Balanced Line Driver ICs

THAT 1280, 1283,THAT

1286 and 1260
1606, 1646_

FEATURES APPLICATIONS
• Balanced, transformer-like floating • Differential Line Drivers
output • Audio Mixing Consoles
• OutSmarts® technology improves
• Distribution Amplifiers
clipping into single-ended loads
• Stable driving long cables and • Hi-Fi Equipment
capacitive loads • Audio Equalizers
• High output: 18Vrms into 600 Ω • Dynamic Range Processors
• Low noise: -101 dBu • Digital Effects Processors
• Low distortion: 0.0007% @ 1kHz • Telecommunications Systems
• Industry-standard pinout • Instrumentation

Description
The THAT 1606 and 1646 are a new generation mode output currents, making the designs
of monolithic audio differential line drivers offering inherently more stable and less sensitive to
improved performance over conventional cross- component tolerances than common CCOSes. As a
coupled designs. Based on a high-performance, fully result, THAT's topology prevents the loss of
differential opamp and laser-trimmed thin-film common-mode feedback that plagues common
resistors, both families exhibit low noise and CCOS designs when clipping into single-ended loads.
distortion, high slew rate, and wide output swing. This avoids excessive ground currents that would
The parts are stable when driving difficult loads, and otherwise upset power supplies and create
have short-circuit protected outputs. additional distortion, even in adjacent channels.
Designed from the ground up in THAT's The 1646 is pin-compatible with the TI DRV134
complementary dielectric isolation process, both and DRV135, as well as the Analog Devices
models incorporate THAT's patented OutSmarts1 SSM2142. The 1606 offers an advanced common-
technology. This is a dual feedback-loop design that mode offset voltage reduction scheme, which
prevents the excessive ground currents typical of requires a small single capacitor instead of the two
cross-coupled output stages (CCOS) when clipping electrolytics required by the 1646 and its pin-
into single-ended loads. OutSmarts uses two compatible cousins. Additionally, the 1606 features
individual negative-feedback loops to separately differential inputs in a space-saving 16-pin QSOP
control the differential output voltage and common package. Both parts offer +6 dB gain.

1646 1606
Pin DIP8 SO8 SO16W QSOP16
THAT 1646
1 Out- Out- NC Gnd*
2 Sns- Sns- NC NC
10k 25
Vcc Out- 3 Gnd Gnd Out- Out-
CEXT 4 In In Sns- Cap1
Sns- 5 Vee Vee Gnd Gnd
10k
5k Din+ 10k 20k
6 Vcc Vcc In In-
In+ Dout-
Cin+ 10p 7 Sns+ Sns+ NC In+
Cin- 8 Out+ Out+ NC Gnd*
5k Din-
Dout+
9 — — NC Gnd*
Gnd 10k 20k
10k
10 — — NC NC
Sns+ 11 — — Vee Vee
10k 25 CEXT 12 — — Vcc Vcc
Vee Out+ 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
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

1646 Electrical Characteristics3

Parameter Symbol Conditions Min. Typ. Max Units

Input Impedance ZIN 4.00 5.00 kΩ

Gain G1 RL=100 kΩ per output

Balanced 5.80 6.00 6.20 dB
Single Ended 5.76 5.96 6.16 dB

Gain G2 RL= 600 Ω

Balanced 5.00 5.30 5.60 dB
Single Ended 4.96 5.26 5.56 dB

Gain Error G1 RL=100 kΩ per output, Balanced 0.02 0.20 dB

DC Power Supply
Rejection Ratio PSRR ±4V to ±18V 85 107 dB

Output Common-Mode
Rejection Ratio CMRROUT f=1kHz, BBC Method 46 65 dB

Output Signal Balance Ratio SBR f=1kHz, BBC Method 35 54 dB

THD+N (Balanced) THD+N1 VO=10 VRMS, RL=600 Ω

20Hz-5kHz 0.0007 %
20kHz 0.002 0.005 %

THD+N (Single Ended) THD+N2 VO=10 VRMS, RL=600 Ω

20Hz-5kHz 0.0010 %
20kHz 0.0030 0.0090 %

Output Noise Onoise Balanced, 22Hz -20kHz -101 dBu

Maximum Output Level VoMAX 0.1% THD+N 27.5 dBu

Slew Rate SR CL=50pF/output 15 V/µS

Small Signal Bandwidth CL=50pF/output 10 MHz

Output Common Mode

Voltage Offset VOCM1 w/o Sense capacitors -250 ±50 250 mV
VOCM2 w/ Sense capacitors -15 ±3.5 15 mV

