Vout RIPPLE, 50mV/div, AC COUPLED C= Vour RIPPLE, 50mV/div, AC COUPLED 6 MAAXLM1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25C, unless otherwise noted.) POWER- ON DELAY LOAD- TRANSIENT RESPONSE (PFM MODE) MAX1700- 10 MAX1 700-14 a . 3.3V A my 200mA A OA B C OmA 2ms/div 5ms/div Vin =1.1V, Vour =3.3V A= Von, 2V/div B=Vour, 1Wdiv C = INPUT CURRENT, 0.2A/div A=LOAD CURRENT, OmA TO 200mA, 0.2A/div B= Vout RIPPLE, 50mV/div, AC COUPLED DECT LOAD- TRANSIENT RESPONSE MAX1700-13 B Boa ims/div 2ms/div Vin = 3.6V, Vout =5V, Cour = 440uF Vin = 1.2V, Vour = 3.3V, Cour = 440uF A= Vout RIPPLE, 200mV/div, AC COUPLED A= Vour RIPPLE, 200mW/div, AC COUPLED B= LOAD CURRENT, 100mA TO 1A, 0.5A/div, B= LOAD CURRENT, 50mA TO 400mA, 0.2A/div, PULSE WIDTH = 5771s PULSE WIDTH = 4161s NOISE SPECTRUM (VouT = 3.3V, Vin=1.2V, RLoAD = 50Q) MAX1700-14, NOISE (mVams) 0.1k 1k 10k 100k 1M FREQUENCY (Hz) MAXUM LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters Pin Description PIN NAME FUNCTION MAX1700 MAX1701 _ 1 LBP Low-Battery Comparator Non-Inverting Input _ 2 LBN Low-Battery Comparator Inverting Input Reference Output. Bypass with a 0.22uF capacitor to GND. REF can source up to 3 3 REF 50pA. Switching-Mode Selection and External-Clock Synchronization Inputs. * CLK/SEL=Low: Low-power, delivers up to 10% of full load current. CLK/SEL=High: High-power PWM mode. Full output power available. Operates in low-noise, constant-frequency mode. 4 4 CLK/SEL CLK/SEL=External Clock: High-power PWM mode with the internal oscillator synchronized to the external clock. Turning on with CLK/SEL=OV also serves as a soft-start function since peak inductor current is limited to 25% of that allowed in PWM mode. 5 5 GND Ground Power-Okay Comparator Output. Open drain N-channel output is low when VouT is _ 6 POK . . : . . 10% below regulation point. No internal delay is provided. 7 7 ONB Shutdown Input. When ONB =high and ONA=low, the IC is off and the load is connect- ed to the battery through the Schottky diode. 8 ONA Turn ON Input. When ONA=high or ONB =low, the IC turns on. _ AO Gain Block Output. This open-drain output sinks when VAIN <VREF. Gain Block AIN input. When AIN is low, AO sinks current. The transconductance from _ 10 AIN . AIN to AO is 9mmhos. DC-DC Converter Dual-Mode Feedback Input. For a fixed output voltage of +3.3V, 11 11 FB connect FB to GND. For adjustable output, connect a divider between POUT and GND to set the output voltage in the range of 2.5V to 5V. 12 12 PGND Source of N-Channel Power MOSFET Switch. Connect to high-current ground path. 13 13 LX Drain of P-Channel Synchronous Rectifier and N-Channel Switch 14 14 OUT Output Sense Input. Power source for the IC. 15 15 POUT Source of P-Channel Synchronous Rectifier MOSFET Switch. Connect an external Schottky diode from LX to POUT. Low-Battery Comparator Output. Open-drain N-channel output is low when LBN > LBP _ 16 LBO ar Input hysteresis is 15mV. 1,2,6,9, 10.16 _ ILC. Internal Connection. Leave open or connect to GND. MAXLA1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters OUT t UNDERVOLTAGE LOCKOUT Ic PWR TT PEM/PWM | pour 2.25 CONTROLLER START-UP D EN ogcilaroR |= & Q Ld ONA 5 __ ON RY [4 EN |__ LX ONB 7 psy REFERENCE EN osc REF REF OSCILLATOR Q GND 4 po 300kHz PEM/PWM CLK/SEL Sax MODE | panp FEEDBACK AND FB - POK" FB POWER-GOOD SELECT | N AINT - = | agp GAIN N BLOCK REF + = LBP* - COMPARATOR | ipo IT I 8 LBN* + = *MAX1701 ONLY Figure 1. Functional Diagram Detailed Description The MAX1700/MAX1701 are highly efficient, low-noise power supplies for portable RF and data acquisition instruments. The MAX1700 combines a boost switching regulator, N-channel power MOSFET, P-channel syn- chronous rectifier, precision reference, and shutdown control. The MAX1701 contains all of the MAX1700 fea- tures plus a versatile gain amplifier, POK output, and a low-battery comparator (Figure 1). The MAX1700/ MAX1701 come in a 16-pin QSOP package, which occupies no more space than an 8-pin SO. The switching DC-DC converter boosts a 1- to 3-cell input to an adjustable output between 2.5V and 5.5V. The MAX1700/MAX1701 start from a low 1.1V input and remain operational down to 