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19-2018; Rev 0; 4/01
500mA, Low-Voltage Linear Regulator in MAX
General Description
The MAX1806 low-dropout linear regulator operates from a +2.25V to +5.5V supply and delivers a guaranteed 500mA load current with low 175mV dropout. The high-accuracy (1%) output voltage is preset at an internally trimmed voltage (see Selector Guide) or can be adjusted from +0.8V to +4.5V with an external resistive-divider. An internal PMOS pass transistor allows low 210A supply current, making this device ideal for portable equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, and other equipment, including base stations and docking stations. Other features include an active-low, power-OK output that indicates when the output is out of regulation, a 0.02A shutdown mode, short-circuit protection, and thermal shutdown protection. The MAX1806 comes in a miniature 1.3W, 8-pin power-MAX package with a metal pad on the underside of the package. o Guaranteed 500mA Output Current o Output Down to 0.8V o Low 175mV Dropout at 500mA o 1% Output Voltage Accuracy Preset at 0.8V, 1.5V, 1.8V, 2.5V, or 3.3V Adjustable from 0.8V to 4.5V o Power-OK Output o Low 210A Ground Current o 0.02A Shutdown Current o Thermal Overload Protection o Output Current Limit o Tiny 1.3W, 8-Pin Power-MAX Package
Features
MAX1806
Ordering Information
PART MAX1806EUA_ _ TEMP. RANGE -40C to +85C PIN-PACKAGE 8 Power-MAX
Applications
Notebook Computers Cellular and Cordless Telephones PDAs Palmtop Computers Base Stations USB Hubs Docking Stations
Selector Guide
PART AND SUFFIX MAX1806EUA33 MAX1806EUA25 MAX1806EUA18 MAX1806EUA15 MAX1806EUA08 VOUT (V) 3.3 2.5 1.8 1.5 0.8 TOP MARK AAAG AAAH AAAI AAAJ AAAK
Typical Operating Circuit
VIN +2.25V TO +5.5V IN NC CIN 1F RPOK 100k POK TO C OUT COUT 10F VOUT 0.8V TO 4.5V
Pin Configuration
TOP VIEW
IN 1 IN 2
8 7
OUT OUT SET GND
MAX1806
ON SHDN OFF
MAX1806
POK 3 6 5 SHDN 4
SET
GND
MAX
________________________________________________________________ Maxim Integrated Products
1
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, POK, SET to GND ...................................-0.3V to +6V OUT to GND ................................................-0.3V to (VIN + 0.3V) Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70C) 8-Pin Power-MAX (derate 17mW/C above +70C) .......1.3W Operating Temperature .......................................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = VOUT(SETPOINT) + 500mV or VIN = +2.25V whichever is greater, SET = GND, SHDN = IN, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage Input Undervoltage Lockout Output Voltage Accuracy (Preset Mode) Adjustable Output Voltage TA = +85C, IOUT = 100mA SET Voltage Threshold (Adjustable Mode) Maximum Output Current Short-Circuit Current Limit SET Dual ModeTM Threshold SET Input Bias Current Ground-Pin Current ISET IQ VSET = +0.8V IOUT = 1mA IOUT = 500mA VOUT = +2.25V Dropout Voltage (Note 1) Line Regulation Load Regulation Output Voltage Noise SHUTDOWN Shutdown Supply Current SHDN Input Threshold SHDN Input Bias Current Startup Time IOFF VIH VIL I SHDN TSTART SHDN = GND or IN COUT = 10F, time from SHDN high to POK high 10 40 SHDN = GND, VIN = 5.5V 1.6 0.6 100 0.02 5 A V nA s VLNR VLDR IOUT = 500mA VOUT = +2.8V VOUT = +4.0V VIN from (VOUT + 100mV) to 5.5V, ILOAD = 5mA IOUT = 1mA to 500mA 10Hz to 1MHz, COUT = 10F (ESR < 0.1) VSET TA = +85C, IOUT = 1mA to 500mA TA = 0C to +85C, IOUT = 1mA to 500mA, VIN > VOUT + 0.5V VOUT = 0V SYMBOL VIN VUVLO Rising, 40mV hysteresis TA = +85C, IOUT = 100mA VOUT TA = +85C, IOUT = 1mA to 500mA TA = 0C to +85C, IOUT = 1mA to 500mA, VIN > VOUT + 0.5V CONDITIONS MIN 2.25 1.85 -1 -1.5 -3 0.8 790 786 774 500 700 35 -100 210 575 259 201 147 0 15.5 300 384 315 255 0.125 35 %/V ppm/mA VRMS mV 1400 80 2300 125 +100 400 800 2.0 TYP MAX 5.5 2.15 +1 +1.5 +3 4.5 810 814 826 mARMS mA mV nA A mV V % UNITS V V
IOUT ILIM
Dual Mode is a trademark of Maxim Integrated Products, Inc. 2 _______________________________________________________________________________________
500mA, Low-Voltage Linear Regulator in MAX
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(SETPOINT) + 500mV or VIN = +2.25V whichever is greater, SET = GND, SHDN = IN, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER POWER-OK POK Output Low Voltage Operating Voltage Range for Valid POK Output Output High-Leakage Current Threshold THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN TSHDN 170 20 C C VOL Sinking 2mA Sinking 100A VPOK = +5.5V Rising edge, referred to VOUT(NOMINAL) 90 93 1.0 5 50 5.5 100 96 mV V nA % SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX1806
ELECTRICAL CHARACTERISTICS
(VIN = VOUT(SETPOINT) + 500mV or VIN = +2.25V whichever is greater, SET = GND, SHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 2)
PARAMETER Input Voltage Input Undervoltage Lockout Output Voltage Accuracy (Preset Mode) Adjustable Output Voltage SET Voltage Threshold (Adjustable Mode) Maximum Output Current Short-Circuit Current Limit SET Dual ModeTM Threshold ISET IQ VSET = +0.8V IOUT = 1mA VOUT = +2.25V Dropout Voltage (Note 1) Line Regulation Load Regulation SHUTDOWN Shutdown Supply Current SHDN Input Threshold SHDN Input Bias Current IOFF VIH VIL I SHDN SHDN = GND, VIN = 5.5V 2.5V < VIN < 5.5V 2.5V < VIN < 5.5V SHDN = GND or IN 1.6 0.6 100 5 A V nA VLNR VLDR IOUT = 500mA VOUT = +2.8V VOUT = +4.0V VIN from (VOUT + 100mV) to 5.5V, ILOAD = 5mA IOUT = 1mA to 500mA -0.175 259 201 147 SET Input Bias Current Ground-Pin Current VSET IOUT ILIM VOUT = 0V IOUT = 1mA to 500mA SYMBOL VIN VUVLO VOUT Rising, 40mV hysteresis IOUT = 1mA to 500mA CONDITIONS MIN 2.25 1.85 -4 0.8 766 500 700 35 -100 2500 125 +100 400 384 315 255 +0.175 35 %/V ppm/mA mV TYP MAX 5.5 2.15 +4 4.5 834 UNITS V V % V mV mARMS mA mV nA A
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(SETPOINT) + 500mV or VIN = +2.25V whichever is greater, SET = GND, SHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 2)
PARAMETER POWER-OK POK Output Low Voltage Operating Voltage Range for Valid POK Output Output High-Leakage Current Threshold VOL Sinking 2mA Sinking 100A VPOK = +5.5V Rising edge, referred to VOUT(NOMINAL) 89 1.0 50 5.5 100 97 mV V nA % SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT and when VIN = VOUT(NOM) +0.5V. For 2.25V VOUT 4.0V, dropout voltage limits are linearly interpolated from the values listed. For VOUT < 4.0V, dropout voltage limit is equal to the value for VOUT = 4.0V. Note 2: Specifications to -40C are guaranteed by design, not production tested.