Differential Output Offset VOD -15 ±4 15 mV

Output Voltage Swing, Positive No Load VCC–2.9 VCC–2.2 V

Output Voltage Swing, Negative No Load VEE+2.25 VEE+2.9 V

Output Impedance ZO 40 50 60 Ω

2. All specifications are subject to change without notice.

3. Unless otherwise noted,.all measurements taken with VS=±18V, T=25°C, RL = 600 Ω Balanced, RSOURCE = 0 Ω

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

Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
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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 Symbol Conditions Min. Typ. Max. Units

Maximum Capacitive Load Stable Operation Unlimited µF

Quiescent Supply Current IS Unloaded 4.9 5.75 mA

Output Short Circuit Current ISC Both outputs to ground 70 mA

Power Supply Voltage Range ±4 ±18 V

1606 Electrical Characteristics3

Parameter Symbol Conditions Min. Typ. Max. Units
Input Impedance ZIN 4.00 5.00 kΩ

Gain G1 RL=100 kΩ per output

Balanced 5.80 6.00 6.20 dB
Single Ended 5.76 5.96 6.16 dB

Gain G2 RL= 600 Ω

Balanced 5.00 5.30 5.60 dB
Single Ended 4.96 5.26 5.56 dB

Gain Error G1 RL=100 kΩ / output, Balanced 0.02 0.20 dB

DC Power Supply
Rejection Ratio PSRR ±4V to ±18V 85 107 dB

Output Common-Mode
Rejection Ratio CMRROUT f=1kHz, BBC Method 46 65 dB

Input Common-Mode
Rejection Ratio CMRRIN f=1kHz 40 60 dB

Output Signal Balance Ratio SBR f=1kHz, BBC Method 35 54 dB

THD+N (Balanced) THD+N1 VO=10 VRMS, RL=600 Ω

20Hz-5kHz 0.0007 %
20kHz 0.002 0.005 %

THD+N (Single Ended) THD+N2 VO=10 VRMS, RL=600 Ω

20Hz-5kHz 0.0010 %
20kHz 0.0060 0.0090 %

Output Noise Onoise Balanced, 22Hz -20kHz -101 dBu

Maximum Output Level VoMAX 0.1% THD+N 27.5 dBu

Slew Rate SR CL=50pF/output 15 V/µS

Small Signal Bandwidth CL=50pF/output 10 MHz

Output Common Mode

Voltage Offset VOCM1 w/o CM coupling capacitor -250 ±50 250 mV
VOCM2 w/ CM coupling capacitor -20 -5 20 mV

Differential Output Offset VOD -15 ±4 15 mV

Output Voltage Swing, Positive No Load VCC–2.9 VCC–2.2 V

Output Voltage Swing, Negative No Load VEE+2.25 VEE+2.9 V

Output Impedance ZO 40 50 60 Ω

Maximum Capacitive Load Stable Operation Unlimited µF

Quiescent Supply Current IS Unloaded 4.9 5.75 mA

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.
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. Units

Output Short Circuit Current ISC Both outputs to ground 70 mA

Power Supply Voltage Range ±4 ±18 V

THAT 1646
10k 25
Vcc Out-
CEXT
Sns-
10k
5k Din+
In+ Dout- 10k 20k
Cin+ 10p

Cin-
5k Din-
Gnd Dout+ 10k 20k
10k
Sns+
10k 25 CEXT
Vee Out+

Figure 2. THAT 1646 Equivalent Circuit Diagram

CEXT
Cap2 Cap1

REXT
THAT 1606
25
Vcc Out-
10k

5k 10k
Din+ Dout- 10k 7k
In+ 10p
Cin+
Cin- AD & AC Gnd
5k Din-
In- 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

