0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter Efficiency 0.7V 5.
|
|
|
Top Searches for this datasheet
19-1660; 1/01
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter
Efficiency 0.7V 5.5V Input Range 800mA Output Fixed 3.3V Output from 2.5V 5.5V) Synchronous Rectified Topology Low-Noise, Constant Frequency Operation (1MHz) 0.1µA Logic-Controlled Shutdown Synchronizable Switching Frequency Adjustable Current Limit Adjustable Soft-Start 10-Pin µMAX Package
General Description
MAX1760 high-efficiency, low-noise, step-up DC-DC converter intended battery-powered wireless applications. maintains exceptionally quiescent supply current (100µA) despite high 1MHz operating frequency. Small external components tiny 10-pin µMAX package make this device excellent choice small hand-held applications requiring longest possible battery life. MAX1760 uses synchronous-rectified pulsewidth-modulation (PWM) boost topology generate 2.5V 5.5V outputs from wide range input sources, such alkaline NiCd/NiMH cells single lithium-ion (Li+) cell. Maxim's proprietary IdleModecircuitry significantly improves efficiency light load currents while smoothly transitioning fixedfrequency operation higher load currents maintain excellent full-load efficiency. Low-noise, forced mode available applications requiring constant-frequency operation load currents. MAX1760 also synchronized external clock protect sensitive frequency bands communications equipment. Analog soft-start adjustable current limit permit optimization efficiency, external component size, output voltage ripple.
PART
MAX1760
Ordering Information
TEMP. RANGE -40°C +85°C PIN-PACKAGE µMAX MAX1760EUB
Applications
Digital Cordless Phones Wireless Handsets Palmtop Computers Two-Way Pagers Phones Hand-Held Instruments Personal Communicators
Typical Operating Circuit
VIEW
INPUT 0.7V VOUT
Configuration
MAX1760 POUT VOUT 3.3V, 800mA
ISET POUT PGND CLK/SEL
CLK/SEL
MAX1760
ISET PGND
µMAX
Idle Mode trademark Maxim Integrated Products. Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim/Dallas Direct! 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
ABSOLUTE MAXIMUM RATINGS
OUT, CLK/SEL .-0.3V PGND GND.±0.3V PGND .-0.3V (VPOUT 0.3V) POUT .±0.3V REF, ISET, POUT GND.-0.3V (VOUT 0.3V) Continuous Power Dissipation +70°C) 10-Pin µMAX (derate 5.6mW/°C above +70°C) .444mW Operating Temperature Range .-40°C +85°C Junction Temperature .+150°C Storage Temperature Range .-65°C +150°C Lead Temperature (soldering, 10s) .+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, ISET REF, POUT, VOUT 3.6V, +85°C. Typical values +25°C, unless otherwise noted.)
PARAMETER DC-DC CONVERTER Input Voltage Range (Note Minimum Startup Voltage (Note Temperature Coefficient Startup Voltage Frequency Startup Mode Internal Oscillator Frequency Oscillator Maximum Duty Cycle (Note External Clock Frequency Range Output Voltage Regulation Voltage Input Leakage Current Load Regulation Output Voltage Adjust Range Output Voltage Lockout Threshold (Note ISET Input Leakage Current Supply Current Shutdown No-Load Supply Current (Note No-Load Supply Current Forced Mode DC-DC SWITCHES POUT Leakage Current Leakage Current Switch On-Resistance N-Channel Current Limit P-Channel Turn-Off Current CLK/SEL VOUT 5.5V VOUT 5.5V N-channel P-channel 0.15 0.25 1.25 0.28 0.45 Rising edge VISET 1.25V 3.6V CLK/SEL CLK/SEL 0.1V, CLK/SEL OUT, includes load regulation 0.55A Adjustable output, CLK/SEL OUT, includes load regulation 0.55A 1.35V CLK/SEL OUT, load full load 1.0A) 2.00 2.15 ±0.01 ILOAD 1mA, +25°C ILOAD VOUT 1.5V CLK/SEL 3.17 1.215 1.240 0.01 -1.5 2.30 -2.3 1000 3.38 1.270 mV/°C CONDITIONS UNITS
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL PGND GND, ISET REF, POUT, VOUT 3.6V, +85°C. Typical values +25°C unless otherwise noted.)
