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MAX4072ATA

Bidirectional, High-Side, Current-Sense Amplifiers with Reference

Maxim Integrated 

MAX4069–MAX4072

Bidirectional, High-Side, Current-Sense

Amplifiers with Reference

IDISCHARGE

2

CELLS

RSENSE

ICHARGE

5V

RS-

RS+

VCC

MAX4070

LOAD

VOUT - VREF

2.5V

GSEL

OUT TO ADC

-25mV

0

SHDN

REFOUT 2.5V

GND

DISCHARGE

CURRENT -2.5V

AV = 100

CHARGE

CURRENT

25mV

50mV

VSENSE

Figure 2. Bidirectional Current Monitor

External Reference (MAX4072)

The MAX4072 contains REFIN pin for external reference

voltage. The allowable voltage range on REFIN is 1V

(min) to 4V (max) with VCC ≥ 5.1V.

Reference Output

(MAX4069/MAX4060/MAX4071)

The REFOUT of the MAX4069/MAX4070/MAX4071 can

sink 100µA and source 500µA. Keep the total capacitance

on REFOUT under 500pF to maintain stability.

Recommended Component Values

Ideally, the maximum load current develops the full-scale

sense voltage across the current-sense resistor. Choose

the gain needed to yield the maximum output voltage

required for the application:

VOUT = VSENSE x AV

where VSENSE is the full-scale sense voltage, 75mV for

gain of 50V/V, or 50mV for gain of 100V/V. AV is the gain

of the device.

In applications monitoring high current, ensure that

RSENSE is able to dissipate its own I2R loss. If the resis-

tor’s power dissipation is exceeded, its value may drift or

it may fail altogether, causing a differential voltage across

the terminals in excess of the absolute maximum ratings.

Use resistors specified for current-sensing applications.

The MAX4069–MAX4072 sense a wide variety of currents

with different sense-resistor values. Table 1 lists common

resistor values for typical operation of these devices.

Listed output voltage is with respect to REF.

Sense Resistor, RSENSE

Choose RSENSE based on the following criteria:

Voltage Loss: A high RSENSE value causes the power-

source voltage to degrade through IR loss. For minimal

voltage loss, use the lowest RSENSE value.

Accuracy: A high RSENSE value allows lower currents

to be measured more accurately. This is because offsets

become less significant when the sense voltage is larger.

For best performance, select RSENSE to provide approxi-

mately 75mV (gain of 50V/V) or 50mV (gain of 100V/V) of

sense voltage for the full-scale current in each application.

Efficiency and Power Dissipation: At high-current lev-

els, the I2R losses in RSENSE can be significant. Take

this into consideration when choosing the resistor value

and its power dissipation (wattage) rating. Also, the

sense resistor’s value might drift if it is allowed to heat up

excessively.

Inductance: Keep inductance low if ISENSE has a

large high-frequency component. Wire-wound resistors

have the highest inductance, while metal film is some-

what better. Low-inductance metal-film resistors are

also available. Instead of being spiral-wrapped round a

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