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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 common mode equation is more complicated
in that it is dependent on the attached load, and in
The THAT 1606 and 1646 family employs the
any event doesn't yield much insight into the device's
OutSmarts topology, a variation of circuitry originally
operation. For those who are interested, a more
developed by Chris Strahm at Audio Teknology Inc.,
complete discussion is given in the reference
(and later acquired by Audio Toys, Inc.). THAT's
mentioned in note 1.
OutSmarts topology employs two negative-feedback
loops -- one to control the differential signal, and a In op-amp analysis using negative feedback loops,
separate loop to control the common mode output the combination of negative feedback and high open-
levels. loop gain usually results in the open-loop gain
"dropping out" of the equation, and the differential
Figures 2 and 3 show the gain core common to
inputs being forced to the same potential. This is true
the 1606 and 1646. The gain core is a single
for the core of the 1606 and 1646 ICs. If we start
amplifier that includes two differential input pairs,
with that assumption, the operation of the common-
Cin+/- and Din+/-, and complementary outputs,
mode feedback loop can be intuited as follows:
Vout+ and Vout-, related to each other by two gain
expressions, AD(s) and AC(s). The first pair of Referring again to Figures 2 and 3, the common-
differential inputs, Din+/-, is connected to the mode input actually senses the sum of each IC's
differential feedback network between the outputs output currents by way of two 25 Ω resistors and the
and the input signal. The second differential input bridge network4. The resulting error signal is
pair, Cin+/-, is connected to a bridge circuit which amplified and then summed into both outputs, with
generates an error signal used to servo the common- the net effect being to force the sum of the currents to
mode behavior of the outputs. The loop equations are be zero, and thus the common mode output current
then: to zero.

∆ , To see why this is important, consider what

happens when the IC is loaded with a single-ended
where AD is the differential open-loop gain, and
load, which shorts one or the other output to ground.
Σ , Suppose Out- is grounded. In this case, the
differential feedback loop increases the voltage at
where AC is the common-mode open-loop gain.
Dout+ to make up for most of the signal lost to the
These equations can be solved much like short at Out-. The common-mode feedback loop
standard op-amp loop equations. forces the current from Out- to be equal and opposite
to that from Out+. But, during peak signals which
For the differential case, using superposition, we
drive Dout+ into clipping (exceeding its maximum
can see that this results in:
output voltage capability), the differential loop is
, and 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
Substituting and simplifying into the equation
weakness of conventional cross-coupled output
that defines differential operation yields:
designs – common-mode feedback is lost when one
, output is clipped while the other is grounded.

Dividing through by AD (assuming that AD >> 3) With OutSmarts, however, the common mode
and simplifying yields feedback loop senses this happening because of the
increase in current at Out- (compared to that at
2 , Out+), and prevents the voltage at Out- from rising
out of control. This causes the OutSmarts design to
as one would expect for a +6 dB line driver. more closely mimic the behavior of a true floating
For the 1646, In- is hard-wired to ground (0v), so balanced source (such as a transformer), compared
the differential equation above simplifies to: 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

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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 conductor-to-shield capacitance of 33 pF/ft (the
1646 are relatively straightforward. A quiet, solid difference between 67 and 34) for each conductor.
ground reference, stiff voltage supplies, and adequate For balanced signals, the load capacitance across the
supply bypassing are all that are required to achieve 1646 outputs will be 34 pF/ft + 16.5 pF/ft = 50.5
excellent performance out of both ICs. pF/ft. The corner frequency of the THAT 1646 driving
500 ft of this cable (25.25 nF) will be 126 kHz.
2. Both devices must be driven from a low-
impedance source, preferably directly from opamp 126 ,
∙ ∙ ∙ .
outputs, to maintain the specified performance.
One must also consider the slew rate limitations
3. Please refer to Figure 8 for a complete posed by excessive cable and other capacitances. We
applications circuit. know that

Stability and Load Capacitance

The devices are stable into any capacitive load, and that
and the maximum capacitance is limited only by slew
rate and frequency response considerations. 2 ∙ ∙

