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Data Sheet

ADA4622-1/ADA4622-2/ADA4622-4

APPLICATIONS INFORMATION

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Rev. F | 29 of 36

RECOMMENDED POWER SOLUTION

The ADA4622-1/ADA4622-2/ADA4622-4 can operate from a ±2.5 V

to ±15 V dual supply or a 5 V to 30 V single supply. The ADP7118

and the ADP7182 are recommended to generate the clean posi-

tive and negative rails for the ADA4622-1/ADA4622-2/ADA4622-4.

Both low dropout (LDO) regulators are available in fixed output

voltage or adjustable output voltage versions. To generate the input

voltages for the LDOs, the ADP5070 dc-to-dc switching regulator is

recommended. Figure 91 shows the recommended power solution

configuration for the ADA4622-1/ADA4622-2/ADA4622-4.

Figure 91. Power Solution Configuration for the ADA4622-1/ADA4622-2/

ADA4622-4

Table 12. Recommended Power Management Devices

Product

Description

ADP5070

DC-to-DC switching regulator with independent positive and neg-

ative outputs

ADP7118

20 V, 200 mA, low noise, CMOS LDO regulator

ADP7182

−28 V, −200 mA, low noise, linear regulator

MAXIMUM POWER DISSIPATION

The maximum power the ADA4622-1/ADA4622-2/ADA4622-4 can

safely dissipate is limited by the associated rise in junction tempera-

ture. For plastic packages, the maximum safe junction temperature

is 150°C. If this maximum temperature is exceeded, reduce the die

temperature to restore proper circuit operation. Leaving the device

in the overheated condition for an extended period of time can

result in device burnout. To ensure proper operation, it is important

to observe the specifications shown in the Absolute Maximum

Ratings and Thermal Resistance sections.

SECOND-ORDER LOW-PASS FILTER

Figure 92 shows the ADA4622-1/ADA4622-2/ADA4622-4 config-

ured as a second-order, Butterworth, low-pass filter. With the values

as shown, the corner frequency equals 200 kHz. The following

equations show the component selection:

R1 = R2 = User Selected (Typical Values: 10 kΩ to 100 kΩ)

C1 = 1.414

2πfCUTOFF×R1

(2)

C2 = 0.707

2πfCUTOFF×R1

(3)

Figure 92. Second-Order, Butterworth, Low-Pass Filter

Figure 93 shows a plot of the filter; greater than 35 dB of high

frequency rejection is achieved.

Figure 93. Frequency Response of the Filter

WIDEBAND PHOTODIODE PREAMPLIFIER

The ADA4622-1/ADA4622-2/ADA4622-4 are an excellent choice

for photodiode preamplifier applications. The low input bias current

minimizes the dc error at the output of the preamplifier. In addition,

the high gain bandwidth product and low input capacitance maxi-

mizes the signal bandwidth of the photodiode preamplifier. Figure

94 shows the ADA4622-1/ADA4622-2/ADA4622-4 as a current to

voltage (I to V) converter with an electrical model of a photodiode.

Figure 94. Wideband Photodiode Preamplifier

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