Document
19-2847; Rev 0; 4/03
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White LED 1x/1.5x Charge Pump in UCSP
General Description
The MAX1573 fractional charge pump drives up to four white LEDs with regulated constant current for uniform intensity. By utilizing proprietary adaptive 1x/1.5x modes and ultra-low-dropout current regulators, it maintains the highest possible efficiency over the full 1-cell Li+ battery input voltage range. The 1MHz fixedfrequency switching allows for tiny external components and the regulation scheme is optimized to ensure low EMI and low input ripple. An external resistor sets the full-scale LED current, while two digital inputs control on/off and select amongst three levels of brightness. A pulse-width modulation (PWM) signal can also be used to modulate LED brightness, requiring no additional components. The MAX1573 is available in the chip-scale package (UCSP™) (4 x 4 grid) to minimize PC board area. o Proprietary Adaptive 1x/1.5x Modes o High Efficiency (PLEDs/PBATT), Up to 92% o 2% LED Current Matching and Accuracy o 28mA/LED Drive Capability o Low Input Ripple and EMI o Eliminates Ballast Resistors o Logic or PWM Dimming Control o Low 0.1µA Shutdown Current o 2.7V to 5.5V Input Voltage Range o Soft-Start Limits Inrush Current o Output Overvoltage Protection o Thermal Shutdown Protection o No External Schottky Diode Required o Tiny 2.1mm x 2.1mm x 0.6mm UCSP Package
Features
MAX1573
Applications
Cell Phones, Smart Phones PDAs, Digital Cameras, Camcorders MP3 Players Other Handhelds with Color Displays
PART MAX1573EBE-T
Ordering Information
TEMP RANGE -40°C to +85°C PIN-PACKAGE 14 UCSP (4 x 4)
Typical Operating Circuit
1µF 1µF
Pin Configuration
TOP VIEW
1 2 3 4
VIN 2.7V TO 5.5V 1µF ON/OFF AND DIMMING CONTROL
C1N IN
C1P
C2N
C2P OUT 1µF
VOUT UP TO 4 LEDS
C1P A C2N B IN C C1N D
OUT
EN1
EN2
C2P
SET
EN1 EN2
MAX1573
LED1 LED2 LED3
LED4
LED2
SET GND RSET
LED4
GND
LED3
LED1
UCSP 4 ✕ 4 UCSP is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
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White LED 1x/1.5x Charge Pump in UCSP MAX1573
ABSOLUTE MAXIMUM RATINGS
IN, OUT, EN1, EN2 to GND ...................................-0.3V to +6.0V SET, LED1, LED2, LED3, LED4 to GND ......-0.3V to (VIN + 0.3V) C1N, C2N to GND ..........................................-0.3V to (VIN + 1V) C1P, C2P to GND ............................................-0.3V to greater of .............................................................(VOUT + 1V) or (VIN + 1V) OUT Short Circuit to GND ..........................................Continuous Continuous Power Dissipation (TA = +70°C) 14-Bump UCSP (derate 7.36mW/°C above +70°C) ....589mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°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
(VIN = VEN1 = VEN2 = 3.6V, CIN = C1 = C2 = COUT = 1µF, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER IN Operating Voltage Undervoltage Lockout Threshold Supply Current Shutdown Supply Current Soft-Start Completion Time SET Bias Voltage SET Leakage in Shutdown SET Current Range EN1 = EN2 = IN SET to LED_ Current Ratio (ILED/ISET) LED_ Current Accuracy LED_ Current Matching Maximum LED_ Sink Current LED_ Dropout Voltage LED_ Minimum Regulation Voltage (1.5x Mode) LED Leakage in Shutdown Maximum OUT Current Open-Loop OUT Resistance Switching Frequency EN1, EN2 Logic High Voltage EN1, EN2 Logic Low Voltage EN1, EN2 Input Current Thermal-Shutdown Threshold VIN = 2.7V to 5.5V VIN = 2.7V to 5.5V VEN_ = GND or 5.5V, TA = +25°C 20°C hysteresis 0.01 160 1.6 0.4 1 ISET = 60µA EN1 = IN, EN2 = GND EN1 = GND, EN2 = IN EN1 = EN2 = IN, RSET = 10kΩ, TA = 0°C to +85°C ISET = 60µA, TA = 0°C to +85°C (Note 2) ISET = 130µA, EN1 = EN2 = IN ISET = 87µA (Note 3) EN1 = EN2 = IN, ISET = 87µA EN1 = EN2 = GND, VLED = 5.5V, TA = +25°C VIN ≥ 3.4V, VOUT ≥ 3.9V, EN1 = EN2 = IN 1x mode (1 x VIN - VOUT) / IOUT 1.5x mode (1.5 x VIN - VOUT) / IOUT 1 120 1.5 10 100 25.9 EN1 = EN2 = GND, TA = +25°C 40 190 58 19.5 215 65 22 ±2.0 ±2.0 28 40 150 0.01 80 200 1 0.570 VIN rising or falling, 35mV hysteresis Switching, no load EN1 = EN2 = OUT = GND, TA = +25°C CONDITIONS MIN 2.7 2.25 2.45 2 0.1 2.1 0.6 0.01 0.630 1 130 245 74 25.0.