AD9624 datasheet(3/6 Pages) AD

3 / 6 page

OBSOLETE

AD9624

REV. 0

–3–

ABSOLUTE MAXIMUM RATINGS

Supply Voltages (

±V

S) . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 6 V

Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . .

±V

Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V

Continuous Output Current

2 . . . . . . . . . . . . . . . . . . . . . 90 mA

Operating Temperature Ranges

AN, AQ, AR . . . . . . . . . . . . . . . . . . . . . . . . –40

°C to +85°C

SQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55

°C to +125°C

Storage Temperature

Ceramic . . . . . . . . . . . . . . . . . . . . . . . . . . . –65

°C to +150°C

Plastic . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65

°C to +125°C

Junction Temperature

Ceramic

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +175

°C

Plastic

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150

°C

Lead Soldering Temperature (1 minute)

. . . . . . . . . . +220

°C

NOTES

1Absolute maximum ratings are limiting values to be applied individually, and

beyond which the serviceability of the circuit may be impaired. Functional

operability is not necessarily implied. Exposure to absolute maximum rating

conditions for an extended period of time may affect device reliability.

2Output is short-circuit protected; for maximum reliability, 90 mA continuous

current should not be exceeded.

3Typical thermal impedances (part soldered onto board; no air flow):

Ceramic DIP:

JA = 100°C/W; θJC = 30°C/W

Plastic SOIC:

JA = 125°C/W; θJC = 45°C/W

Plastic DIP:

JA = 90°C/W; θJC = 45°C/W

4Temperature shown is for surface mount devices, mounted by vapor phase

soldering. Throughhole devices (ceramic and plastic DIPs) can be soldered at

+300

°C for 10 seconds.

ORDERING GUIDE

Temperature

Package

Model

Range

Description

Option

AD9624AN

–40

°C to +85°C

8-Pin Plastic DIP

N-8

AD9624AQ

–40

°C to +85°C

8-Pin Cerdip

Q-8

AD9624AR

–40

°C to +85°C

8-Pin SOIC

R-8

AD9624SQ

–55

°C to +125°C 8-Pin Cerdip

Q-8

EXPLANATION OF TEST LEVELS

Test Level

– 100% production tested.

II – 100% production tested at +25

°C, and sample tested at

specified temperatures. AC testing of “A” grade devices

done on sample basis.

III – Sample tested only.

IV – Parameter is guaranteed by design and characterization

testing.

– Parameter is a typical value only.

VI – All devices are 100% production tested at +25

°C. 100%

production tested at temperature extremes for extended

temperature devices; sample tested at temperature ex-

tremes for commercial/industrial devices.

–V

46.5mm

– INPUT

46.5 MILS

CB–

CB+

–INPUT +INPUT

OUTPUT

MILS

Chip Layout

THEORY OF OPERATION

The AD9624 is a wide bandwidth voltage feedback amplifier

that is guaranteed for minimum gain stability of +6. Since its

open-loop frequency response follows the conventional 6 dB/

octave roll-off, its gain bandwidth product is basically constant.

Increasing its closed-loop gain results in a corresponding de-

crease in small signal bandwidth. The AD9624 typically main-

tains a 60 degree unity loop gain phase margin with RF ≅ 510 Ω.

This high margin minimizes the effects of signal and noise

peaking.

Feedback Resistor Choice

At minimum stable gain (+6), the AD9624 provides optimum

dynamic performance with RF = 510

Ω. When using this value

and following the high speed layout guidelines, a shunt capacitor

(CF) should not be required. This value for RF provides the best

combination of wide bandwidth, low peaking, and distortion.

However, if improved gain flatness is desired, a shunt capacitor

(CF) will provide extra phase margin. This reduces both over-

shoot and peaking with only a slight reduction of bandwidth.

As an example, if the amplifier exhibits (worst case) peaking of

1.2 dB with RG RF = 85

Ω (A

V = 6), then using a CF of

≈ 0.5 pF(two 1 pF capacitors in series) across R

F will reduce this

peaking to 0 dB. In addition, overshoot, noise, and settling time

(<0.01%) will also improve. This comes at the expense of

slightly decreased closed-loop bandwidth due to the RF

time constant created.

If the equivalent input capacitance greatly exceeds 4 pF (due to

source drive or long input traces to the amplifier), then added

shunt capacitance (CF) will be necessary to maintain stability at

minimum gain.

As a rule of thumb, if the product of RF RG

CI ≤ 300

–12

seconds, then CF is not required (for maximum bandwidth ap-

plications) and the amplifier’s phase margin will maintain

about 60

°. Generally, this should be the case.

Pulse Response

Unlike a traditional voltage feedback amplifier in which slew

speed is usually dictated by its front end dc quiescent current

and gain bandwidth product, the AD9624 provides “on de-

mand” transconductance current that increases proportionally

to the input “step” signal amplitude. This results in slew speeds

(2000 V/

µs) comparable to wideband current feedback designs.

This, combined with relatively low input noise current

(2.5 pA/

√Hz), gives the AD9624 the best attributes of both volt-

age and current feedback amplifiers.

AD9624 Datasheet(PDF) 3 Page - Analog Devices

AD9624 Datasheet(HTML) 3 Page - Analog Devices

Html Pages

1 2 3 4 5 6

Datasheet Download

Link URL