High-Performance Digital
Preamplifier Controller IC
THAT
5171
FEATURES
Ideal mate for THAT1580 preamplifier
Wide gain range:
–
+13.6 to +68.6dB in 1dB steps, and
–
+5.6dB
Wide supply range: ±5V to ±17V
Wide output swing:+27dBu (±17V sup.)
Wide input swing: +22dBu (±17V sup.)
Low THD+N: 0.0003% @ 22dB gain
Integrated differential servo minimizes
output offset
Zero-crossing detector minimizes
switching noise
Flexible, addressable SPI interface
Four general-purpose digital outputs
Small 7mm x 7mm QFN32 package
APPLICATIONS
Digitally controlled microphone
preamplifiers
Digitally-controlled instrumentation
amplifiers
Digitally-controlled differential
amplifiers
Audio mixing consoles
PC audio breakout boxes
Audio distribution systems
Digital audio snakes
Portable audio recorders
Description
The THAT5171 is a digital gain controller for
low-noise, analog, differential, current-feedback
audio preamplifiers such as the THAT 1580. When
used in conjunction with an appropriate analog gain
block, the 5171 can set gain to 5.6dB, or any gain
from 13.6dB to 68.6dB in 1dB steps, while
preserving low noise and distortion. It operates
from ±5V to ±17V supplies, supporting input signal
levels as high as +22 dBu (at 5.6dB gain, and ±17V
supplies) in combination with the 1580 (without an
external input pad). The 5171 includes a differential
servo and zero-crossing detector to minimize dc
offsets and glitches (zipper noise) during gain
adjustments.
The 5171 is controlled via an addressable
serial-peripheral interface (SPI) port. Four General
Purpose Outputs (GPOs) can be controlled
via this interface. The GPOs may be connected to
input pads, analog switches, mute circuits, LEDs,
etc. The SPI bus supports read-back so that host
software can verify proper operation.
The 5171 was designed to mate perfectly with
the THAT 1580 Differential Audio Preamplifier IC.
Together, these two ICs provide a best-of-class
solution for digitally-controllable audio preamplifier
applications. However, for designers who prefer a
more customized solution, the 5171 may also be
used to control a discrete preamplifier.
Fabricated in a high-voltage CMOS process, the
5171 integrates an astonishing amount of circuitry
within a very small package. It comes in a small
(7x7 mm) 32-pin QFN package, making it suitable
for small portable devices.
DGnd
TRC
DGnd
RST
BSY
Vdd
Vdd
IN2
AGnd
AGnd
Rg2
SOUT2
SOUT1
SCAP1
Figure 1. THAT 5171 Block Diagram
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 508 478-9200; Fax +1 508 478-0990; Web:
www.thatcorp.com
Copyright © 2017, THAT Corporation; Document 600133 Rev 10
SCAP2
DOUT
DIN
SCLK
CS
GPO3
GPO2
GPO1
GPO0
Rg1
IN1
THAT 5171 High-Performance
Digital Preamplifier Controller IC
Page 2 of 20
Document 600133 Rev 10
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Thermal
Pad
NC
NC
RG1
IN1
IN2
RG2
NC
NC
VCC
Pin Name
Pin Description
No Connect
No Connect
Attenuator Network Output 1 [Connects to preamplifier feedback 1 (RG1)]
Attenuator Network Input 1 [Connects to preamplifier Output 1]
Attenuator Network Input 2 [Connects to preamplifier Output 2]
Attenuator Network Output 2 [Connects to preamplifier feedback Input 2 (RG2)]
No Connect
No Connect
Positive Analog Supply Voltage
Analog Ground Reference
Negative Analog Supply Voltage
Logic Ground Reference
Logic Positive Supply Voltage
R/C Timeout or External Clock Input
Reset Input (Active Low)
Chip Select Input (Active Low)
Serial Clock Input
Serial Data Input
Serial Data Output
Logic Ground Reference
Logic Positive Power Supply
Busy Output (Active High)
During Reset: SPI address bit 0 input; During run time: General Purpose Output 0
During Reset: SPI address bit 1 input; During run time: General Purpose Output 1
During Reset: SPI address bit 2 input; During run time: General Purpose Output 2
General Purpose Output 3
No Connect
Analog Ground Reference
DC Servo Capacitor Input 1
DC Servo Capacitor Input 2
DC Servo Output 1
DC Servo Output 2
Connected internally to Vee. Solder to PCB (optionally connect to Vee) for optimal
performance.
Table 1. Pin Assignments
AGND
VEE
DGND
VDD
TRC
RST'
CS'
SCLK
DIN
DOUT
DGND
VDD
BSY
GPO0
GPO1
GPO2
GPO3
NC
AGND
SCAP1
SCAP2
SOUT1
SOUT2
PAD
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 508 478-9200; Fax +1 508 478-0990; Web:
www.thatcorp.com
Copyright © 2017, THAT Corporation; All rights reserved.
