ANUAL LUATIO SHEET FOLLO 1-Cell 3-Cell, High-Power (1A), Low-Nois

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ANUAL LUATIO SHEET FOLLO 1-Cell 3-Cell, High-Power (1A), Low-Nois

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ANUAL LUATIO SHEET FOLLO
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
Efficiency Guaranteed Start-Up 0.7V 5.5V Input Range 800mA Output Step-Up Output (adjustable from 2.5V 5.5V) PWM/PFM Synchronous-Rectified Topology External Clock Internal 300kHz Oscillator Logic-Controlled Shutdown Power-Good Output (MAX1701) Low-Battery Comparator (MAX1701) Uncommitted Gain Block (MAX1701)
MAX1700/MAX1701
MAX1700/MAX1701 high-efficiency, low-noise, step-up DC-DC converters intended batterypowered wireless applications. They synchronous-rectified pulse-width-modulation (PWM) boost topology generate 2.5V 5.5V outputs from battery inputs such three NiCd/NiMH cells LiIon cell. Both devices have internal 130m Nchannel MOSFET switch 250m P-channel synchronous rectifier. With their internal synchronous rectifier, MAX1700/ MAX1701 deliver better efficiency than similar nonsynchronous converters. They also feature pulsefrequency-modulation (PFM) standby mode improve efficiency light loads, shutdown mode. MAX1700/MAX1701 come 16-pin QSOP packages (which occupy same space 8-pin SO). MAX1701 includes comparators generate power-good low-battery warning outputs. also contains gain block that used build linear regulator using external P-channel pass device. higher-power outputs, refer MAX1703. dual outputs (step-up linear regulator), refer MAX1705/MAX1706. on-board analog-to-digital converter, refer MAX848/MAX849. MAX1701 evaluation available speed design time.
Ordering Information
PART MAX1700EEE MAX1701EEE TEMP. RANGE -40°C +85°C -40°C +85°C PIN-PACKAGE QSOP QSOP
Applications
Digital Cordless Phones Phones Wireless Handsets Two-Way Pagers
VIEW
I.C. I.C. CLK/SEL I.C. I.C. POUT
Typical Operating Circuit
INPUT 0.7V 5.5V
Personal Communicators Palmtop Computers Hand-Held Instruments
Configurations
CLK/SEL POUT
MAX1700
OUTPUT 3.3V 800mA
SYNC
MAX1700
PGND I.C. I.C.
PGND
QSOP
I.C. INTERNAL CONNECTION. LEAVE OPEN CONNECT
Configurations continued data sheet.
Maxim Integrated Products
free samples latest literature: http://www.maxim-ic.com, phone 1-800-998-8800. small orders, phone 1-800-835-8769.
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
ABSOLUTE MAXIMUM RATINGS
ONA, ONB, OUT, POK, GND.-0.3V, PGND GND.±0.3V PGND.-0.3V,VPOUT+0.3V CLK/SEL, AIN, REF, LBP, LBN, POUT GND.-0.3V, VOUT+0.3V Continuous Power Dissipation (TA=+70°C) 16-QSOP (Derate 8.30mW/°C above +70°C) .667mW Operating Temperature Ranges MAX1700EEE, MAX1701EEE .-40°C +85°C Junction Temperature .+150°C Storage Temperature Range .