Datasheet THAT1246, THAT1240, THAT1243 Datasheet (THAT Corporation)

THAT Corporation

Balanced Line Receiver ICs

THAT 1240, 1243, 1246

FEATURES

High CMRR: typically 90dB at 60Hz

·

Wide bandwidth and high slew rate

·

Low distortion and low noise

·

Available in 0 dB, -3 dB, and -6 dB

·

versions

Pin compatible with SSM2143 and

·

INA137

Description

The THAT 124x series of precision differential
amplifiers are designed primarily for use as audio
balanced line receivers. Gains of 0 db, -3 dB, and

-6 dB are available to suit various applications re­quirements.

The THAT 1246 is drop-in compatible with
the Burr-Brown INA137 and Analog Devices
SSM2143, while the THAT 1240 is drop-in com­patible with the SSM2140.

All devices exhibit 90 dB of typical com­mon-mode rejection, slew rates of 12 V/ms, a

APPLICATIONS

Balanced Audio Line Receivers

·

Summing Amplifiers

·

Differential Amplifiers

·

Current Shunt Monitors

·

Ground Loop Eliminator

·

20MHz bandwidth, and 0.0006% THD. Both sur
face-mount and DIP packages are available.

The THAT 124x family are laser-trimmed to
obtain the precision resistor matching needed for
high CMR performance. Fashioned in THAT Cor­poration's proprietary dielectric isolation (DI)
process, the THAT 124x series provides the sonic
benefit of discrete designs, with the compact size,
reliability, matching, and thermal tracking of a
fully integrated solution.

-

Vcc

In-

In+

Vee

Figure 1. THAT1240-series equivalent circuit diagram

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com

NC

Sense

Vout

Ref

Pin Name DIP Pin SO Pin

Ref 1 1

In- 2 2

In+ 3 3

Vee 4 4

Sense 5 5

Vout 6 6

Vcc 7 7

NC 8 8

Table 1. 1240 Series pin assignments

Gain Plastic DIP Plastic SO

0 dB 1240P 1240S

-3 dB 1243P 1243S

-6 dB 1246P 1246S

Table 2. Ordering information

Page 2 Balanced Line Receiver ICs

Preliminary Information

SPECIFICATIONS

1

Absolute Maximum Ratings (TA= 25°C)

Positive Supply Voltage (VCC) +18 V Power Dissipation (PD)(TA= 75°C) TBD mW

Negative Supply Voltage (V

Storage Temperature Range (T

Output Short-Circuit Duration (t

) -18 V Operating Temperature Range (TOP) 0 to +70°C

EE

) -40 to +125°C Junction Temperature (TJ) 150°C

ST

) Continuous Lead Temperature (Soldering 60 seconds) TBD °C

SH

Positive Input Voltage (Ref, Sense) +18 V Negative Input Voltage (Ref, Sense) -18 V

THAT1240 THAT1243 THAT1246

Positive Input Voltage (In+,In-) Vcc x 2 Vcc x 2.4 Vcc x 3

Negative Input Voltage (In+, In-) Vee x 2 Vee x 2.4 Vee x 3

Recommended Operating Conditions

Parameter Symbol Conditions Min Typ Max Units

Positive Supply Voltage V

Negative Supply Voltage V

CC

EE

+2.2 +18 V

-2.2 -18 V

Electrical Characteristics

2

Parameter Symbol Conditions Min Typ Max Units

Supply Current I

Input Voltage Range V

CC

IN-DIFF

Differential (equal and opposite swing)

No signal — 2.1 3.4 mA

THAT1240 (0 dB gain) — 21.5 — dBu
THAT1243 (-3 dB gain) — 24.5 — dBu
THAT1246 (-6 dB gain) — 27.5 — dBu

V

IN-CM

Common mode

THAT1240 (0 dB gain) — 27.5 — dBu
THAT1243 (-3 dB gain) — 29.1 — dBu
THAT1246 (-6 dB gain) — 31.0 — dBu

Input Impedance

4

Z

Z

IN-DIFF

IN-CM

Common mode (all versions) — 9 — kW

Differential
THAT1240 — 18 — kW
THAT1243 — 21 — kW
THAT1246 — 24 — kW

Common Mode Rejection CMR Matched source impedances; VCM= ±10V

DC 70 90 — dB

60 Hz 70 90 — dB
20 kHz — 85 — dB
44 kHz — 60 — dB

Power Supply Rejection

5

PSR At 60 Hz, with VCC=-V

EE

THAT1240 — 82 — dB
THAT1243 — 80 — dB

3

1. All specifications are subject to change without notice.

2. Unless otherwise noted, T

3. 0 dBu = 0.775Vrms.

