19-1198; Rev 0; 4/97 ANUAL N KIT M IO T A U EVAL BLE AVAILA 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator The MAX1705/MAX1706 are high-efficiency, low-noise, step-up DC-DC converters with an auxiliary linearregulator output. These devices are intended for use in battery-powered wireless applications. They use a synchronous rectifier pulse-width-modulation (PWM) boost topology to generate 2.5V to 5.5V outputs from battery inputs, such as 1 to 3 NiCd/NiMH cells or 1 Li-Ion cell. The MAX1705 has an internal 1A N-channel MOSFET switch. The MAX1706 has a 0.5A switch. Both devices also have a built-in low-dropout linear regulator that delivers up to 200mA. ____________________________Features ♦ Up to 96% Efficiency ♦ 1.1VIN Guaranteed Start-Up ♦ Up to 850mA Output (MAX1705) ♦ Step-Up Output (2.5V to 5.5V adjustable) ♦ Linear Regulator (1.25V to 5.0V adjustable) ♦ PWM/PFM Synchronous-Rectified Topology ♦ 300kHz PWM Mode or Synchronizable ♦ 1µA Shutdown Mode With an internal synchronous rectifier, the MAX1705/ MAX1706 deliver 5% better efficiency than similar nonsynchronous converters. They also feature a pulsefrequency-modulation (PFM) standby mode to improve efficiency at light loads, and a 1µA shutdown mode. An efficiency-enhancing track mode reduces the step-up DC-DC converter output to 300mV above the linear-regulator output. ♦ Voltage Monitor Both devices come in a 16-pin QSOP package, which occupies the same space as an 8-pin SO. Other features include two shutdown-control inputs for push-on/push-off control, and an uncommitted comparator for use as a voltage monitor. 16 QSOP -40°C to +85°C MAX1705EEE Dice* MAX1706C/D 0°C to +70°C 16 QSOP MAX1706EEE -40°C to +85°C *Dice are tested at TA = +25°C, DC parameters only. ________________________Applications Digital Cordless Phones Personal Communicators PCS Phones Wireless Handsets Palmtop Computers Hand-Held Instruments Two-Way Pagers ♦ Pushbutton On/Off Control ______________Ordering Information TEMP. RANGE PART MAX1705C/D __________Typical Operating Circuit INPUT 0.7V TO 5.5V LX __________________Pin Configuration POUT OUT 16 POUT LBP 1 LBO LBN 2 15 ONA REF 3 14 ONB TRACK 4 GND 5 MAX1705 MAX1706 OUT 6 13 LX 12 PGND 11 CLK/SEL ON/OFF CONTROL HIGH EFFICIENCY LOW NOISE 10 LBO 9 FBLDO 8 MAX1705 MAX1706 FB ONA LINEAR REGULATOR OUTPUT ONB CLK/SEL TRACK LBN REF FB 7 STEP-UP OUTPUT LBP LOW-BATTERY DETECTION TOP VIEW PIN-PACKAGE Dice* 0°C to +70°C LDO FBLDO GND PGND LDO QSOP ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX1705/MAX1706 _______________General Description MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator ABSOLUTE MAXIMUM RATINGS ONA, ONB, FBLDO, OUT, POUT to GND...................-0.3V to 6V PGND to GND.....................................................................±0.3V POUT to OUT ......................................................................±0.3V LX to PGND ............................................-0.3V to (VPOUT + 0.3V) CLK/SEL, REF, FB, TRACK, LDO, LBN, LBP, LBO to GND.......................-0.3V to (VOUT + 0.3V) LDO Short Circuit .......................................................Continuous Continuous Power Dissipation (TA = +70°C) QSOP (derate 8.70mW/°C above +70°C) ...................696mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +160°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 (VOUT = VPOUT = VLBP = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF), LX = open, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.1 V DC-DC CONVERTER Minimum Start-Up Voltage TA = +25°C, ILOAD < 1mA, Figure 2 0.9 Minimum Operating Battery Voltage (Note 1) 0.7 FB Regulation Voltage CLK/SEL = OUT FB Input Current VFB = 1.5V 1.219 OUT Adjust Range V 1.233 1.247 V 0.01 50 nA 5.5 V 0.65 1.25 % 2.5 Load Regulation MAX1705, 0A ≤ ILX ≤ 0.5A; MAX1706, 0A ≤ ILX ≤ 0.25A; CLK/SEL = OUT OUT Voltage in Track Mode TRACK = VLDO > 2.3V VLDO + 0.2 VLDO + 0.3 VLDO + 0.4 V VPOUT = VOUT = 1.5V 40 150 300 kHz 2.00 2.15 2.30 V 1 20 µA 100 190 µA VFB = VFBLDO = 1.5V, no load 180 360 µA FB = GND (LX switching) 2.1 Frequency in Start-Up Mode fLX Start-Up to Normal Mode Transition Voltage (Note 2) Supply Current in Shutdown IOUT ONA = GND, ONB = OUT, measure IOUT Supply Current in Low-Power Mode IOUT CLK/SEL = GND, VFB = VFBLDO = 1.5V, no load Supply Current in Low-Noise Mode IOUT CLK/SEL = OUT mA REFERENCE Reference Output Voltage IREF = 0µA 1.250 1.262 V Reference Load Regulation -1µA < IREF < 50µA 4 15 mV Reference Supply Regulation 2.5V < VOUT < 5.5V 0.2 5 mV 2 1.238 _______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator (VOUT = VPOUT = VLBP = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF), LX = open, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.1 20 µA µA DC-DC SWITCHES POUT Leakage Current VLX = 0V, V ONB = VOUT = 5.5V LX Leakage Current VLX = 0V, V ONB = VOUT = 5.5V N-channel, ILX = 100mA Switch On-Resistance 0.1 20 CLK/SEL = GND 0.23 0.45 CLK/SEL = OUT 0.16 0.28 0.27 0.50 P-channel, ILX = 100mA CLK/SEL = OUT N-Channel MOSFET Current Limit ILIM CLK/SEL = GND P-Channel SynchronousRectifier Turn-Off Current Ω MAX1705 1000 