THAT1646 (THAT Corporation)
Balanced Line Driver ICs

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FEATURES
Balanced, transformer-like floating
output
OutSmarts® technology improves
clipping into single-ended loads
Stable driving long cables and
capacitive loads
High output: 18Vrms into 600
Low noise: -101 dBu
Low distortion: 0.0007% @ 1kHz
Industry-standard pinout
Balanced Line Driver ICs
THAT 1280, 1283,T1H2A8T6 a1n6d061,2166046_
APPLICATIONS
Differential Line Drivers
Audio Mixing Consoles
Distribution Amplifiers
Hi-Fi Equipment
Audio Equalizers
Dynamic Range Processors
Digital Effects Processors
Telecommunications Systems
Instrumentation
Description
The THAT 1606 and 1646 are a new generation
of monolithic audio differential line drivers offering
improved performance over conventional cross-
coupled designs. Based on a high-performance, fully
differential opamp and laser-trimmed thin-film
resistors, both families exhibit low noise and
distortion, high slew rate, and wide output swing.
The parts are stable when driving difficult loads, and
have short-circuit protected outputs.
Designed from the ground up in THAT's
complementary dielectric isolation process, both
models incorporate THAT's patented OutSmarts1
technology. This is a dual feedback-loop design that
prevents the excessive ground currents typical of
cross-coupled output stages (CCOS) when clipping
into single-ended loads. OutSmarts uses two
individual negative-feedback loops to separately
control the differential output voltage and common
mode output currents, making the designs
inherently more stable and less sensitive to
component tolerances than common CCOSes. As a
result, THAT's topology prevents the loss of
common-mode feedback that plagues common
CCOS designs when clipping into single-ended loads.
This avoids excessive ground currents that would
otherwise upset power supplies and create
additional distortion, even in adjacent channels.
The 1646 is pin-compatible with the TI DRV134
and DRV135, as well as the Analog Devices
SSM2142. The 1606 offers an advanced common-
mode offset voltage reduction scheme, which
requires a small single capacitor instead of the two
electrolytics required by the 1646 and its pin-
compatible cousins. Additionally, the 1606 features
differential inputs in a space-saving 16-pin QSOP
package. Both parts offer +6 dB gain.
10k
Vcc
In+ 5k Din+
Cin+
Cin-
Gnd 5k Din-
10k
Dout-
Dout+
10k
10k
Vee
THAT 1646
25
Out-
Sns-
10k 20k
10p
CEXT
10k 20k
Sns+
25 CEXT
Out+
1646
1606
Pin
DIP8
SO8
SO16W QSOP16
1
Out- Out-
NC Gnd*
2
Sns-
Sns-
NC
NC
3
Gnd Gnd
Out- Out-
4
In
In
Sns-
Cap1
5
Vee Vee
Gnd Gnd
6 Vcc Vcc In In-
7
Sns+
Sns+
NC
In+
8
Out+
Out+
NC Gnd*
9 — — NC Gnd*
10 — — NC NC
11 — — Vee Vee
12 — — Vcc Vcc
13
Sns+
Cap2
14
Out+
Out+
15 — — NC NC
16 — — NC Gnd*
* See "Thermal Considerations" section on page 10
Figure 1. THAT 1646 Equivalent Circuit Diagram
Table 1. THAT 1606/1646 pin assignments
1. For complete details of OutSmarts, see Hebert, Gary K., "An Improved Balanced, Floating Output Driver IC", presented at the 108th AES Convention, February 2000.
Protected under US Patents numbers 4,979,218 and 6,316,970. Additional patents pending. THAT and OutSmarts are registered trademarks of THAT Corporation.
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; Document 600078 Rev. 07


THAT1646 (THAT Corporation)
Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 2 of 12
THAT 1606/1646 Balanced Line Driver ICs
SPECIFICATIONS2
Absolute Maximum Ratings (TA = 25°C)
Postive Supply Voltage (VCC)
+20 V
Storage Temperature (TST)
-55 to +125°C
Negative Supply Voltage (VEE)
-20 V
Junction Temperature (TJ)
125°C
Output Short Circuit Duration
Continuous Lead Temperature (TLEAD)(Soldering 60 sec) 300°C
Operating Temperature Range (TOP)
-40 to +85°C
Parameter
Input Impedance
Gain
Gain
Gain Error
DC Power Supply
Rejection Ratio
1646 Electrical Characteristics3
Symbol
Conditions
Min. Typ.