THAT 5171 High-Performance
Digital Preamplifier Controller IC
Page 3 of 20
Document 600133 Rev 10
SPECIFICATIONS
1
Absolute Maximum Ratings
2,3
Total Analog Supply Voltage (V
CC
-V
EE
)
Positive Analog Supply Voltage (V
CC
-A
GND
)
Negative Analog Supply Voltage (V
EE
-A
GND
)
Digital Supply Voltage (V
DD
-D
GND
)
Analog and Digital Ground Difference (D
GND
-A
GND
)
Maximum Analog Voltage at IN1, IN2 (V
iAMax
)
Maximum Current Through V
DD
, D
GND
36 V
18 V
-18 V
4.5 V
±0.3 V
V
CC
100 mA
Minimum Analog Voltage at IN1, IN2 (V
iAMin
)
Maximum Digital Input Voltage (V
IDMax
)
Minimum Digital Input Voltage (V
IDMin
)
Storage Temperature Range (T
STG
)
Operating Temperature Range (T
OP
)
Junction Temperature (T
JMAX
)
V
EE
V
DD
+ 0.3 V
D
GND
- 0.3 V
-40 to +125 ºC
-40 to +85 ºC
+125 ºC
Elec trical Characteristics
2,4
Parameter
Power Supply
Analog Supply Voltage
Digital Supply Voltage
Analog Supply Current
Digital Supply Current
V
CC
; -V
EE
V
DD
I
CC
; -I
EE
I
DD
Referenced to A
GND
Referenced to D
GND
No Signal
No Signal
4.75
3.0
—
—
—
—
8.3
2
17
3.6
11
11
V
V
mA
µA
Symbol
Conditions
Min.
Typ.
Max.
Units
Resistor Ladder Characteristics (DC)
Gain Range
[-20log (V
IN1
-V
IN2
)/(V
RG1
-V
RG2
)]
Gain Step Size
Gain Error
R
G
Range (Resistance from IN
1
to IN
2
)
R
A
, R
B
Range (Resistance from IN
1
to Rg
1
)
(Resistance from IN
2
to Rg
2
)
Servo Amp Characteristics (DC)
Input Offset Voltage
Power Supply Rejection Ratio
Maximum Output Voltage
Minimum Output Voltage
Maximum Output Current
1
2
3
V
CC
– 1.6 > V
IN1
> V
EE
+ 1.6
V
CC
– 1.6 > V
IN2
> V
EE
+ 1.6
13.6dB ≤ Gain ≤ 68.6dB
All gain settings
All gain settings
5.6
—
-0.5
4.5
—
1
±0.15
5.6~1.41k
68.6
—
0.5
1.69k
dB
dB
dB
Ω
All gain.settings
2.1
2.65~7.5
9
kΩ
V
OS
PSRR
V
OMax
V
OMin
I
OMax
Includes bias current effects
V
CC
= -V
EE
; ±5V to ±15V
-1.6
100
V
CC
-4.5
—
0.70
—
115
—
—
1.0
+1.6
—
—
V
EE
+4.5
—
mV
dB
V
V
mA
All specifications subject to change without notice.
Unless otherwise noted, T
A
= 25°C, V
CC
= +15V, V
EE
= -15V, V
DD
= +3.3V.
Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only; the
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.
0 dBu = 0.775 Vrms
4
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 508 478-9200; Fax +1 508 478-0990; Web:
www.thatcorp.com
Copyright © 2017, THAT Corporation; All rights reserved.
THAT 5171 High-Performance
Digital Preamplifier Controller IC
Page 4 of 20
Document 600133 Rev 10
Elec trical Characteristics ( con 't)
Parameter
Symbol
Conditions
Min.
1,3,4
Typ.
Max.
Units
Zero-Crossing Detector Characteristics (DC)
Zero-Crossing Detector Threshold
ZCD Timeout
ZCD Timing Capacitor
ZCD Timing Resistor
AC Characteristics
THD+N (Differential signal applied to f = 1 kHz, Gain = 21.6 dB,
IN
1
, IN
2
, measured at RG
1
, RG
2
) V
IN1
- V
IN2
< = +22 dBu
Maximum Signal Voltage at IN
1
, IN
2
Minimum Signal Voltage at IN
1
, IN
2
Maximum Signal Voltage at RG
1
, RG
2
Minimum Signal Voltage at RG
1
, RG
2
Digital I/O Characteristics
High-Level Input Voltage
Low-Level Input Voltage
High-Level Output Voltage
Low-Level Output Voltage
High-Level Output Current
Low-Level Output Current
Input Leakage Current
Serial Clock (SCLK) Characteristics
Frequency
Pulse Width Low
Pulse Width High
Input Timing
DIN Setup; Hold Time
CS Falling to SCLK Rising;
SCLK Falling to CS Inactive
CS Inactive to SCLK Rising
RST Hold Time
TRC Hold Time
Output Timing
SCLK Rising to D
OUT
Active
SCLK Falling to D
OUT
Data Valid
CS Inactive to D
OUT
High Impedance
t
CRDA
t
CFDO
t
CSZ
5
—
5
—
—
—
10
15
20
ns
ns
ns
t
SDS
, t
SDH
t
CSCR
t
CFCS
t
CICR
t
RST
t
TRC
15
50
100
50
50
—
—
—
—
—
—
—
—
—
—
ns
ns
ns
ns
ns
f
SCLK
t
PL
t
PH
0
40
40
—
—
—
10
—
—
MHz
ns
ns
V
IH
V
IL
V
OH
V
OL
I
OH
I
OL
I
IN
I
O
= 4 mA
I
O
= -4 mA
.7*V
DD
-0.3
.8*V
DD
—
—
—
—
—
—
—
—
4
-4
2
V
DD
+ 0.3
0.3*V
DD
—
0.4
25
-25
10
V
V
V
V
mA
mA
µA
—
—
—
—
—
0.0003
V
CC
- 2.5
V
EE
+ 2.5
V
CC
- 2.5
V
EE
+ 1.5
—
—
—
—
—
%
V
V
V
V
t
ZTO
C
T
R
T
1k
R
T
= 22MΩ, C
T
= 1 nF
—
—
±5
22
1
22M
—
—
2
100M
mV
ms
nF
Ω
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 508 478-9200; Fax +1 508 478-0990; Web:
www.thatcorp.com
Copyright © 2017, THAT Corporation; All rights reserved.
