Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - In-amp InAmp uMAX 8

General Description

The MAX4208/MAX4209 ultra-low offset and drift instrumen-

tation amplifiers feature exceptional precision specifications,

low power consumption, rail-to-rail output, excellent gain-

bandwidth product, and buffered REFIN/MODE input in a

very small μMAX

package. These devices use a spread-

spectrum, autozeroing technique that constantly measures

and corrects the input offset, eliminating drift over time

and temperature and the effect of 1/f noise. This technique

achieves less than 20μV offset voltage, allows ground-sens-

ing capability, provides ultra-low CMOS input bias current

and increased common-mode rejection performance.

The MAX4208/MAX4209 provide high-impedance inputs

optimized for small-signal differential voltages (±100mV).

All devices provide a gain-bandwidth product of 750kHz.

The MAX4208 provides an adjustable gain with two exter-

nal resistors or unity gain with FB connected to OUT. The

MAX4209 is available with a fixed gain of 100V/V with

±0.03% (typ) accuracy. Both devices include a reference

input (REF) to level-shift the output, allowing for bipolar sig-

nals in single-supply applications. In both devices, REFIN/

MODE is an input to a precision unity-gain buffer, which

sets the REF voltage to level-shift the output. The internal

REF buffer allows the reference to be set by a simple resis-

tive divider or an ADC reference without any loading error.

The MAX4208/MAX4209 operate with a 2.85V to 5.5V

single-supply voltage and consume only 750μA of qui-

escent current (when the internal buffer is off) and only

1.4μA in shutdown mode. These amplifiers also operate

with ±2.5V dual supplies with REF connected to ground

and REFIN/MODE to V

. The MAX4208/MAX4209 are

available in space-saving 8-pin μMAX packages and

are specified over the automotive operating temperature

range (-40°C to +125°C).

Applications

● Strain-Gauge Ampliers

● Industrial Process Control

● Battery-Powered Medical Equipment

● Precision Low-Side Current Sense

● Notebook Computers

● Differential Voltage Amplication

Features

● Ultra-Low Input Offset Voltage

• ±20μV (max) at +25°C

● ±0.25% (max) Gain Error

● Low 0.2μV/°C Offset Voltage Drift

● 1pA CMOS Input Bias Current

● True Ground Sensing with Rail-to-Rail Output

● Buffered REF Input for High Accuracy and Bipolar

Operation

● 2.85V to 5.5V Single-Supply Operation (or ±1.425V

to ±2.75V Dual Supplies)

● 750μA Supply Current

● 1.4μA Shutdown Mode

● 750kHz Gain-Bandwidth Product

● Operate Over the -40°C to +125°C Automotive

Temperature Range

● Tiny 8-Pin μMAX Package

μMAX is a registered trademark of Maxim Integrated Products, Inc.

19-0924; Rev 2; 5/14

Ordering Information

+Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

PART TEMP RANGE

PIN-

PACKAGE

GAIN

(V/V)