ZIN 4.00 5.00
G1 RL=100 kper output
Balanced
5.80 6.00
Single Ended
5.76
5.96
G2 RL= 600
Balanced
5.00 5.30
Single Ended
4.96
5.26
G1 RL=100 kper output, Balanced
0.02
PSRR
±4V to ±18V 85 107
Output Common-Mode
Rejection Ratio
CMRROUT
f=1kHz, BBC Method
46
65
Output Signal Balance Ratio
SBR
f=1kHz, BBC Method
35
54
THD+N (Balanced)
THD+N1
THD+N (Single Ended)
THD+N2
Output Noise
Onoise
Maximum Output Level
Slew Rate
VoMAX
SR
Small Signal Bandwidth
Output Common Mode
Voltage Offset
VOCM1
VOCM2
Differential Output Offset
Output Voltage Swing, Positive
VOD
Output Voltage Swing, Negative
Output Impedance
ZO
VO=10 VRMS, RL=600
20Hz-5kHz
20kHz
VO=10 VRMS, RL=600
20Hz-5kHz
20kHz
Balanced, 22Hz -20kHz
0.1% THD+N
CL=50pF/output
CL=50pF/output
0.0007
0.002
0.0010
0.0030
-101
27.5
15
10
w/o Sense capacitors
w/ Sense capacitors
-250
-15
-15
No Load
No Load
VCC–2.9
40
±50
±3.5
±4
VCC–2.2
VEE+2.25
50
Max
6.20
6.16
5.60
5.56
0.20
0.005
0.0090
250
15
15
VEE+2.9
60
2. All specifications are subject to change without notice.
3. Unless otherwise noted,.all measurements taken with VS=±18V, T=25°C, RL = 600 Balanced, RSOURCE = 0
Units
k
dB
dB
dB
dB
dB
dB
dB
dB
%
%
%
%
dBu
dBu
V/µS
MHz
mV
mV
mV
V
V
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 3 of 12
THAT 1606/1646 Balanced Line Driver ICs
1646 Electrical Characteristics (cont'd)
Parameter
Maximum Capacitive Load
Symbol
Conditions
Stable Operation
Min.
Typ. Max.
Unlimited
Quiescent Supply Current
IS
Unloaded
4.9 5.75
Output Short Circuit Current
ISC
Both outputs to ground
70
Power Supply Voltage Range
±4 ±18
Parameter
Input Impedance
Gain
Gain
Gain Error
DC Power Supply
Rejection Ratio
1606 Electrical Characteristics3
Symbol
ZIN
G1
Conditions
RL=100 kper output
Balanced
Single Ended
Min.
4.00
5.80
5.76
Typ.
5.00
6.00
5.96
G2 RL= 600
Balanced
5.00 5.30
Single Ended
4.96
5.26
G1 RL=100 k/ output, Balanced
0.02
PSRR
±4V to ±18V 85 107
Output Common-Mode
Rejection Ratio
CMRROUT
Input Common-Mode
Rejection Ratio
Output Signal Balance Ratio
CMRRIN
SBR
THD+N (Balanced)
THD+N1
THD+N (Single Ended)
THD+N2
Output Noise
Onoise
Maximum Output Level
Slew Rate
VoMAX
SR
Small Signal Bandwidth
Output Common Mode
Voltage Offset
Differential Output Offset
Output Voltage Swing, Positive
VOCM1
VOCM2
VOD
Output Voltage Swing, Negative
Output Impedance
Maximum Capacitive Load
ZO
Quiescent Supply Current
IS
f=1kHz, BBC Method
46
f=1kHz
f=1kHz, BBC Method
VO=10 VRMS, RL=600
20Hz-5kHz
20kHz
VO=10 VRMS, RL=600
20Hz-5kHz
20kHz
Balanced, 22Hz -20kHz
0.1% THD+N
CL=50pF/output
CL=50pF/output
40
35
w/o CM coupling capacitor -250
w/ CM coupling capacitor -20
-15
No Load
No Load
VCC–2.9
40
Stable Operation
Unloaded
65
60
54
0.0007
0.002
0.0010
0.0060
-101
27.5
15
10
±50
-5
±4
VCC–2.2
VEE+2.25
50
4.9
Max.