For the purposes of the frequency response Dennis Bohn of Rane Corporation has
calculation, the line driver's 25Ω sense resistors can published work specifying some of the requirements
be lumped into a single 50Ω resistor. The correct for a balanced line driver, including a) stability into
cable capacitance to use for the balanced-signal case reactive loads, b) differential output voltage swing of
is the sum of the inter-conductor capacitance and the at least ±11 volts peak (+20dBu), and c) reliability5.
two conductor-to-shield capacitances in series. Some This work suggests a reasonable rule by which to
manufacturers only specify the inter-conductor calculate the output current requirements at 20 kHz.
capacitance and the capacitance of one conductor to The author concludes that the actual worst case peak
the other while connected to the shield, and some level for various types of music and speech will be
extraction may be required. flat out to 5 kHz, and roll off at 6dB/octave above this
frequency. Thus the peak levels at 20 kHz will be
As an example, Belden 8451 is specified as
12 dB below those at 5 kHz.
having with 34 pF/ft of inter-conductor capacitance
and 67 pF/ft of conductor to "other conductor + Using these, we can calculate the required slew
shield capacitance". Thus, we can assume a single rate and current drive. For the +26 dBu output

Vcc

C4
100n
6
7
In Vcc 8 Out+
4
In Sns+
Out+
3 Out-
Gnd Sns- Out-
Vee 1
2 U1
5 THAT1646
C5
100n
Vee

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.
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 undue problems being overdriven at their inputs
(below 5 kHz), and at 20 kHz, VPeak is 5.5 V. when the outputs are clipping into single-ended
Therefore, loads.

2 ∙ 5.5 ∙ 20 0.69 1646 circuits

As a consequence, Figure 4 shows the most basic connection for a
1646. The only external components needed are the
500 ∙ 34 16.5 ∙ 0.69 17.5 .
local 100 nF bypass capacitors. These should be
Thus, driving this 25.25 nF cable requires within 1 inch of the 1646 pins.
17.5 mAPeak, which is well within the capability of the
1606 and 1646. Output DC offset
Because the 1646's outputs are connected
Gain structure directly to their respective sense inputs, this circuit
The 1606 and 1646 both provide +6 dB gain may produce up to 250 mV of common-mode dc
(factor of 2) between their inputs and differential offset at its outputs. As shown, the outputs are DC
outputs. This is appropriate, since with a balanced coupled to the output connector, so this dc will
output, twice the voltage between the power supply appear directly at the output of the system.
rails is available at the output of the stage. The The output common-mode offset of a 1646 may
single-ended input of the 1646 can accept signals be reduced by adding capacitors in the feedback
that swing to nearly the power supply rails without loop, as shown in Figure 5. Capacitors C1 and C2 ac-
distortion, when driving into a differential (floating) couple the common-mode feedback loop. This
load. The balanced input of the 1606 can accept changes the loop operation from servoing the
signals at each input that swing to nearly one-half the common-mode output current at audio frequencies
power supply rails without distortion, when driving to servoing the common-mode output voltage to 0 at
into differential loads. DC. This results in much lower common-mode
Both devices, when driving single-ended loads, output offset voltage, as indicated in the
will clip at about half the output voltage as compared specifications section. C1 and C2 are typically high
to a differential load. This is because only one of the quality non-polarized electrolytic capacitors.
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

Vcc
C1
C4
100n
6 10u
7 NP
In Vcc Out+
4 8
In Sns+
Out+
3 Out-
Gnd Sns- Out-
Vee 1
2 U1
5 THAT1646
C5 C2
100n
Vee 10u
NP
Figure 5. THAT 1646 with common-mode offset reduction

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

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Document 600078 Rev. 07 Page 8 of 12 THAT 1606/1646 Balanced Line Driver ICs

Vcc C1 R1
1M0
100n
C4
100n
12
4
In Vcc Out+
7 14
In+ Cap1
6 Out+
In- Out-
5 Gnd Out-
Cap2
3
Vee
13 U1
11 THAT1606
C5
100n
Vee

Figure 6. THAT 1606 with output common-mode offset reduction and single-ended input drive