-65°C +160°C Lead Temperature (soldering, 10sec) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(CLK/SEL PGND GND, POUT, VOUT 3.6V (Note MAX1701: GND, REF, +85°C, unless otherwise noted. Typical values +25°C.) PARAMETER DC-DC CONVERTER Input Voltage Range (Note Minimum Start-Up Voltage (Note Frequency Start-Up Mode Output Voltage (Note Regulation Voltage Input Current Output Voltage Adjust Range Output Voltage Lockout Threshold Load Regulation (Note Supply Current Shutdown Supply Current Low-Power Mode (Note Supply Current Low-Noise Mode (Note DC-DC SWITCHES POUT Leakage Current Leakage Current Switch On-Resistance VOUT 5.5V VOUT 5.5V N-channel P-channel N-Channel Current Limit P-Channel Turn-Off Current CLK/SEL CLK/SEL CLK/SEL 1100 CLK/SEL CLK/SEL 0.13 0.25 1300 0.45 0.28 1600 (Note CLK/SEL OUT, load full load 3.6V CLK/SEL (MAX1700) CLK/SEL (MAX1701) CLK/SEL (MAX1700) CLK/SEL (MAX1701) MAX1700 MAX1701 ILOAD 1mA, +25°C VOUT 1.5V 0.1V, CLK/SEL OUT, VBATT 2.4V, includes load regulation error 0.55A Adjustable output, CLK/SEL OUT, VBATT 2.4V, includes load regulation error 0.55A 1.25V 2.15 -1.6 3.17 1.210 3.30 1.24 0.01 3.38 1.255 CONDITIONS UNITS
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL PGND GND, POUT, VOUT 3.6V (Note MAX1701: GND, REF, +85°C, unless otherwise noted. Typical values +25°C.) PARAMETER GAIN BLOCK (MAX1701) Reference Voltage Input Current Transconductance Output Voltage Output High Leakage POWER GOOD (MAX1701) Internal Trip Level External Trip Level Voltage High Leakage Current LOW-BATTERY COMPARATOR LBN, Input Offset LBN, Common Mode Range Output Voltage High Leakage LBN, Input Current REFERENCE Reference Output Voltage Load Regulation Supply Rejection LOGIC CONTROL INPUTS Input Voltage (Note Input High Voltage (Note Input High Voltage (Note Logic Input Current Internal Oscillator Frequency Oscillator Maximum Duty Cycle External Clock Frequency Range Minimum CLK/SEL Pulse Width Maximum CLK/SEL Rise/Fall Time 1.2V VOUT 5.5V, 2.5V VOUT 5.5V, CLK/SEL 1.2V VOUT 5.5V, 2.5V VOUT 5.5V, CLK/SEL ONA, ONB, CLK/SEL CLK/SEL 0.8VOUT 0.8VOUT 0.2VOUT 0.2VOUT IREF -1µA IREF 50µA 2.5V VOUT 1.237 1.250 1.263 falling, 15mV hysteresis maintain input offset ±5mV least input must within this range) ISINK 1mA, VOUT 3.6V ISINK 20µA, VOUT VOUT VLBO VLBP VLBN 1.5V 0.03 0.01 ±0.5 Rising VOUT, 0.1V Rising ISINK 1mA, VOUT 3.6V ISINK 20µA, VOUT VOUT VPOK 5.5V 2.93 2.97 1.12 0.03 0.01 3.02 1.14 20µA VAIN 1.5V 10µA 100µA VAIN 0.7V, 100µA VAIN 1.5V, 5.5V 1.237 0.01 1.25 1.263 mmho CONDITIONS UNITS
MAX1700/MAX1701
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL PGND GND, POUT, VOUT 3.6V (Note MAX1701: GND, REF, -40°C +85°C, unless otherwise noted.) (Note PARAMETER DC-DC CONVERTER Output Voltage (Note Regulation Voltage Output Voltage Lockout Threshold Supply Current Shutdown Supply Current Low-Power Mode (Note Supply Current Low-Noise Mode (Note DC-DC SWITCHES Switch On-Resistance N-channel P-channel N-Channel Current Limit GAIN BLOCK (MAX1701) Reference Voltage Transconductance POWER-GOOD (MAX1701) Internal Trip Level External Trip Level LBN, Input Offset LBN, Common Mode Range REFERENCE Reference Output Voltage IREF 1.23 1.27 Rising VOUT, 0.1V Rising falling, 15mV hysteresis maintain input offset ±5mV least input must within this range) 2.92 3.03 1.14 20µA 10µA 100µA 1.23 1.27 mmho CLK/SEL CLK/SEL 1100 CLK/SEL CLK/SEL 0.45 0.28 1800 0.1V, CLK/SEL OUT, VBATT 2.4V, includes load regulation error 0.55A Adjustable output, CLK/SEL OUT, VBATT 2.4V, includes load regulation error 0.55A (Note 3.6V CLK/SEL (MAX1700) CLK/SEL (MAX1701) CLK/SEL (MAX1700) CLK/SEL (MAX1701) 3.17 1.20 3.38 1.27 CONDITIONS UNITS
LOW-BATTERY COMPARATOR (MAX1701)
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL PGND GND, POUT, 3.6V, MAX1701: GND, REF, -40°C +85°C, unless otherwise noted.) (Note PARAMETER LOGIC CONTROL INPUTS Input Voltage (Note Input High Voltage (Note Input High Voltage (Note Logic Input Current Internal Oscillator Frequency Oscillator Maximum Duty Cycle External Clock Frequency Range 1.2V VOUT 5.5V, 2.5V VOUT 5.5V, CLK/SEL 1.2V VOUT 5.5V, 2.5V VOUT 5.5V, CLK/SEL ONA, ONB, CLK/SEL CLK/SEL 0.8VOUT 0.8VOUT 0.2VOUT 0.2VOUT CONDITIONS UNITS
MAX1700/MAX1701
Note Operating voltage. Since regulator bootstrapped output, once started will operate down 0.7V input. Note Start-up tested with circuit Figure Note low-power mode (CLK/SEL GND), output voltage regulates higher than low-noise mode (CLK/SEL synchronized). Note regulator start-up mode until this voltage reached. apply full load current. Note Load regulation measured from no-load full load where full load determined N-channel switch current limit. Note Supply current from 3.30V output measured between 3.30V output pin. This current correlates directly actual battery supply current, reduced value according step-up ratio efficiency. VOUT 3.6V keep internal switch open when measuring current into device. Note have hysteresis approximately 0.15xVOUT. Note Specifications -40°C guaranteed design production tested.
Typical Operating Characteristics
+25°C, unless otherwise noted.)
MAX1701 SHUTDOWN CURRENT INPUT VOLTAGE
MAX1700-02 MAX1770-03
EFFICIENCY LOAD CURRENT (VOUT 3.3V)
MAX1700-01
EFFICIENCY LOAD CURRENT (VOUT
3.6V 1.2V 2.4V SHUTDOWN CURRENT (µA) 1000
EFFICIENCY 1.2V 2.4V
25°C
EFFICIENCY
85°C
0.9V 1000
-40°C
LOAD CURRENT (mA)
LOAD CURRENT (mA)
INPUT VOLTAGE
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
Typical Operating Characteristics (continued)
+25°C, unless otherwise noted.)
REFERENCE VOLTAGE TEMPERATURE
MAX1700-04
REFERENCE VOLTAGE REFERENCE CURRENT
MAX1700-05
FREQUENCY TEMPERATURE
FREQUENCY (kHz) VOUT 3.3V VOUT
MAX1700-06
1.254
1.254
REFERENCE VOLTAGE
1.250
REFERENCE VOLTAGE
1.252
1.252
1.250
1.248
1.248
1.246
1.246
1.244 TEMPERATURE (°C)
1.244 REFERENCE CURRENT (µA)
TEMPERATURE (°C)
START-UP INPUT VOLTAGE OUTPUT CURRENT
MAX1700/01 TOC06a
PEAK INDUCTOR CURRENT OUTPUT VOLTAGE
MAX1700-08