MAX4208AUA+T -40°C to +125°C 8 µMAX ADJ

MAX4209HAUA+T -40°C to +125°C 8 µMAX 100

IN-

IN+

REFIN/MODE

REF

MAX4208

OUT

REF

G = 1 +

BUFFER OUT =

MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision

Instrumentation Amplifiers with REF Buffer

Typical Application Circuit

EVALUATION KIT AVAILABLE

Summary of content (17 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer General Description The MAX4208/MAX4209 ultra-low offset and drift instrumentation amplifiers feature exceptional precision specifications, low power consumption, rail-to-rail output, excellent gainbandwidth product, and buffered REFIN/MODE input in a very small μMAX® package.
PAGE 2
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Absolute Maximum Ratings VDD to VSS...............................................................-0.3V to +6V All Other Pins................................. (VSS - 0.3V) to (VDD + 0.3V) OUT Short-Circuit Duration........................................Continuous Current Into OUT, VDD, and VSS......................................±25mA Current Into Any Other Pin................................................
PAGE 3
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Electrical Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER Power-Supply Rejection Ratio SYMBOL PSRR CONDITIONS VDD = 2.85V to 5.5V, VREF = VCM = (VSS + 0.
PAGE 4
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Electrical Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Settling Time Maximum Capacitive Load Input Voltage Noise MIN TYP MAX4208, G = 1V/V 10 MAX4209H 120 MAX UNITS tS To within 0.
PAGE 5
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Electrical Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = -40°C to +125°C, unless otherwise noted.
PAGE 6
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Electrical Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL REFIN/MODE Input-Voltage High VIH CONDITIONS MIN MAX4208/MAX4209 in shutdown TYP MAX VDD - 0.
PAGE 7
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Typical Operating Characteristics (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) 15 10 -5 0 5 10 15 20 VOS DRIFT (nV/°C) INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE INPUT OFFSET VOLTAGE vs. INPUT COMMON-MODE VOLTAGE MAX4208/9 toc03 20 15 -20 TA = -40°C 2.
PAGE 8
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Typical Operating Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY MAX4208 INPUT-REFERRED NOISE MAX4208/9 toc11 MAX4208/9 toc10 0 -20 GAIN (dB) -40 -60 1.
PAGE 9
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Typical Operating Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) LARGE-SIGNAL PULSE RESPONSE TIME LARGE-SIGNAL PULSE RESPONSE TIME MAX4208/9 toc18 MAX4208/9 toc17 VIN+ 5mV/div 2.5V VIN+ 5mV/div 2.5V OUTPUT 50mV/div 2.
PAGE 10
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Typical Operating Characteristics (continued) (VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, VREFIN/MODE = VSS, RL = 100kΩ to VDD/2, VDIFF = (VIN+ - VIN-) = 0V, MAX4208 set for G = 100V/V (R1 = 1kΩ, R2 = 99kΩ), TA = +25°C, unless otherwise noted.) 0.1% SETTLING TIME vs. GAIN 1000 100 G = 100 160 140 MAX4208/9 toc22 MAX4208/9 toc21 180 SETTLING TIME (µs) SETTLING TIME (µs) 10,000 SETTLING TIME vs.
PAGE 11
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer VDD VDD MAX4208 MAX4209 OUT AMP OUT AMP R2 FB INgm R2 R1 gm REF IN+ +1 FB INgm gm R1 REF IN+ REFIN/MODE +1 SHDN G = 1 + R2 R1 VSS REFIN/MODE SHDN G = 1 + R2 R1 VSS Figure 1. MAX4208 Functional Diagram Figure 2. MAX4209 Functional Diagram Detailed Description cation. The maximum recommended differential input voltage is ±100mV. Linearity and accuracy are degraded above that level.
PAGE 12
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Table 1. REFIN/MODE Pin Functions REFIN/MODE VOLTAGE* VDD (typically +5V) STATE OF MAX4208/MAX4209 and REFIN BUFFER The entire IC is in SHDN mode and draws 1.4µA of supply current. Between VSS + 200mV and (VDD - 1.3V) The internal REF buffer is activated. REF MUST NOT be fed by any external source. The voltage at REFIN/MODE is transferred to REF within ±40FV, max (VOS of the internal REF buffer).
PAGE 13
MAX4208/MAX4209 Applications Information Setting the Gain (MAX4208) Connect a resistive divider from OUT to REF with the center tap connected to FB to set the gain for the MAX4208 (see the Typical Application Circuit). Calculate the gain using the following formula:  R2  GAIN= 1 +    R1  Choose a value for R1 ≤ 1kΩ. Resistor accuracy ratio directly affects gain accuracy. Resistor sum less than 10kΩ should not be used because their loading can slightly affect output accuracy. Input Common Mode vs.
PAGE 14
MAX4208/MAX4209 VCM Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer CLASSIC THREE OP-AMP INA VCM VCC VDD VCM-MAX VCM-MAX MAX4208/MAX4209 3/4 VCC 1/2 VCC VREF = 1/2 VCC VREF = 1/2 VDD 1/4 VCC VOUT ( = GAIN x VDIFF + VREF) 0 VCC/2 VCC VOUT ( = GAIN x VDIFF + VREF) 0 VDD/2 VDD Figure 3. Limited Common Mode vs. Output Voltage of a Three Op-Amp INA Figure 4. Input Common Mode vs.
PAGE 15
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer The ultra-low VOS of the MAX4208/MAX4209 allows full-scale VSENSE of only 10mV to 20mV for minimally invasive current sensing using milliohm sense resistors to get high accuracy. Previous methods used the internal resistance of the inductor in the step-down DC-DC converter to measure the current, but the accuracy was only 20% to 30%. Using a full-scale VSENSE of 20mV, a 20μV max, VOS error term is less than 0.
PAGE 16
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Pin Configuration TOP VIEW REFIN/MODE 1 IN- 2 IN+ 3 + MAX4208 MAX4209 VSS 4 8 VDD 7 OUT 6 FB 5 REF µMAX Chip Information PROCESS: BiCMOS www.maximintegrated.com Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only.
PAGE 17
MAX4208/MAX4209 Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer Revision History REVISION NUMBER REVISION DATE 0 9/07 Initial release 1 4/09 Removed future products 2 5/14 Updated Applications DESCRIPTION PAGES CHANGED — 1–5, 11, 12, 13 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.