1280 1550 MAX1706 550 750 950 MAX1705 250 435 550 MAX1706 250 435 550 20 70 120 mA 1.238 1.250 1.262 V 50 nA CLK/SEL = GND mA LINEAR REGULATOR FBLDO Regulation Voltage FBLDO = LDO, ILOAD = 1mA FBLDO Input Current VFBLDO = 1.5V LDO Adjust Range 0.01 1.25 220 5.0 V 300 500 mA Short-Circuit Current Limit FBLDO = GND Dropout Resistance VFBLDO = 1V, ILDO = 200mA 0.5 1.2 Ω Load Regulation 10µA < ILDO < 200mA, FBLDO = LDO 0.4 1.2 % Line Regulation 2.5V < VOUT < 5.5V, FBLDO = LDO, ILDO = 1mA 0.1 0.5 % AC Power-Supply Rejection f = 300kHz 38 dB Thermal Shutdown Hysteresis approximately 10°C 155 °C LOW-BATTERY COMPARATOR LBN, LBP Offset LBP falling LBN, LBP Hysteresis LBP rising LBN, LBP Common-Mode Input Range VLBN = 0.5V and 1.5V (at least one input must be within this range) LBN, LBP Input Current VLBN = VLBP = 1V LBO Output Low Voltage ISINK = 1mA, VOUT = 2.5V, LBP = GND, LBN = OUT LBO High Leakage VLBO = VOUT = 5V -5 5 16 0.5 0.01 mV mV 1.5 V 50 nA 0.4 V 1 µA CONTROL INPUTS Input Low Level Input High Level Input Leakage Current (CLK/SEL, ONA, ONB, TRACK) 1.2V < VOUT < 5.5V, ONA, ONB (Note 3) 0.2VOUT VOUT = 2.5V, CLK/SEL, TRACK 0.2VOUT 1.2V < VOUT < 5.5V, ONA, ONB (Note 3) 0.8VOUT VOUT = 5.5V, CLK/SEL, TRACK 0.8VOUT V V 1 µA _______________________________________________________________________________________ 3 MAX1705/MAX1706 ELECTRICAL CHARACTERISTICS (continued) MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator ELECTRICAL CHARACTERISTICS (continued) (VOUT = VPOUT = VLBP = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF), LX = open, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Internal Oscillator Frequency CONDITIONS CLK/SEL = OUT MIN TYP MAX UNITS 260 300 340 kHz 400 kHz External Oscillator Synchronization Range 200 Oscillator Maximum Duty Cycle 80 86 90 % Minimum CLK/SEL Pulse 200 ns Maximum CLK/SEL Rise/Fall Time 100 ns ELECTRICAL CHARACTERISTICS (VOUT = VPOUT = VLBP = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF), LX = open, TA = -40°C to +85°C, unless otherwise noted, Note 4.) PARAMETER SYMBOL DC-DC CONVERTER FB Regulation Voltage CONDITIONS MIN CLK/SEL = OUT OUT Voltage in Track Mode TRACK = OUT, VLDO > 2.3V Start-Up to Normal Mode Transition Voltage TYP MAX UNITS 1.215 1.251 V VLDO + 0.2 VLDO + 0.4 V 2.0 2.3 V Supply Current in Shutdown IOUT ONA = 0V, ONB = OUT, measure IOUT 20 µA Supply Current in Low-Power Mode IOUT CLK/SEL = 0V, FB = FBLDO = 1.5V, no load 190 µA Supply Current in Low-Noise Mode IOUT CLK/SEL = OUT, VFB = VFBLDO = 1.5V, no load 360 µA 1.265 V REFERENCE Reference Output Voltage IREF = 0µA 1.235 DC-DC CONVERTER N-channel, ILX = 100mA Switch On-Resistance P-channel, ILX = 100mA CLK/SEL = OUT N-Channel MOSFET Current Limit ILIM CLK/SEL = 0V P-Channel SynchronousRectifier Turn-Off Current 4 CLK/SEL = 0V CLK/SEL = 0V 0.45 CLK/SEL = OUT 0.28 CLK/SEL = OUT 0.50 MAX1705 1000 1700 MAX1706 550 950 MAX1705 250 570 MAX1706 250 570 20 120 _______________________________________________________________________________________ Ω mA mA 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator (VOUT = VPOUT = VLBP = 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF), LX = open, TA = -40°C to +85°C, unless otherwise noted, Note 4.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.268 V LINEAR REGULATOR FBLDO Regulation Voltage FBLDO = LDO, ILOAD = 1mA FBLDO Input Current VFBLDO = 1.5V Short-Circuit Current Limit FBLDO = LDO = GND Dropout Resistance VFBLDO = 1V, ILDO = 200mA 1.233 0.01 220 50 nA 600 mA 1.2 Ω LOW-BATTERY COMPARATOR LBN, LBP Offset LBP falling -5 5 mV LBN, LBP Common-Mode Input Range LBN = 0.5V and 1.5V (at least one input must be within this range) 0.5 1.5 V LBO High Leakage LBO = OUT = 5V 1 µA CONTROL INPUTS Input Low Level Input High Level Internal Oscillator Frequency External Oscillator Synchronization Range Note 1: Note 2: Note 3: Note 4: 1.2V < VOUT < 5.5V, ONA, ONB (Note 2) 0.15VOUT VOUT = 2.5V, CLK/SEL, TRACK 0.15VOUT 1.2V < VOUT < 5.5V, ONA, ONB (Note 2) 0.85VOUT VOUT = 5.5V, CLK/SEL, TRACK 0.85VOUT CLK/SEL = OUT V V 260 340 kHz 200 400 kHz Once the output is in regulation, the MAX1705/MAX1706 operate down to a 0.7V input voltage. The device is in start-up mode when VOUT is below this value (see Low-Voltage Start-Up Oscillator section). ONA and ONB inputs have a hysteresis of approximately 0.15VOUT. Specifications to -40°C to are guaranteed by design, not production tested. _______________________________________________________________________________________ 5 MAX1705/MAX1706 ELECTRICAL CHARACTERISTICS (continued) __________________________________________Typical Operating Characteristics (Circuit of Figure 2, TA = +25°C, unless otherwise noted.) MAX1705 EFFICIENCY vs. OUTPUT CURRENT (VOUT = 5V) 70 60 50 L = 10µH VOUT = 3.3V A: VIN = 0.9V B: VIN = 2.7V 1: PFM MODE 2: PWM MODE 40 30 20 10 A.1 60 50 L = 10µH VOUT = 5V A: VIN = 0.9V C: VIN = 2.4V E: VIN = 3.6V 1: PFM MODE 2: PWM MODE 40 20 10 1 10 100 VOUT = 3.3V 200 VOUT = 5V 100 1 10 100 1000 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 80 EFFICIENCY (%) 50 L = 22µH VOUT = 3.3V A: VIN = 0.9V B: VIN = 2.7V 1: PFM