START-UP INPUT VOLTAGE 0.01 NO-LOAD START-UP: 1.0V -40°C 0.79 +25°C 0.64V +85°C CONSTANT-CURRENT LOAD VOUT 3.3V 10µH MBR0520L -40°C +25°C +85°C
CURRENT LIMIT
1000
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE
HEAVY-LOAD SWITCHING WAVEFORMS (VOUT 3.3V)
MAX1700-08
LINE-TRANSIENT RESPONSE
MAX1700-09
VOUT
1µs/div 1.1V, IOUT 200mA, VOUT 3.3V VOLTAGE, 2V/div INDUCTOR CURRENT, 0.5A/div VOUT RIPPLE, 50mV/div, COUPLED IOUT 0mA, VOUT 3.3V
5ms/div VIN, 1.1V 2.1V, 1V/div VOUT RIPPLE, 50mV/div, COUPLED
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
Typical Operating Characteristics (continued)
(Circuit Figure +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
MAX1700-10
MAX1700/MAX1701
POWER-ON DELAY (PFM MODE)
MAX1700-11
3.3V 200mA
2ms/div 1.1V, VOUT 3.3V LOAD CURRENT, 200mA, 0.2A/div VOUT RIPPLE, 50mV/div, COUPLED
5ms/div VON1, 2V/div VOUT, 1V/div INPUT CURRENT, 0.2A/div
LOAD-TRANSIENT RESPONSE
MAX1700-12
DECT LOAD-TRANSIENT RESPONSE
MAX1700-13
3.3V
1ms/div 3.6V, VOUT COUT 440µF VOUT RIPPLE, 200mV/div, COUPLED LOAD CURRENT, 100mA 0.5A/div, PULSE WIDTH 577µs
2ms/div 1.2V, VOUT 3.3V, COUT 440µF VOUT RIPPLE, 200mV/div, COUPLED LOAD CURRENT, 50mA 400mA, 0.2A/div, PULSE WIDTH 416µs
NOISE SPECTRUM (VOUT 3.3V, 1.2V, RLOAD
MAX1700-14
NOISE (mVRMS) 0.1k FREQUENCY (Hz) 100k
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
Description
MAX1700 MAX1701 Low-Battery Comparator Non-Inverting Input Low-Battery Comparator Inverting Input Reference Output. Bypass with 0.22µF capacitor GND. source 50µA. Switching-Mode Selection External-Clock Synchronization Inputs. CLK/SEL=Low: Low-power, delivers full load current. CLK/SEL=High: High-power mode. Full output power available. Operates low-noise, constant-frequency mode. CLK/SEL=External Clock: High-power mode with internal oscillator synchronized external clock. Turning with CLK/SEL=0V also serves soft-start function since peak inductor current limited that allowed mode. Ground Power-Okay Comparator Output. Open drain N-channel output when VOUT below regulation point. internal delay provided. Shutdown Input. When =high ONA=low, load connected battery through Schottky diode. Turn Input. When ONA=high =low, turns Gain Block Output. This open-drain output sinks when VAIN <VREF. Gain Block input. When low, sinks current. transconductance from 9mmhos. DC-DC Converter Dual-Mode Feedback Input. fixed output voltage +3.3V, connect GND. adjustable output, connect divider between POUT output voltage range 2.5V Source N-Channel Power MOSFET Switch. Connect high-current ground path. Drain P-Channel Synchronous Rectifier N-Channel Switch Output Sense Input. Power source Source P-Channel Synchronous Rectifier MOSFET Switch. Connect external Schottky diode from POUT. Low-Battery Comparator Output. Open-drain N-channel output when Input hysteresis 15mV. Internal Connection. Leave open connect GND. NAME FUNCTION
CLK/SEL
PGND POUT I.C.
