ANALOG DEVICES AD845 Service Manual

Precision, 16 MHz

www.BDTIC.com/ADI

FEATURES Replaces Hybrid Amplifiers in Many Applications

AC PERFORMANCE: Settles to 0.01% in 350 ns 100 V/␮s Slew Rate

12.8 MHz Min Unity Gain Bandwidth

1.75 MHz Full Power Bandwidth at 20 V p-p

DC PERFORMANCE:

0.25 mV Max Input Offset Voltage 5 ␮V/ⴗC Max Offset Voltage Drift

0.5 nA Input Bias Current 250 V/mV Min Open-Loop Gain 4 ␮V p-p Max Voltage Noise, 0.1 Hz to 10 Hz 94 dB Min CMRR Available in Plastic Mini-DIP, Hermetic CERDIP, and

SOIC Packages. Also Available in Tape and Reel in Accordance with EIA-481A Standard

GENERAL DESCRIPTION

The AD845 is a fast, precise, N channel JFET input, monolithic operational amplifier. It is fabricated using Analog Devices’ complementary bipolar (CB) process. Advanced laser-wafer trimming technology enables the very low input offset voltage and offset voltage drift performance to be realized. This precision, when coupled with a slew rate of 100 V/ms, a stable unity gain bandwidth of 16 MHz, and a settling time of 350 ns to

0.01%—while driving a parallel load of 100 pF and 500 W— represents a combination of features unmatched by any FET input IC amplifier. The AD845 can easily be used to upgrade many existing designs that use BiFET or FET input hybrid amplifiers and, in some cases, those which use bipolar input op amps.

The AD845 is ideal for use in applications such as active filters, high speed integrators, photodiode preamps, sample-and-hold amplifiers, and log amplifiers, and for buffering A/D and D/A converters. The 250 mV max input offset voltage makes offset nulling unnecessary in many applications. The common-mode rejection ratio of 110 dB over a ±10 V input voltage range represents exceptional performance for a JFET input high speed op amp. This, together with a minimum open-loop gain of 250 V/mV ensures that 12-bit performance is achieved, even in unity gain buffer circuits.

CBFET Op Amp

AD845

CONNECTION DIAGRAMS

Plastic Mini-DIP (N) Package

and CERDIP (Q) Package

The AD845 conforms to the standard op amp pinout except that offset nulling is to V+. The AD845J and AD845K grade devices are available specified to operate over the commercial 0∞C to 70∞C temperature range. AD845A and AD845B devices are specified for operation over the –40∞C to +85∞C industrial temperature range. The AD845S is specified to operate over the full military temperature range of –55∞C to +125∞C. Both the industrial and military versions are available in 8-lead CERDIP packages. The commercial version is available in an 8-lead plastic mini-DIP and 16-lead SOIC; J and S grade chips are also available.

PRODUCT HIGHLIGHTS

1. The high slew rate, fast settling time, and dc precision of the AD845 make it ideal for high speed applications requiring 12-bit accuracy.

2. The performance of circuits using the LF400, HA2520, HA2522, HA2525, HA2620, HA2622, HA2625, 3550, OPA605, and LH0062 can be upgraded in most cases.

3. The AD845 is unity gain stable and internally compensated.

4. The AD845 is specified while driving 100 pF/500 W loads.

16-Lead SOIC

(R-16) Package

REV. E

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

AD845–SPECIFICATIONS

www.BDTIC.com/ADI

(@ 25ⴗC and ⴞ15 V dc, unless otherwise noted.)

AD845J/A AD845K/B AD845S

Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit

INPUT OFFSET VOLTAGE

Initial Offset 0.7 1.5 0.1 0.25 0.25 1.0 mV

MIN

to T

MAX

2.5 0.4 2.0 mV

Offset Drift 20 1.5 5.0 10 mV/∞C

INPUT BIAS CURRENT

Initial VCM = 0 V 0.75 2 0.5 1 0.75 2 nA

MIN

to T

MAX

45/75 18/38 500 nA

INPUT OFFSET CURRENT

Initial VCM = 0 V 25 300 15 100 25 300 pA

to T

MIN

MAX

INPUT CHARACTERISTICS

Input Resistance 10

3/6.5 1.2/2.6 20 nA

Input Capacitance 4.0 4.0 4.0 pF

INPUT VOLTAGE RANGE

Differential ±20 ±20 ± 20 V Common-Mode ⴞ10 +10.5/–13 ⴞ10 +10.5/–13 ⴞ10 +10.5/–13 V Common-Mode Rejection VCM = ±10 V 86 110 94 113 86 110 dB

INPUT VOLTAGE NOISE 0.1 Hz to 10 Hz 4 4 4 mV p-p

f = 10 Hz 80 80 80 nV/÷Hz f = 100 Hz 60 60 60 nV/÷Hz f = 1 kHz 25 25 25 nV/÷Hz f = 10 kHz 18 18 18 nV/÷Hz f = 100 kHz 12 12 12 nV/÷Hz

