White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
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19-2526; 7/02
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
MAX1570 fractional charge pump drives five white LEDs with regulated constant current uniform intensity. MAX1570 maintains highest possible efficiency over full 1-cell lithium-ion (Li+) battery input voltage range utilizing 1x/1.5x fractional charge pump very-low-dropout current regulators. MAX1570 operates with 1MHz fixed-frequency switching, allowing tiny external components. regulation scheme optimized ensure input ripple. external resistor sets full-scale current, while digital inputs control on/off select between three levels brightness. pulse-width modulation (PWM) signal also used modulate brightness. MAX1570 available 16-pin Thin packaging (0.8mm height). 30mA/LED Drive Capability Proprietary 1x/1.5x Modes Ultra-High Efficiency Input Ripple Eliminates Ballast Resistors Digital Dimming Control 0.1µA Shutdown Current 2.7V 5.5V Supply Voltage Range Soft-Start Limits Inrush Current Thermal-Shutdown Protection External Inductor, Schottky, Zener Diode Required Tiny 16-Pin Thin Package
Features
Excellent 0.3% LED-to-LED Current Matching
MAX1570
Applications
White Backlighting Cell Phones Smart Phones Palmtop Computers Portable Players Digital Cameras Camcorders
Ordering Information
PART MAX1570ETE TEMP RANGE -40°C +85°C PIN-PACKAGE Thin
Configuration
LED5 PGND
ON/OFF DIMMING 2.7V 5.5V
Typical Operating Circuit
4.7µF
1x/1.5x REGULATING CHARGE PUMP
MAX1570
MAX1570
LED1 REFERENCE CONTROL LED2 LOW-DROPOUT CURRENT REGULATORS LED3 LED4 LED5 RSET PGND
LED4 LED3 LED2 LED1
THIN (4mm 4mm)
Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim/Dallas Direct! 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump MAX1570
ABSOLUTE MAXIMUM RATINGS
OUT, EN1, .-0.3V SET, LED1, LED2, LED3, LED4, LED5 .-0.3V (VIN 0.3V) PGND GND.-0.3 +0.3V C1N, .-0.3V (VIN C1P, .-0.3V greater (VOUT (VIN Short Circuit GND.Indefinite Continuous Power Dissipation +70°C) 16-Pin Thin (derate 16.9 mW/°C) .1349mW 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
(VIN 3.6V, PGND 1µF, COUT 4.7µF, +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER Operating Voltage Undervoltage Lockout Threshold Undervoltage Lockout Hysteresis Supply Current Shutdown Supply Current Soft-Start Done Time GND, ISET 33µA Bias Voltage Leakage Shutdown Current Range LED_ Current Ratio LED_ LED_ Current Matching Maximum LED_ Sink Current LED_ Dropout Voltage ILED/ISET, ISET 67µA, VLED_= ISET 67µA, VLED_= ISET 130µA, VLED_= ISET 33µA (Note ISET 67µA (Note ISET 100µA (Note LED1 Regulation Voltage (1.5x Mode) Leakage Shutdown Maximum Current Open-Loop Resistance Switching Frequency EN1, High Voltage EN1, Voltage EN1, Input Current 2.7V 5.5V 2.7V 5.5V 5.5V 0.01 1.00 GND, ISET 33µA GND, ISET 67µA ISET 100µA GND, GND, VLED_= 5.5V 3.4V, 3.9V mode (VIN VOUT)/IOUT 1.5x mode (1.5VIN VOUT)/IOUT 1.00 1.75 GND, ISET 67µA ISET 100µA GND, 5.5V, VSET 5.5V 0.01 1.00 0.190 0.380 0.570 1MHz switching, load rising falling CONDITIONS 2.25 2.45 0.200 0.400 0.600 0.01 0.210 0.420 0.630 1.00 2.60 UNITS
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
ELECTRICAL CHARACTERISTICS (continued)
(VIN 3.6V, PGND 1µF, COUT 4.7µF, +85°C, unless otherwise noted. Typical values +25°C.)