MODE 2: PWM MODE 40 30 20 10 C.1 B.2 C.2 B.1 70 A.2 A.1 60 50 L = 22µH VOUT = 5V A: VIN = 0.9V B: VIN = 2.4V C: VIN = 3.6V 1: PFM MODE 2: PWM MODE 40 30 20 10 700 L = 22µH 0.1 1 10 100 600 PWM MODE 500 VOUT = 5V 400 VOUT = 3.3V 300 VOUT = 3.3V 200 VOUT = 5V 100 PFM MODE 0 0 0 MAX1705/6 TOC06 B.2 90 MAXIMUM OUTPUT CURRENT (mA) MAX1705/6 TOC04 100 MAX1705/6 TOC05 MAX1706 MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE 60 0.1 1000 1 10 100 1000 0 0.5 1.0 1.5 2.0 2.5 3 3.5 4 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) INPUT VOLTAGE (V) MAX1705 START-UP INPUT VOLTAGE vs. OUTPUT CURRENT NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE LINEAR-REGULATOR DROPOUT VOLTAGE vs. LOAD CURRENT TA = -40°C 0.9 TA = +25°C 0.7 TA = +85°C 0.5 0.1 1 10 OUTPUT CURRENT (mA) 100 1000 VOUT = 3.3V L = 10µH 11 10 9 8 7 6 5 4 PWM MODE 3 2 1 0 140 VLDO = 3.3V 120 DROPOUT VOLTAGE (mV) 1.1 12 MAX1705/6 TOC8 NO-LOAD START-UP: 1.0V AT -40°C 0.79 AT +25°C 0.64V AT +85°C CONSTANT-CURRENT LOAD VOUT = 3.3V L = 10µH D1 = MBR0520L NO-LOAD SUPPLY CURRENT (mA) MAX1705/6 TOC07 2.3 0.01 PFM MODE 300 MAX1706 EFFICIENCY vs. OUTPUT CURRENT (VOUT = 5V) A.2 1.3 400 MAX1706 EFFICIENCY vs. OUTPUT CURRENT (VOUT = 3.3V) 70 1.5 VOUT = 3.3V 500 INPUT VOLTAGE (V) A.1 1.7 VOUT = 5V 600 OUTPUT CURRENT (mA) B.1 1.9 PWM MODE 700 OUTPUT CURRENT (mA) 90 2.1 800 0 0.1 1000 100 80 L = 10µH 900 0 0.1 EFFICIENCY (%) B.2 C.2 A.2 70 30 0 6 B.1 80 EFFICIENCY (%) EFFICIENCY (%) A.2 MAX1705/6 TOC03 B.2 80 1000 4.5 MAX1705/6 TOC09 A.1 C.1 90 MAXIMUM OUTPUT CURRENT (mA) B.1 90 100 MAX1705/6 TOC01 100 MAX1705 MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE MAX1705/6 TOC02 MAX1705 EFFICIENCY vs. OUTPUT CURRENT (VOUT = 3.3V) START-UP INPUT VOLTAGE (V) MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator 100 80 VLDO = 2.5V 60 VLDO = 5V 40 20 PFM MODE 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 0 40 80 120 LOAD CURRENT (mA) _______________________________________________________________________________________ 160 200 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator (Circuit of Figure 2, TA = +25°C, unless otherwise noted.) LINEAR-REGULATOR REGION OF STABLE C6 ESR vs. LOAD CURRENT LINEAR-REGULATOR POWER-SUPPLY REJECTION RATIO vs. FREQUENCY 50 MAX1705/6 TOC11 100 MAX1705/6 TOC10 60 C6 = 22µF UNCOMPENSATED 10 C6 ESR (Ω) 30 20 0.1 0 1k 10k 100k 1M 0 10M 1 50 MAX1705 NOISE SPECTRUM AT POUT (VOUT = 4.5V, VIN = 1.2V, 200mA LOAD) 100 150 200 250 300 LOAD CURRENT (mA) MAX1705/6 TOC13 FREQUENCY (Hz) NOISE (5mVRMS/div) 0V 1k 10k 100k 1M 10M FREQUENCY (Hz) MAX1705 LINEAR-REGULATOR OUTPUT NOISE SPECTRUM (VLDO = 3.3V, VOUT = 4.5V, VIN = 1.2V, ILDO = 200mA) MAX1705/6 TOC14 100 1 STABLE REGION VOUT = 4V TO 5V VLDO = 3.3V ILDO = 200mA C5 = 0.33µF 10 C2 = 22pF (FEED FORWARD) NOISE (50µV/div) PSRR (dB) 40 0V 1k 10k 100k 1M 10M FREQUENCY (Hz) _______________________________________________________________________________________ 7 MAX1705/MAX1706 ____________________________Typical Operating Characteristics (continued) ____________________________Typical Operating Characteristics (continued) (Circuit of Figure 2, TA = +25°C, unless otherwise noted.) MAX1705/6 TOC17 MAX1705/6 TOC16 A MAX1705 POWER-ON DELAY (PWM MODE) MAX1705 LOAD-TRANSIENT RESPONSE MAX1705 LINE-TRANSIENT RESPONSE MAX1705/6 TOC15 A B A 3V 2.5V 3.3V C B B 0mA D VIN = 1.2V, LOAD = 1kΩ A = ONA, 2V/div B = VLDO, 2V/div C = VOUT, 2V/div D = INDUCTOR CURRENT, 500mA/div VIN = 1.2V, VOUT = 3.3V A = VOUT, 50mV/div, 3.3V DC OFFSET B = IOUT, 0mA TO 200mA, 200mA/div MAX1705/6 TOC18 B 1A A DC TO 500kHz 0mA 0V B 0V C D 8 MAX1705/6 TOC20 MAX1705 LINEAR-REGULATOR OUTPUT NOISE MAX1705 PFM SWITCHING WAVEFORMS MAX1705 PWM SWITCHING WAVEFORMS A 200µs/div 200µs/div 200µs/div IOUT = 0mA, VOUT = 3.3V A = VIN, 1.5V TO 2.0V, 200mV/div B = VOUT, 10mV/div, 3.3V DC OFFSET MAX1705/6 TOC19 MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator VOUT C VOUT VLDO D VLDO 1µs/div 2µs/div VIN = 1.2V, VOUT = 4.5V, VLDO = 3.3V, ILDO = 200mA A = INDUCTOR CURRENT, 500mA/div B = LX VOLTAGE, 5V/div C = VOUT RIPPLE, 50m/div AC COUPLED D = VLDO RIPPLE, 5m/div AC COUPLED C5 = 0.33µF VIN = 1.2V, VOUT = 4.5V, VLDO = 3.3V, ILDO = 40mA A = INDUCTOR CURRENT, 500mA/div B = LX VOLTAGE, 5V/div C = VOUT RIPPLE, 50mV/div AC COUPLED D = VLDO RIPPLE, 5mV/div AC COUPLED C5 = 0.33µF VLDO 1ms/div VLDO IS AC COUPLED, 1mv/div ILDO = 200mA C5 = 0.33µF _______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator PIN NAME FUNCTION 1 LBP Low-Battery Comparator Noninverting Input. Common-mode range is 0.5V to 1.5V. 2 LBN Low-Battery Comparator Inverting Input. Common-mode range is 0.5V to 1.5V. 3 REF 1.250V Reference Output. Bypass REF with a 0.33µF capacitor to GND. REF can source up to 50µA. 4 TRACK 5 GND Ground 6 OUT Step-Up Converter Feedback Input, used during track mode. IC power and low-dropout linear-regulator input. Bypass OUT to GND with a 0.1µF ceramic capacitor placed as close to the IC as possible. 7 FB Step-Up DC-DC Converter Feedback Input. Connect FB to a resistor voltage divider between POUT and GND to set the output voltage between 2.5V and 5.5V. FB regulates to 1.233V. 8 FBLDO 9 LDO Low-Dropout Linear-Regulator Output. LDO sources up to 200mA. Bypass to GND with a 22µF capacitor. 