5171N32-U THAT Corporation, 5171N32-U Datasheet - Page 8

• 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

Document 600133 Rev 04
tion to discrete current-feedback differential pream-
plifiers,
exclusively based on use with the companion
THAT1570 IC. This part provides the essential low-
noise, current-feedback, differential analog gain stage
whose gain the 5171 can control.
application of the 5171 and 1570 to form a complete
low-noise microphone preamplifier.
Gain Ranges in Basic Configurations
varies from 5.6 to 68.6dB. There is one large ~8dB
step from 5.6dB to 13.6dB. Above 13.6dB, gain may
be controlled in 1dB steps to +68.6dB. For single-
ended analog outputs, the circuit of Figure 3 can be
followed by a differential-to-single-ended converter,
as shown in Figure 4. Here, the differential amplifier
is configured for -5.6dB gain in order to minimize
noise and maximize headroom at the output of the
circuit. Including the 5.6dB attenuation in the differ-
ential amplifier, the system gain can be set to 0dB, or
any gain from +8dB to +63dB in 1dB steps.
supply rails, the maximum (differential) input signal
level is +21dBu, and the maximum (differential) out-
put signal level (at the OUT
While the 5171 is perfectly suitable for applica-
The circuit of Figure 3 shows the most basic
The circuit of Figure 3 offers differential gain that
At minimum system gain (0dB) and with ±15V
the
applications
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
THAT
1
5171
discussed
U1
Copyright © 2010, THAT Corporation; All rights reserved.
and OUT
19 18 17 16
To: Host
MCU
Figure 3. 5171/1570 basic application circuit.
2
herein
pins of the
15
26 25 24 23
Control
14
Logic
Applications
22
are
Page 8 of 20
32
13
31
Servo
21
-
+
Vcc
Vee
+
-
1570) is +26.6dBu.
(+63dB), the maximum input signal level is -42dBu,
and the maximum output signal level remains
+26.6dBu. All these figures increase by a little over
1dB if the circuit is run from ±17V supplies.
signal levels remain the same, but the (now single-
ended) output levels drop by 5.6dB due to the loss of
the differential amplifier. When converting to single-
ended signals, take care to select a low-noise opamp,
and pay attention to the noise generated by the
impedances. The component values shown in Figure
4 will largely preserve the dynamic range of the 1570
and 5171 combination, though they do compromise
noise by 1dB at the lowest gain settings.
phone preamplifier must drive an analog-to-digital
converter. Most high-performance A/D converters
have differential inputs, and cannot accept differen-
tial signals greater than ~+8dBu. For such applica-
tions, the output of the mic preamp must be
attenuated to prevent overload of the A/D converter.
The circuit of Figure 5 shows one typical circuit,
using a simple resistive attenuator (R
The impedance levels of the attenuator are chosen to
minimize their self-generated voltage noise, and to
stay within the load limits of the 1570 which drives
them. Figure 5 assumes that the maximum differen-
tial input to the A/D converter is +8dBu. For higher
29
20
30
With the circuit of Figure 4, the maximum input
For many applications, the output of the micro-
12
10
with FET
Switches
Network
Resistor
6
5
3
4
11
THAT
1570
U2
9
7
10
6
15
Vcc
Digital Preamplifier Controller IC
At maximum system gain
THAT5171 High-Performance
13
12
3
2
9
through R
11
).