6.20
6.16
5.60
5.56
0.20
0.005
0.0090
250
20
15
VEE+2.9
60
Unlimited
5.75
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.
Units
µF
mA
mA
V
Units
k
dB
dB
dB
dB
dB
dB
dB
dB
dB
%
%
%
%
dBu
dBu
V/µS
MHz
mV
mV
mV
V
V
µF
mA


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 4 of 12
THAT 1606/1646 Balanced Line Driver ICs
1606 Electrical Characteristics (cont'd)
Parameter
Symbol
Conditions
Min. Typ. Max.
Output Short Circuit Current
ISC
Both outputs to ground
70
Power Supply Voltage Range
±4 ±18
Units
mA
V
10k
Vcc
In+ 5k Din+
Cin+
Cin-
Gnd 5k Din-
10k
Dout-
Dout+
10k
10k
Vee
THAT 1646
25
Out-
Sns-
10k 20k
10p
CEXT
10k 20k
Sns+
25 CEXT
Out+
Figure 2. THAT 1646 Equivalent Circuit Diagram
Cap2
CEXT
Cap1
REXT
Vcc
10k
THAT 1606
25
Out-
In+ 5k Din+
Cin+
10k
Dout-
10k 10p 7k
Cin- AD & AC
Gnd
In- 5k Din-
Dout+
10k 7k
10k
10k 25
Vee Out+
Figure 3. THAT 1606 Equivalent Circuit Diagram
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 5 of 12
THAT 1606/1646 Balanced Line Driver ICs
Theory of Operation
OutSmarts® technology
The THAT 1606 and 1646 family employs the
OutSmarts topology, a variation of circuitry originally
developed by Chris Strahm at Audio Teknology Inc.,
(and later acquired by Audio Toys, Inc.). THAT's
OutSmarts topology employs two negative-feedback
loops -- one to control the differential signal, and a
separate loop to control the common mode output
levels.
Figures 2 and 3 show the gain core common to
the 1606 and 1646. The gain core is a single
amplifier that includes two differential input pairs,
Cin+/- and Din+/-, and complementary outputs,
Vout+ and Vout-, related to each other by two gain
expressions, AD(s) and AC(s). The first pair of
differential inputs, Din+/-, is connected to the
differential feedback network between the outputs
and the input signal. The second differential input
pair, Cin+/-, is connected to a bridge circuit which
generates an error signal used to servo the common-
mode behavior of the outputs. The loop equations are
then:
The common mode equation is more complicated
in that it is dependent on the attached load, and in
any event doesn't yield much insight into the device's
operation. For those who are interested, a more
complete discussion is given in the reference
mentioned in note 1.
In op-amp analysis using negative feedback loops,
the combination of negative feedback and high open-
loop gain usually results in the open-loop gain
"dropping out" of the equation, and the differential
inputs being forced to the same potential. This is true
for the core of the 1606 and 1646 ICs. If we start
with that assumption, the operation of the common-
mode feedback loop can be intuited as follows:
Referring again to Figures 2 and 3, the common-
mode input actually senses the sum of each IC's
output currents by way of two 25 resistors and the
bridge network4. The resulting error signal is
amplified and then summed into both outputs, with
the net effect being to force the sum of the currents to
be zero, and thus the common mode output current
to zero.
,
where AD is the differential open-loop gain, and
Σ ,
where AC is the common-mode open-loop gain.
These equations can be solved much like
standard op-amp loop equations.
For the differential case, using superposition, we
can see that this results in:
, and
,
Substituting and simplifying into the equation
that defines differential operation yields:
,
Dividing through by AD (assuming that AD >> 3)
and simplifying yields
2
,
as one would expect for a +6 dB line driver.
For the 1646, In- is hard-wired to ground (0v), so
the differential equation above simplifies to:
To see why this is important, consider what
happens when the IC is loaded with a single-ended
load, which shorts one or the other output to ground.
Suppose Out- is grounded. In this case, the
differential feedback loop increases the voltage at
Dout+ to make up for most of the signal lost to the
short at Out-. The common-mode feedback loop
forces the current from Out- to be equal and opposite
to that from Out+. But, during peak signals which
drive Dout+ into clipping (exceeding its maximum
output voltage capability), the differential loop is
starved for feedback. Without the common-mode
feedback, the result would be for the voltage at Dout-
to decrease in an attempt to satisfy the differential
loop's demand for feedback. This is one significant
weakness of conventional cross-coupled output
designs – common-mode feedback is lost when one
output is clipped while the other is grounded.
