Datasheet

LMP8278Q Operating Conditions

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3 LMP8278Q Operating Conditions

• Temperature Range −40°C to 125°C

• Power Supply Voltage 4.5V ≤ V

≤ 5.5V

• CMVR for ±1.0% gain accuracy −2V to +40V

• CMVR for ±0.5% gain accuracy −2V to 28V

4 Description of the LMP8278Q Evaluation Board

The LMP8278Q evaluation board requires a power supply with a voltage between 4.5V and 5.5V. The

supply current will be <1 mA in normal operation with high impedance load on the output of the part. The

positive supply voltage is connected to VCC (CON3) The negative supply voltage is connected to GND

(CON4).

The input signal is connected between –IN and +IN (pins 2 and 3 of P1) and the output signal is available

at OUT (pin 2 of P2).

There is the option to place a capacitor C1 on the board to create a low pass filter between the first and

second stage of the amplifier. 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 LMP8278Q High Common Mode, 14 x Gain, Precision

Current Sensing Amplifier (SNAS575)).

Additional test points, TP1 and GND, are provided at the output of the LMP8278Q for convenience of use.

Figure 2. Power Supply Connectors and Headers

5 PCB Layout Guidelines

This section provides general practical guidelines for PCB layouts that use various power and ground

traces. Designers should note that these are only "rule-of-thumb" recommendations and the actual results

are predicated on the final layout.

5.1 Differential Signals

The two input pins of the LMP8278Q form a differential pair that must be handled following the rules given

below:

• Keep both signals coupled by routing them closely together and keeping them of equal length.

• Do not allow any other signal in between these two signals of the differential pair.

• Keep all impedances in both traces of the signal equal.

AN-2223 LMP8278Q VSSOP Evaluation Board SNAA135A–February 2012–Revised April 2013

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