0.7V. These devices are optimized for use in cellular phones and other applications requiring low noise during full- MAXUM power operation, as well as low-quiescent current for maximum battery life during standby and shutdown modes. They feature constant-frequency (300kHz), low- noise PWM operation with up to 800mA output capabili- ty. See Table 1 for typical available output current. A low-quiescent-current, low-power mode offers an out- put up to 100mA and reduces quiescent power con- sumption to 200UW. In shutdown mode, the quiescent current is further reduced to just 3HA. Figure 2 shows the standard application circuit for the MAX1700/MAX1701. Additional features include synchronous rectification for high efficiency and improved battery life, a POK output, and an uncommitted comparator for low-battery detec- tion (MAX1701). A CLK input allows frequency synchro- nization to reduce interference. Dual shutdown controls allow shutdown using a momentary pushbutton switch and microprocessor control (MAX1701). LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters 0.7V TO5.5V 10uH MAXIM MBRO0520L OUT MAX1700 LX OUTPUT |_| MAX1701 ; CLK/SEL 2x pour TD 100pF ONA ~ 0.22uF reo = Ri cE] RE FB =r ~~ ADJUSTABLE 0.22uF GND PGND POUT Pp Q LX N 4.3A CURRENT PGND LIMIT osc ~LPLI Figure 2. Fixed or Adjustable Output (PWM mode). Table 1. Typical Available Output Current NUMBER INPUT OUTPUT OUTPUT OF CELLS | VOLTAGE (V) | VOLTAGE (V) | CURRENT (mA) 1 NiGd/NiMH 1.2 3.3 300 2 NiCd/NiMH 24 3.3 750 2 NiCd/NiMH 2.4 5.0 525 3 NiCd/NIMHA 3.6 5.0 850 or 1 Li-lon Table 2. Selecting the Operating Mode CLK/SEL MODE FEATURES 0 Low Power Low supply current 1 PWM Low noise, high output current Low noise, high output current External Clock Synchronized (200kHz to 400kHz) PWM Step-Up Converter The step-up switching DC-DC converter generates an adjustable output from 2.5V to 5.5V. During the first part of each cycle, the internal N-channel MOSFET switch is turned on. This allows current to ramp up in the induc- tor and store energy in a magnetic field. During the second part of each cycle, when the MOSFET is turned off, the voltage across the inductor reverses and forces current through the diode and synchronous rectifier to 10 Figure 3. Simplified PWM Controller Block Diagram the output filter capacitor and load. As the energy stored in the inductor is depleted, the current ramps down and the output diode and synchronous rectifier turn off. Voltage across the load is regulated using either low-noise PWM or low-power operation, depend- ing on the CLK/SEL pin setting (Table 2). Low-Noise PWM Operation When CLK/SEL is pulled high, the MAX1700/MAX1701 operate in a higher power, low-noise pulse-width- modulation (PWM) mode. During PWM operation, they switch at a constant frequency (800kHz) and then mod- ulate the MOSFET switch pulse width to control the power transferred per cycle and regulate the voltage across the load. In PWM mode the devices can output up to 800mA. Switching harmonics generated by fixed- frequency operation are consistent and easily filtered. See the Noise Spectrum Plot in the Typical Operating Characteristics. During PWM operation, each rising edge of the internal clock sets a flip-flop, which turns on the N-channel MOSFET switch (Figure 3). The switch is turned off when the sum of the voltage-error, slope compensation, and current-feedback signals trips a multi-input com- parator and resets the flip-flop; the switch remains off for the rest of the cycle. When a change occurs in the output-voltage error signal into the comparator, it shifts the level to which the inductor current is allowed to ramp during each cycle and modulates the MOSFET switch pulse width. A second comparator enforces an inductor current limit of 1.6A max. MAXLA1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters [ LOGIC HIGH Oo ERROR COMPARATOR REF 400mA CURRENT LIMIT Figure 4. Controller Block Diagram in Low-Power PFM Mode Synchronized PWM Operation By applying an external clock to CLK/SEL, the MAX1700/MAX1701 can also be synchronized in PWM mode to a frequency between 200kHz and 400kHz. This allows the user to set the harmonics to