PARAMETER LED1 Dual ModeThreshold Thermal-Shutdown Threshold Thermal-Shutdown Hysteresis CONDITIONS UNITS
MAX1570
ELECTRICAL CHARACTERISTICS
(VIN 3.6V, PGND 1µF, COUT 4.7µF, -40°C +85°C, unless otherwise noted.) (Note
PARAMETER Operating Voltage Undervoltage Lockout Threshold Supply Current Shutdown Supply Current Bias Voltage Leakage Shutdown Current Range LED_ Current Ratio LED_ LED_ Current Matching Maximum LED_ Sink Current LED_ Dropout Voltage ILED/ISET, ISET 67µA, VLED_= ISET 67µA, VLED_= ISET 130µA, VLED_= ISET 33µA (Note ISET 67µA (Note ISET 100µA (Note LED1 Regulation Voltage (1.5x Mode) Leakage Shutdown Maximum Current Open-Loop Resistance EN1, High Voltage EN1, Voltage EN1, Input Current LED1 Dual Mode Threshold GND, ISET 33µA GND, ISET 67µA ISET 100µA GND, GND, VLED_= 5.5V 3.4V, 3.9V mode (VIN VOUT)/IOUT 1.5x mode (1.5VIN VOUT)/IOUT 2.7V 5.5V 2.7V 5.5V 5.5V 1.75 rising falling 1MHz switching, load GND, ISET 33µA GND, ISET 67µA ISET 100µA GND, 5.5V, VSET 5.5V 0.190 0.380 0.570 CONDITIONS 2.25 2.60 0.210 0.420 0.630 UNITS
Note Dropout voltage defined LED_ voltage which current sink into LED_ drops from value LED_ Note Dropout voltage defined LED_ voltage which current sink into LED_ drops from value LED_ Note Specifications -40°C guaranteed design production tested.
Dual Mode trademark Maxim Integrated Products, Inc.
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump MAX1570
Typical Operating Characteristics
(EN1 1µF, 1µF, COUT 4.7µF, RSET 9.09k, +25°C, unless otherwise noted.)
EFFICIENCY SUPPLY VOLTAGE LEDs)
MAX1570 toc01
SUPPLY POWER SUPPLY VOLTAGE LEDs)
SUPPLY POWER (mW) 10mA/LED, VIN, 5mA/LED, GND, 15mA/LED,
MAX1570 toc02
SUPPLY CURRENT SUPPLY VOLTAGE LEDs)
SUPPLY CURRENT (mA) 15mA/LED,
MAX1570 toc03
EFFICIENCY PLED/PSUPPLY 5mA/LED, GND, 15mA/LED, 10mA/LED, VIN,
10mA/LED, VIN, 5mA/LED, GND,
SUPPLY VOLTAGE
SUPPLY VOLTAGE
SUPPLY VOLTAGE
EFFICIENCY SUPPLY VOLTAGE LEDs)
MAX1570 toc04
SUPPLY POWER SUPPLY VOLTAGE LEDs)
MAX1570 toc05
SUPPLY CURRENT SUPPLY VOLTAGE LEDs)
MAX1570 toc06
EFFICIENCY PLED/PSUPPLY 5mA/LED, GND, 15mA/LED, 10mA/LED, VIN,
SUPPLY POWER (mW) 5mA/LED, GND, SUPPLY VOLTAGE 10mA/LED, VIN, 15mA/LED,
SUPPLY CURRENT (mA) 10mA/LED, VIN, 5mA/LED, GND, 15mA/LED,
SUPPLY VOLTAGE
SUPPLY VOLTAGE
EFFICIENCY CURRENT LEDs, 1kHz)
MAX1570 toc07
CURRENT DIMMING DUTY CYCLE INTO LEDs)
MAX1570 toc08
SUPPLY CURRENT SUPPLY VOLTAGE LEDs, LED1 OPEN 1.5X ONLY MODE)
MAX1570 toc09
EFFICIENCY PLED/PSUPPLY 3.9V
CURRENT (mA) fPWM 1kHz 3.3V
SUPPLY CURRENT (mA) 5mA/LED, GND, 15mA/LED,
10mA/LED, VIN,
DUTY CYCLE
CURRENT (mA)
SUPPLY VOLTAGE
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
Typical Operating Characteristics (continued)
(EN1 1µF, 1µF, COUT 4.7µF, RSET 9.09k, +25°C, unless otherwise noted.)