Typical Operating Characteristics
(MAX1806EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1F, COUT = 10F, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1806 toc01
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1806 toc02
OUTPUT VOLTAGE vs. TEMPERATURE
VIN = VOUT + 500mV IOUT = 0
MAX1806 toc03
3.5 IOUT = 0mA 3.0 OUTPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 0 IOUT = 500mA
3.32 3.31 OUTPUT VOLTAGE (V) 3.30 3.29 3.28 3.27 3.26 3.25
3.34 3.33 OUTPUT VOLTAGE (V) 3.32 3.31 3.30 3.29 3.28
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 INPUT VOLTAGE (V)
0
100 200 300 400 500 600 700 800 LOAD CURRENT (mA)
-40
-15
10
35
60
85
TEMPERATURE (C)
DROPOUT VOLTAGE vs. LOAD CURRENT
350 DROPOUT VOLTAGE (mV) 300 250 200 150 100 50 0 0 100 200 300 400 500 600 700 800 LOAD CURRENT (mA) TA = -40C TA = +25C TA = +85C
MAX1806 toc04
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
0.28 DROPOUT VOLTAGE (V) 0.26 0.24 0.22 0.20 0.18 0.16 0.14 2.0 2.5 3.0 3.5 4.0 4.5 OUTPUT VOLTAGE (V) 600 550 500 450 400 350 300 250 200 150 100 50 0 2.0
MAX1806 toc05
GROUND-PIN CURRENT vs. INPUT VOLTAGE
MAX1806 toc06
400
GROUND-PIN CURRENT (A)
IOUT = 500mA
IOUT = 0mA
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
INPUT VOLTAGE (V)
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
Typical Operating Characteristics (continued)
(MAX1806EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1F, COUT = 10F, TA = +25C, unless otherwise noted.)
GROUND-PIN CURRENT vs. LOAD CURRENT
MAX1806 toc07
450 GROUND-PIN CURRENT (A) 400 350 300 250 200 150 100 0 VIN = 5.5V VIN = 3.8V
VIN = VOUT + 500mV IOUT = 0
MAX1806 toc08
GROUND-PIN CURRENT (A)
190
-50 -40
180
PSRR (dB)
-30 -20
170
160
-10 0 -40 -15 10 35 60 85 TEMPERATURE (C)
150 100 200 300 400 500 600 700 800 LOAD CURRENT (A)
COUT = 10F IOUT = 50mA 0.01 0.1 1 10 100 1000 FREQUENCY (kHz)
OUTPUT SPECTRAL NOISE DENSITY vs. FREQUENCY
OUTPUT SPECTRAL NOISE DENSITY (V/Hz) COUT = 10F IOUT = 50mA
MAX1806 toc10
OUTPUT NOISE DC TO 1MHz
MAX1806 toc11
10
1
0.1
VOUT 1mV/div
0.01 0.001 0.1 1 10 FREQUENCY (kHz) 100 1000 VOUT = 3.3V ROUT = 66 (50mA) 20ms/div
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX1806 toc12
LOAD-TRANSIENT RESPONSE
MAX1806 toc13
100
REGION OF COUT ESR
10 COUT = 10F 1 STABLE REGION 0.1 VIN = VOUT + 500mV CIN = 10F ROUT = 660 TO 6.6 (5mA TO 500mA) 0 100 200 300 400 500 600 700 800 FREQUENCY (kHz) 10s/div
IOUT 200mA/div
VOUT 20mV/div
0.01
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MAX1806 toc09
500
GROUND-PIN CURRENT vs. TEMPERATURE
200 -60
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
5
500mA, Low-Voltage Linear Regulator in MAX MAX1806
Typical Operating Characteristics (continued)
(MAX1806EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1F, COUT = 10F, TA = +25C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX1806 toc14
LINE-TRANSIENT RESPONSE
MAX1806 toc15
6V
IOUT 200mA/div
VIN 1V/div 3V
VOUT 50mV/div VIN = VOUT + 100mV CIN = 10F ROUT = 660 TO 6.6 (5mA TO 500mA) 10s/div 200s/div VOUT 10mV/div
SHUTDOWN WAVEFORM
MAX1806 toc16
POK WAVEFORM
MAX1806 toc17
5V 2V VSHDN 1V/div 0 3V VOUT 1V/div 0 ROUT = 6.6 (500mA) 20s/div ROUT = 66 (50mA) 200s/div VIN 2V/div 0 VOUT 2V/div 0 VPOK 2V/div 0
Pin Description
PIN 1, 2 3 4 5 6 7, 8 NAME IN POK SHDN GND SET OUT FUNCTION Regulator Input. Supply voltage can range from +2.25V to +5.5V. Bypass with a 1F capacitor to GND (see Capacitor Selection and Regulation Stability). Connect both input pins together externally. Open-Drain, Active-Low Power-OK Output. POK remains low while the output voltage (VOUT) is below the POK threshold. Connect a 100k pullup resistor from POK to OUT. Active-Low Shutdown Input. A logic low at SHDN reduces supply current to 0.02A. In shutdown, the POK output is low. Connect SHDN to IN for normal operation. Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the circuit-board ground plane to maximize power dissipation. Voltage-Setting Input. Connect SET to GND for preset output. Connect an external resistive voltage-divider from OUT to SET to set the output voltage between 0.8V and 4.5V. The SET regulation voltage is 800mV. Regulator Output. OUT sources up to 500mA. Bypass OUT with a 10F low-ESR capacitor to GND. Connect both OUT pins together externally.