PARAMETER REFERENCES Reference Output Voltage Reference Load Regulation Reference Supply Rejection LOGIC INPUTS CLK/SEL Input Level CLK/SEL Input High Level Input Level (Note 2.5V VOUT 5.5V 2.5V VOUT 5.5V 1.1V VOUT 1.8V 1.8V VOUT 5.5V 1.1V VOUT 1.8V 1.8V VOUT 5.5V Input Leakage Current Minimum CLK/SEL Pulse Width Maximum CLK/SEL Rise/Fall Time CLK/SEL, VOUT 0.01 (0.8)VOUT (0.2)VOUT IREF -1µA IREF 50µA 2.5V VOUT 1.230 1.250 1.270 CONDITIONS UNITS
MAX1760
Input High Level (Note
ELECTRICAL CHARACTERISTICS
(CLK/SEL PGND GND, ISET REF, POUT, VOUT 3.6V, -40°C +85°C, unless otherwise noted.) (Note
PARAMETER DC-DC CONVERTER Output Voltage Regulation Voltage Internal Oscillator Frequency Oscillator Maximum Duty Cycle (Note Output Voltage Lockout Threshold (Note Supply Current Shutdown No-Load Supply Current (Note DC-DC SWITCHES Switch On-Resistance N-Channel Current Limit REFERENCE Reference Output Voltage IREF 1.230 1.270 N-channel P-channel 0.28 0.45 Rising edge 3.6V CLK/SEL 0.1V, CLK/SEL OUT, includes load regulation 0.55A Adjustable output, CLK/SEL OUT, includes load regulation 0.55A CLK/SEL 3.17 1.215 0.75 2.00 3.38 1.270 2.30 CONDITIONS UNITS
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL PGND GND, ISET REF, POUT, VOUT 3.6V, -40°C +85°C, unless otherwise noted.) (Note
PARAMETER LOGIC INPUTS CLK/SEL Input Level CLK/SEL Input High Level Input Level (Note Input High Level (Note Input Leakage Current 2.5V VOUT 5.5V 2.5V VOUT 5.5V 1.1V VOUT 1.8V 1.8V VOUT 5.5V 1.1V VOUT 1.8V 1.8V VOUT 5.5V CLK/SEL, VOUT (0.8)VOUT (0.2)VOUT CONDITIONS UNITS
Note Operating voltage-since regulator bootstrapped output, once started MAX1760 will operate down 0.7V input. Note Startup tested with circuit shown Figure Note Defines maximum step-up ratio. Note regulator startup mode until this voltage reached. apply full load current until output exceeds 2.3V. Note Supply current into pin. This current correlates directly actual battery-supply current, reduced value according step-up ratio efficiency. Note hysteresis approximately 0.15 VOUT. Note Specifications -40°C guaranteed design production tested.
Typical Operating Characteristics
(Circuit Figure 2.4V, VOUT 3.3V, +25°C, unless otherwise noted.)
EFFICIENCY OUTPUT CURRENT VOUT 3.3V
MAX1760 toc01
EFFICIENCY OUTPUT CURRENT VOUT
EFFICIENCY 0.0001 0.001 AUTO MODE FPWM MODE 3.6V 2.4V 1.2V 0.01
MAX1760-02
MAXIMUM OUTPUT CURRENT INPUT VOLTAGE
OUTPUT CURRENT VOUT VOUT 3.3V
MAX1760-03
EFFICIENCY 0.0001 0.001
AUTO MODE FPWM MODE 2.4V 1.2V 0.9V 0.01
OUTPUT CURRENT
OUTPUT CURRENT
INPUT VOLTAGE
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter
Typical Operating Characteristics (continued)
(Circuit Figure 2.4V, VOUT 3.3V, +25°C, unless otherwise noted.)