With OutSmarts, however, the common mode
feedback loop senses this happening because of the
increase in current at Out- (compared to that at
Out+), and prevents the voltage at Out- from rising
out of control. This causes the OutSmarts design to
more closely mimic the behavior of a true floating
balanced source (such as a transformer), compared
to the behavior of a conventional CCOS design.
2 ,
4. The 10 pF capacitor can be ignored for the purposes of this analysis. It simply limits the maximum frequency at which the current-sensing action occurs.
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 6 of 12
THAT 1606/1646 Balanced Line Driver ICs
Applications
1. Circuit implementations using the 1606 and
1646 are relatively straightforward. A quiet, solid
ground reference, stiff voltage supplies, and adequate
supply bypassing are all that are required to achieve
excellent performance out of both ICs.
2. Both devices must be driven from a low-
impedance source, preferably directly from opamp
outputs, to maintain the specified performance.
3. Please refer to Figure 8 for a complete
applications circuit.
Stability and Load Capacitance
The devices are stable into any capacitive load,
and the maximum capacitance is limited only by slew
rate and frequency response considerations.
For the purposes of the frequency response
calculation, the line driver's 25sense resistors can
be lumped into a single 50resistor. The correct
cable capacitance to use for the balanced-signal case
is the sum of the inter-conductor capacitance and the
two conductor-to-shield capacitances in series. Some
manufacturers only specify the inter-conductor
capacitance and the capacitance of one conductor to
the other while connected to the shield, and some
extraction may be required.
As an example, Belden 8451 is specified as
having with 34 pF/ft of inter-conductor capacitance
and 67 pF/ft of conductor to "other conductor +
shield capacitance". Thus, we can assume a single
conductor-to-shield capacitance of 33 pF/ft (the
difference between 67 and 34) for each conductor.
For balanced signals, the load capacitance across the
1646 outputs will be 34 pF/ft + 16.5 pF/ft = 50.5
pF/ft. The corner frequency of the THAT 1646 driving
500 ft of this cable (25.25 nF) will be 126 kHz.
∙ ∙ ∙
.
126 ,
One must also consider the slew rate limitations
posed by excessive cable and other capacitances. We
know that
and that
2 ∙ ∙
Dennis Bohn of Rane Corporation has
published work specifying some of the requirements
for a balanced line driver, including a) stability into
reactive loads, b) differential output voltage swing of
at least ±11 volts peak (+20dBu), and c) reliability5.
This work suggests a reasonable rule by which to
calculate the output current requirements at 20 kHz.
The author concludes that the actual worst case peak
level for various types of music and speech will be
flat out to 5 kHz, and roll off at 6dB/octave above this
frequency. Thus the peak levels at 20 kHz will be
12 dB below those at 5 kHz.
Using these, we can calculate the required slew
rate and current drive. For the +26 dBu output
Vcc
C4
100n
In
C5
100n
6
7
4
In
Vcc
Sns+
8
Out+
3
Gnd Sns-
Vee
52
Out-
1
U1
THAT1646
Vee
Out+
Out-
Figure 4. THAT 1646 without common-mode offset reduction
5. Dennis A. Bohn, “Practical Line-Driving Current Requirements“(Rane Note 126), Rane Corporation, 1991, revised 5/1996. Available at www.rane.com/note126.html.
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 7 of 12
THAT 1606/1646 Balanced Line Driver ICs
levels that the 1646 is capable of, VPeak is 22 V
(below 5 kHz), and at 20 kHz, VPeak is 5.5 V.
Therefore,
2 ∙ 5.5 ∙ 20
0.69
As a consequence,
500 ∙ 34 16.5
∙ 0.69
17.5 .
Thus, driving this 25.25 nF cable requires
17.5 mAPeak, which is well within the capability of the
1606 and 1646.
Gain structure
The 1606 and 1646 both provide +6 dB gain
(factor of 2) between their inputs and differential
outputs. This is appropriate, since with a balanced
output, twice the voltage between the power supply
rails is available at the output of the stage. The
single-ended input of the 1646 can accept signals
that swing to nearly the power supply rails without
distortion, when driving into a differential (floating)
load. The balanced input of the 1606 can accept
signals at each input that swing to nearly one-half the
power supply rails without distortion, when driving
into differential loads.