avoid IF bands in wireless applications. The synchronous rectifi- er is also active during synchronized PWM operation. Low-Power PFIM Operation Pulling CLK/SEL low places the MAX1700/MAX1701 in a low-power mode. During low-power mode, PFM oper- ation regulates the output voltage by transferring a fixed amount of energy during each cycle and then modulating the switching frequency to control the power delivered to the output. The devices switch only as needed to service the load, resulting in the highest possible efficiency at light loads. Output current capa- bility in PFM mode is 100mA. The output voltage is typi- cally 1% higher than the output voltage in PWM mode. During PFM operation, the error comparator detects the output voltage falling out of regulation and sets a flip- flop, turning on the N-channel MOSFET switch (Figure 4). When the inductor current ramps to the PFM mode current limit (400mA typical) and stores a fixed amount of energy, the current-sense comparator resets a flip- flop. The flip-flop turns off the N-channel switch and turns on the P-channel synchronous rectifier. A second flip-flop, previously reset by the switchs on signal, inhibits the error comparator from initiating another cycle until the energy stored in the inductor is trans- ferred to the output filter capacitor and the synchronous MAXUM rectifier current has ramped down to 70mA. This forces operation with a discontinuous inductor current. Synchronous Rectifier The MAX1700/MAX1701 feature an internal 250mQ, P- channel synchronous rectifier to enhance efficiency. Synchronous rectification provides a 5% efficiency improvement over similar nonsynchronous boost regu- lators. In PWM mode, the synchronous rectifier is turned on during the second half of each switching cycle. In low-power mode, an internal comparator turns on the synchronous rectifier when the voltage at LX exceeds the boost-regulator output and then turns it off when the inductor current drops below 70mA. Low-Voltage Start-Up Oscillator The MAX1700/MAX1701 use a CMOS, low-voltage start-up oscillator for a 1.1V guaranteed minimum start- up input voltage at +25C. On start-up, the low-voltage oscillator switches the N-channel MOSFET until the out- put voltage reaches 2.15V. Above this level, the normal boost-converter feedback and control circuitry take over. Once the device is in regulation, it can operate down to a 0.7V input since internal power for the IC is bootstrapped from the output using the OUT pin. Do not apply full load until the output exceeds 2.4V. Table 3. On/Off Logic Control ONA ONB Status 0 0 On 0 1 Off 1 0 On 1 1 On Shutdown The MAX1700/MAX1701 shut down to reduce quies- cent current to typically 3A. During shutdown, the ref- erence, low-battery comparator, gain block, and all feedback and control circuitry are off. The boost con- verter's output drops to one Schottky diode drop below the input. Table 3 shows the control logic with ONA and ONB. Both inputs have trip points near 0.5VouT with 0.15VouT hysteresis. Low-Battery Comparator (MAX1701) The internal low-battery comparator has uncommitted inputs and an open-drain output (LBO) capable of sink- ing 1mA. To use it as a low-battery-detection compara- tor, connect the LBN input to the reference, and connect the LBP input to an external resistor divider 11 LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters 0.7V TO5.5V MAXUM MAX1701 LX POUT CLK/SEL ONA ONB + Tc toa 0.22uF ARBITRARY = VOLTAGE LBP POK FH VOLTAGE MONITOR LBN LBO ;H LOW- BATTERY MONITOR BB REF AO [> ARBITRARY VOLTAGE MONITOR R3 Figure 5. Detecting Battery Voltage Above 1.25V POUT OUT MAXLAA MAX1701 R3 LBO LBP LBN Fe | Lt 2 Zz Oo WH Figure 6. Using the Low-Battery Comparator to Sense the Output Voltage (MAX1701) between the positive battery terminal and GND (Figure 5). The resistor values are then calculated as follows: R3 = R4(VTH/VLBN -1) where VTH is the desired input voltage trip threshold and VLBN = VREF = 1.25V. Since the input bias current into LBP is less than 20nA, R4 can be a large value (such as 270k or less) without sacrificing accuracy. The inputs have a common-mode input range from 0.5V to 1.5V and an