MAX4080EVKIT+ - Maxim Integrated Products, Inc.

Evaluates: MAX4080/MAX4081

MAX4080 Evaluation Kit

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Maxim Integrated Products

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

19-3102; Rev 0; 12/07

General Description

The MAX4080 evaluation kit (EV kit) is a fully assembled

and tested surface-mount printed-circuit board (PCB)

that contains a MAX4080SAUA (8-pin µMAX®) IC. The

MAX4080 is a high-side, current-sense amplifier with an

input common-mode voltage range that extends from

4.5V to 76V. The current-sense amplifier provides an

analog voltage output proportional to the load current

flowing through an external sense resistor.

The EV kit can also be used to evaluate the MAX4081,

which is a bidirectional version of the current-sense

amplifier. The MAX4081’s single output pin continuously

monitors the transition from charge to discharge and

avoids the need for a separate polarity output pin. The

MAX4081 requires an external reference to set the zero-

current output level (VSENSE = 0V). Charging current is

represented by an output voltage from VREF to VCC,

while discharge current is given from VREF to GND.

All gain versions of the MAX4080 and MAX4081 are

footprint-compatible and the MAX4080SAUA can easily

be replaced by a MAX4080FAUA, MAX4080TAUA,

MAX4081FAUA, MAX4081TAUA, or MAX4081SAUA.

With a combination of three gain versions (5V/V, 20V/V,

60V/V = F, T, S suffix) and a user-selectable, external

sense resistor, the user can easily match the full-scale

load current to the required output-voltage range.

For maximum versatility, these parts can operate with

76V input common-mode voltage at RS+ and RS- pins,

independent of operating supply voltage (VCC) used.

These parts also allow a large differential voltage

between RS+ and RS- pins for high reliability. High-side

current monitoring does not interfere with the ground

path of the load being measured, making the

MAX4080/MAX4081 particularly useful in a wide range

of high-voltage systems.

Features

♦Real-Time Current Monitoring

♦Wide 4.5V to 76V Input Common-Mode Range

Independent of Operating Supply Voltage

♦Bidirectional or Unidirectional ISENSE

♦±0.1% Full-Scale Accuracy

♦8-Pin µMAX Package

♦Fully Assembled and Tested

Ordering Information

Component List

PART TYPE

MAX4080EVKIT+ EV Kit

DESIGNATION QTY DESCRIPTION

C1 1

4.7µF ±10%, 100V X5R ceramic

capacitor (2220)

TDK C5750X5R2A475M

C2 1

0.1µF ±10%, 100V X5R ceramic

capacitor (1206)

TDK C3216X5R2A104K

C3, C4, C5 0 Not installed, ceramic capacitors

(1206)

C6, C7 2

0.1µF ±10%, 25V X5R ceramic

capacitors (0603)

TDK C1608X5R1E104K

C8 0 Not installed, ceramic capacitor

(0603)

JU1, JU2 2 3-pin headers

R1 1

0.1Ω ±1% current-sense resistor

(1206)

IRC LRC-LR1206LF-01-R100-F

R2, R3, R4 0 Not installed, resistors—short (PC

trace) (0603)

U1 1

Maxim high-side, current-sense

amplifier with voltage output

MAX4080SAUA+ (8-pin µMAX)

— 2 Shunts

— 1 PCB: MAX4080 Evaluation Kit+

Denotes lead-free and RoHS-compliant.

µMAX is a registered trademark of Maxim Integrated Products,

Inc.

Evaluates: MAX4080/MAX4081

MAX4080 Evaluation Kit

2 _______________________________________________________________________________________

Quick Start

Recommended Equipment

Before beginning, the following equipment is needed:

•One 12V, 1A power supply

•One electronic load capable of sinking 1A

•Two digital voltmeters (DVMs)

Procedure

The MAX4080 EV kit is fully assembled and tested.

Follow the steps below to verify board operation.

Caution: Do not turn on the power supply or the

electronic load until all connections are completed.

1) MAX4081 only: Verify that a shunt is installed across

pins 1-2 of jumper JU1.

2) MAX4081 only: Verify that a shunt is installed across

pins 1-2 of jumper JU2.

3) Set the power supply to 12V and connect the posi-

tive terminal to the VCC pad. Connect the ground of

the power supply to the GND pad closest to the

VCC pad.

4) Connect the VCC pad and the VSENSE+ pad.

5) Set the electronic load to sink 1A.

6) Connect the electronic load’s positive terminal to

the VSENSE- pad. Connect the load’s ground to the

GND pad closest to the VCC pad.

7) Connect a voltmeter across the VSENSE+ and

VSENSE- pads. (Note that this voltmeter measure-

ment will not accurately reflect actual sense voltage

across the sense resistor due to voltage drop in the

trace and in the connectors. Accurate measurement

of sense voltage across low-value sense resistors

requires the use of 4-wire Kelvin-connected sense

resistors. The EV kit board shows one example of

good layout practice by which RS+ and RS- of the

current-sense amplifier can connect to commonly

available 2-wire sense resistors.)

8) Connect the second voltmeter across the VOUT

pad and the closest GND pad.

9) Turn on the power supply.

10) Turn on the electronic load.

11) Verify that the first DVM reading is approximately

100mV and the second DVM is approximately 6V.

12) Adjust the electronic load current to between 1A

and 0A and verify that the reading of the second

DVM is about 60 times the reading of the first DVM.