NO-LOAD BATTERY CURRENT INPUT VOLTAGE
MAX1760-04
MAX1760
TOTAL SHUTDOWN CURRENT (ILX IOUT) INPUT VOLTAGE
MAX1760-05
INTERNAL OSCILLATOR FREQUENCY TEMPERATURE
1.15 1.10 FREQUENCY (MHz) 1.05 1.00 0.95 0.90 0.85 0.80
MAX1760-06
1.20
SHUTDOWN CURRENT (nA)
INPUT CURRENT (mA)
VOUT VOUT 3.3V INPUT VOLTAGE
INPUT VOLTAGE
0.75 TEMPERATURE (°C)
STARTUP VOLTAGE OUTPUT CURRENT
MAX1760-07
PEAK INDUCTOR CURRENT VISET
MAX1760-08
HEAVY-LOAD SWITCHING WAVEFORMS
MAX1760-09
STARTUP VOLTAGE
PEAK INDUCTOR CURRENT
+85°C +25°C -40°C
VISET PIN, 5V/div INDUCTOR CURRENT, 200mA/div OUTPUT RIPPLE, 50mV/div AC-COUPLED 400ns/div
CIRCUIT FIGURE 0.001 0.01
OUTPUT CURRENT
LIGHT-LOAD SWITCHING WAVEFORMS
MAX1760-10
LOAD-TRANSIENT RESPONSE
MAX1760-11
LINE-TRANSIENT RESPONSE
MAX1760-12
400ns/div PIN, 5V/div INDUCTOR CURRENT, 200mA/div OUTPUT RIPPLE, 50mV/div, AC-COUPLED
200ms/div 1.1V, VOUT 3.3V, IOUT 0.2A IOUT, 100mA/div VOUT, 50mV/div, AC-COUPLED
400µs/div 2.4V 1.4V, IOUT 70mA VIN, 1V/div VOUT, 5mA/div, AC-COUPLED
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
Typical Operating Characteristics (continued)
(Circuit Figure 2.4V, VOUT 3.3V, +25°C, unless otherwise noted.)
TURN-ON WAVEFORMS SOFT-START COMPONENTS
MAX1760-13 MAX1760-14
NOISE SPECTRUM
SOFT-START WAVEFORMS 500k, 0.1µF
MAX1760-15
NOISE (mVRMS)
FREQUENCY (MHz) 2ms/div 5V/div INPUT CURRENT, 500mA/div VOUT, 2V/div 2.00ms/div 5V/div INPUT CURRENT, 100mA/div VOUT, 2V/div
Description
NAME FUNCTION N-Channel Current-Limit Control. maximum current limit, connect REF. reduce current, supply voltage between means resistive voltage-divider. soft-start desired, connect capacitor from ISET GND. When high, VREF <80% nominal value, on-chip 100k switched resistor discharges this GND. 1.250V Voltage Reference Bypass. Connect 0.22µF ceramic bypass capacitor GND. 50µA external load current allowed. Ground. Connect PGND with short trace. DC-DC Converter Feedback Input. fixed output voltage +3.3V, connect ground. adjustable output 2.5V 5.5V, connect resistive divider from GND. point 1.24V. Power, Supplied from Output. Bypass with 0.68µF ceramic capacitor, connect POUT with series resistor (Figure Clock Input DC-DC Converter. Also serves program operating mode switcher follows: CLK/SEL Normal operation-operates fixed frequency, automatically switching low-power mode load minimized. CLK/SEL Forced mode-operates low-noise, constant-frequency mode loads. CLK/SEL Clocked: Forced mode with internal oscillator synchronized 500kHz 1200kHz range. Source N-Channel Power MOSFET Switch Inductor Connection Power Output. P-channel synchronous-rectifier source. Shutdown Control Input. When high, shutdown. Connect normal operation.
ISET
CLK/SEL
PGND POUT
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
POWER CONTROLLER 2.15V STARTUP OSCILLATOR POUT UNDERVOLTAGE LOCKOUT
1.25V
REFERENCE OSCILLATOR 1MHz CLK/SEL MODE
MODE PGND
CLK/SEL
ISET
ISET
MAX1760
Figure Functional Diagram
Detailed Description
MAX1760 highly efficient, low-noise power supply portable hand-held instruments. combines boost switching regulator, N-channel power MOSFET, P-channel synchronous rectifier, precision reference, shutdown control (Figure DC-DC converter boosts 1-cell 3-cell battery voltage input fixed 3.3V adjustable voltage between 2.5V 5.5V. external Schottky diode required output voltages greater than MAX1760 guarantees startup with input voltage 1.1V remains operational down input just 0.7V. optimized cellular phones other applications requiring noise quiescent current maximum battery life. features fixed-frequency operation medium heavy loads, light loads, switches only needed optimum efficiency. This device also capable constant-frequency (1MHz), low-noise operation load currents, frequency-synchronized operation when connected external clock. Table lists some typical outputs. Shutdown reduces quiescent current just 1µA. Figure shows standard application circuit MAX1760.