input-referred hysteresis of 15mV. The low-battery comparator can also be used to moni- tor the output voltage, as shown in Figure 6. To set the low-battery threshold to a voltage below the 1.25V reference, insert a resistor divider between REF 12 POUT REF MAXIMA MAX1701 0.22uF 10k LBP BATTERY GND VOLTAGE _ Figure 7. Detecting Battery Voltages Below 1.25V (MAX1701) OUTPUT pp 100 , L C5 0.22 uF OUT POUT + 270k " - 8 Tt cu! == | = ca LBN ANAXIM = MAX1701 mM LBO LBP d REF + GND LL 0.22uF Figure 8. Using the Low-Battery Comparator for Load Control During Start-Up and LBN and connect the battery to the LBP input through a 10k current-limiting resistor (Figure 7). The equation for setting the resistors for the low-battery threshold is then as follows: R5 = R6(VREF/VLBP -1) where VLBp is the desired voltage threshold. In Figures 5, 6, and 7, LBO goes low for a low-voltage input. The low-battery comparator can be used to check the out- put voltage or to control the load directly on PouT dur- ing start-up (Figure 8). Use the following equation to set the resistor values: R3 = R4(VoOUTTH/VLBP - 1) where VouUTTH is the desired output-voltage trip point and V_pp is connected to the reference or 1.25V. MAXLA1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters Reference The MAX1700/MAX1701 have an internal 1.250V, 1% bandgap reference. Connect a 0.22uF bypass capaci- tor to GND within 0.2in. (6mm) of the REF pin. REF can source up to 50uA of external load current. Power-OK (MAX1701) The MAX1701 features a power-good comparator. This comparators open-drain output (POK) is pulled low when the output voltage falls to 10% below the regula- tion point. MAXIM MAX1701 REF Hh Figure 9. Using Gain Block as a Linear Regulator Table 4. Component Suppliers SUPPLIER PHONE FAX AVX USA: (803) 946-0690 (803) 626-3123 800) 282-4975 Coilcraft USA: (847) 639-6400 (847) 639-1469 Matsuo USA: (714) 969-2491 (714) 960-6492 Motorola USA: (602) 303-5454 (602) 994-6430 Sanyo USA: (619) 661-6835 (619) 661-1055 Japan: 81-7-2070-6306 | 81-7-2070-1174 Sumid USA: (847) 956-0666 (847) 956-0702 a Japan: 81-3-3607-5111 | 81-3-3607-51 44 Table 5. Component Selection Guide Gain Block (MAX1701) The MAX1701s gain block can function as a third com- parator or can be used to build a linear regulator using an external P-channel MOSFET pass device. The gain- block output is a single-stage transconductance ampli- fier that drives an open-drain N-channel MOSFET. Figure 9 shows the gain block used in a linear regula- tor. The output of an external P-channel pass element is compared to the internal reference. The difference is amplified and used to drive the gate of the pass ele- ment. Use a logic-level PFET such as the Fairchild NDS336P (RDS(ON) = 270m If the PFET Rps(on) is less than 250mQ, the linear regulator output filter capacitance may need to be increased to above 47pF. Design Procedure Setting the Output Voltages Set the output voltage between 2.5V and 5.5V by con- necting a resistor voltage-divider to FB from OUT to GND, as shown in Figure 2. The resistor values are then as follows: R1 = R2 (VouT/Ves - 1) where Vrp, the boost-regulator feedback setpoint, is 1.23V. Since the input bias current into FB is less than 20nA, R2 can have a large value (such as 270kQ or less) without sacrificing accuracy. Connect the resistor voltage-divider as close to the IC as possible, within 0.2in. (6mm) of the FB pin. Inductor Selection The MAX1700/MAX1701s high switching frequency allows the use of a small surface-mount inductor. A 10H inductor should have a saturation-current rating that exceeds the N-channel switch current limit of 1.6A. However, it is generally acceptable to bias the inductor current into saturation by as much as 20%, although this will slightly reduce efficiency. For high efficiency, choose an inductor with a high-frequency core material (such as ferrite) to reduce core losses. To minimize radiated noise, use a toroid, pot core, or shielded bob- bin inductor. Connect the inductor from the battery to the LX pin as close to the IC as possible. See Table 4 for a list of component suppliers and Table 5 for sug- gested components. PRODUCTION INDUCTORS