Detailed Description

The MAX4080 EV kit is a current-sense amplifier that

measures the load current and provides an analog volt-

age output. The full-scale VSENSE is set to 100mV. The

full-scale ISENSE is set at 1A. They can be changed by

replacing current-sense resistor R1 to another appropri-

ate value.

Applying the VCC Power Supply and the

Load Power Supply

The EV kit is installed with a MAX4080SAUA, which has

a gain of 60. The current-sense-resistor value is 0.1Ω.

The VOUT is given by:

where VSENSE is the sense voltage, ISENSE is the load

current, and AVis the gain of the device.

Note: Output voltage is internally clamped not to

exceed 18V.

Normal operating VCC, VSENSE+, and VSENSE- range is

4.5V to 76V.

Measuring the Load Current

The load current is measured as a voltage drop

(VSENSE) across an external sense resistor. This volt-

age is then amplified by the current-sense amplifier and

presented at its OUT pin. Like all differential amplifiers,

the output voltage has two components of error (an off-

set error and a gain error). The offset error affects accu-

racy of measurement at low currents and a gain error

affects output accuracy at large currents—both errors

affect accuracy of measurement at intermediate cur-

rents. By minimizing both offset and gain errors, accu-

rate measurements can be obtained from the

MAX4080/MAX4081 over a wide dynamic range.

VV AI

OUT SENSE V SENSE

=×=××01 60.

Component Suppliers

SUPPLIER PHONE WEBSITE

IRC, Inc. 361-992-7900 www.irctt.com

TDK Corp. 847-803-6100 www.component.tdk.com

Note: Indicate that you are using the MAX4080 or MAX4081

when contacting these component suppliers.

The MAX4080 EV kit, which is assembled with the

MAX4080SAUA, is designed with a full-scale sense

voltage drop of 100mV. For a typical 1A full-scale load

current, this results in the use of a 0.1Ωsense resistor

on the MAX4080 EV kit using the following equation:

For different full-scale sense voltage and full-scale load-

current arrangements, the equation above can be used

to determine the appropriate current-sense-resistor val-

ues. Refer to

Table 1. Typical Component Values

in the

MAX4080/MAX4081 IC data sheet for further guidance.

Evaluating the

MAX4080FAUA/MAX4080TAUA

The MAX4080 EV kit can be used to evaluate other gain

versions of the MAX4080 (5V/V, 20V/V, 60V/V = F, T, S

suffix). Replace U1 with a different version of the

MAX4080 and refer to

Table 1. Typical Component

Values

in the MAX4080/MAX4081 IC data sheet for

additional information.

Evaluating the MAX4081 Bidirectional

Current-Sense Amplifiers

The MAX4080 EV kit can also be used to evaluate the

MAX4081 bidirectional current-sense amplifiers.

Replace U1 with a MAX4081SAUA, MAX4081TAUA, or

MAX4081FAUA. The MAX4081 requires an external ref-

erence to set the zero-current output level (VSENSE =

0V). The charging current is represented by an output

voltage from VREF to VCC, while discharge current is

given from VREF to GND. Measuring VOUT with respect

to VREF (instead of GND) gives a ± output voltage.

The VOUT reference level is controlled by REF1A and

REF1B. VREF is defined as the average voltage of

VREF1A and VREF1B. Connect REF1A and REF1B

together to a low-noise, regulated voltage source to set

the output reference level. In this mode, VOUT equals

VREF1A when VSENSE equals zero.

Alternatively, connect REF1B to ground and REF1A to a

low-noise, regulated voltage source. In this case, the

output reference level (VREF) is equal to VREF1A divid-

ed by two. VOUT equals half of VREF1A when VSENSE

equals zero.

In either mode, the output swings above the reference

voltage for positive current sensing (VRS+ > VRS-). The

output swings below the reference voltage for negative

current sensing (VRS+ < VRS-).

Use jumpers JU1 and JU2 to set the VREF on the EV kit.

See Table 1 for jumper settings and the corresponding

VREF values.

SENSE FULL SCALE

LOAD FULL SCALE

1=__

Evaluates: MAX4080/MAX4081

MAX4080 Evaluation Kit

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Table 1. JU1 and JU2 Jumper Settings

SHUNT POSITION

JU1 JU2 VREF

1-2 1-2 REFIN*

1-2 2-3 REFIN/2

2-3 1-2 (VCC + REFIN)/2

2-3 2-3 VCC/2

*Default position.

MAX4080

VCC

REFIN

MAX4081

ONLY

GND

VOUT

VSENSE-

N.C. (REF1B)*

N.C. (REF1A)*

OUT

RS-

VCC

N.C.

RS+

GND

*MAX4081 ONLY.

0.1μF

OPEN

GND

VCC

VSENSE+

VCC

0.1μF

4.7μF

0.1Ω

SHORT

(PC TRACE)

SHORT

(PC TRACE)

SHORT

(PC TRACE)

JU2

JU1

Figure 1. MAX4080 EV Kit Schematic

Evaluates: MAX4080/MAX4081

MAX4080 Evaluation Kit

4 _______________________________________________________________________________________

Figure 2. MAX4080 EV Kit Component Placement Guide—

Component Side

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________

Evaluates: MAX4080/MAX4081

MAX4080 Evaluation Kit

Figure 4. MAX4080 EV Kit PCB Layout—Solder Side

Figure 3. MAX4080 EV Kit PCB Layout—Component Side