Vcc C1 R1
1M0
100n
C4
100n
12
4
In+ 7 Vcc Out+
14
In+ Cap1
6 Out+
In- Out-
In- Out-
5 Gnd Cap2
3
Vee
13 U1
11 THAT1606
C5
100n
Vee

Figure 7. THAT 1606 with output common-mode offset reduction and differential input drive
up less space on the circuit board than the two large
1606 circuits capacitors required for the 1646. C1 should be a
high-quality film type capacitor to minimize low-
Figures 6 and 7 show the basic amplifier
frequency distortion when driving single-ended loads.
configurations for a 1606. The 1606 differs from the
1646 in two respects. First, the 1606 includes a
RFI protection
negative-sense input pin (pin 6), so offers a
differential input. This can be useful in connecting These line drivers can easily drive cables
the output driver to the output of modern D/A hundreds of feet in length without becoming
converters, which usually present differential unstable, but such long cables can act as antennae
outputs. Second, instead of two 10 uF capacitors, the which can pick up RFI and direct it into the circuit.
1606 uses an 0.1 uF capacitor (C1) and 1 MΩ (R1) The circuit of Figure 8 includes two 100 pF bypass
resistor to reduce common-mode dc offset. capacitors (C3 and C8) and two ferrite beads, whose
Generally, these components will cost less, and take purpose is to redirect this RF energy to the chassis

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

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Document 600078 Rev. 07 Page 9 of 12 THAT 1606/1646 Balanced Line Driver ICs

Vcc

D4
1N4004
U1 D3 XLR (M)
Input Vcc 1N4004 L1
Input 1 2
Out+ Ferrite Bead C8 3
Out- D5
Amplifier Gnd 1N4004 100p
Block L2
Vee
(from fig.
5, 6, or 7) D6 Ferrite Bead C3
1N4004 100p

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 control. The 1606/1646's internal protection network
couple RF into other portions of the circuit. The will withstand this abuse for coupling capacitors up
capacitors should be located as close as possible to to about 33 uF.
the output connector and connected via a low-
To protect against microphone preamplifiers
inductance path to chassis ground, with the ferrite
that incorporate larger values of capacitance, a pair
beads placed very nearby. These components ensure
1N4004 diodes from each output to the supply rails,
that RFI current is directed to the chassis and not
as shown in Figure 8, is recommended. This shunts
through the relatively low-impedance output of the
the discharge current to the power supply bypass
1606/1646. The bypass capacitors and ferrite beads
and filter capacitors, thus protecting the output of
will have no effect on the gain error of these line
the 1606 or 1646.
drivers at audio frequencies.

Closing thoughts
Output protection
The integrated balanced line driver is one of
The 1606 and 1646 each incorporate a
those highly useful, cost-effective functional blocks
proprietary internal protection scheme, which will
that can provide significant improvement over
suffice for many situations seen in the field. However,
discrete designs. The THAT 1646 goes a step or two
one might foresee having the line driver's output
further by improving over existing components. Both
mistakenly plugged directly into a microphone
incorporate OutSmarts technology to tame the
preamplifier input that has +48V phantom power
aberrant single-ended clipping behavior of
applied. When this happens, the ac coupling
conventional cross-coupled output stages.
capacitors on the preamp's input will discharge into
the low-impedance output of the 1606/1646. This can For more information on these or other THAT
result in surge currents of over 2 amperes6. The Corporation integrated circuits, please contact us
amount of energy stored in these capacitors is directly, or through one of our international
directly proportional to the capacitor value, which is, distributors.
of course, not under the 1606/1646 designer's

