MAX4004EUT-T(2003) Просмотр технического описания (PDF) - Maxim Integrated

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MAX4004EUT-T
(Rev.:2003)

High-Accuracy, High-Side Current Monitors in SOT23

Maxim Integrated 

High-Accuracy, High-Side Current Monitors

in SOT23

Functional Diagrams

BIAS

CURRENT

MONITOR

10x

1x

MAX4004

CURRENT

CLAMP

REF

GND

CLAMP

OUT

BIAS

CURRENT

MONITOR

10x

1x

MAX4006

CURRENT

CLAMP

REF

CLAMP

OUT

10kΩ

GND

Detailed Description

The MAX4004/MAX4006 are versatile current monitors

intended for monitoring DC photodiode current in fiber

applications (see the Functional Diagram). The

MAX4004 output is a current that is exactly one-tenth of

the reference current. The MAX4006 outputs a voltage

that is proportional to the reference current with a tran-

simpedance gain of 1V/mA achieved by a factory-

trimmed, internal 10kΩ resistor.

Both current devices have six decades of dynamic

range and monitor reference current ranging from 250nA

to 2.5mA, the nominal operating range, with better than

5% accuracy across the entire reference current, bias

voltage, and temperature ranges. The corresponding

monitor outputs produce 25nA to 0.25mA (MAX4004)

and 0.25mV to 2.5V (MAX4006). When the reference

currents are extended to the broader range of 10nA to

10mA, an accuracy of less than 10% is maintained.

Internal current limiting (20mA, typ) protects the device

against short-circuit-to-ground conditions, and a thermal

shutdown feature reduces both the reference current

and the monitor current to zero if the die temperature

reaches +150°C.

The MAX4004/MAX4006 accept a +2.7V to +22V

supply voltage, suitable for PIN photodiode applica-

tions. A clamping diode, shown in the Functional

Diagram, is provided to protect subsequent output cir-

cuitry from an overvoltage condition.

Applications Information

Clamping the Monitor Output Voltage

CLAMP provides a means for diode clamping the volt-

age at OUT, thus VOUT is limited to VCLAMP + 0.6V.

CLAMP can be connected to either an external supply,

to BIAS, or can be left floating if voltage clamping is not

required.

Using PIN Photodiodes in Fiber

Applications

When using the MAX4004/MAX4006 to monitor PIN

photodiode currents in fiber applications, several

issues must be addressed. In applications where the

photodiode must be fully depleted, keep track of volt-

ages budgeted for each component with respect to the

available supply voltage(s). The current monitor

requires as much as 1.2V between BIAS and REF,

which must be considered as part of the overall voltage

budget.

Additional voltage margin can be created if a negative

supply is used in place of a ground connection, as long

as the overall voltage drop experienced by the

MAX4004/MAX4006 is less than or equal to 22V. For

this type of application, the MAX4004 is suggested so

the output can be referenced to “true” ground and not

the negative supply. The MAX4004’s output current can

be referenced as desired with either a resistor to

ground or a transimpedance amplifier. Take care to

ensure that output voltage excursions do not interfere

with the required margin between BIAS and OUT.

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