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
2.25V START-UP OSCILLATOR PFM/PWM CONTROLLER 0.25 POUT UNDERVOLTAGE LOCKOUT
CLK/SEL FEEDBACK POWER-GOOD SELECT 1.25V REFERENCE OSCILLATOR 300kHz FEEDBACK PFM/PWM MODE 0.13 PGND POK*
AIN* GAIN BLOCK LBP* COMPARATOR LBN*
LBO*
*MAX1701 ONLY
Figure Functional Diagram
_Detailed Description
MAX1700/MAX1701 highly efficient, low-noise power supplies portable data acquisition instruments. MAX1700 combines boost switching regulator, N-channel power MOSFET, P-channel synchronous rectifier, precision reference, shutdown control. MAX1701 contains MAX1700 features plus versatile gain amplifier, output, low-battery comparator (Figure MAX1700/ MAX1701 come 16-pin QSOP package, which occupies more space than 8-pin switching DC-DC converter boosts 3-cell input adjustable output between 2.5V 5.5V. MAX1700/MAX1701 start from 1.1V input remain operational down 0.7V. These devices optimized cellular phones other applications requiring noise during full-
power operation, well low-quiescent current maximum battery life during standby shutdown modes. They feature constant-frequency (300kHz), lownoise operation with 800mA output capability. Table typical available output current. low-quiescent-current, low-power mode offers output 100mA reduces quiescent power consumption 200µW. shutdown mode, quiescent current further reduced just 3µA. Figure shows standard application circuit MAX1700/MAX1701. Additional features include synchronous rectification high efficiency improved battery life, output, uncommitted comparator low-battery detection (MAX1701). input allows frequency synchronization reduce interference. Dual shutdown controls allow shutdown using momentary pushbutton switch microprocessor control (MAX1701).
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
0.7V 5.5V
POUT
22µF 10µH MBR0520L
MAX1700 MAX1701
CLK/SEL
POUT 0.22µF 100µF 0.22µF
OUTPUT
0.22µF PGND FIXED OUTPUT (GND) ADJUSTABLE
1.3A CURRENT LIMIT
PGND
Figure Fixed Adjustable Output (PWM mode).
Figure Simplified Controller Block Diagram
Table Typical Available Output Current
NUMBER CELLS NiCd/NiMH NiCd/NiMH NiCd/NiMH NiCd/NiMH Li-Ion INPUT OUTPUT OUTPUT VOLTAGE VOLTAGE CURRENT (mA)
output filter capacitor load. energy stored inductor depleted, current ramps down output diode synchronous rectifier turn off. Voltage across load regulated using either low-noise low-power operation, depending CLK/SEL setting (Table
Table Selecting Operating Mode
CLK/SEL External Clock (200kHz 400kHz) MODE Power Synchronized FEATURES supply current noise, high output current noise, high output current
Low-Noise Operation When CLK/SEL pulled high, MAX1700/MAX1701 operate higher power, low-noise pulse-widthmodulation (PWM) mode. During operation, they switch constant frequency (300kHz) then modulate MOSFET switch pulse width control power transferred cycle regulate voltage across load. mode devices output 800mA. Switching harmonics generated fixedfrequency operation consistent easily filtered. Noise Spectrum Plot Typical Operating Characteristics.
During operation, each rising edge internal clock sets flip-flop, which turns N-channel MOSFET switch (Figure switch turned when voltage-error, slope compensation, current-feedback signals trips multi-input comparator resets flip-flop; switch remains rest cycle. When change occurs output-voltage error signal into comparator, shifts level which inductor current allowed ramp during each cycle modulates MOSFET switch pulse width. second comparator enforces inductor current limit 1.6A max.
Step-Up Converter
step-up switching DC-DC converter generates adjustable output from 2.5V 5.5V. During first part each cycle, internal N-channel MOSFET switch turned This allows current ramp inductor store energy magnetic field. During second part each cycle, when MOSFET turned off, voltage across inductor reverses forces current through diode synchronous rectifier
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
ERROR COMPARATOR 400mA CURRENT LIMIT LOGIC HIGH POUT
rectifier current ramped down 70mA. This forces operation with discontinuous inductor current.
MAX1700/MAX1701
Synchronous Rectifier MAX1700/MAX1701 feature internal 250m, Pchannel synchronous rectifier enhance efficiency. Synchronous rectification provides efficiency improvement over similar nonsynchronous boost regulators. mode, synchronous rectifier turned during second half each switching cycle. low-power mode, internal comparator turns synchronous rectifier when voltage exceeds boost-regulator output then turns when inductor current drops below 70mA.