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500mA, Low-Voltage Linear Regulator in MAX
Detailed Description
The MAX1806 is a low-dropout, low-quiescent-current linear regulator. The device supplies loads up to 500mA and is available with preset output voltages. As illustrated in Figure 1, the MAX1806 includes a 0.8V reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider. The reference is connected to the error amplifier, which compares it with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled lower, which allows more current to pass to the output increasing the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up, allowing less current to pass to the output. The output voltage is fed back through either an internal resistive voltage-divider connected to OUT or an external resistor network connected to SET. The dualmode comparator examines VSET and selects the feedback path. If VSET is below 35mV, the internal feedback path is used, and the output is regulated to the factorypreset voltage. Additional blocks include an output current limiter, thermal sensor, and shutdown logic. current drops to 0.02A. When in shutdown, POK pulls low. The capacitance and load at OUT determine the rate at which VOUT decays. SHDN can be pulled as high as +6V, regardless of the input and output voltage.
MAX1806
Power-OK Output
The POK output pulls low when OUT is less than 93% of the nominal regulation voltage. Once OUT exceeds 93% of the nominal voltage, POK goes high impedance. POK is an open-drain N-channel output. To obtain a logic voltage output, connect a pullup resistor from POK to OUT. A 100k resistor works well for most applications. POK can be used to signal a microcontroller (C), or drive an external LED to indicate power failure. When the MAX1806 is shutdown, POK is held low independent of the output voltage. If unused, leave POK grounded or unconnected.
Current Limit
The MAX1806 monitors and controls the pass transistor's gate voltage, limiting the output current to 1.4A (typ). The output can be shorted to ground for an indefinite period of time without damaging the part.
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the MAX1806. When the junction temperature exceeds TJ = +170C, a thermal sensor turns off the pass transistor, allowing the device to cool. The thermal sensor turns the pass transistor on again after the junction temperature cools by 20C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection protects the MAX1806 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150C.
Internal P-Channel Pass Transistor
The MAX1806 features a 0.4 P-channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P-channel MOSFETs require no base drive, which reduces operating current. PNP-based regulators also waste considerable current in dropout when the pass transistor saturates, and use high base-drive currents under large loads. The MAX1806 does not suffer from these problems.
Output Voltage Selection
The MAX1806's dual-mode operation allows operation in either a preset voltage mode or an adjustable mode. Connect SET to GND to select the preset output voltage. The two-digit part number suffix identifies the output voltage (see Selector Guide). For example, the MAX1806EUA33 has a preset 3.3V output voltage. The output voltage may also be adjusted by connecting a voltage-divider from OUT to SET (Figure 2). Select R2 in the 25k to 100k range. Calculate R1 with the following equation: R1 = R2 [(VOUT / VSET) - 1] where VSET = 0.8V, and VOUT may range from 0.8V to 4.5V.