4. See test circuit in Figure 2.

5. Defined with respect to differential gain.

=25°C, VCC= +15V, VEE= -15V, Gain=-6dB

A

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Rev. 04/29/02 Page 3
Preliminary Information

Electrical Characteristics (Cont’d)

Parameter Symbol Conditions Min Typ Max Units

Total Harmonic Distortion THD V

=10dBV;BW=20kHz;f=1kHz

IN-DIFF

R

=2kW — 0.0006 — %

L

Output Noise e

n(OUT)

BW=20kHz

THAT1240 — -106 — dBu
THAT1243 — -107 — dBu
THAT1246 — -109 — dBu

Slew Rate SR RL=2kW;CL= 300 pF 7 12 — V/µs

Small Signal Bandwidth BW

-3dB

RL=2kW;CL=10pF

THAT1240 12 24 — MHz
THAT1243 17 33 — MHz
THAT1246 23 44 — MHz

R

=2kW;CL= 300 pF

L

THAT1240 11 17 — MHz
THAT1243 13 18 — MHz
THAT1246 14 20 — MHz

Output Gain Error G

ER(OUT)

Output Voltage Swing V

Output Offset Voltage V

Output Short Circuit Current I

Resistive Load R

Capacitive Load C

O

OFF

SC

Lmin

Lmax

f = 1 kHz — ±0.03 ±0.5 %

RL=2kW ±12.5 ±13 — V

No signal -7 0 +7 mV

RL=0W — ±25 — mA

—— 2 kW

300 — — pF

Vcc

In-

½U

diff

~

R

1

b

R

2

Sense

Vout

½U

diff

~

In+

R

3

a

V

~

CM

R

4

Ref

R

L

C

L

Vee

Part no.

THAT1240

THAT1243

THAT1246

Gain

0dB

-3 dB

-6 dB

R=R

13

9k

Ù

Ù

10.5 k

Ù

12 k

R=R

24

9k

Ù

Ù

7.5 k

Ù

6k

Figure 2. THAT1240 series test circuit

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Page 4 Balanced Line Receiver ICs

Preliminary Information

Application Notes

The THAT 1240, 1243, and 1246 are precision
differential amplifiers with gains of zero, -3 and -6 dB
respectively, and are primarily intended as balanced
line receivers for pro audio. However, their topology
lends itself to other applications as well.

Figures 3 and 4 show the THAT 1240 and
THAT 1246 configured as zero and -6 dB line receiv
ers respectively. These devices can be used to retrofit
circuits currently using the SSM 2141, INA134,
SSM2143, or INA137. While the THAT 1240 and
THAT 1246 are form, fit and functionally compatible
with their competitors’ equivalent versions, their slew
rate and bandwidth are superior.

Like other amplifiers of this type, all of THAT
Corporation’s line receivers can accept common
mode voltages that exceed the power supply rails.
Consider Figure 2. Assume that the circuit is con
figured as shown, but with no differential excitation.
In+ and In- are shorted together, as are Vout and
Sense. Ref is tied to ground. a and b will be held at
the same voltage by feedback.

Figure 5 shows a THAT 1240 configured as a pre
cision summing amplifier. This circuit uses both the
In+ and Ref pins as inputs. Refering to Figure 2, it
can be shown by superposition that the voltage at a
will be

R

aIn R

=+ +

()[][]

-

Lo

4

++

RR

43

2

In-

Sense

5

ef

R

3

RR

43

6

Hi - Lo

-

Vout

Hi

3

-

In+

Ref

1

U1

1240

Figure 3. Zero dB line receiver

The maximum voltage allowed at the internal
node a is V
V

plus 2V. The voltage at a can be calculated

EE

aV

Isolating V

Va

PK CM

Thus, the maximum input in dBu would be

V

IN dbu

With ±18V supplies, the THAT 1240 can tolerate
a maximum common mode input of 29.3 dBu. Un
der the same conditions, the THAT1243 can tolerate

30.0 dBu and the THAT 1246 can tolerate 32.9 dBu.
These numbers are slightly higher than the datasheet
specifications, since they’re calculated with a slightly
higher supply voltage. Also note that high levels of
common mode input compromise the maximum dif
ferential mode signal that can be handled by these
ICs.

minus 2V, while the minimum voltage is

CC

R4

[ ]

PK CM=-

= []

-

max

-

+

R3 R4

, we see that

PK-CM

RR

+

43

R

=

20

4

log

é
ê
ê

ë

Vcc V

()

-

2

RR

[]

´

2

.

0775

+

43

R

4

ù
ú
ú

û

Lo

2

In-

Sense

5

(Hi-Lo)*0.5

6

Vout

Hi

Ref

3

In+

U1

1

1246

Figure 4. -6 dB line receiver

-

2

In-

Sense

5

(In+)+ Ref

6

Vout

In+

-

Ref

3

In+

Ref

U1

1

1240

Figure 5. Precision summing circuit

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Rev. 04/29/02 Page 5
Preliminary Information

In Hi

+24 dBu In

In Lo

2

3

In-

In+

Sense

Ref

1

5

Vout

U2
THAT
1246

Figure 6. Circuit for audio ADCs with balanced inputs

Since R3=R4 in the THAT 1240, this equation
can be simplified to

In R=++()ef

a

2

The output voltage would then be

2

3

5

In-

Sense

Vout

Ref

In+

U1

1

THAT
1246

6

U3A

1

4570

6

+24 dBu

3

2

R8

2k10

C4
6n8

R19

2k10

1/2 Vref of ADC

R9
249R

AIN- to ADC

Zero dBu Out

AIN+ to ADC

Figure 6 shows a convenient method of driving a
typical audio ADC with balanced inputs. This circuit
accepts +24 dBu in, and using a pair of
THAT 1246s, the signal level between their respective
outputs is +24 dBu. An attenuator network brings
the signal down another 24 dB while attenuating the
noise of the line receivers as well.

