DIO2240

Version 1.2, Jan 2026

www.dioo.com

© 2026 Dioo Microcircuits Co., Ltd. Jiangsu

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9. Function Description

9.1. Amplifier input signal

The DIO2240 device is an automotive qualified voltage output and current sense amplifier with enhanced

PWM rejection. The device sense drops across the shunt resistor over a wide common-mode voltage range.

Input signals from current measurement applications for linear and PWM applications can be connected to

the amplifier to provide a highly accurate output, with minimal common-mode transient artifacts.

9.1.1. Enhance PWM rejection operation

The enhanced PWM rejection function provides a high level of suppression of large common-mode

transients (ΔV/Δt) in systems that use pulse width modulation (PWM) signals. Large ΔV/Δt common-mode

transients associated with PWM signals are used in applications such as motor or solenoid drive and

switching power supplies. The traditional way to handle the large ΔV/Δt commonmode transitions is to

increase the amplifier signal bandwidth, and it will enlarger the chip size, make the design complexity

increase the cost. The DIO2240 features high common-mode rejection techniques, which reduces large

ΔV/Δt transients before the system is disturbed as a result of these large signals. So the DIO2240 provides

minimal output transients and ringing because of its high AC CMRR with signal bandwidth.

9.1.2. Input signal bandwidth

As mentioned before, the input signal which represents the current being measured is accurately measured

with minimal disturbance from large ΔV/Δt common-mode transients. For PWM signals (commonly motors,

solenoids, and other switching applications), the current being monitored fluctuates at a greatly slower rate

than the faster PWM frequency.

The internal current-sense amplifier defines the DIO2240 bandwidth by the -3dB bandwidth. As required for

the rapid detection and processing of overcurrent events, the device bandwidth provides fast throughput

and fast response. The higher bandwidth enables the protection circuitry to get enough response time so

that the monitored application or circuit will not be damaged.

9.2. RSENSE selection

The current magnitude is determined from measuring the differential voltage developed across a resistor,

which refers to either a current-sensing resistor or a current-shunt resistor. The flexible design of DIO2240

allows a wide input signal range across this current-sensing resistor.

Ideally, the current-sensing resistor is determined solely based on the full-scale current to be measured, the

full-scale input range of the circuitry following the device, and the device gain. The minimum current

sensing resistor is decided by design to maximize the input range of the signal chain circuitry. When the

full-scale output signals that are not maximized to the full input range of the system circuitry, the ability of

the system is limited to exercise the full dynamic range of system control.

When the current-sensing resistor value is finalized, there are two critical factors: the required current

measurement accuracy and the maximum power dissipation across the resistor. A larger resistor voltage

makes the measurement be more accurate, but increases the power dissipation in the resistor. The power

dissipation increase generates the heat and it leads to the sense resistor accuracy decreasing. The larger

input signal can reduce the uncertainty of voltage signal measuring because any fixed errors become a

smaller percentage of the measured signal. The design trade-off to improve measurement accuracy