ANALOG DEVICES SSM2018T Service Manual

a

Trimless

Voltage Controlled Amplifiers

FEATURES
117 dB Dynamic Range

0.006% Typical THD+N (@ 1 kHz, Unity Gain)
140 dB Gain Range
No External Trimming Required
Differential Inputs
Complementary Gain Outputs
Buffered Control Port
I–V Converter On-Chip
Low External Parts Count
Low Cost

GENERAL DESCRIPTION

The SSM2018T represents continuing evolution of the Frey
Operational Voltage Controlled Element (OVCE) topology that
permits flexibility in the design of high performance volume
control systems. The SSM2018T is laser trimmed for gain core
symmetry and offset. As a result, the SSM2018T is the first
professional audio quality VCA to offer trimless operation.

Due to careful gain core layout, the SSM2018T combines the
low noise of Class AB topologies with the low distortion of
Class A circuits to offer an unprecedented level of sonic trans-

SSM2018T

FUNCTIONAL BLOCK DIAGRAM

V

C

+IN

–IN

parency. Additional features include differential inputs, a 140 dB
(–100 dB to +40 dB) gain range and a high impedance control
port. The SSM2018T provides an internal current-to-voltage
converter. Thus no external active components are required.

This device is offered in 16-lead plastic DIP and SOIC packages
and guaranteed for operation over the extended industrial tempera­ture range of –40∞C to +85∞C.

GAIN

CORE

SSM2018T

G

1–G

*

V

G

–I

G

V

1–G

–I

1–G

NEW E GRADE

0.01% THD+N MAX

*Protected by U.S. Patent Nos. 4,471,320 and 4,560,947.

REV. B

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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©Analog Devices, Inc., 2002

SSM2018T–SPECIFICATIONS

ELECTRICAL SPECIFICATIONS

(VS = ⴞ15 V, AV = 0 dB, RL = 100 k⍀, f = 1 kHz, 0 dBu = 0.775 V rms, simple VCA application
circuit with 18 k⍀ resistors, –VIN floating, and Class AB gain core bias (RB = 150 k⍀), –40ⴗC < TA < +85ⴗC, unless otherwise noted. Typical
specifications apply at TA = 25ⴗC.)

Parameter Conditions Min Typ Max Max (E Grade) Unit

AUDIO PERFORMANCE

Noise VIN = GND, 20 kHz Bandwidth –95 –93 dBu
Headroom Clip Point = 1% THD + N 22 dBu
Total Harmonic Distortion plus Noise 2nd and 3rd Harmonics Only

(25∞Cto85∞C)

AV = 0 dB, VIN = +10 dBu 0.006 0.020 0.01 %

= +20 dB, VIN = –10 dBu 0.013 0.03 0.02 %

A

V

AV = –20 dB, VIN = +10 dBu 0.013 0.03 0.02 %

INPUT AMPLIFIER

Bias Current V
Offset Voltage V
Offset Current V
Input Impedance 4 MW
Common-Mode Range ± 13 V
Gain Bandwidth VCA Configuration 0.7 MHz

Slew Rate 5V/ms

OUTPUT AMPLIFIER

Offset Voltage VIN = 0 V, VC = 4 V 1.0 15 mV
Output Voltage Swing I

Minimum Load Resistance For Full Output Swing 9 kW

CONTROL PORT

Bias Current 0.36 1 mA
Input Impedance 1 MW
Gain Constant Device Powered in Socket > 60 sec –30 mV/dB
Gain Constant Temperature Coefficient –3500 ppm/∞C
Control Feedthrough 0 dB to –40 dB Gain Range ± 1 ±4 ± 3mV
Maximum Gain V
Maximum Attenuation VC = 4 V 100 dB

POWER SUPPLIES

Supply Voltage Range ± 5 ± 18 V
Supply Current 11 15 mA
Power Supply Rejection Ratio 80 dB

= 0 V 0.25 1 mA

CM

= 0 V 1 15 mV

CM

= 0 V 10 100 nA

CM

VCP Configuration 14 MHz

= 1.5 mA

OUT

Positive 10 13 V

Negative –10 –14 V

= –1.3 V 40 mV

C

Specifications subject to change without notice.

–2–

REV. B

SSM2018T

WARNING!

ESD SENSITIVE DEVICE

ABSOLUTE MAXIMUM RATINGS

1

Supply Voltage

Dual Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±18 V

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± V

S

Operating Temperature Range . . . . . . . . . . . .–40∞C to +85∞C

Storage Temperature . . . . . . . . . . . . . . . . . . . –65∞C to +150∞C

Junction Temperature (T

) . . . . . . . . . . . . . . . . . . . . . . 150∞C

J

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

THERMAL CHARACTERISTICS

Thermal Resistance

2

16-Lead Plastic DIP

␪

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76∞C/W

JA

␪

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33∞C/W

JC

16-Lead SOIC

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92∞C/W

␪

JA

␪

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27∞C/W

JC

TRANSISTOR COUNT

Number of Transistors

SSM2018T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

ESD RATINGS

883 (Human Body) Model . . . . . . . . . . . . . . . . . . . . . . . 500 V

EIAJ Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 V

NOTES

1

Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operation
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

2

␪JA is specified for worst-case conditions, i.e.; ␪JA is specified for device in socket for

P-DIP and device soldered in circuit board for SOIC package.