R

Vout a

=´+()1

2

R

1

Since R2=R1, combining equations results in

Vout In R=++() ef

-3dB

U3
2180B

In Lo

In Hi

2

3

In-

Sense

In+

Ref

5

C2

6

Vout

U1

1

1243

22u

R2

20k0

2

EC+

1

IN

EC-

3

Control Voltage

SYM

GND

-3dB

4

6

VCC

V+

OUT

V-

VEE

7

5

R4
5k1

The output noise of a THAT 1246 is -109 dBu,
and since there are two of them, the total noise level
going into the resistive pad will be -106 dBu. The
pad reduces the noise level to -130 dBu at the input
to the ADC. The noise density resulting from the line
receivers will therefore be

+6dB

C3

6

Cap2

Cap1

5

C1

100n

7

8

Out+
Out-

2

U2
THAT1430

1

22p

R3

14k0

8

2

1

3

U4A
4570

VCC

Vcc

4

In

3

Gnd

Vee

VEE

R1

1M0

Out Hi

Out Lo

Figure 7. Automated gain control of a balanced signal

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Page 6 Balanced Line Receiver ICs

Preliminary Information

dBu

-

130

e

n line receiver

(),

==

The noise of the 249W resistor is 2.05 nV/ÖHz.

We can assume that the noise contribution of R8 and
R19 will be negligible, and therefore, the total noise
density going into the input of the ADC will be

´10 0 775

20

kHz

20

173

.

nV

Hz

gain on each half of the balanced signal. Unfortu
nately, this can results in common mode to differen
tial mode conversion (degradation of CMRR) when
there are even slight differences in gain between the
VCAs. A better approach is to convert the signal to
single-ended, alter the gain, and then convert back to
balanced.

22

e

ntotal

=+=(. ) ( . ) .173 206 2 68

nV

Hz

The noise floor can then be calculated to be

nV

Hz

nV

Hz

In Figure 7 we use a THAT 1243 -3 dB line re
ceiver to do the balanced to single-ended conversion.
The VCA section also has a static gain of -3 dB due to
the ratio of R2 and R3. This circuit can accept

nV

é

Noise dB

dBu

=

ê

20 126 2

log .

ê

ë

´

268 20

.

Hz

0775

.

kHz

ù
ú
ú

û

=-

u

Figure 7 shows an excellent method for control
ling gain in a balanced system. There is often a
temptation in these systems to keep the signal bal
anced and use two VCAs to independently control the

-

-

24 dBu, since the THAT 1243 output stage is capable
of 21 dBu without distortion. Reducing R3 to 14 kW
results in a 3 dB reduction in VCA output noise.
This arrangement results in 3 dB greater dynamic
range compared to the case where a -6 dB line re
ceiver and a VCA with zero dB static gain are used.
After the VCA, the signal is restored to 24 dBu by the
THAT 1430.

-

-

-

-

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Rev. 04/29/02 Page 7
Preliminary Information

Package Information

The THAT 1240 series is available in both 8-pin
mini-DIP and 8-pin SOIC packages. The package di

C

B

J

1

A

K

F

G

H

D

ITEM

A
B
C
D
E
F
G
H
J
K

E

MILLIMETERS

±

9.52 0.10

±

6.35 0.10

7.49/8.13

0.46

2.54

3.68/4.32

0.25

±

3.18 0.10

8.13/9.40

±

3.30 0.10

INCHES

±0.004

0.375

±

0.250 0.004

0.295/0.320

0.018

0.100

0.145/0.170

0.010

±

0.125 0.004

0.320/0.370

±

0.130 0.004

mensions are shown in Figures 8 and 9, while the

-

pinouts are given in Table 1.

E

F

CB

H

D

G

A

ITEM MILLIMETERS

A

4.80/4.98

B

3.81/3.99

C

5.80/6.20

D

0.36/0.46

E

1.27

F

1.35/1.73

G

0.19/0.25

0.41/1.27H 0.016/0.05

INCHES

0.189/0.196

0.150/0.157

0.228/0.244

0.014/0.018

0.050

0.053/0.068

0.0075/0.0098

Figure 8. -P (DIP) version package outline drawing

Figure 9. -S (SO) version package outline drawing

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

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Page 8 Balanced Line Receiver ICs

Preliminary Information

Notes:

THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com