CURRENT TEMPERATURE (VIN 3.3V, RSET 7.5k)
MAX1570 toc11
MAX1570
CURRENT SUPPLY VOLTAGE
MAX1570 toc10
CURRENT RSET
MAX1570 toc12
CURRENT (mA) GND, VIN,
12.0 11.9 11.8 CURRENT (mA) 11.7 11.6 11.5 11.4 11.3 11.2 11.1 11.0 TEMPERATURE (°C)
CURRENT (mA)
10.0 RSET
12.5
15.0
SUPPLY VOLTAGE
TYPICAL OPERATING WAVEFORM MODE
MAX1570 toc13
TYPICAL OPERATING WAVEFORM 1.5X MODE (ILOAD 90mA, 3.6V)
MAX1570 toc14
STARTUP RESPONSE (VIN 3.3V) LEDs 15mA/LED)
MAX1570 toc15
AC-COUPLED 10mA/div AC-COUPLED 1mV/div VOUT AC-COUPLED 1mV/div
AC-COUPLED 10mA/div AC-COUPLED 20mV/div VOUT AC-COUPLED 5mV/div
50mA/div
VOUT 2V/div
2µs/div
400ns/div
400µs/div
DIMMING RESPONSE USING INTO
MAX1570 toc16
LINE-TRANSIENT RESPONSE
MAX1570 toc17
ILED 15mA 5mA/div
ILED 15mA 5mA/div
VOUT AC-COUPLED 500mV/div 2V/div 100µs/div 100µs/div
VOUT AC-COUPLED 500mV/div 3.6V 500mV/div
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump MAX1570
Description
NAME LED5 Transfer Capacitor Positive Connection Enable, Dimming Control Input control shutdown, current, current, full current (see Table1). Analog Ground. Connect directly exposed paddle underneath LED5 Cathode Connection. Current flowing into LED5 times current flowing SET. When using fewer than five LEDs, this left unconnected. LED5 high impedance during shutdown. LED4 Cathode Connection. Current flowing into LED4 times current flowing SET. When using fewer than five LEDs, this left unconnected. LED4 high impedance during shutdown. LED3 Cathode Connection. Current flowing into LED3 times current flowing SET. When using fewer than five LEDs, this left unconnected. LED3 high impedance during shutdown. LED2 Cathode Connection. Current flowing into LED2 times current flowing SET. When using fewer than five LEDs, this left unconnected. LED2 high impedance during shutdown. LED1 Cathode Connection Charge-Pump Feedback. Current flowing into LED1 times current flowing SET. charge pump regulates voltage LED1 various voltages depending upon status (see Table Grounding LED1 forces operate while LED2-LED5 regulate current VSET/RSET. LED1 high impedance during shutdown. Bias Current Input. current flowing programs bias current into each ILED_ ISET. VSET internally biased various voltages (see Table Connect resistor bias current VSET/RSET. high impedance during shutdown. Enable, Dimming Control Input control shutdown, current, current, full current (see Table Power Ground. Charge-pump switching current flows through this pin. Connect system ground close MAX1570 input bypass capacitor possible. Transfer Capacitor Negative Connection Supply Voltage Input. Bypass PGND with ceramic capacitor. input voltage range 2.7V 5.5V. high impedance during shutdown. Transfer Capacitor Positive Connection Charge-Pump Output. Bypass PGND with 4.7µF ceramic capacitor close possible. Connect anodes LEDs. high impedance during shutdown. Transfer Capacitor Negative Connection Exposed paddle. Connect GND. FUNCTION
LED4
LED3
LED2
LED1
PGND
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
Detailed Description
MAX1570 complete charge-pump buck/boost converter requiring only four small ceramic capacitors. MAX1570 utilizes proprietary 1x/1.5x fractional charge-pump topology drive five white LEDs with regulated constant current uniform intensity. MAX1570 operates with 1MHz fixed frequency. external resistor (RSET) programs full-scale current, while digital inputs control on/off provide brightness control.
Thermal Shutdown
MAX1570 includes thermal-limit circuit that shuts down about 160°C. Turn-on occurs after cools approximately 20°C.
MAX1570
Setting Output Current
controls bias current. Current flowing into LED1, LED2, LED3, LED4, LED5 times greater than current flowing SET. output current follows: ILED RSET where VSET 0.2V, 0.4V, 0.6V (depending upon EN2, Table RSET resistor connected between (see Typical Operating Circuit).
Output Regulation
MAX1570 operates charge-pump mode until just above dropout. Then MAX1570 switches 1.5x charge-pump mode regulate voltage LED1 maintain constant brightness even very battery voltages. Using this topology, there brightness change during 1x/1.5x switchover, which guarantees flicker display. switchover scheme hysteresis, minimizing operation less efficient 1.5x mode. mode produces almost ripple, while 1.5x mode regulates output voltage controlling rate which transfer capacitors charged. this way, switching frequency remains constant reduced input ripple stable noise spectrum.
Applications Information
Dimming Using
inputs digital 2-bit number control on/off, 1/3, 2/3, full current (see Table control voltage Adjusting voltage controls current (ISET) through resistor (RSET). Increasing VSET reducing RSET increases ISET, which then increases current (ILED_). charge-pump feedback threshold LED1 increased current increased prevent dropout current regulators while improving efficiency lower current settings. LED1 regulated 0.2V, 0.3V, 0.4V when adjusted 1/3, 2/3, full current, respectively (see Table higher threshold improves LED-to-LED current matching, while lower threshold improves efficiency allowing mode lower input voltages.