10 LBO Low-Battery Comparator Output. This open-drain, N-channel output is low when LBP < LBN. Input hysteresis is 16mV. Track-Mode Control Input for DC-DC Converter. In track mode, the boost-converter output is sensed at OUT and set 0.3V above LDO to improve efficiency. Set TRACK to OUT for track mode. Connect TRACK to GND for normal operation. Low-Dropout Linear-Regulator Feedback Input. Connect FBLDO to a resistor voltage divider between LDO to GND to set the output voltage from 1.25V to VOUT - 0.3V (5.0V max). FBLDO regulates to 1.250V. Switching-Mode Selection and External-Clock Synchronization Input: • CLK/SEL = low: low-power, low-quiescent-current PFM mode. • CLK/SEL = high: low-noise, high-power PWM mode. Switches at a constant frequency (300kHz). Full output power is available. • CLK/SEL = driven with an external clock: low-noise, high-power synchronized PWM mode. Synchronizes to an external clock (from 200kHz to 400kHz). Turning on the DC-DC converter with CLK/SEL = GND also serves as a soft-start function, since peak inductor current is reduced. 11 CLK/SEL 12 PGND 13 LX 14 ONB Off Control Input. When ONB = high and ONA = low, the IC is off. Connect ONB to GND for normal operation (Table 2). 15 ONA On Control Input. When ONA = high or ONB = low, the IC turns on. Connect ONA to OUT for normal operation (Table 2). 16 POUT Boost DC-DC Converter Power Output. POUT is the source of the P-channel synchronous-rectifier MOSFET switch. Connect an external Schottky diode from LX to POUT. The output current available from POUT is reduced by the current drawn from the LDO linear-regulator output. Power Ground for the source of the N-channel power MOSFET switch Inductor connection to the drains of the P-channel synchronous rectifier and N-channel switch _______________________________________________________________________________________ 9 MAX1705/MAX1706 ______________________________________________________________Pin Description MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator _______________Detailed Description The MAX1705/MAX1706 are designed to supply both power and low-noise circuitry in portable RF and dataacquisition instruments. They combine a linear regulator, step-up switching regulator, N-channel power MOSFET, P-channel synchronous rectifier, precision reference, and low-battery comparator in a single 16pin QSOP package (Figure 1). The switching DC-DC converter boosts a 1- or 2-cell input to an adjustable output between 2.5V and 5.5V. The internal low-dropout regulator provides linear post-regulation for noisesensitive circuitry, as well as outputs from 1.25V to 300mV below the switching-regulator output. The MAX1705/MAX1706 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 fullpower operation, as well as low quiescent current for LBO maximum battery life during standby and shutdown. They feature constant-frequency (300kHz), low-noise pulse-width-modulation (PWM) operation with 300mA or 730mA output capability from one or two cells, respectively, with 3.3V output. A low-quiescent-current standby pulse-frequency-modulation (PFM) mode offers an output up to 60mA and 140µA, respectively, and reduces quiescent power consumption to 500µW. In shutdown mode, the quiescent current is further reduced to just 1µA. Figure 2 shows the standard application circuit for the MAX1705 configured in highpower PWM mode. Additional features include synchronous rectification for high efficiency and improved battery life, and an uncommitted comparator for low-battery detection. A CLK/SEL input allows frequency synchronization to reduce interference. Dual shutdown controls allow shutdown using a momentary pushbutton switch and microprocessor control. MAX1705 MAX1706 THERMAL SENSOR LBP N SHUTDOWN LOGIC LBN OUT FBLDO MOSFET DRIVER WITH CURRENT LIMITING ERROR AMP OUT REF P LDO IC PWR POUT 2.15V EN GND START-UP OSCILLATOR Q D Q P PFM/PWM CONTROLLER ONA ON ONB REF OSC EN 300kHz OSCILLATOR CLK/SEL VLDO LX EN RDY 1.250V REFERENCE PFM/PWM MODE Q ICS IREF FB TRACK PGND VOUT - 300mV IFB Figure 1. Functional Diagram 10 N ______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator MAX1705/MAX1706 INPUT 0.9V TO 3.6V L1 10µH (22µH) C7 22µF D1 R5 LX BOOST OUTPUT 3.6V POUT (TO PGND) R6 LBP OUT LBN TRACK REF C8 0.33µF C3 0.1µF C9 0.33µF R1 191k C4 220µF (100µF) C1* PGND (TO PGND) MAX1705 MAX1706 R2 100k FB ONA LDO OUTPUT 3.3V ONB LDO CLK/SEL FBLDO C5* 0.33µF LBO GND NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATH. R7 100k R3 165k C6 22µF C2* R4 100k *OPTIONAL. ( ) ARE FOR MAX1706. Figure 2. Typical Operating Circuit (PWM Mode) Step-Up Converter The step-up switching DC-DC converter generates an adjustable output to supply both power circuitry (such as RF power amplifiers) and the internal low-dropout linear regulator. During the first part of each cycle, the internal N-channel MOSFET switch is turned on. This allows current to ramp up in the inductor 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 