ADHV4702-1BCPZ-R7 datasheet(20/22 Pages) AD

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Data Sheet

ADHV4702-1

APPLICATIONS INFORMATION

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Rev. D | 20 of 22

POWER SUPPLY AND DECOUPLING

The ADHV4702-1 can operate from a single supply or dual supply.

The ADHV4702-1 requires a minimum supply voltage (VCC - VEE)

of 24 V. Single supply of ADHV4702-1 is VEE = DGND, VCC = 24

V and ±12 V for dual supplies. Decouple each supply pin to ground

using high quality, low effective series resistance (ESR), 0.1 µF ca-

pacitors. Place decoupling capacitors as close to the supply pins as

possible. Additionally, place 1.2 µF tantalum capacitors from each

supply to ground to provide sufficient low frequency decoupling and

supply the needed current to support large, fast slewing signals at

the ADHV4702-1 output. To ensure reliable operation under high

voltages, the voltage ratings for the bypass capacitors must be

higher than the supply voltages of the ADHV4702-1.

HIGH VOLTAGE GUARD RING

The ADHV4702-1 features a pin placement that facilitates the use

of a guard ring around the noninverting input of the amplifier.

Guarding minimizes leakage from nearby pins and helps to achieve

the benefit of low input bias current. The guard must be free of

solder mask so that it remains exposed on the surface of the PCB.

Drive the guard ring to a potential that tracks the input of the

amplifier.

HIGH VOLTAGE DAC VOLTAGE SUBTRACTOR

The ADHV4702-1 can be combined with a dual, 16-bit voltage out-

put, DAC, such as the AD5752R, to produce a versatile high volt-

age DAC solution. For this configuration, set up the ADHV4702-1

as a voltage subtractor with a gain of 20, which is ideally suited

for chemical analysis (mass spectrometry), piezodrive, scanning

electron microscope (SEM), LiDAR APD/SPAD, and silicon photo-

multiplier bias control applications.

Figure 63. ADHV4702-1 Configured as a Voltage Subtractor Using DACs

HIGH CURRENT OUTPUT DRIVER

Figure 64 shows a system level application of the ADHV4702-1 that

boosts the output current drive of the amplifier. By introducing a

discrete unity-gain output stage, the ADHV4702-1 can be used as a

high power output driver retaining the precision performance capa-

bilities of the standalone amplifier, such as offset, drift, open-loop

gain, and CMRR, while increasing the output current drive up to the

current handling capabilities of the discrete devices.

Figure 64. High Current Output Driver Schematic

SIGNAL RANGE EXTENDER

Figure 65 shows an example of a signal range extender configu-

ration. By introducing two additional high power, discrete, metal-ox-

ide semiconductor field effect transistors (MOSFETs), the range

extender can deliver at least twice the signal range (depending on

the MOSFET selection), while retaining the original performance

characteristics of the amplifier.

Figure 65. Voltage Extender Schematic

ASYMMETRICAL POWER SUPPLIES

OPERATION

If an application requires asymmetrical power supplies operation of

the ADHV4702-1, certain boundary conditions, respective to each

power supply, is observed for accurate and reliable operation. Table

6 details some typical asymmetrical power supply cases. Input

common-mode voltage range and output voltage swing limits are

observed as shown in Table 6. Due to the higher gains needed for

a high voltage use case, the input common-mode voltage range is

usually not the limitation but always check the final application. The

cases shown in Table 6 use the 20 mA load current for the output

voltage range given in Table 1. Figure 66 shows a typical simulation

schematic for an asymmetrical supplies operation with VCC = 48 V

and VEE = −172 V. Note that in Figure 67, the performance aligns

with that of Table 6. The schematic shown in Figure 66 is simulated

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