Both devices, when driving single-ended loads,
will clip at about half the output voltage as compared
to a differential load. This is because only one of the
two output signals will be available. Despite the
output clipping, the input to the devices does not
need to be constrained - they will work without
undue problems being overdriven at their inputs
when the outputs are clipping into single-ended
loads.
1646 circuits
Figure 4 shows the most basic connection for a
1646. The only external components needed are the
local 100 nF bypass capacitors. These should be
within 1 inch of the 1646 pins.
Output DC offset
Because the 1646's outputs are connected
directly to their respective sense inputs, this circuit
may produce up to 250 mV of common-mode dc
offset at its outputs. As shown, the outputs are DC
coupled to the output connector, so this dc will
appear directly at the output of the system.
The output common-mode offset of a 1646 may
be reduced by adding capacitors in the feedback
loop, as shown in Figure 5. Capacitors C1 and C2 ac-
couple the common-mode feedback loop. This
changes the loop operation from servoing the
common-mode output current at audio frequencies
to servoing the common-mode output voltage to 0 at
DC. This results in much lower common-mode
output offset voltage, as indicated in the
specifications section. C1 and C2 are typically high
quality non-polarized electrolytic capacitors.
C4
100n
In
C5
100n
Vcc
C1
6
7
10u
NP
4
In
Vcc
Sns+
8
Out+
3
Gnd Sns-
Vee
Out-
1
52
U1
THAT1646
C2
Vee 10u
NP
Out+
Out-
Figure 5. THAT 1646 with common-mode offset reduction
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 8 of 12
THAT 1606/1646 Balanced Line Driver ICs
Vcc C1
C4
100n
In
C5
100n
100n
12
4
7
Vcc
In+ Cap1
14
6
5
In-
Gnd Cap2
Vee
Out+
Out-
3
11 13
U1
THAT1606
Vee
R1
1M0
Out+
Out-
Figure 6. THAT 1606 with output common-mode offset reduction and single-ended input drive
Vcc C1
C4
100n
In+
In-
C5
100n
100n
12
4
7 Vcc
In+ Cap1
14
6
5
GInn-VdeeCap2OOuu3tt+-
11 13
U1
THAT1606
Vee
R1
1M0
Out+
Out-
Figure 7. THAT 1606 with output common-mode offset reduction and differential input drive
1606 circuits
Figures 6 and 7 show the basic amplifier
configurations for a 1606. The 1606 differs from the
1646 in two respects. First, the 1606 includes a
negative-sense input pin (pin 6), so offers a
differential input. This can be useful in connecting
the output driver to the output of modern D/A
converters, which usually present differential
outputs. Second, instead of two 10 uF capacitors, the
1606 uses an 0.1 uF capacitor (C1) and 1 M(R1)
resistor to reduce common-mode dc offset.
Generally, these components will cost less, and take
up less space on the circuit board than the two large
capacitors required for the 1646. C1 should be a
high-quality film type capacitor to minimize low-
frequency distortion when driving single-ended loads.
RFI protection
These line drivers can easily drive cables
hundreds of feet in length without becoming
unstable, but such long cables can act as antennae
which can pick up RFI and direct it into the circuit.
The circuit of Figure 8 includes two 100 pF bypass
capacitors (C3 and C8) and two ferrite beads, whose
purpose is to redirect this RF energy to the chassis
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


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Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 9 of 12
THAT 1606/1646 Balanced Line Driver ICs
Vcc
Input
Amplifier
Block
(from fig.
5, 6, or 7)
Vcc
Input
Gnd
Vee
U1
Out+
Out-
D3
1N4004
D5
1N4004
D6
1N4004
D4
1N4004
L1
Ferrite Bead
L2
C8
100p
Ferrite Bead
C3
100p
XLR (M)
12
3
Vee
Figure 8. THAT 16x6 applications circuit with output common-mode offset protection, RFI protection, and surge protection
before it can circulate inside the product's box and
couple RF into other portions of the circuit. The
capacitors should be located as close as possible to
the output connector and connected via a low-
inductance path to chassis ground, with the ferrite
beads placed very nearby. These components ensure
that RFI current is directed to the chassis and not
through the relatively low-impedance output of the
1606/1646. The bypass capacitors and ferrite beads
will have no effect on the gain error of these line
drivers at audio frequencies.
control. The 1606/1646's internal protection network
will withstand this abuse for coupling capacitors up
to about 33 uF.