Low-Voltage Start-Up Oscillator
PGND
Figure Controller Block Diagram Low-Power Mode
Synchronized Operation applying external clock CLK/SEL, MAX1700/MAX1701 also synchronized mode frequency between 200kHz 400kHz. This allows user harmonics avoid bands wireless applications. synchronous rectifier also active during synchronized operation. Low-Power Operation Pulling CLK/SEL places MAX1700/MAX1701 low-power mode. During low-power mode, operation regulates output voltage transferring fixed amount energy during each cycle then modulating switching frequency control power delivered output. devices switch only needed service load, resulting highest possible efficiency light loads. Output current capability mode 100mA. output voltage typically higher than output voltage mode. During operation, error comparator detects output voltage falling regulation sets flipflop, turning N-channel MOSFET switch (Figure When inductor current ramps mode current limit (400mA typical) stores fixed amount energy, current-sense comparator resets flipflop. flip-flop turns N-channel switch turns P-channel synchronous rectifier. second flip-flop, previously reset switch's "on" signal, inhibits error comparator from initiating another cycle until energy stored inductor transferred output filter capacitor synchronous
MAX1700/MAX1701 CMOS, low-voltage start-up oscillator 1.1V guaranteed minimum startup input voltage +25°C. start-up, low-voltage oscillator switches N-channel MOSFET until output voltage reaches 2.15V. Above this level, normal boost-converter feedback control circuitry take over. Once device regulation, operate down 0.7V input since internal power bootstrapped from output using pin. apply full load until output exceeds 2.4V.
Table On/Off Logic Control
Status
Shutdown
MAX1700/MAX1701 shut down reduce quiescent current typically 3µA. During shutdown, reference, low-battery comparator, gain block, feedback control circuitry off. boost converter's output drops Schottky diode drop below input. Table shows control logic with ONB. Both inputs have trip points near 0.5V with 0.15VOUT hysteresis.
Low-Battery Comparator (MAX1701)
internal low-battery comparator uncommitted inputs open-drain output (LBO) capable sinking 1mA. low-battery-detection comparator, connect input reference, connect input external resistor divider
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
0.7V 5.5V
POUT
MAX1701
MAX1701
CLK/SEL
POUT 0.22µF VOLTAGE MONITOR LOW-BATTERY MONITOR ARBITRARY VOLTAGE MONITOR 0.22µF
0.22µF
ARBITRARY VOLTAGE
BATTERY VOLTAGE
PGND
Figure Detecting Battery Voltages Below 1.25V (MAX1701)
OUTPUT
Figure Detecting Battery Voltage Above 1.25V
270k
POUT
POUT
MAX1701
0.22µF
MAX1701
0.22µF
Figure Using Low-Battery Comparator Load Control During Start-Up
Figure Using Low-Battery Comparator Sense Output Voltage (MAX1701)
between positive battery terminal (Figure resistor values then calculated follows: R4(VTH/VLBN where desired input voltage trip threshold VLBN VREF 1.25V. Since input bias current into less than 20nA, large value (such 270k less) without sacrificing accuracy. inputs have common-mode input range from 0.5V 1.5V input-referred hysteresis 15mV. low-battery comparator also used monitor output voltage, shown Figure low-battery threshold voltage below 1.25V reference, insert resistor divider between
connect battery input through current-limiting resistor (Figure equation setting resistors low-battery threshold then follows: R6(VREF/VLBP where VLBP desired voltage threshold. Figures goes low-voltage input. low-battery comparator used check output voltage control load directly POUT during start-up (Figure following equation resistor values: R4(VOUTTH/VLBP where VOUTTH desired output-voltage trip point VLBP connected reference 1.25V.
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
Reference
MAX1700/MAX1701 have internal 1.250V, bandgap reference. Connect 0.22µF bypass capacitor within 0.2in. (5mm) pin. source 50µA external load current.