ORDERING GUIDE

Model Temperature Range Package Option

1

SSM2018TP –40∞C to +85∞C N-16
SSM2018TS2–40∞C to +85∞C R-16

1

N = Plastic DIP; R = SOL.

2

Not for new designs; obsolete April 2002.

PIN CONFIGURATION

16-Lead Plastic DIP

and SOL

+I

1–G

V+

–I

G

1–G

+IN

–IN

SSM2018T

TOP VIEW

(Not to Scale)

50pF

18k

SSM2018T

–I

COMP 1

COMP 2 COMP 3

V+

1␮F

V

V

18k

IN+

IN–

18k

1␮F

47pF

V

1–G

BAL

V

G

GND

MODE

V

C

V–

150k

1␮F

V

OUT

V–

V+

V

CONTROL

3k

1k

SSM2018T Typical Application Circuit

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the SSM2018T features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precau­tions are recommended to avoid performance degradation or loss of functionality.

REV. B

–3–

SSM2018T–Typical Performance Characteristics

0.1

TA = +25ⴗC

= ⴞ15V

V

S

R

= 18k⍀

F

0.010

THD + N – %

0.001
20 10k

FREQUENCY – Hz

AV = +20dB

AV = –20dB

AV = 0dB

1k100 20k

A

TPC 1. SSM2018T THD + N Frequency (80 kHz Low-Pass
Filter, for A

= 0.3 V rms; for AV = –20 dB, VIN = 3 V rms)

V

IN

= 0 dB, VIN = 3 V rms; for AV = +20 dB,

V

0.1

TA = +25ⴗC

= ⴞ15V

V

S

= 18k⍀

R

F

0.010

THD + N – %

0.001
10m 1

0.1 2

AMPLITUDE – V

RMS

TPC 4. SSM2018T THD + N vs. Amplitude
(Gain = +20 dB, f

1.0

0.1

=1 kHz, 80 kHz Low-Pass Filter)

IN

TA = +25ⴗC
V

= ⴞ15V

S

R

= 18k⍀

F

A

TPC 2. SSM2018T Distortion Distribution

0.1

TA = +25ⴗC
R

= 18k⍀

F

= ⴞ15V

V

S

0.1

THD + N – %

0.010

0.001

0.1 10

120

AMPLITUDE – V

RMS

A

TPC 3. SSM2018T THD + N vs. Amplitude (Gain = 0 dB,

= 1 kHz, 80 kHz Low-Pass Filter)

f

IN

THD + N – %

0.01

0.001
–60 –40 20–20

GAIN – dB

040

TPC 5. SSM2018T THD + N vs. Gain (fIN = 1 kHz;

£

for –60 dB
for 0 dB

0.1

0.01

THD + N – %

0.001

AV £ –20 dB, VIN = 10 V rms;

£

AV £ +20 dB, VIN = 1 V rms)

TA = +25ⴗC

= 18k⍀

R

F

ⴞ5

ⴞ6 ⴞ9 ⴞ15 ⴞ18

SUPPLY VOLTAGE – Volts

ⴞ12

TPC 6. SSM2018T THD + N vs. Supply Voltage
(A

= 0 dB, VIN = 1 V rms, fIN = 1 kHz, 80 kHz

V

Low-Pass Filter)

–4–

REV. B

SSM2018T

LOAD RESISTANCE – ⍀

MAXIMUM OUTPUT SWING – V

PEAK

ⴞ15

ⴞ12

0

100 1k 100k10k

ⴞ9

ⴞ6

ⴞ3

RF = 18k⍀
T

A

= +25ⴗC

VS = ⴞ15V

+10

0

–15

1k 1M100k10k100

–5

–10

+5

FREQUENCY – Hz

TA = +25ⴗC
V

S

= ⴞ15V

GAIN – dB

0

–135

–45

–90

PHASE – Degrees

GAIN

PHASE

500

TA = +25ⴗC
V

= ⴞ15V

S

400

300

200

NOISE DENSITY – nV/冪Hz

100

0

100 100k10k1k10

FREQUENCY – Hz

TPC 7. SSM2018T Noise Density vs. Frequency
(Unity Gain, Referred to Input)

RF = ⴥ⍀

= +25ⴗC

T

A

ⴞ20

PEAK

ⴞ15

RL = ⴥ

ⴞ10

RL = 10k⍀

ⴞ5

OUTPUT VOLTAGE SWING – V

0

ⴞ5

SUPPLY VOLTAGE – Volts

TPC 8. SSM2018T Maximum Output Swing vs.
Supply Voltage (THD = 1% max)

TPC 10. SSM2018T Maximum Output Swing vs.
Load Resistance (THD = 1 % max)

100

TA = +25ⴗC

90

V

= ⴞ15V

S

80

70

60

50

40

30

OUTPUT OFFSET – mV

20

10

ⴞ18 ⴞ15 ⴞ10

0

–80

–60

GAIN – dB

40

200–20–40

TPC 11. SSM2018T Typical Output Offset vs. Gain

ⴞ15

PEAK

ⴞ12

ⴞ9

ⴞ6

ⴞ3

MAXIMUM OUTPUT SWING – V

0

1k 10k 100k

TPC 9. SSM2018T Maximum Output Swing vs.
Frequency (THD = 1 % max)

REV. B

RF = ⴥ⍀

= +25ⴗC

T

A

= ⴞ15V

V

S

RL = ⴥ

RL = 10k

FREQUENCY – Hz

TPC 12. SSM2018T Gain/Phase vs. Frequency

–5–