To protect against microphone preamplifiers
that incorporate larger values of capacitance, a pair
1N4004 diodes from each output to the supply rails,
as shown in Figure 8, is recommended. This shunts
the discharge current to the power supply bypass
and filter capacitors, thus protecting the output of
the 1606 or 1646.
Output protection
The 1606 and 1646 each incorporate a
proprietary internal protection scheme, which will
suffice for many situations seen in the field. However,
one might foresee having the line driver's output
mistakenly plugged directly into a microphone
preamplifier input that has +48V phantom power
applied. When this happens, the ac coupling
capacitors on the preamp's input will discharge into
the low-impedance output of the 1606/1646. This can
result in surge currents of over 2 amperes6. The
amount of energy stored in these capacitors is
directly proportional to the capacitor value, which is,
of course, not under the 1606/1646 designer's
Closing thoughts
The integrated balanced line driver is one of
those highly useful, cost-effective functional blocks
that can provide significant improvement over
discrete designs. The THAT 1646 goes a step or two
further by improving over existing components. Both
incorporate OutSmarts technology to tame the
aberrant single-ended clipping behavior of
conventional cross-coupled output stages.
For more information on these or other THAT
Corporation integrated circuits, please contact us
directly, or through one of our international
distributors.
6. Hebert, Gary K., Thomas, Frank W., "The 48V Phantom Menace", presented at the 110th Audio Engineering Society Convention, May, 2001
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


THAT1646 (THAT Corporation)
Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 10 of 12
THAT 1606/1646 Balanced Line Driver ICs
Package and Soldering Information
Package Characteristics
Parameter
Symbol
Conditions
Typ Units
SO-8
Package Style
See Fig. 9 for dimensions
8 Pin SO
Thermal Resistance
θJA
SO package soldered to board
150
ºC/W
Environmental Regulation Compliance
Complies with July 21, 2011 RoHS 2 requirements
Soldering Reflow Profile
JEDEC JESD22-A113-D (250 ºC)
Moisture Sensitivity Level MSL Above-referenced JEDEC soldering profile
MSL-1
DIP-8
Package Style
See Fig. 10 for dimensions
8 Pin DIP
Thermal Resistance θJA DIP package soldered to board
100
ºC/W
Environmental Regulation Compliance
Complies with July 21, 2011 RoHS 2 requirements
Soldering Reflow Profile
JEDEC JESD22-A113-D (250 ºC)
Moisture Sensitivity Level MSL Above-referenced JEDEC soldering profile
MSL-1
SO-16
Package Style
See Fig. 11 for dimensions
16 Pin SO
Thermal Resistance
θJA
SO package soldered to board
80
ºC/W
Environmental Regulation Compliance
Complies with July 21, 2011 RoHS 2 requirements
Soldering Reflow Profile
JEDEC JESD22-A113-D (250 ºC)
Moisture Sensitivity Level MSL Above-referenced JEDEC soldering profile
MSL-1
QSOP-16
Package Style
See Fig. 12 for dimensions
16 Pin QSOP
Thermal Resistance
θJA QSOP package soldered to top-side
ground plane of 1 sq in or larger
125
ºC/W
Environmental Regulation Compliance
Complies with July 21, 2011 RoHS 2 requirements
Soldering Reflow Profile
JEDEC JESD22-A113-D (250 ºC)
Moisture Sensitivity Level MSL Above-referenced JEDEC soldering profile
MSL-1
The THAT1646 in available in 8-pin SO, 8-pin
mini-DIP and 16-pin wide SOIC packages. The 1606
comes in a 16-pin QSOP package. Package
dimensions are shown in Figures 9, 10, 11, and 12,
while pinouts are given in Table 1.
Thermal Considerations
As mentioned. the 1646 is available in an 8-pin
DIP, and 16-pin wide SO, and an 8-pin SO, with
junction-to-ambient thermal resistances of
100°C/watt, 80°C/watt, and 150°C/watt, respectively,
assuming a 2-sided PCB with no ground planes.