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 PWM or PFM operation, depending on the CLK/SEL pin setting (Table 1). Low-Noise, High-Power PWM Operation When CLK/SEL is pulled high, the MAX1705/MAX1706 operate in a high-power, low-noise PWM mode. During PWM operation, they switch at a constant frequency (300kHz), and modulate the MOSFET switch pulse width to control the power transferred per cycle and regulate the voltage across the load. In PWM mode, the Table 1. Selecting the Operating Mode CLK/SEL MODE FEATURES 0 PFM Low supply current 1 PWM Low noise, high output current External Clock (200kHz to 400kHz) Synchronized PWM Low noise, high output current devices can output up to 850mA. Switching harmonics generated by fixed-frequency operation are consistent and easily filtered. During PWM operation, each of the internal clock’s rising edges 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 and currentfeedback signals trips a multi-input comparator 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 that the inductor current is allowed to ramp to during each cycle and modulates the MOSFET switch pulse width. A second comparator enforces a 1.55A (max) inductor- ______________________________________________________________________________________ 11 MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator POUT POUT Q P IFB* LOGIC HIGH D Q R IREF* R P LX Q N S LX IFB* ICS S N Q IREF* CURRENT LIMIT LEVEL R PGND OSC CURRENT LIMIT LEVEL PGND *SEE FIGURE 1 Figure 3. Simplified PWM Controller Block Diagram current limit for the MAX1705, and 950mA (max) for the MAX1706. During PWM operation, the circuit operates with a continuous inductor current. Synchronized PWM Operation The MAX1705/MAX1706 can also be synchronized to a 200kHz to 400kHz frequency by applying an external clock to CLK/SEL. This allows the user to set the harmonics, to avoid IF bands in wireless applications. The synchronous rectifier is also active during synchronized PWM operation. Low-Power PFM Operation Pulling CLK/SEL low places the MAX1705/MAX1706 in low-power standby mode. During standby mode, PFM operation 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 capability in PFM mode is 140mA (from 2.4V input to 3.3V output). The output is regulated at 1.3% above the PWM threshold. During PFM operation, the error comparator detects 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 (435mA) and stores a fixed amount of energy, the current-sense comparator resets a flipflop. 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 switch’s “on” signal, inhibits the error comparator from initiating another 12 *SEE FIGURE 1 Figure 4. Controller Block Diagram in PFM Mode cycle until the energy stored in the inductor is dumped into the output filter capacitor and the synchronous rectifier current ramps down to 70mA. This forces operation with a discontinuous inductor current. Synchronous Rectifier The MAX1705/MAX1706 feature an internal 270mΩ, P-channel synchronous rectifier to enhance efficiency. Synchronous rectification provides a 5% efficiency improvement over similar nonsynchronous step-up regulators. In PWM mode, the synchronous rectifier is turned on during the second half of each cycle. In PFM mode, an internal comparator turns on the synchronous rectifier when the voltage at LX exceeds the step-up converter output, and then turns it off when the inductor current drops below 70mA. Linear Regulator The internal low-dropout linear regulator steps down the output from the step-up converter and reduces switching ripple. It is intended to power noise-sensitive analog circuitry, such as low-noise amplifiers and IF stages in cellular phones and other instruments, and can deliver up to 200mA. However, in practice, the maximum output current is further limited by the current available from the boost converter and by the voltage differential between OUT and LDO. Use a 22µF capacitor with a 1Ω or less equivalent series resistance (ESR) at the output for stability (see the Linear Regulator Region of Stable C6 ESR vs. Load Current graph in the Typical Operating Characteristics). During power-up, the linear regulator remains off until the step-up converter goes into regulation for the first time. ______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator The linear-regulator error amplifier compares the output feedback sensed at the FBLDO input against the internal 1.250V reference, and amplifies the difference (Figure 1). The MOSFET driver reads the error signal and applies the appropriate drive to the P-channel pass transistor. If the feedback signal is lower than the reference, the pass-transistor gate is pulled lower, allowing more current to pass to the output, thereby increasing the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up, allowing less current to pass to the output. Additional blocks include a current-limiting block and a thermal-overload protection block. Low-Voltage Start-Up Oscillator The MAX1705/MAX1706 use a CMOS, low-voltage start-up oscillator for a 1.1V guaranteed minimum startup input voltage at +25°C. On start-up, the low-voltage oscillator