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

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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 125 ºC/W
ground plane of 1 sq in or larger
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 The 1606 is supplied in a 16-pin QSOP package
mini-DIP and 16-pin wide SOIC packages. The 1606 in which pins 1, 8, 9, and 16 are fused to the die
comes in a 16-pin QSOP package. Package paddle to assist in conducting heat away from the
dimensions are shown in Figures 9, 10, 11, and 12, die. These pins are connected to the die substrate,
while pinouts are given in Table 1. which is, in turn, connected to the ground pin of the
device. When these pins are connected to a top-side
Thermal Considerations ground plane of 1 square inch area, the junction-to-
ambient thermal resistance is 125°C/watt. Internal
As mentioned. the 1646 is available in an 8-pin
planes on multi-layer PCBs will reduce the thermal
DIP, and 16-pin wide SO, and an 8-pin SO, with
resistance further.
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 SO8 DIP8 SO16W QSOP16
Model
Pkg Pkg Pkg Pkg
600 Ω loads or very long cables (several hundred
feet) at high ambient temperatures (above 55°C) 1646 1646S08-U 1646P08-U 1646W16-U —
continuously could lead to internal die temperatures 1606 — — — 1606Q16-U
that exceed the maximum rating and result in
Table 2. Order Number Information
performance degradation.

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

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Document 600078 Rev. 07 Page 11 of 12 THAT 1606/1646 Balanced Line Driver ICs

0-8°
E F
B C J

1
B C A G
H
1 K F
hx45°
D
G H
A
a1 D E
ITEM MILLIMETERS INCHES
A 9.52±0.10 0.375±0.004
ITEM MILLIMETERS INCHES B 6.35±0.10 0.250±0.004
A 4.78/5.00 0.188/0.197 C 7.49/8.13 0.295/0.320
a1 0.10/0.20 0.004/0.008 D 0.46 0.018
B 3.81/3.99 0.150/0.157
E 2.54 0.100
C 5.84/6.20 0.230/0.244
D 0.36/0.46 0.014/0.018 F 3.68/4.32 0.145/0.170
E 1.27 0.050 G 0.25 0.010
F 1.52/1.73 0.060/0.068 H 3.18±0.10 0.125±0.004
G 0.18/0.25 0.007/0.010 J 8.13/9.40 0.320/0.370
H 0.41/0.89 0.016/0.035
h 0.31/0.71 0.012/0.027
K 3.30±0.10 0.130±0.004

Figure 9. 8 pin SO package outline drawing Figure 10. 8 pin DIP package outline drawing

E F 1

D A
B C
H
E
1 B
C G
D
G J H
A
J
0-8º
I
ITEM MILLIMETERS INCHES
ITEM MILLIMETERS INCHES
A 10.11/10.31 0.398/O.406
A 4.80 - 4.98 0.189 - 0.196
B 7.40/7.60 0.291/0.299
B 3.81 - 3.99 0.150 - 0.157
C 10.11/10.51 0.398/0.414 C 5.79 - 6.20 0.228 - 0.244
D 0.36/0.46 0.014/0.018 D 0.20 - 0.30 0.008 - 0.012
E 1.27 0.050 E 0.635 BSC 0.025 BSC
F 2.44/2.64 0.096/0.104 G 1.35 - 1.75 0.0532 - 0.0688
G 0.23/0.32 0.009/0.013 H 0.10 - 0.25 0.004 - 0.010
H 0.51/1.01 0.020/0.040 I 0.40 - 1.27 0.016 - 0.050
J 0.19 - 0.25 0.0075 - 0.0098
J 0.10/0.30 0.004/0.012

Figure 11. 16 pin wide SO package outline drawing 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.
Document 600078 Rev. 07 Page 12 of 12 THAT 1606/1646 Balanced Line Driver ICs

Revision History

Revision ECO Date Changes Page

00 — 9/26/2006 Released —

- Changed 1606 THD+N specification. 3

- Changed the XLR orientation in Figures 4 - 9. 6-9
01 — 1/12/2007
- Changed the recommendation for common-mode offset 8
capacitors to be high quality film type.

02 — 8/6/2007 Reversed the SNS+ and SNS- pins in Figure 1 and 2. 1, 4

- Changed the Quiescent Supply Current specification. 2, 3

03 — 9/24/2007
- Correction to the output pins in figures 4 through 9 6-9
Changed Table 1. to include all the pin numbers including unused
04 2323 10/16/2009 1
and ground pins.
Revised Figures 4 - 9 and accompanying text to clarify the
05 2526 5/11/2011 6 - 10
recommended application circuits.

06 2765 2/19/2013 Changed the spec. for THD+N (Single-ended) @20kHz. 2, 3

07 2932 7/7/2015 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.