Users of the SO-8 package should recognize driving
600 loads or very long cables (several hundred
feet) at high ambient temperatures (above 55°C)
continuously could lead to internal die temperatures
that exceed the maximum rating and result in
performance degradation.
The 1606 is supplied in a 16-pin QSOP package
in which pins 1, 8, 9, and 16 are fused to the die
paddle to assist in conducting heat away from the
die. These pins are connected to the die substrate,
which is, in turn, connected to the ground pin of the
device. When these pins are connected to a top-side
ground plane of 1 square inch area, the junction-to-
ambient thermal resistance is 125°C/watt. Internal
planes on multi-layer PCBs will reduce the thermal
resistance further.
Model
SO8
Pkg
DIP8
Pkg
SO16W QSOP16
Pkg Pkg
1646
1606
1646S08-U 1646P08-U 1646W16-U —
— — — 1606Q16-U
Table 2. Order Number Information
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


THAT1646 (THAT Corporation)
Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 11 of 12
THAT 1606/1646 Balanced Line Driver ICs
0-8°
EF
1
D
A
BC
hx45°
G
a1
H
ITEM
A
a1
B
C
D
E
F
G
H
h
MILLIMETERS
4.78/5.00
0.10/0.20
3.81/3.99
5.84/6.20
0.36/0.46
1.27
1.52/1.73
0.18/0.25
0.41/0.89
0.31/0.71
INCHES
0.188/0.197
0.004/0.008
0.150/0.157
0.230/0.244
0.014/0.018
0.050
0.060/0.068
0.007/0.010
0.016/0.035
0.012/0.027
Figure 9. 8 pin SO package outline drawing
EF
1
D
A
BC
G
J
H
ITEM
A
B
C
D
E
F
G
H
J
MILLIMETERS
10.11/10.31
7.40/7.60
10.11/10.51
0.36/0.46
1.27
2.44/2.64
0.23/0.32
0.51/1.01
0.10/0.30
INCHES
0.398/O.406
0.291/0.299
0.398/0.414
0.014/0.018
0.050
0.096/0.104
0.009/0.013
0.020/0.040
0.004/0.012
Figure 11. 16 pin wide SO package outline drawing
BC
1
A
G
KF
H
DE
ITEM
A
B
C
D
E
F
G
H
J
K
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
0.375±0.004
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
J
Figure 10. 8 pin DIP package outline drawing
1
DA
B
C
J
E
G
H
I 0-8º
ITEM
A
B
C
D
E
G
H
I
J
MILLIMETERS
4.80 - 4.98
3.81 - 3.99
5.79 - 6.20
0.20 - 0.30
0.635 BSC
1.35 - 1.75
0.10 - 0.25
0.40 - 1.27
0.19 - 0.25
INCHES
0.189 - 0.196
0.150 - 0.157
0.228 - 0.244
0.008 - 0.012
0.025 BSC
0.0532 - 0.0688
0.004 - 0.010
0.016 - 0.050
0.0075 - 0.0098
Figure 12. 16 pin QSOP package outline drawing
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.


THAT1646 (THAT Corporation)
Balanced Line Driver ICs

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Document 600078 Rev. 07
Page 12 of 12
THAT 1606/1646 Balanced Line Driver ICs
Revision
00
ECO
01 —
02 —
03 —
04 2323
05 2526
06 2765
07 2932
Revision History
Date
9/26/2006
1/12/2007
8/6/2007
9/24/2007
10/16/2009
5/11/2011
2/19/2013
7/7/2015
Changes
Page
Released
- Changed 1606 THD+N specification.
- Changed the XLR orientation in Figures 4 - 9.
- Changed the recommendation for common-mode offset
capacitors to be high quality film type.
Reversed the SNS+ and SNS- pins in Figure 1 and 2.
- Changed the Quiescent Supply Current specification.
- Correction to the output pins in figures 4 through 9
Changed Table 1. to include all the pin numbers including unused
and ground pins.
Revised Figures 4 - 9 and accompanying text to clarify the
recommended application circuits.
Changed the spec. for THD+N (Single-ended) @20kHz.
3
6-9
8
1, 4
2, 3
6-9
1
6 - 10
2, 3
Added the Package Characteristics table.
10
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2015, THAT Corporation; All rights reserved.




THAT1646.pdf
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