Low-Cost, Micropower, High-Side Current-Sense

Amplifier + Comparator + Reference ICs

10

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the Electrical Characteristics and Typical Operating

Characteristics.

Internal Comparator(s)

The MAX4373/MAX4374/MAX4375 contain a latching

output comparator. The negative terminal of the com-

parator is internally connected to the internal reference.

The positive terminal is accessible at CIN1. When

RESET is high, the comparator output latches high

once the comparator threshold is exceeded. When

RESET is low, the latch is transparent.

The MAX4374 and MAX4375 each contain an addition-

al comparator for use in window detection. The nega-

tive terminal of the MAX4374 and the positive terminal

of the MAX4375 are internally connected to the internal

reference. The positive terminal of the MAX4374 and

the negative terminal of the MAX4375 are accessible at

CIN2.

___________Applications Information

Recommended Component Values

Ideally, the maximum load current will develop the full-

scale sense voltage across the current-sense resistor.

Choose the gain version needed to yield the maximum

output voltage required for the application:

gains of +20V/V and +50V/V or 100mV for a gain of

the gain of +100V/V is internally clamped at 12V.

differential voltage across RS+ and RS- does not

exceed the full-scale sense voltage:

Choose the highest value resistance possible to maxi-

In applications monitoring high current, ensure that

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.

Overcurrent Protection Circuit

The overcurrent protection circuit, shown in Figure 2,

uses the MAX4373 to control an external P-channel

MOSFET. The MOSFET controlled by the MAX4373

opens the current path under overload conditions. The

latched output of the MAX4373’s comparator prevents

the circuit from oscillating, and the pushbutton resets

the current path after an overcurrent condition.

Window Detection Circuit

Figure 3 shows a simple circuit suitable for window

a high state at COUT1:

nal reference voltage (0.6V typ).

Connect COUT1 and COUT2; the resulting comparator

output will be high when the current is inside the cur-

rent window and low when the current is outside the

window. The window is defined as load currents less

RS-

RS+

OUT

CIN1

LOAD

MAX4373

GND

COUT1

RESET

PUSHBUTTON

2.7V TO 5.5V

Figure 2. MAX4373 Overcurrent Protection Circuit

VV

A

OUT

SENSE

V

=

×

R

V

I

SENSE MAX

LOAD

SENSE MAX

()

()

=

I

V

RA

RR

R

and

I

V

RA

RR

R

UNDER

REF

SENSE

V

OVER

REF

SENSE

V

=

+









=

+









×

×

45

5

12

2