Gain Block (MAX1701)
MAX1701's gain block function third comparator used build linear regulator using external P-channel MOSFET pass device. gainblock output single-stage transconductance amplifier that drives open-drain N-channel MOSFET. Figure shows gain block used linear regulator. output external P-channel pass element compared internal reference. difference amplified used drive gate pass element. logic-level PFET such Fairchild NDS336P (RDS(ON) 270m PFET RDS(ON) less than 250m, linear regulator output filter capacitance need increased above 47µF.
MAX1700/MAX1701
Power-OK (MAX1701)
MAX1701 features power-good comparator. This comparator's open-drain output (POK) pulled when output voltage falls below regulation point.
100µF
_Design Procedure
47µF
MAX1701
Setting Output Voltages
output voltage between 2.5V 5.5V connecting resistor voltage-divider from GND, shown Figure resistor values then follows: (VOUT/VFB
Figure Using Gain Block Linear Regulator
where VFB, boost-regulator feedback setpoint, 1.23V. Since input bias current into less than 20nA, have large value (such 270k less) without sacrificing accuracy. Connect resistor voltage-divider close possible, within 0.2in. (5mm) pin.
Table Component Suppliers
SUPPLIER Coilcraft Matsuo Motorola Sanyo Sumida PHONE USA: (803) 946-0690 (800) 282-4975 USA: (847) 639-6400 USA: (714) 969-2491 USA: (602) 303-5454 USA: (619) 661-6835 Japan: 81-7-2070-6306 USA: (847) 956-0666 Japan: 81-3-3607-5111 (803) 626-3123 (847) 639-1469 (714) 960-6492 (602) 994-6430 (619) 661-1055 81-7-2070-1174 (847) 956-0702 81-3-3607-5144
Inductor Selection
MAX1700/MAX1701's high switching frequency allows small surface-mount inductor. 10µH inductor should have saturation-current rating that exceeds N-channel switch current limit 1.6A. However, generally acceptable bias inductor current into saturation much 20%, although this will slightly reduce efficiency. high efficiency, choose inductor with high-frequency core material (such ferrite) reduce core losses. minimize radiated noise, toroid, core, shielded bobbin inductor. Connect inductor from battery close possible. Table list component suppliers Table suggested components.
CAPACITORS Matsuo series Sprague 595D series series Sanyo OS-CON series Nichicon series DIODES Motorola MBR0520L 1N5817
Table Component Selection Guide
PRODUCTION Surface Mount Through Hole INDUCTORS Sumida CDR63B, CD73, CDR73B, CD74B series Coilcraft DO1608, DO3308, DT3316 series Sumida RCH654 series
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
POUT
270k
MAX1701
ON/OFF
MAX1700
MAX8865/MAX8866 DUAL MAX8863/MAX8864 SINGLE LOW-DROPOUT LINEAR REGULATORS
0.1µF
270k RADIO
Figure Momentary Pushbutton On/Off Switch
Figure Typical Phone Application
Output Diode
Schottky diode, such 1N5817, MBR0520L, equivalent. Schottky diode carries current during start-up, mode after synchronous rectifier turns off. Thus, current rating only needs 500mA. Connect diode between POUT close possible. ordinary rectifier diodes since slow switching speeds long reverse recovery times will compromise efficiency load regulation.
exceed ripple current ratings tantalum capacitors. Avoid most aluminum-electrolytic capacitors, since their often high.
Bypass Capacitors
ceramic bypass capacitors required proper operation. Bypass with 0.22µF capacitor GND. Also connect 0.22µF ceramic capacitor from GND. Each should placed close their respective pins possible, within 0.2in. (5mm) DC-DC converter Table suggested suppliers.