CAPACITORS DIODES : : Matsuo 267 series Surface Mount Sumida CDRESB, CD73, CDR/SB, CD74B series Sprague 595D series Motorola MBRO520L Coilcraft DO1608, DO3308, DT3316 series AVX TPS series Through Hole Sumida RCH654 series Sanyo OS-CON series Nichicon PL series 1N5817 MAXUM 13 LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAAXIAA uc 270k MAX1701 onorr | o | os OUT Yoo ~g| 1/0 ONA V0 0.1pF S 270k + t_ fr Tt [re r MAXIAN MAXIM MAX1700 MAX8865/MAX8866 DUAL OR MAX8863/MAX8864 SINGLE LOW- DROPOUT LINEAR REGULATORS _Z uc RADIO Figure 10. Momentary Pushbutton On/Off Switch Output Diode Use a Schottky diode, such as a 1N5817, MBRO520L, or equivalent. The Schottky diode carries current during start-up, and in PFM mode after the synchronous rectifier turns off. Thus, its current rating only needs to be 500mA. Connect the diode between LX and PouT as close to the IC as possible. Do not use ordinary rectifier diodes since slow switching speeds and long reverse recovery times will compromise efficiency and load regulation. Input and Output Filter Capacitors Choose input and output filter capacitors that will ser- vice the input and output peak currents with accept- able voltage ripple. Choose input capacitors with working voltage ratings over the maximum input volt- age, and output capacitors with working voltage ratings higher than the output. For full output, two 100UF, 100mQ, low-ESR tantalum out- put filter capacitors are recommended. For loads below 250mA, a single 100UF output capacitor will suffice. The input filter capacitor (CIN) reduces peak currents drawn from the input source and reduces input switching noise. The input voltage source impedance determines the required size of the input capacitor. When operating directly from one or two NiCd cells placed close to the MAX1700/MAX1 701, use a 22uF, low-ESR input filter capacitor. When operating from a power source placed farther away, or from higher impedance batteries such as alkaline or lithium cells, use one or two 100yF, 100mQ, low-ESR tantalum capacitors. Sanyo OS-CON and Panasonic SP/CB-series ceramic capacitors offer the lowest ESR. Low-ESR tantalum capacitors are a good choice and generally offer a good tradeoff between price and performance. Do not 14 Figure 11. Typical Phone Application exceed the ripple current ratings of tantalum capaci- tors. Avoid most aluminum-electrolytic capacitors, since their ESR is often too high. Bypass Capacitors Two ceramic bypass capacitors are required for proper operation. Bypass REF with a 0.22uF capacitor to GND. Also connect a 0.22uF ceramic capacitor from OUT to GND. Each should be placed as close to their respec- tive pins as possible, within 0.2in. (6mm) of the DC-DC converter IC. See Table 4 for suggested suppliers. Applications Information Push-On/Push-Off Control A momentary pushbutton switch can be used to turn the MAX1700/MAX1701 on and off. In Figure 10, ONA is pulled low and ONB is pulled high when the part is off. When the momentary switch is pressed, ONB is pulled low and the regulator turns on. The switch must be pressed long enough for the microcontroller to exit reset (200ms) and drive ONA high. A small capacitor is added to help debounce the switch. The controller issues a logic high to ONA, which holds the part on regardless of the switch state. To turn the regulator off, press the switch again, allowing the controller to read the switch status and pull ONA low. When the switch is released, ONB is pulled high. Use ina Typical Wireless Phone Application The MAX1700/MAX1701 are ideal for use in digital cordless and PCS phones. The power amplifier (PA) is connected directly to the boost-converter output for maximum voltage swing (Figure 11). Low-dropout linear regulators are used for post-regulation to generate MAXLA1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters low-noise power for DSP, control, and RF circuitry. Typically, RF phones spend most of their life in standby mode with only short periods in transmit/receive mode. During standby, maximize battery life by setting CLK/SEL = 0; this places the IC in low-power mode (for the lowest quiescent power consumption). Designing