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LMP8601 Operating Conditions

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The part has a precise gain of 20x, which is adequate in most targeted applications to drive an ADC to its

full scale value. The fixed gain is achieved in two separate stages, a pre-amplifier with a gain of 10x and

an output stage buffer amplifier with a gain of 2x. The connection between the two stages of the signal

path is brought out on two pins to enable the possibility to create an additional filter network around the

output buffer amplifier. These pins can also be used for alternative configurations with different gain as

described in the Applications Information section of the LMP8601, LMP8601-Q1 60-V Common-Mode

Bidirectional Precision Current Sensing Amplifier Data Sheet (SNOSAR2).

The mid-rail offset adjustment pin enables you to use these devices for bidirectional single supply voltage

current sensing. The output signal is bidirectional and mid-rail referenced when this pin is connected to the

positive supply rail. With the offset pin connected to ground, the output signal is unidirectional and ground-

referenced.

The LMP8601Q incorporates enhanced manufacturing and support processes for the automotive market,

including defect detection methodologies. Reliability qualification is compliant with the requirements and

temperature grades defined in the AEC Q100 standard.

3 LMP8601 Operating Conditions

• Temperature Range −40°C to 125°C

• Power Supply Voltage 3.0 V ≤ V

≤ 5.5 V

• CMVR at V

= 3.3 V −4 V to 27 V

• CMVR at V

= 5.0 V −22 V to 60 V

4 Description of the LMP8601 Evaluation Board

The LMP8601 evaluation board requires a power supply with a voltage between 3.0 V and 5.5 V, the

supply current will be <2 mA in normal operation with high-impedance load on the output of the part. The

positive supply voltage is connected to V

(P5). The negative supply voltage is connected to GND (P6).

The offset voltage on the output of the LMP8601 is determined by the voltage on the offset pin, which is

connected to pin2 of J1 and the offset voltage will be V

Offset

/2. This pin is normally connected with a jumper

to GND or V

, but this pin can also be driven from a low impedance source (<10 Ω).

With a jumper on J1 between 1–2, the offset pin is connected to V

and the offset voltage is half the value

of V

. In this configuration, the LMP8601 can be used for measuring bidirectional currents.

With a jumper on J1 between 2–3, the offset pin is connected to GND and the output voltage is ground

referenced. In this configuration, the LMP8601 is used for measuring unidirectional currents.

The input signal is connected between +IN (P1) and −IN (P2) and the output signal is available at OUT

(P3).

On the board there is the possibility to place a capacitor C2 that creates a low-pass filter between the first

and second stage. This can be used to reduce the output noise and glitches that might appear from

switching large common mode voltages with very fast transients at the input. (For more details about this

filter, see the Application Information section of the LMP8601, LMP8601-Q1 60-V Common-Mode

Bidirectional Precision Current Sensing Amplifier Data Sheet (SNOSAR2).

The Header J2 is normally shorted with a jumper and connects the first stage to the second stage. The

Application Information section of the LMP8601, LMP8601-Q1 60-V Common-Mode Bidirectional Precision

Current Sensing Amplifier Data Sheet (SNOSAR2) explains more about the alternative configurations that

can be made after removing the jumper on J2.

AN-1940 LMP8601 Evaluation Board SNOA539A–February 2009–Revised April 2013

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