switches the N-channel MOSFET until the output voltage reaches 2.15V. Above this level, the normal step-up 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. To reduce current loading during step-up, the linear regulator is kept off until the start-up converter goes into regulation. Minimum start-up voltage is influenced by load and temperature (see the Typical Operating Characteristics). To allow proper start-up, do not apply a full load at POUT until after the device has exited start-up mode and entered normal operation. Shutdown The MAX1705/MAX1706 feature a shutdown mode that reduces quiescent current to less than 1µA, preserving battery life when the system is not in use. During shutdown, the reference, the low-battery comparator, and all feedback and control circuitry are off. The step-up converter’s output drops to one Schottky diode drop below the input, but the linear regulator output is turned off. Entry into shutdown mode is controlled by logic input pins ONA and ONB (Table 2). Both inputs have trip points near 0.5VOUT with 0.15VOUT hysteresis. Table 2. On/Off Logic Control ONA ONB MAX1705/MAX1706 0 0 On 0 1 Off 1 0 On 1 1 On Tracking Connecting TRACK to the step-up converter output implements a tracking mode that sets the step-up converter output to 300mV above the linear-regulator output, improving efficiency. In track mode, feedback for the step-up converter is derived from the OUT pin. When TRACK is low, the step-up converter and linear regulator are separately controlled by their respective feedback inputs, FB and FBLDO. TRACK is a logic input with a 0.5VOUT threshold, and should be hardwired or switched with a slew rate exceeding 1V/µs. VLDO must be set above 2.3V for track mode to operate properly. On power-up with TRACK = OUT, the step-up converter initially uses the FB input to regulate its output. After the step-up converter goes into regulation for the first time, the linear regulator turns on. When the linear regulator reaches 2.3V, track mode is enabled and the stepup converter is regulated to 300mV above the linearregulator output. Low-Battery Comparator The internal low-battery comparator has uncommitted inputs and an open-drain output capable of sinking 1mA. To use it as a low-battery-detection comparator, connect the LBN input to the reference, and connect the LBP input to an external resistor divider between the positive battery terminal and GND (Figure 2). The resistor values are then as follows: VIN,TH - 1 R5 = R6 V LBN where VIN,TH is the desired input voltage trip point and VLBN = VREF = 1.25V. Since the input bias current into LBP is less than 50nA, R6 can be a large value (such as 270kΩ or less) without sacrificing accuracy. Connect the resistor voltage divider as close to the IC as possible, within 0.2in. (5mm) of the LBP pin. The inputs have a 0.5V to 1.5V common-mode input range, and a 16mV input-referred hysteresis. ______________________________________________________________________________________ 13 MAX1705/MAX1706 The linear regulator in the MAX1705/MAX1706 features a 0.5Ω, P-channel MOSFET pass transistor. This provides several advantages, including longer battery life, over similar designs using a PNP pass transistor. The P-channel MOSFET requires no base-drive current, which reduces quiescent current considerably. PNPbased regulators tend to waste base-drive current in dropout when the pass transistor saturates. The MAX1705/MAX1706 eliminate this problem. MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator The low-battery comparator can also be used to monitor the output voltage, as shown in Figure 5. To set the low-battery threshold to a voltage below the 1.25V reference, insert a resistor divider between REF and LBN, and connect the battery to the LBP input through a 10kΩ current-limiting resistor (Figure 6). The equation for setting the resistors for the low-battery threshold is then as follows: POUT LDO MAX1705 MAX1706 LBO R5 LBP LBN R6 REF V R5 = R6 REF - 1 VIN,TH GND 0.33µF Alternatively, the low-battery comparator can be used to check the output voltage or to control the load directly on POUT during start-up (Figure 7). Use the following equation to set the resistor values: Figure 5. Using the Low-Battery Comparator to Sense the Output Voltage VOUT,TH - 1 R5 = R6 VLBP POUT REF where VOUT,TH is the desired output voltage trip point and VLBP is connected to the reference or 1.25V. MAX1705 MAX1706 LBO Reference The MAX1705/MAX1706 have an internal 1.250V, 1% bandgap reference. Connect a 0.33µF bypass capacitor to GND within 0.2in. (5mm) of the REF pin. REF can source up to 50µA of external load current. 