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Part: MAX1809ETI
Category:
Power Management
-> Battery Management
Description: MAX1809 3A, 1MHz, DDR Memory Termination Supply
Company: Maxim Integrated Products
Datasheet: Download MAX1809ETI datasheet File size : 750 kB
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Datasheet text preview:
19-2142; Rev 1; 9/02
3A, 1MHz, DDR Memory Termination Supply
General Description
The MAX1809 is a reversible energy flow, constant-offtime, pulse-width modulated (PWM), step-down DC-DC converter. It is ideal for use in notebook and subnoteb o o k computers that require 1.1V to 5V active termination power supplies. This device features an internal PMOS power switch and internal synchronous rectifier for high efficiency and reduced component c o u n t . The internal 90m P M O S power switch and 70m NMOS synchronous-rectifier switch easily deliver continuous load currents up to 3A. The MAX1809 accurately tracks an external reference voltage, produces an adjustable output from 1.1V to VIN, and achieves efficiencies as high as 93%. The MAX1809 uses a unique current-mode, constantoff-time, PWM control scheme that allows the output to source or sink current. This feature allows energy to return to the input power supply that otherwise would be wasted. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1809 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low-dropout operation, and a low-power shutd o w n mode that disables the power switches and reduces supply current below 1µA. The MAX1809 is available in a 28-pin QFN with an exposed backside pad, a 28-pin thin QFN, or a 16-pin QSOP. o Source/Sink 3A o ±1% Output Accuracy o Up to 1MHz Switching Frequency o 93% Efficiency o Internal PMOS/NMOS Switches 90m/70m On-Resistance at VIN = 4.5V 110m/80m On-Resistance at VIN = 3V o 1.1V to VIN Adjustable Output Voltage o 3V to 5.5V Input Voltage Range o <1µA Shutdown Supply Current o Programmable Constant-Off-Time Operation o Thermal Shutdown o Adjustable Soft-Start Inrush Current Limiting o Output Short-Circuit Protection
Features
MAX1809
Ordering Information
PART MAX1809EGI* MAX1809EEE MAX1809ETI TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 28 QFN 16 QSOP 28 Thin QFN
Applications
DDR Memory Termination Active Termination Buses
*Contact factory for availability.
Pin Configurations
SHDN N.C. LX LX
Typical Operating Circuit
VIN IN MAX1809 VCC SHDN VSET EXTREF TOFF REF SS LX PGND VOUT
TOP VIEW
28
N.C.
27
26
25
24
N.C.
23
N.C. IN LX IN
22
N.C.
1 2 3 4 5 6 7 10 11 12 13 14 8 9
21 20 19
PGND PGND LX LX PGND VCC GND
GND
N.C.
MAX1809
18 17 16 15
FB
SS EXTREF
N.C.
N.C.
N.C.
TOFF
THIN QFN
Pin Configurations continued at end of data sheet. ________________________________________________________________ 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.
GND
REF
FB
3A, 1MHz, DDR Memory Termination Supply MAX1809
ABSOLUTE MAXIMUM RATINGS
VCC, IN to GND ........-0.3V to +6V IN to VCC ...........±0.3V GND to PGND............±0.3V SHDN, SS, FB, TOFF, RREF, EXTREF to GND......-0.3V to (VCC + 0.3V) LX Current (Note 1)....±4.7A REF Short Circuit to GND Duration ....Continuous Continuous Power Dissipation (TA = +70°C) 28-Pin QFN (derate 20mW/°C above +70°C; part mounted on 1in2 of 1oz copper) ......1.6W 16-Pin QSOP (derate 12.5mW/°C above +70°C; part mounted on 1in2 of 1oz copper) .........1W Operating Temperature Range ...-40°C to +85°C Junction Temperature ......+150°C Storage Temperature Range .....-65°C to +150°C Lead Temperature (soldering, 10s) .........+300°C
Note 1: LX has clamp diodes to PGND and IN. If continuous current is applied through these diodes, thermal limits must be observed.