Input Output Filter Capacitors
Choose input output filter capacitors that will service input output peak currents with acceptable voltage ripple. Choose input capacitors with working voltage ratings over maximum input voltage, output capacitors with working voltage ratings higher than output. full output, 100µF, 100m, low-ESR tantalum output filter capacitors recommended. loads below 250mA, single 100µF output capacitor will suffice. input filter capacitor (CIN) reduces peak currents drawn from input source reduces input switching noise. input voltage source impedance determines required size input capacitor. When operating directly from NiCd cells placed close MAX1700/MAX1701, 22µF, low-ESR input filter capacitor. When operating from power source placed farther away, from higher impedance batteries such alkaline lithium cells, 100µF, 100m, low-ESR tantalum capacitors. Sanyo OS-CON Panasonic SP/CB-series ceramic capacitors offer lowest ESR. Low-ESR tantalum capacitors good choice generally offer good tradeoff between price performance.
_Applications Information
Push-On/Push-Off Control
momentary pushbutton switch used turn MAX1700/MAX1701 off. Figure pulled pulled high when part off. When momentary switch pressed, pulled regulator turns switch must pressed long enough microcontroller exit reset (200ms) drive high. small capacitor added help debounce switch. controller issues logic high ONA, which holds part regardless switch state. turn regulator off, press switch again, allowing controller read switch status pull low. When switch released, pulled high.
Typical Wireless Phone Application
MAX1700/MAX1701 ideal digital cordless phones. power amplifier (PA) connected directly boost-converter output maximum voltage swing (Figure 11). Low-dropout linear regulators used post-regulation generate
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters
low-noise power DSP, control, circuitry. Typically, phones spend most their life standby mode with only short periods transmit/receive mode. During standby, maximize battery life setting CLK/SEL this places low-power mode (for lowest quiescent power consumption).
Soft-Start
implement soft-start, CLK/SEL power-up; this forces low-power operation reduces peak switching current 550mA max. Once circuit regulation start-up transients have settled, CLK/SEL high full-power operation.
MAX1700/MAX1701
Designing Board
High switching frequencies large peak currents make board layout important part design. Poor design cause excessive groundbounce, both which cause instability regulation errors corrupting voltage current feedback signals. Power components (such inductor, converter filter capacitors, output diode) should placed close together possible, their traces should kept short, direct, wide. separate low-noise ground plane containing reference signal grounds should only connect power-ground plane point. This minimizes effect powerground currents part. Consult MAX1701 manual layout example. multilayer boards, connect ground pins power components using vias through internal ground plane. Instead, place them close together route them star-ground configuration using component-side copper. Then vias connect star ground internal ground plane. Keep voltage feedback network very close within 0.2in. (5mm) pins. Keep noisy traces, such from pin, away from voltage feedback networks. Separate them with grounded copper. Consult MAX1700 evaluation full board example.
Intermittent Supply/Battery Connections
When boosting input supply connected with mechanical switch, battery connected with spring contacts, input power sometimes intermittent result contact bounce. When operating mode with input voltages greater than 2.5V, restarting after such dropouts initiate high current pulses that interfere with MAX1700/MAX1701 internal MOSFET switch control. contact switch bounce anticipated design, following solutions. Connect capacitor (CONB) from VIN, resistor (RONB) from GND, (Figure 12). This network differentiates fast input edges momentarily holds until settles. appropriate value CONB 10-5 times total output filter capacitance (COUT), COUT 200µF results CONB 2nF. system microcontroller hold MAX1700/MAX1701 shut down from time when power applied reapplied) until output capacitance (COUT) charged least input voltage. Power-on reset times tens milliseconds accomplish this. Ensure that operates, least powers mode (CLK/SEL high). Activate mode only after VOUT settled system's poweron reset flags cleared.
Configurations (continued)
VIEW
CLK/SEL POUT RONB CONB COUT 200µF
MAX1701
PGND
MAX1700 MAX1701
POUT
QSOP
Figure Connecting CONB RONB when Switch Battery-Contact Bounce Anticipated
1-Cell 3-Cell, High-Power (1A), Low-Noise, Step-Up DC-DC Converters MAX1700/MAX1701
Chip Information
TRANSISTOR COUNT: SUBSTRATE CONNECTED
_Package Information
QSOP.EPS

ANUAL LUATIO SHEET FOLLO 1-Cell 3-Cell, High-Power (1A), Low-Nois

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