Operating Region and Power Dissipation
The MAX1806's maximum power dissipation depends on the thermal resistance of the IC package and circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipated in the device is P = IOUT (VIN V OUT ). The maximum allowed power dissipation is 1.3W or: PMAX = (TJ(MAX) - TA) / (JC + CA) where TJ - TA is the temperature difference between the MAX1806 die junction and the surrounding air, JC is the thermal resistance from the junction to the case, and CA is the thermal resistance from the case through the PC board, copper traces, and other materials to the surrounding air. The MAX1806 package features an exposed thermal pad on its underside. This pad lowers the package's thermal resistance by provid7
Shutdown
Drive SHDN low to enter shutdown. During shutdown, the output is disconnected from the input, and supply
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
VIN +2.25V TO +5.5V CIN 1F
IN IN
THERMAL SENSOR MOSFET DRIVER WITH ILIM OUT PRESET MODE VOUT 0.8V TO 3.3V COUT 10F
ON OFF
SHDN OUT SHUTDOWN LOGIC ERROR AMPLIFIER VREF 0.8V
LOGIC SUPPLY VOLTAGE (VOUT) RPOK 100k TO C POK
MAX1806
SET
93% VREF
80mV GND
Figure 1. Functional Diagram
ing a direct heat conduction path from the die to the PC board. Connect the exposed backside pad and GND to the system ground using a large pad or ground plane, or multiple vias to the ground plane layer. The MAX1806 delivers up to 0.5A(RMS) and operates with input voltages up to 5.5V, but not simultaneously. High output currents can only be sustained when inputoutput differential is within the limits outlined.
output capacitors. The output capacitor's (COUT) ESR affects stability and output noise. Use output capacitors with an ESR of 0.1 or less to ensure stability and optimum transient response. Surface-mount ceramic capacitors have very low ESR and are commonly available in values up to 10F. Connect CIN and COUT as close to the MAX1806 as possible.
Noise, PSRR, and Transient Response
The MAX1806 is designed to operate with low dropout voltages and low quiescent currents, while still maintaining good noise, transient response, and AC rejection. See the Typical Operating Characteristics for a plot of Power-Supply Rejection Ratio (PSRR) vs. Frequency. When operating from noisy sources, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors and through passivefiltering techniques. The MAX1806 load-transient
Applications Information
Capacitor Selection and Regulator Stability
Connect a 1F capacitor between IN and ground and a 10F low equivalent series resistance (ESR) capacitor between OUT and ground. The input capacitor (CIN) lowers the source impedance of the input supply. Reduce noise and improve load-transient response, stability, and power-supply rejection by using larger
8
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
0.8 R1 = R2 IN VIN +2.25V TO +5.5V IN OUT OUT VOUT VOUT 0.8V -1 MAXIMUM OUTPUT CURRENT (A) CONTINUOUS CURRENT LIMIT 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 R2 POK GND 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT-OUTPUT VOLTAGE DIFFERENTIAL (V) TA = +85C TA = +70C TYPICAL VDROPOUT LIMIT POWER-MAX PACKAGE OPERATING REGION AT TJ(MAX) = +150C TA = +50C
CIN 1F ON SHDN OFF
MAX1806
COUT 10F
R1
SET
Figure 3. Power Operating Regions: Maximum Output Current vs. Supply Voltage
Figure 2. Adjustable Output Using External Feedback Resistors
response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. A typical transient overshoot for a step change in the load current from 5mA to 500mA is 40mV. Increasing the output capacitor's value and decreasing the ESR attenuates the overshoot.
Input-Output (Dropout) Voltage
A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the MAX1806 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-tosource on-resistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics): VDROPOUT = VIN - VOUT = RDS(ON) IOUT
Chip Information
TRANSISTOR COUNT: 949
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500mA, Low-Voltage Linear Regulator in MAX MAX1806
Package Information
8L, MAX, EXP PAD.EPS
Note: The MAX1806 has on exposed thermal pad on the bottom side of the package.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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