THAT 5171 High-Performance
Digital Preamplifier Controller IC
Page 5 of 20
Document 600133 Rev 10
Theory o f Operation
The THAT 5171 is a gain controller in the form
of a digitally controlled differential attenuator; it is
not an amplifier. It contains a set of precision
resistors, switched by a set of CMOS FET switches,
configured to create a variable, switched, differential
attenuation network. The network's impedances are
ideal for controlling gain in low-voltage-noise,
current-feedback instrumentation amplifiers, and are
optimized for low source impedance applications.
For example, when coupled with a low-noise gain
stage like the THAT 1580, it maintains 1.5nV/√Hz
noise floor at 68.6dB gain in the complete circuit.
the impedance levels are chosen to minimize noise
and distortion within the circuit as a whole.
Table 2 lists the typical internal attenuator
resistor values for each gain setting.
Gain
Setting
5.6
13.6
14.6
15.6
16.6
17.6
18.6
19.6
20.6
21.6
22.6
23.6
24.6
25.6
26.6
27.6
28.6
29.6
30.6
31.6
32.6
33.6
34.6
35.6
36.6
37.6
38.6
39.6
40.6
41.6
42.6
43.6
44.6
45.6
46.6
47.6
48.6
49.6
50.6
51.6
52.6
53.6
54.6
55.6
56.6
57.6
58.6
59.6
60.6
61.6
62.6
63.6
64.6
65.6
66.6
67.6
68.6
Rg
(ohms)
7.9k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
560
560
560
560
560
560
560
560
220
220
220
220
220
220
220
220
89
89
89
89
89
89
89
89
35
35
35
35
35
35
35
35
14
14
14
14
14
14
14
14
5.6
5.6
5.6
5.6
5.6
5.6
5.6
5.6
Ra, Rb
(ohms)
3.6k
2.7k
3.1k
3.5k
4.0k
4.6k
5.3k
6.0k
6.8k
3.1k
3.5k
3.9k
4.5k
5.0k
5.7k
6.4k
7.2k
3.2k
3.7k
4.1k
4.6k
5.2k
5.9k
6.6k
7.4k
3.3k
3.7k
4.2k
4.7k
5.3k
5.9k
6.7k
7.5k
3.3k
3.8k
4.2k
4.7k
5.3k
6.0k
6.7k
7.5k
3.4k
3.8k
4.2k
4.7k
5.3k
6.0k
6.7k
7.5k
3.4k
3.8k
4.2k
4.7k
5.3k
6.0k
6.7k
7.5k
“Gain”
Register
0
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Using the 5171
The attenuator is intended primarily for use in
the feedback loop of differential current-feedback
gain stages, such as the THAT 1580. Designed
specifically for use in high-performance microphone
preamplifiers, THAT's engineers paid careful
attention to precision, stability, and control over the
resistors and their switches, in order to maintain
excellent audio performance over a wide range of
gains and signal levels.
IN2
IN1
U1
THAT5171
U2
THAT158x
Figure 2. Analog portion of 5171 connected to a 158x.
Figure 2 shows the analog portion of the 5171
connected to a 1580. Resistors R
A
, R
B
, and R
G
form a
differential
attenuator
("U-pad").
The
1580's
differential output is applied to R
A
and R
B
. The
output of the attenuator, appearing across R
G
, is
connected to the inverting differential input of the
dual current-feedback amplifiers in the 1580 (the R
G1
and R
G2
pins). The voltage divider ratio thus controls
the differential gain of the circuit.
The 5171 changes the attenuator settings based
on the gain command provided via the SPI control
interface. At minimum gain, R
G
is ~7.93kΩ, while
R
A
=R
B
=~3.56kΩ, which sets the circuit gain to
+5.6dB. To achieve other gains, all three resistors
are varied by CMOS switches in order to produce
1dB gain steps from +13.6 to +68.5dB. At all gains,
Rg2
Rg1
Table 2. Internal attenuator resistor values.
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 508 478-9200; Fax +1 508 478-0990; Web:
www.thatcorp.com
Copyright © 2017, THAT Corporation; All rights reserved.
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