ADA4522-4ARZ-R7 datasheet(29/48 Pages) AD

29 / 48 page

Data Sheet

ADA4522-1/ADA4522-

2/ADA4522-4

analog.com

Rev I 29 of 48

On-Chip Input EMI Filter and Clamp Circuit

Figure 72

shows the input EMI filter and clamp circuit. The ADA4522-1/ADA4522-2/ADA4522-4 have internal ESD

protection diodes (D1, D2, D3, and D4) that are connected between the inputs and each supply rail. These diodes

protect the input transistors in the event of electrostatic discharge and are reverse biased during normal operation.

This protection scheme allows voltages as high as approximately 300 mV beyond the rails to be applied at the input

of either terminal without causing permanent damage. See Table 5 in the Absolute Maximum Ratings section for more

information.

The EMI filter is composed of two 200 Ω input series resistors (RS1 and RS2), two common-mode capacitors (CCM1 and

CCM2), and a differential capacitor (CDM). These RC networks set the −3 dB low-pass cutoff frequencies at 50 MHz for

common-mode signals, and at 33 MHz for differential signals. After the EMI filter, back to back diodes (D5 and D6) are

added to protect internal circuit devices from high voltage input transients. Each diode has about 1 V of forward turn

on voltage. See the Large Signal Transient Response section for more information on the effect of high voltage input

transient on the ADA4522-1/ADA4522-2/ADA4522-4.

As specified in the Absolute Maximum Ratings section (see Table 5), the maximum input differential voltage is limited

to ±5 V. If more than ±5 V is applied, a continuous current larger than ±10 mA flows through one of the back to back

diodes. This current compromises long-term reliability and can cause permanent damage to the device.

Figure 72.Input EMI Filter and Clamp Circuit

Thermal Shutdown

The ADA4522-1/ADA4522-2/ADA4522-4 have internal thermal shutdown circuitry for each channel of the amplifier.

The thermal shutdown circuitry prevents internal devices from being damaged by an overheat condition in the die.

Overheating can occur due to a high ambient temperature, a high supply voltage, and/or high output currents. As

specified in Table 5, take care to maintain the junction temperature below 150°C.

Two conditions affect junction temperature (TJ): the total power dissipation of the device (PD) and the ambient

temperature surrounding the package (TA). Use the following equation to estimate the approximate junction

temperature:

TJ = PD × θJA + TA

(1)

where θJA is the thermal resistance between the die and the ambient environment, as shown in Table 6.

The total power dissipation is the sum of quiescent power of the device and the power required to drive a load for

all channels of an amplifier. The power dissipation per amplifier (PD_PER_AMP) for sourcing a load is shown in Equation

PD_PER_AMP = (VSY+− VSY−) × ISY_PER_AMP + IOUT × (VSY+ − VOUT)

(2)

When sinking current, replace (VSY+ − VOUT) in Equation 2 with (VOUT − VSY−).

V+

+IN x

–IN x

V–

RS1

200Ω

RS2

200Ω

CCM1

CDM

CCM2

NOTES

1. THE INPUTS ARE +IN x/–IN x ON THE ADA4522-2

AND ADA4522-4, AND +IN/–IN ON THE ADA4522-1.

ADA4522-4ARZ-R7 Datasheet(PDF) 29 Page - Analog Devices

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