0.33µF R5 LBN R8 10k R6 LBP GND BATTERY VOLTAGE _________________ Design Procedure Setting the Output Voltages Figure 6. Detecting Battery Voltages Below 1.25V Set the step-up converter output voltage between 2.5V and 5.5V by connecting a resistor voltage-divider to FB from OUT to GND, as shown in Figure 8. The resistor values are then as follows: V R1 = R2 POUT - 1 VFB where VFB, the step-up regulator feedback setpoint, is 1.233V. Since the input bias current into FB is less than 50nA, R2 can have a large value (such as 270kΩ or less) without sacrificing accuracy. Connect the resistor voltage-divider as close to the IC as possible, within 0.2in. (5mm) of the FB pin. Alternatively, set the step-up converter output to track the linear regulator by 300mV. To accomplish this, set TRACK to OUT. 14 STEP-UP OUTPUT P C5 270k C3 0.1µF OUT POUT R5 LBN C4 MAX1705 LBO MAX1706 R6 LBP REF GND 0.33µF Figure 7. Using the Low-Battery Comparator for Load Control During Start-Up ______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator V R3 = R4 LDO - 1 VFBLDO where VFBLDO, the linear-regulator feedback trip point, is 1.250V. Since the input bias current into FBLDO is less than 50nA, R4 can be a large value (such as 270kΩ or less). Connect the resistor voltage-divider as close to the IC as possible, within 0.2in. (5mm) of the FBLDO pin. Inductor Selection The MAX1705/MAX1706’s high switching frequency allows the use of a small surface-mount inductor. Use a 10µH inductor for the MAX1705 and a 22µH inductor for the MAX1706. Make sure the saturation-current rating exceeds the N-channel switch current limit of 1.55A for the MAX1705 and 950mA for the MAX1706. For high efficiency, chose an inductor with a high-frequency core material, such as ferrite, to reduce core losses. To minimize radiated noise, use a torroid, pot core, or shielded-bobbin inductor. See Table 3 for suggested parts and Table 4 for a list of inductor suppliers. Connect the inductor from the battery to the LX pin as close to the IC as possible. Attaching the Output Diode Use a Schottky diode, such as a 1N5817, MBR0520L, or equivalent. The Schottky diode carries current during start-up, and in PFM mode after the synchronous rectifier turns off. Thus, the current rating only needs to be 500mA. Attach the diode between the LX and POUT pins, as close to the IC as possible. In high-temperature applications, some Schottky diodes may be unsuitable due to high reverse-leakage currents. Try substituting a Schottky diode with a higher reverse voltage rating, or use an ultra-fast silicon rectifier with reverse recover times less than 60ns (such as a MUR150 or EC11FS1). Do not use ordinary rectifier diodes, since slow switching speeds and long reverse recovery times compromise efficiency and load regulation. Choose Input and Output Filter Capacitors Choose input and output filter capacitors that service the input and output peak currents with acceptable voltage ripple. Choose input capacitors with working voltage ratings over the maximum input voltage, and output capacitors with working voltage ratings higher than the output. A 100µF, 100mΩ, low-ESR tantalum capacitor is recommended at the MAX1706’s step-up output. For the MAX1705, use two in parallel or a 220µF low-ESR tantalum capacitor. The input filter capacitor (C7) also reduces peak currents drawn from the input source and reduces input switching noise. The input voltage source impedance determines the size required for the input capacitor. When operating directly from one or two NiCd cells placed close to the MAX1705/MAX1706, use a 22µF, low-ESR input filter capacitor. When operating from a power source placed farther away, or LINEARREGULATOR OUTPUT C2* LDO MAX1705 MAX1706 R3 STEP-UP OUTPUT POUT R1 C1* OUT FBLDO R4 GND FB PGND R2 * OPTIONAL COMPENSATION CAPACITORS Figure 8. Feedback Connections for the MAX1705/MAX1706 Table 3. Component Selection Guide PRODUCTION INDUCTORS CAPACITORS Surface Mount Sumida CDR63B, CD73, CDR73B, CD74B series Coilcraft DO1608, DO3308, DT3316 series Matsuo 267 series Sprague 595D series AVX TPS series Through Hole Sumida RCH654 series Sanyo OS-CON series Nichicon PL series DIODES Motorola MBR0520L Motorola 1N5817 ______________________________________________________________________________________ 15 MAX1705/MAX1706 To set the low-dropout linear-regulator output, use a resistor voltage-divider connected to FBLDO from LDO to GND. Set the output to a value at least 300mV less than the step-up converter output using the following formula: MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator from higher-impedance batteries, consider using one or two 100µF, 100mΩ, low-ESR tantalum capacitors. Low-ESR capacitors are recommended. Capacitor ESR is a major contributor to output ripple—often more than 70%. Ceramic, Sanyo OS-CON, and Panasonic SP/CB-series capacitors offer the lowest ESR. Low-ESR tantalum capacitors are second best and generally offer a good trade-off between price and performance. Do not exceed the ripple-current ratings of tantalum capacitors. Avoid aluminum-electrolytic capacitors, since their ESR is too high. Adding Bypass Capacitors Several ceramic bypass capacitors are required for proper operation of the MAX1705/MAX1706. Bypass REF with a 0.33µF capacitor to GND. Connect a 0.1µF ceramic capacitor from OUT to GND and a 0.33µF ceramic capacitor from POUT to PGND. Place a 22µF, low-ESR capacitor and an optional 0.33µF ceramic capacitor from the linear-regulator output LDO to GND. An optional 22pF ceramic capacitor can be added to the linear-regulator feedback network to reduce noise (C2, Figure 2). Place each of these as close to their respective pins as possible, within 0.2in. (5mm) of the DC-DC converter IC. High-value, low-voltage, surfacemount ceramic capacitors are now readily available in small packages; see Table 4 for suggested suppliers. 