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 = VCC = 3.3V, VEXTREF = 1.1V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER Input Voltage Feedback Voltage Accuracy (VFB - VEXTREF) Feedback Load Regulation Error External Reference Voltage Range Reference Voltage Reference Load Regulation PMOS Switch On-Resistance NMOS Switch On-Resistance Current-Limit Threshold Switching Frequency No Load Supply Current Shutdown Supply Current Thermal-Shutdown Threshold Undervoltage Lockout Threshold FB Input Bias Current Off-Time Startup Off-Time On-Time tON (Note 3) 0.35 IFB tOFF RP M O S RN M O S IL I M I T fSW ICC IIN ISHDN VFB V EXTREF V REF IREF = -1µA to +10µA ILX = 0.5A ILX = 0.5A VIN > VLX (Note 3) fSW = 500kHz fSW = 500kHz SHDN = GND, ICC + IIN Hysteresis = 15°C VCC falling, hysteresis = 90mV VFB = VEXTREF + 0.1V RTOFF = 30.1k RTOFF = 110k RTOFF = 499k 2.5 0 0.24 0.9 3.8 1 16 <1 160 2.6 60 0.30 1.0 4.5 4 x t OFF 2.7 250 0.37 1.1 5.2 µs µs µs 15 VIN = 4.5V VIN = 3V VIN = 4.5V VIN = 3V 3.5 SYMBOL VIN,VCC VIN = VCC = 3V to 5.5V, ILOAD = 0, VEXTREF = 1.25V (Note 2) ILOAD = -3A to +3A, VEXTREF = 1.25V VIN = VCC = 3V to 5.5V V REF 0.01 1.078 1.100 0.5 90 110 70 80 4.1 CONDITIONS MIN 3.0 -12 20 VIN 1.7 1.122 2.0 200 250 150 200 4.7 1 TYP MAX 5.5 +12 UNITS V mV mV V V mV m m A MHz mA µA °C V nA
2
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3A, 1MHz, DDR Memory Termination Supply
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VCC = 3.3V, VEXTREF = 1.1V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER SS Source Current SS Sink Current SHDN Input Current SHDN Logic Levels Maximum Output RMS Current VIL VIH IO U T ( R M S ) 2 3.1 SYMBOL ISS ISS VSS = 1V V SHDN = 0, VCC CONDITIONS MIN 4 1 -1 TYP 5 50 +1 0.8 MAX 6 UNITS µA mA µA V ARMS
MAX1809
ELECTRICAL CHARACTERISTICS
(VIN = VCC = 3.3V, VEXTREF = 1.1V, TA = -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER Input Voltage Feedback Voltage Accuracy (VFB - VEXTREF) External Reference Voltage Range Reference Voltage PMOS Switch On-Resistance NMOS Switch On-Resistance Current-Limit Threshold FB Input Bias Current Off-Time V EXTREF V REF RP M O S RN M O S IL I M I T IFB tOFF ILX = 0.5A ILX = 0.5A VIN > VLX VFB = VEXTREF + 0.1V RTOFF = 110k 0.85 VIN = 4.5V VIN = 3V VIN = 4.5V VIN = 3V 3.3 SYMBOL VIN, VCC VIN = VCC = 3V to 5.5V, ILOAD = 0, VEXTREF = 1.25V VIN = VCC = 3 V to 5.5V CONDITIONS MIN 3.0 -24 V REF 0.01V 1.067 TYP MAX 5.5 +24 VIN 1.9V 1.133 200 250 150 200 4.9 300 1.15 UNITS V mV V V m m A nA µs
Note 2: The output voltage will have a DC-regulation level lower than the feedback error comparator threshold by 50% of the ripple. Note 3: Recommended operating frequency, not production tested. Note 4: Specifications from 0°C to -40°C are guaranteed by design, not production tested.
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