3.3µH 2.4V 33µF CLK/SEL MAX1760 ISET 0.22µF PGND 0.68µF POUT VOUT 3.3V, 800mA 100µF
Figure Standard Application Circuit
Step-Up Converter
During DC-DC converter operation, internal N-channel MOSFET switch turns first part each cycle, allowing current ramp inductor store energy magnetic field. During second part each cycle, MOSFET turns inductor current flows through synchronous rectifier
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
Table Typical Available Output Current
NUMBER NiCd/NiMH CELLS INPUT VOLTAGE OUTPUT VOLTAGE OUTPUT CURRENT (mA)
Table Selecting Operating Mode
CLK/SEL External Clock 500kHz 1.2MHz MODE Normal Operation Forced Synchronized FEATURES High efficiency loads. Fixed frequency light loads. noise, fixed frequency loads. noise, fixed frequency loads.
output filter capacitor load. energy stored inductor depleted, current ramps down synchronous rectifier turns off. light loads, device operates fixed frequency only needed maintain regulation, depending CLK/SEL setting (Table
Synchronous Rectifier
MAX1760 features internal, P-channel synchronous rectifier enhance efficiency. Synchronous rectification provides improved efficiency 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, turns when inductor current drops below 60mA. When setting output voltages greater than external 0.5A Schottky diode must connected parallel with on-chip synchronous rectifier.
Normal Operation
Pulling CLK/SEL selects MAX1760's normal operating mode. this mode, device operates when driving medium-to-heavy loads, automatically switches load requires less power. operation allows higher efficiency than under light load conditions.
Forced Operation
When CLK/SEL high, MAX1760 operates lownoise PWM-only mode. During forced operation, MAX1760 switches constant frequency (1MHz), modulates MOSFET switch pulse width control power transferred cycle regulate output voltage. Switching harmonics generated fixed-frequency operation consistent easily filtered. Noise Spectrum plot Typical Operating Characteristics.
Low-Voltage Startup Oscillator
MAX1760 uses CMOS, low-voltage startup oscillator 1.1V guaranteed minimum startup input voltage. startup, 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 through OUT. apply full load until output exceeds 2.3V.
Synchronized Operation
MAX1760 synchronized mode external frequency 500kHz 1.2MHz applying external clock signal CLK/SEL. This allows interference minimized wireless applications. synchronous rectifier active during synchronized operation.
Shutdown
MAX1760 shutdown mode that reduces quiescent current 0.1µA. During shutdown high), reference feedback control circuitry off. During shutdown, output voltage diode drop below input voltage.
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter
3.3µH 2.4V 33µF CLK/SEL MAX1760 ISET 0.22µF PGND POUT 0.68µF VOUT 100µF
MAX1760
VOUT
1.24V
Figure Connecting Resistors External Feedback
0.22µF ILIM 1.25A 0.22µF RSS1
ILIM 1.25A
RSS2
RSS1 RSS2
MAX1760
ISET
RSSCSS
MAX1760
ISET
(RSS1 RSS2)
470k
RSS2
RSS1 470k
Figure Soft-Start with Maximum Switch Limit Current
Figure Soft-Start with Reduced Switch Current Limit
Reference
MAX1760 internal 1.250V reference. Connect 0.22µF ceramic bypass capacitor from within 0.2in (5mm) pin. source 50µA external load current.
where VFB, boost-regulator feedback point, 1.24V.
Setting Switch Current Limit Soft-Start
ISET adjusts inductor current limit implements soft-start. With ISET connected REF, inductor current limits 1.25A. With ISET connected resistive divider from GND, current limit reduced according ILIM 1.25A ISET 1.25V Implement soft-start placing resistor from ISET capacitor from ISET GND. shutdown, ISET discharged through on-chip 100k resistor. power-up, ISET current zero. capacitor voltage rises, current increases output voltage rises. soft-start
Design Procedure
Setting Output Voltages
fixed 3.3V output, connect GND. other output voltages between 2.5V 5.5V, connect resistor voltage-divider from (Figure input bias current into <20nA, allowing large-value divider resistors without sacrificing accuracy. Connect resistor voltage-divider close possible, within 0.2in (5mm) Choose 270k less, then calculate using:
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
Table Component Selection Guide
PRODUCTION METHOD INDUCTORS Coilcraft DS3316P Coilcraft LPT3305 Surface Mount Sumida CDRH5D18 Sumida CD43 Sanyo POSCAP series CAPACITORS series Kemet T510 series DIODES series Motorola MBR0520L
Table Component Suppliers
SUPPLIER Coilcraft Kemet Motorola Sumida PHONE USA: 843-448-9411 USA: 847-639-6400 USA: 916-941-0712 USA: 810-287-2536 USA: 408-629-4789 Japan: 81-45-474-7030 USA: 847-956-0666 Japan: 011-81-3-3667-3302
External Diode
output voltages greater than external Schottky diode must connected from POUT, parallel with on-chip synchronous rectifier (Figure diode should rated 0.5A. Representative devices Motorola MBR0520L, Nihon EP05Q03L, generic 1N5817. This external diode also recommended applications that must start with input voltages below 1.8V. Schottky diode carries current during startup after synchronous rectifier turns off; thus, current rating only needs 500mA. Connect diode close possible. ordinary rectifier diodes; their slow switching speeds long reverse-recovery times render them unacceptable. circuits that require startup with inputs below 1.8V, have output less, external diode needed.
