ADHV4702-1, a high-precision operational amplifier that can directly input 220V

Precision operational amplifier ADHV4702-1 capable of direct 220V input

Applications such as high-side current sensing, high-voltage drivers, ATE (automatic test equipment), and LiDAR require high-voltage analog circuitry exceeding tens of volts.
Until now, high-voltage analog circuits have been realized using discrete circuits such as transistors, but there were issues such as expensive components, difficulty in miniaturizing the circuits, and heat generation.

The ADHV4702-1 from Analog Devices, Inc. is a high-voltage, high-precision operational amplifier that solves these challenges using Analog Devices' proprietary next-generation semiconductor process and innovative architecture.

Here we will introduce the following four features of ADHV4702-1.

Low noise measurement of high voltage signals with few parts
Drives signal outputs up to 220V without expensive discrete transistor circuits
Thermal protection with internal temperature sensor and shutdown function (thermal shutdown)
Small package with EC61010-1 compliant pinout

Low noise measurement of high voltage signals with few parts

The ADHV4702-1 is designed using Analog Devices' proprietary next generation bipolar/complementary metal oxide semiconductor (CMOS)/laterally diffused metal oxide semiconductor (BCDMOS) process.

With these technologies, the ADHV4702-1 realizes high-voltage, high-precision analog circuits with a small number of components.
The functional block diagram of ADHV4702-1 is shown below.

Functional block diagram of ADHV4702-1 (Source: Excerpt from ADHV7402-1 data sheet)

The input stage architecture of the ADHV4702-1 offers the benefits of high input impedance with low input bias current, low input offset voltage, low drift, and low noise for precision applications such as automatic test equipment (ATE). Offers.

The ADHV7402-1 provides precision performance of 170 dB (typical) open-loop gain (AOL) and 160 dB (typical) common-mode rejection ratio (CMRR) as shown in the following characteristic graphs. increase. The ADHV4702-1 also achieves an input offset voltage (VOS) drift of 2 µV/°C (maximum) and an input voltage noise of 8 nV/√Hz.

High accuracy performance of ADHV7402-1 (Source: Excerpt from ADHV7402-1 data sheet)

Drives signal outputs up to 220V without expensive discrete transistor circuits

The ADHV4702-1 operates from ±110 V symmetrical split supplies, asymmetric split supplies, or a 220 V single supply.
This wide supply voltage range enables high voltage circuits with few external components, as in the typical application circuit below.

ADHV4702-1 typical application circuit (Source: Excerpt from ADHV7402-1 data sheet)

The ADHV4702-1 can also realize the following functions depending on the peripheral circuit configuration.

Voltage Subtractor with High Voltage DAC

In this configuration, the ADHV4702-1 can be set up as a voltage subtractor with a gain of 20 for biasing chemical analysis (mass spectrometry), driving piezos, scanning electron microscopes (SEM), LiDAR APD/SPAD, silicon photomultiplier tubes, etc. Great for control.

Voltage subtractor with ADHV4702-1 and high voltage DAC (Source: Excerpt from ADHV7402-1 datasheet)

high current output driver

By implementing a unity gain output stage using discrete components, the ADHV47021 can be used as a high power output driver.
The output current drive can be amplified to the currents that can be handled by discrete products while maintaining the precision performance of the amplifier alone, such as offset, drift, open-loop gain, and CMRR.

Thermal protection with internal temperature sensor and shutdown function (thermal shutdown)

Operating an IC above the operating temperature specified by its absolute maximum ratings may affect product reliability.

To minimize this risk, the ADHV4702-1 includes a resistor-adjustable thermal shutdown option.

The ADHV4702-1 is disabled and enters a low power state when the SD pin voltage drops to within 0.8V of DGND. This reduces the quiescent current to approximately 0.18mA.

Additionally, the temperature information output as a voltage on the TMP pin represents the approximate temperature of the IC chip, so it can also be used to monitor power consumption. A one-time calibration of the TMP pin at room temperature allows for more accurate temperature measurements.
The graph below shows the relationship between TMP pin voltage and junction temperature.

ADHV4702-1 TMP pin voltage versus junction temperature (Source: Excerpt from ADHV7402-1 datasheet)

The thermal shutdown feature is enabled by connecting TMP to SD and connecting a 200 kΩ resistor (RTMP) between TMP and SD to DGND, as close to the ADHV4702-1 as possible, as shown in the schematic below. It can be realized.

ADHV4702-1 Configuration for Short-Circuit Protection and Thermal Shutdown (Source: Excerpt from ADHV7402-1 Datasheet)

Small package with IEC61010-1 compliant pinout

The ADHV4702-1 has a package configuration that complies with IEC61010-1, a safety standard related to measurement equipment.
In addition, the package size is 7 mm × 7 mm (LFCSP), which contributes to circuit miniaturization and multi-channel development.