Document
19-1563; Rev 3; 9/05
KIT ATION EVALU LE B A IL A AV
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Low-Noise Step-Up DC-DC Converters
General Description Features
♦ 90% Efficiency ♦ Adjustable Output from VIN to 12V ♦ 1.6A, 0.21Ω, 14V Power MOSFET (MAX1790) ♦ 2.4A, 0.15Ω, 14V Power MOSFET (MAX8715) ♦ +2.6V to +5.5V Input Range ♦ Pin-Selectable 640kHz or 1.2MHz Switching Frequency ♦ 0.1µA Shutdown Current ♦ Programmable Soft-Start ♦ Small 8-Pin µMAX Package
MAX1790/MAX8715
The MAX1790/MAX8715 boost converters incorporate high-performance (at 1.2MHz), current-mode, fixed-frequency, pulse-width modulation (PWM) circuitry with a built-in 0.21Ω/0.15Ω n-channel MOSFET to provide a highly efficient regulator with fast response. High switching frequency (640kHz or 1.2MHz selectable) allows easy filtering and faster loop performance. An external compensation pin provides the user flexibility in determining loop dynamics, allowing the use of small, low equivalent-series-resistance (ESR) ceramic output capacitors. The device can produce an output voltage as high as 12V from an input as low as 2.6V. Soft-start is programmed with an external capacitor, which sets the input-current ramp rate. In shutdown mode, current consumption is reduced to 0.1µA. The MAX1790/ MAX8715 are available in a space-saving 8-pin µMAX® package. The ultra-small package and high switching frequency allow the total solution to be less than 1.1mm high.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Ordering Information
PART MAX1790EUA MAX1790EUA+ MAX8715EUA MAX8715EUA+ TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 8 µMAX 8 µMAX 8 µMAX 8 µMAX
Applications
LCD Displays PCMCIA Cards Portable Applications Hand-Held Devices
+ Denotes lead-free package.
Typical Operating Circuit
VIN 2.6V TO 5V
Pin Configuration
TOP VIEW
COMP
IN ON/OFF
SHDN
1 2 3
8 7
SS FREQ IN LX
VOUT LX
FB SHDN
MAX1790 MAX8715 FREQ GND
MAX1790 MAX8715
6 5
GND 4
μMAX
SS COMP
FB
________________________________________________________________ Maxim Integrated Products
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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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Low-Noise Step-Up DC-DC Converters MAX1790/MAX8715
ABSOLUTE MAXIMUM RATINGS
LX to GND ..............................................................-0.3V to +14V IN, SHDN, FREQ, FB to GND ................................-0.3V to +6.2V SS, COMP to GND .......................................-0.3V to (VIN + 0.3V) RMS LX Pin Current ..............................................................1.2A Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW Operating Temperature Range MAX1790EUA/MAX8715EUA ........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+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
(VIN = SHDN = 3V, FREQ = GND, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER Input Supply Range VIN Undervoltage Lockout SYMBOL VIN UVLO VIN rising, typical hysteresis is 40mV, LX remains off below this level MAX1790 Quiescent Current IIN MAX8715 Shutdown Supply Current ERROR AMPLIFIER Feedback Voltage FB Input Bias Current Feedback-Voltage Line Regulation Transconductance Voltage Gain OSCILLATOR Frequency Maximum Duty Cycle N-CHANNEL SWITCH Current Limit ILIM VFB = 1V, duty cycle = 65% (Note 1) MAX1790 MAX8715 VLX = 12V MAX1790 MAX8715 MAX1790 MAX8715 1.2 1.8 1.6 2.4 0.21 0.15 0.01 5 2.3 A 3.4 0.5 0.35 20 30 Ω µA fOSC DC FREQ = GND FREQ = IN FREQ = GND FREQ = IN 540 1000 79 640 1220 85 84 740 1500 92 kHz % gm AV VFB IFB Level to produce VCOMP = 1.24V VFB = 1.24V MAX1790 MAX8715 1.222 1.24 0 125 0.05 70 70 140 160 700 1.258 40 190 0.15 240 240 V nA %/V µS V/V IIN SHDN = GND VFB = 1.3V, not switching VFB = 1.0V, switching VFB = 1.3V, not switching VFB = 1.0V, switching CONDITIONS MIN 2.6 2.25 2.38 0.18 2 0.21 2.5 0.1 TYP MAX 5.5 2.52 0.35 5 0.35 5.0 10 µA mA UNITS V V
Level to produce VCOMP = 1.24V, 2.6V < VIN < 5.5V ΔI = 5µA MAX1790 MAX8715
On-Resistance Leakage Current
RON ILXOFF
2
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Low-Noise Step-Up DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)
(VIN = SHDN = 3V, FREQ = GND, TA = 0°C to +85°C, unless otherwise noted. T.