5171N32-U THAT Corporation, 5171N32-U Datasheet - Page 5

• Manufacturer Part Number: 5171N32-U
• Description: Microphone Preamplifiers High-Perform Digital Pre-Amp Controller
• Manufacturer: THAT Corporation

Specifications of 5171N32-U

• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 17 V
• Operating Temperature Range: - 40 C to + 85 C
• Supply Current: 8.3 mA
• Supply Voltage (max): 17 V
• Supply Voltage (min): 3 V
• Thd Plus Noise: 0.0003 %
• Available Set Gain: 13.6 dB to 68.6 dB
• Input Offset Voltage: +/- 1.5 mV
• Maximum Operating Temperature: + 85 C
• Package / Case: QFN-32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

THAT5171 High-Performance
Digital Preamplifier Controller IC
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-feed-
back instrumentation amplifiers, and are optimized
for low source impedance applications. For example,
when coupled with a low-noise gain stage like the
THAT 1570, it maintains 1.5nV/√Hz noise floor at
68.6dB gain in the complete circuit.
Using the 5171
the feedback loop of differential current-feedback
gain stages, such as the THAT 1570. Designed spe-
cifically for use in high-performance microphone pre-
amplifiers, 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.
connected to a 1570. Resistors R
differential attenuator (“U-pad”). The 1570’s differen-
tial output is applied to R
attenuator, appearing across R
inverting differential input of the dual current-
feedback amplifiers in the 1570 (the R
pins). The voltage divider ratio thus controls the dif-
ferential gain of the circuit.
on the gain command provided via the SPI control
interface. At minimum gain, R
R
+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,
A
Figure 2. Analog portion of 5171 connected to a 1570.
= R
The THAT 5171 is a gain controller in the form of
The attenuator is intended primarily for use in
Figure 2 shows the analog portion of the 5171
The 5171 changes the attenuator settings based
B
= ~3.56kΩ, which sets the circuit gain to
U1
THAT5171
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
A
and R
Copyright © 2010, THAT Corporation; All rights reserved.
G
, is connected to the
G
U2
THAT1570
A
B
, R
. The output of the
is ~7.93kΩ, while
B
, and R
G1
Theory of Operation
G
and R
form a
G2
Page 5 of 20
the impedance levels are chosen to minimize noise
and distortion within the circuit as a whole.
tor values for each gain setting.
Table 2 lists the typical internal attenuator resis-
Setting
Gain
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
5.6
Table 2. Internal attenuator resistor values.
(ohms)
7.9k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
1.4k
Rg
560
560
560
560
560
560
560
560
220
220
220
220
220
220
220
220
5.6
5.6
5.6
5.6
5.6
5.6
5.6
5.6
89
89
89
89
89
89
89
89
35
35
35
35
35
35
35
35
14
14
14
14
14
14
14
14
Document 600133 Rev 04
(ohms)
Ra, Rb
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
Register
“Gain”
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
0
8
9