MAX4072AUA(2003) 查看數據表（PDF） - Maxim Integrated

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MAX4072AUA
(Rev.:2003)

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

Maxim Integrated 

Bidirectional, High-Side, Current-Sense

Amplifiers with Reference

IDISCHARGE

2

CELLS

RSENSE

ICHARGE

5V

RS-

RS+

VCC

LOAD

VOUT - VREF

2.5V

MAX4070

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 refer-

ence 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 capaci-

tance 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 maxi-

mum ratings. Use resistors specified for current- sens-

ing applications.

The MAX4069–MAX4072 sense a wide variety of cur-

rents 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 off-

sets become less significant when the sense voltage is

larger. For best performance, select RSENSE to provide

approximately 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 somewhat

better. Low-inductance metal-film resistors are also

available. Instead of being spiral-wrapped round a

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