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 groundbounce, both of which can cause instability or regulation errors by corrupting voltage- and currentfeedback signals. It is highly recommended that the PC board example of the MAX1705 evaluation kit (EV kit) be followed. 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. Place the LDO output capacitor as close to the LDO pin as possible. Make the connection between POUT and OUT very short. Keep the extra copper on the board, and integrate it into ground as a pseudo-ground plane. On multilayer boards, do not connect the ground pins of the power components using vias through an internal 16 Table 4. Component Suppliers SUPPLIER PHONE FAX AVX USA: (803) 946-0690 (800) 282-4975 (803) 626-3123 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 Japan: 81-7-2070-6306 (619) 661-1055 81-7-2070-1174 Sumida USA: (847) 956-0666 Japan: 81-3-3607-5111 (847) 956-0702 81-3-3607-5144 ground plane. Instead, place them close together and route them in a star-ground configuration using component-side copper. Then connect the star ground to the internal ground plane using vias. Keep the voltage-feedback networks very close to the MAX1705/MAX1706—within 0.2in. (5mm) of the FB and FBLDO pins. Keep noisy traces, such as from the LX pin, away from the reference and voltage-feedback networks, especially the LDO feedback, and separated from them using grounded copper. Consult the MAX1705/MAX1706 EV kit for a full PC board example. __________ Applications Information Use in a Typical Wireless Phone Application The MAX1705/MAX1706 are ideal for use in digital cordless and PCS phones. The power amplifier (PA) is connected directly to the step-up converter output for maximum voltage swing (Figure 9). The internal linear regulator is used for post-regulation to generate lownoise power for DSP, control, and RF circuitry. Typically, RF phones spend most of their life in standby mode and short periods in transmit/receive mode. During standby, maximize battery life by setting CLK/SEL = GND and TRACK = OUT; this places the IC in PFM and track modes (for lowest quiescent power consumption). In transmit/receive mode, set TRACK = GND and CLK/SEL = OUT to increase the PA supply voltage and initiate high-power, low-noise PWM operation. Table 5 lists the typical available output current when operating with one or more NiCd/NiMH cells or one Li-Ion cell. ______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator LX CONTROL INPUTS MAX1705 MAX1706 POUT GND ONB ON/OFF MAX1705 MAX1706 MAX1705/MAX1706 µC 270k OUT VDD I/O LDO ONA I/O PA I/O µC RF 0.1µF 270k Figure 10. Momentary Pushbutton On/Off Switch Figure 9. Typical Phone Application Table 5. Typical Available Output Current TOTAL OUTPUT CURRENT (mA) INPUT VOLTAGE (V) STEP-UP OUTPUT VOLTAGE: (PA POWER SUPPLY) (V) MAX1705 MAX1706 1 NiCd/NiMH 1.2 3.3 300 200 2 NiCd/NiMH 2.4 3.3 730 450 2 NiCd/NiMH 2.4 5.0 500 350 3 NiCd/NiMH or 1 Li-Ion 3.6 5.0 850 550 NUMBER OF CELLS Implementing Soft-Start To implement soft-start, set CLK/SEL low on power-up; this forces PFM operation and reduces the peak switching current to 435mA. Once the circuit is in regulation, CLK/SEL can be set high for full-power operation. ___________________Chip Information TRANSISTOR COUNT: 1649 SUBSTRATE CONNECTED TO GND Adding a Manual Power Reset A momentary pushbutton switch can be used to turn the MAX1705/MAX1706 on and off (Figure 10). ONA is pulled low and ONB is pulled high to turn the part 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 (µC) to exit reset (200ms) and drive ONA high. A small capacitor is added to help debounce the switch. The µC 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 µC to read the switch status and pull ONA low. When the switch is released, ONB is pulled high. ______________________________________________________________________________________ 17 MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator __________________________________________________Tape-and-Reel Information 4.0 ±0.1 1.0 ±0.1 2.0 ±0.05 1.5 +0.1/-0.0 DIAMETER 1.75 ±0.1 A 3.5 ±0.05 8.0 ±0.3 2.2 ±0.1 0.5 RADIUS TYPICAL 4.0 ±0.1 A0 A Bo 0.30 ±0.05 0.8 ±0.05 1.0 MINIMUM Ko Ao = 3.1mm ±0.1 Bo = 2.7mm ±0.1 Ko = 1.2mm ±0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD. 0.30R MAX. 18 ______________________________________________________________________________________ 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator QSOP.EPS ______________________________________________________________________________________ 19 MAX1705/MAX1706 ________________________________________________________Package Information MAX1705/MAX1706 1- to 3-Cell, High-Current, Low-Noise, Step-Up DC-DC Converters with Linear Regulator NOTES 20 ______________________________________________________________________________________