a PC Board High switching frequencies and large peak currents make PC board layout an important part of design. Poor design can cause excessive EMI and ground- bounce, both of which can cause instability or regula- tion errors by corrupting the voltage and current feedback signals. Power components (such as the inductor, converter IC, filter capacitors, and output diode) should be placed as close together as possible, and their traces should be kept short, direct, and wide. A separate low-noise ground plane containing the reference and signal grounds should only connect to the power-ground plane at one point. This minimizes the effect of power- ground currents on the part. Consult the MAX1701 EV kit manual for a layout example. On multilayer boards, do not connect the ground pins of the power components using vias through an internal ground plane. Instead, place them close together and route them in a star-ground configuration using compo- nent-side copper. Then use vias to connect the star ground to the internal ground plane. Keep the voltage feedback network very close to the IC, within 0.2in. (6mm) of the FB pins. Keep noisy traces, such as from the LX pin, away from the voltage feedback networks. Separate them with grounded copper. Consult the MAX1700 evaluation kit for a full PC board example. Pin Configurations (continued) TOP VIEW ise [i] * 6] LBO Len [2 | 5] POUT FL} ~naxaan [14] oo cwse. [4] MAxizor [ia] Lx eno [5 | 2] PaND pox [6 | 4] FB one [7 | 0] AIN ona [8 | 9] Ao QSOP MAXUM Soft-Start To implement soft-start, set CLK/SEL low on power-up; this forces low-power operation and reduces the peak switching current to 550mA max. Once the circuit is in regulation and start-up transients have settled, CLK/SEL can be set high for full-power operation. Intermittent Supply/Battery Connections When boosting an input supply connected with a mechanical switch, or a battery connected with spring contacts, inout power may sometimes be intermittent as a result of contact bounce. When operating in PFM mode with input voltages greater than 2.5V, restarting after such dropouts may initiate high current pulses that interfere with the MAX1700/MAX1701 internal MOSFET switch control. If contact or switch bounce is anticipat- ed in the design, use one of the following solutions. 1) Connect a capacitor (CONB) from ONB to Vin, a 1MQ resistor (RONB) from ONB to GND, and tie ONA to GND (Figure 12). This RC network differentiates fast input edges at VIN and momentarily holds the IC off until VIN settles. The appropriate value of Cons is 10 times the total output filter capacitance (COUT), so a CouT of 200LF results in CONB = 2nF. 2) Use the system microcontroller to hold the MAX1700/MAX1701 in shut down from the time when power is applied (or reapplied) until the output capaci- tance (CouT) has charged to at least the input voltage. Power-on reset times of tens of milliseconds accom- plish this. 3) Ensure that the IC operates, or at least powers up, in PWM mode (CLK/SEL = high). Activate PFM mode only after the VouT has settled and all of the system's power- on reset flags are cleared. Cons LX 2nF 7 + Cour | ONB our #4 TD 200uF + Rn MAXUM = tee MAX1700 MAX1701 + = a 8 ONA POUT = L | Figure 12. Connecting Cons and Rong when Switch or Battery-Contact Bounce Is Anticipated 15 LOLLXVW/OOZLXVWMAX1700/MAX1701 1-Cell to 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters Chip Information TRANSISTOR COUNT: 531 SUBSTRATE CONNECTED TO GND Pack age Information E/2 ~| A \\, } Lb 1 U QUOT OI CS Cc B -} je 4 ao 1X AS \ TT T f{.N D NOTES: 1. D & DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS 2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .006% PER SIDE. 3. HEAT SLUG DIMENSIONS X AND Y APPLY ONLY TO 16 AND 28 LEAD POWER-QSOP PACKAGES. 4. CONTROLLING DIMENSIONS: INCHES. , CHA no i INCHES MILLIMETERS B 0075 | .0098 | 0.191 0.249 D T E 3.81 3.99 e 025 BSC 0.635 BSC H h 0.25 0.41 L 035 | 0. 0.89 xX SEE_VARIA Y 071 087 1.803 | 2.209 a ih 8 or 3 VARIATIONS: QSOP.EPS MAX. 7. SVIAAI/JVI PROPRIETARY INFORMATION PACKAGE _[UTLINE APPROVAL TITLE: QSOP, 150, 025" LEAD PITCH DOCUMENT CONTROL NO REV 1 21-0055 B A 16 MAK