INPUT CURRENT NOISE f = 1 kHz 0.1 0.1 0.1 pA/÷Hz

OPEN-LOOP GAIN V

= ±10 V

≥ 2 kW 200 500 250 500 200 500 V/mV

LOAD

≥ 500 W 100 250 125 250 100 250 V/mV

LOAD

MIN–TMAX

70 75 50 V/mV

OUTPUT CHARACTERISTICS

Voltage R

≥ 500 W ⴞ12.5 ⴞ12.5 ⴞ12.5 V

LOAD

Current Short Circuit 50 50 50 mA Output Resistance Open Loop 5 5 5 W

FREQUENCY RESPONSE

Small Signal Unity Gain 12.8 16 13.6 16 13.6 16 MHz Full Power Bandwidth

VO = ±10 V R

= 500 W 1.75 1.75 1.75 MHz

LOAD

Rise Time 20 20 20 ns Overshoot 20 20 20 % Slew Rate 80 100 94 100 94 100 V/ms Settling Time 10 V Step

= 100 pF

LOAD

= 500 W

LOAD

to 0.01% 350 350 500 350 500 ns to 0.1% 250 250 250 ns

DIFFERENTIAL GAIN f = 4.4 MHz 0.04 0.04 0.04 %

DIFFERENTIAL PHASE f = 4.4 MHz 0.02 0.02 0.02 Degree

POWER SUPPLY

Rated Performance ±15 ±15 ± 15 V Operating Range ⴞ4.75 ⴞ18 ⴞ4.75 ⴞ18 ⴞ4.75 ⴞ18 V Rejection Ratio V Quiescent Current T

NOTES

Input offset voltage specifications are guaranteed after five minutes of operation at TA = 25∞C.

Bias current specifications are guaranteed maximum at either input after five minutes of operation at T

FPBW = slew rate/2 p V peak.

S grade T

All min and max specifications are guaranteed. Specifications shown in boldface are tested on all production units at final electrical test. Results from these tests are used to calculate outgoing quality levels.

Specifications subject to change without notice.

MIN–TMAX

are tested with automatic test equipment at TA = –55∞C and TA = +125∞C.

= ± 5 to ±15 V 88 110 95 113 88 110 dB

MIN

to T

MAX

10 12 10 12 10 12 mA

= 25∞C.

–2–

REV. E

AD845

www.BDTIC.com/ADI

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V

Internal Power Dissipation

Plastic Mini-DIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.6 W

CERDIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.4 W

16-Lead SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 W

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +V

Output Short-Circuit Duration . . . . . . . . . . . . . . . . Indefinite

Differential Input Voltage . . . . . . . . . . . . . . . . . . +V

and –V

Storage Temperature Range

Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .–65∞C to +150∞C

N, R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .–65∞C to +125∞C

Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300∞C

NOTES

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only, and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Mini-DIP package: qJA = 100∞C/W; CERDIP package: qJA = 110∞C/W; SOIC package: qJA = 100∞C/W.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

METALIZATION PHOTOGRAPH

Dimensions shown in inches and (mm).

Contact factory for latest dimensions.

SUBSTRATE CONNECTED TO +V

AD845JN 0∞C to 70∞C 8-Lead PDIP N-8 AD845KN 0∞C to 70∞C 8-Lead PDIP N-8 AD845JR-16 0∞C to 70∞C 16-Lead SOIC R-16 AD845JR-16-REEL 0∞C to 70∞CTape and Reel R-16 AD845JR-16-REEL7 0∞C to 70∞CTape and Reel R-16 AD845AQ –40∞C to +85∞C 8-Lead CERDIP Q-8 AD845BQ –40∞C to +85∞C 8-Lead CERDIP Q-8 AD845SQ –55∞C to +125∞C 8-Lead CERDIP Q-8 AD845SQ/883B –55∞C to +125∞C 8-Lead CERDIP Q-8 5962-8964501PA

–55∞C to +125∞C 8-Lead CERDIP Q-8

AD845JCHIPS 0∞C to 70∞CDie

NOTES

N = Plastic DIP; Q = CERDIP; R = Small Outline IC (SOIC).

See military data sheet.

REV. E

–3–

AD845–Typical Performance Characteristics

www.BDTIC.com/ADI

TPC 1. Input Voltage Swing vs. Supply Voltage

TPC 4. Quiescent Current vs. Supply Voltage

TPC 2. Output Voltage Swing vs. Supply Voltage

TPC 5. Input Bias Current vs. Temperature

TPC 3. Output Voltage Swing vs. Resistive Load

TPC 6. Magnitude of Output Impedance vs. Frequency

TPC 7. Input Bias Current vs. Common-Mode Voltage

TPC 8. Short-Circuit Current Limit vs. Temperature

–4–

TPC 9. Unity-Gain Bandwidth vs. Temperature

REV. E

+ 8 hidden pages