ADA4622-2ACPZ-R7 datasheet(27/34 Pages) AD

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Data Sheet

ADA4622-1/ADA4622-2

Rev. B | Page 27 of 34

APPLICATIONS INFORMATION

RECOMMENDED POWER SOLUTION

The ADA4622-1/ADA4622-2 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 positive and

negative rails for the ADA4622-1/ADA4622-2. Both low dropout

regulators (LDOs) 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 90 shows the recommended power

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

ADP5070

ADP7118

ADP7182

+12V

+16V

+15V

–15V

–16V

Figure 90. Power Solution Configuration for the ADA4622-1/ADA4622-2

Table 10. Recommended Power Management Devices

Product

Description

ADP5070

DC-to-DC switching regulator with independent

positive and negative 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 can safely

dissipate is limited by the associated rise in junction

temperature. 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 can result in device burnout. To ensure proper operation, it

is important to observe the Absolute Maximum Ratings and

Thermal Resistance specifications.

SECOND-ORDER LOW-PASS FILTER

Figure 91 shows the ADA4622-1/ADA4622-2 configured 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)

CUTOFF 



2π

1.414

CUTOFF 



2π

0.707

ADA4622-1/

ADA4622-2

0.1µF

+5V

0.1µF

VOUT

VIN

28pF

–5V

56pF

20kΩ

50pF

Figure 91. Second-Order, Butterworth, Low-Pass Filter

Figure 92 shows a plot of the filter; greater than 35 dB of high

frequency rejection is achieved.

100

–50

–40

–30

–20

–10

10k

100k

FREQUENCY (Hz)

10M

100M

Figure 92. Frequency Response of the Filter

WIDEBAND PHOTODIODE PREAMPLIFIER

The ADA4622-1/ADA4622-2 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 maximizes the signal bandwidth of the photodiode

preamplifier. Figure 93 shows the ADA4622-1/ADA4622-2 as a

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

photodiode.

–

VOUT

RSH = 1011Ω

IPHOTO

ADA4622-1/

ADA4622-2

Figure 93. Wideband Photodiode Preamplifier

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