Note: Please indicate that using MAX1760 when contacting these component suppliers.
time constant where 470k. Placing capacitor across lower resistor current-limiting resistive divider provides both current-limit soft-start features simultaneously (Figures
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 volt-
Inductor Selection
MAX1760's high switching frequency allows small 3.3µH surface-mount inductor. chosen inductor should generally have saturation current rating exceeding N-channel switch current limit; however, acceptable bias inductor current into saturation much slight reduction efficiency acceptable. Lower current-rated inductors used ISET employed reduce peak inductor current (see Setting Switch Current Limit Soft-Start). high efficiency, choose inductor with high-frequency ferrite core material reduce core losses. minimize radiated noise, toroid shielded inductor. Table suggested components Table list component suppliers. Connect inductor from battery close possible.
0.7V VOUT 33µF CLK/SEL MAX1760 ISET 0.22µF PGND 0.68µF POUT MRB0520L VOUT 100µF 3.3µH
Figure Connection with External Schottky Diode Output Voltages Greater than Assist Low-Voltage Startup
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter
age, output capacitors with working voltage ratings higher than output. input filter capacitor reduces peak currents drawn from input source also reduces input switching noise. input voltage source impedance determines required value input capacitor. When operating directly from NiMH cells placed close MAX1760, single 33µF low-ESR input filter capacitor. With higher impedance batteries, such alkaline Li+, higher value input capacitor improve efficiency. output filter capacitor reduces output ripple voltage provides load with transient peak currents when necessary. output, 100µF, (ESR) capacitor recommended most applications. Sanyo POSCAP, Panasonic SP/CB, Kemet T510 good low-ESR capacitors. Low-ESR tantalum capacitors offer good tradeoff between price performance. exceed ripple current ratings tantalum capacitors. Avoid aluminum electrolytic capacitors; their high typically results higher output ripple voltage. bypass with 0.68µF ceramic capacitor, connect POUT with resistor. Each these components should placed close respective pins possible, within 0.2in (5mm). Table lists suggested suppliers.
MAX1760
Layout Considerations
High switching frequencies large peak currents make board layout critical part design. Poor design will cause excessive ground bounce, 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. Keep voltage feedback network very close within 0.2in (5mm) pin. Keep noisy traces, such those from pin, away from voltage feedback network guarded from them using grounded copper. Refer MAX1760 full board example.
Chip Information
TRANSISTOR COUNT: 1361
Other External Components
ceramic bypass capacitors required proper operation. Bypass with 0.22µF. Also,
0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter MAX1760
Package Information
10LUMAX.EPS
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600 2001 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.
Other recent searches
W9725G6JB - W9725G6JB W9725G6JB Datasheet
XKA20620 - XKA20620 XKA20620 Datasheet
2001 - 2001 2001 Datasheet
M28F101 - M28F101 M28F101 Datasheet
HY5DU56822E - HY5DU56822E HY5DU56822E Datasheet
HY5DU561622E - HY5DU561622E HY5DU561622E Datasheet
EE-30 - EE-30 EE-30 Datasheet
AT91SAM7S-EK - AT91SAM7S-EK AT91SAM7S-EK Datasheet
2SB514 - 2SB514 2SB514 Datasheet
2SD330 - 2SD330 2SD330 Datasheet
Privacy Policy | Disclaimer
© 2012 Datasheet Archive