Soft-Start
MAX1570 includes soft-start circuitry limit inrush current turn-on. When starting with output voltage that near input voltage, output capacitor charged directly from input with ramped current source (with charge-pump action) until output voltage near input voltage. Once this occurs, charge pump determines 1.5x mode required. case mode, soft-start terminated normal operation begins. case 1.5x mode, soft-start operates until LED1 reaches regulation. case overload condition, soft-start repeats every 2.1ms. output shorted ground, output current limited MAX1570 fractionalswitching technique then device hits thermal shutdown once temperature reaches -160°C.
Dimming Using into
shutdown drive with signal. Current varied from full. waveforms Typical Operating Characteristics show response time dimming. keeps part eliminating soft-start delay that would impede control, allowing frequency 5kHz (Figure
True Shutdown Mode
When grounded, MAX1570 shutdown, charge pump examines whether input voltage greater than less than output voltage shorts transfer capacitor nodes either necessary. output high impedance either case.
Dimming Using Filtered-PWM Signal
high-frequency signal drive R-C-R filter (Figure duty cycle corresponds 20mA/LED, while 100% duty cycle corresponds 0mA/LED. frequencies above 5kHz, reduced.
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump MAX1570
Table Enable Input Modes
INPUT LOGIC LEVELS Shutdown mode VSET 200mV, LED1 threshold 200mV VSET 400mV, LED1 threshold 300mV VSET 600mV, LED1 threshold 400mV MODE CURRENT Full
Table Capacitor Selection
OUTPUT (mA) (µF) (µF) 0.22 0.47 (µF) 0.22 0.47 COUT (µF)
Table Capacitor Manufacturers
COMPONENT NAME COUT VALUE (µF) 0.47 0.22 MANUFACTURER Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden PART JMK107BJ105MA JMK212BJ475MG JMK107BJ105MA LMK107BJ474MA LMK107BJ224KA DESCRIPTION ±20%, 6.3V ceramic capacitor (0603) 4.7µF ±20%, 6.3V ceramic capacitor (0805) ±20%, 6.3V ceramic capacitor (0603) 0.47µF ±20%, ceramic capacitor (0603) 0.22µF ±10%, ceramic capacitor (0603)
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
Input Ripple
drivers, input ripple more important than output ripple. Input ripple depends source supply's impedance. Adding lowpass filter input further reduces input ripple. Figure shows C-R-C filter used reduce input ripple less than 2mVP-P when driving 75mA load. Alternately, increasing 2.2µF 4.7µF yields input ripple 17mVP-P 9mVP-P, respectively, with only small increase footprint. mode very input ripple.
Component Selection
Typical external component values shown Table Table Maximum power dissipation occurs around 4.2V 4.0V with maximum load current.
MAX1570
[((1.5
VOUT 120mA 324mW
Board Layout Routing
MAX1570 high-frequency switched-capacitor voltage regulator. best circuit performance, solid ground plane place COUT close MAX1570 possible. Also, place their ground tails close together. Connect PGND directly under exposed paddle, connect COUT close possible PGND. input supply connections should short; this possible, additional input supply filter capacitor (tantalum electrolytic) required. Refer MAX1570 good layout example.
higher voltages this device switches mode power dissipation lowered.
4.7µF 20mA/LED
14.3k INPUT 14.3k
MAX1570
LED1 LED2 LED3
LED4 LED5
RSET 9.09k
PGND
4.7µF
Figure Dimming Using Filtered-PWM Signal
4.7µF
INPUT
MAX1570
LED1 LED2 LED3
LED4 LED5 RSET PGND
2.2µF
2.2µF LED1 LED2 LED3 LED4 LED5
MAX1570
Figure Dimming Using Signal into
RSET PGND
Figure C-R-C Filter Reduces Input Ripple
Chip Information
TRANSISTOR COUNT: 3187
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump MAX1570
Package Information
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information, www.maxim-ic.com/packages.)
PACKAGE OUTLINE 12,16,20,24L THIN, 4x4x0.8
21-0139
White Current Regulator with 1x/1.5x High-Efficiency Charge Pump
Package Information (continued)
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information, www.maxim-ic.com/packages.)
MAX1570
PACKAGE OUTLINE 12,16,20,24L THIN, 4x4x0.8
21-0139
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 2002 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.
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