that1570 THAT Corporation, that1570 Datasheet

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that1570

Manufacturer Part Number
that1570
Description
Low-noise, Differential Audio Preamplifier Ic
Manufacturer
THAT Corporation
Datasheet
current-feedback amplifier suitable for differential
microphone preamp and bus summing applications.
The IC comes in a small QFN package, which saves
PCB space over discrete and other integrated
solutions.
R
a wide range of gains. The 1570 supports the tradi-
tional approach to gain control (viz., THAT's 1510 or
1512) by fixing R
gain. However, the 1570 also supports varying all
three resistors simultaneously with a dual-gang poten-
tiometer or a switched resistor network. This flexible
approach enables the designer to optimize noise over a
wider range of gains than is possible with fixed R
R
B
B
Low Noise:
Low THD+N:
Low Current: 7.5 mA typ
Wide Bandwidth: 4.2MHz @40dB gain
High Slew Rate: 53 V/μs
Wide Signal Swing: >28.7dBu
Gain adjustable from 0 to >60 dB
Differential output
Small 4 x 4mm QFN16 package
Mates with THAT5171
Digital Preamplifier Controller IC
, and R
.
The THAT1570 is a versatile, high performance
Gain is adjusted via three external resistors (R
1 nV/√Hz input noise (60 dB gain)
0.0003% ≤ 30 dB gain
0.0008% @ 40 dB gain
(±18V supplies)
G
), making it possible to optimize noise over
FEATURES
Figure 1. THAT1570 Block Diagram
A
and R
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Copyright © 2009, THAT Corporation. Document 600132 Rev 01
B
, and varying R
G
to control
A
Description
and
A
,
tion to differential input devices such as A/D convert-
ers. The part operates from as little as
through
at unity gain, the part accepts >+28dBu input signals.
THAT’s 5171 Digital Preamplifier Controller IC. The
part-pair comprises an optimized, digitally controlled
audio preamplifier.
mentary
including laser-trimmed Si-Chrome thin-film resistors,
the 1570 improves on existing integrated microphone
preamps by offering more versatile gain configuration,
lower noise at low gains, higher slew rate, and lower
distortion.
The 1570's differential output simplifies connec-
The 1570 is designed to mate perfectly with
Designed from the ground up in THAT's comple-
Microphone Preamplifiers
Digitally-Controlled Microphone
Preamplifiers
Differential Low-Noise Preamplifiers
Differential Summing Amplifiers
Differential Variable-Gain Amplifiers
Moving-Coil Transducer Amplifiers
Line Input Stages
Audio
Sonar
Instrumentation
±
bipolar
18V supplies. Running on
APPLICATIONS
Pin Name
dielectric-isolation
OUT2
OUT1
Rg1
Rg2
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
IN1
IN2
V
V
V
Table 1. Pin Assignments
EE
CC
EE
Low-Noise, Differential
Audio Preamplifier IC
THAT1570
±
18V supplies,
process
Thermal Pad
QFN Pin
±
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
5V up
and

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that1570 Summary of contents

Page 1

... Differential output Small 4 x 4mm QFN16 package Mates with THAT5171 Digital Preamplifier Controller IC The THAT1570 is a versatile, high performance current-feedback amplifier suitable for differential microphone preamp and bus summing applications. The IC comes in a small QFN package, which saves PCB space over discrete and other integrated solutions ...

Page 2

... No signal; IN1, IN2 connected to GND OSCM kΩ Ω; Cold start Ω; Continuous R L Over entire temperature range L MAX Stable operation 50% overshoot kΩ L THAT1570 Low-Noise Differential Audio Preamplifier IC 2,3 ) -40 to +85 º Continuous SH ) +125 ºC JMAX 2,4,5 Min Typ Max Units — 5 ...

Page 3

... THAT1570 Low-Noise Differential Audio Preamplifier Electrical Characteristics (con’t) Parameter Symbol AC Characteristics Gain Equation G Feedback Impedance R Differential Gain G Power Supply Rejection Ratio PSRR Bandwidth -3dB f -3dB Slew Rate Total Harmonic Distortion THD + N Equivalent Input Noise Voltage Equivalent Input Noise Current Noise Figure THAT Corporation ...

Page 4

... Document 600132 Rev 01 Gain Setting Three external resistors ( and gain of the THAT1570. Gain follows the formula where A is the (differential voltage gain of the part (See Figure 2, in which R made fixed (R ) portion and a variable (R GF portion) ...

Page 5

... THAT1570 Low-Noise Differential Audio Preamplifier this is ~255 mV. As well, if the wiper of the pot loses contact with the element, gain will abruptly change to unity, with an attendant change in dc offset as well. To minimize dc offsets, consider the circuits of Figures 5 and 7, which ac couple Improving Noise Performance The 1570 has extremely low input voltage noise ...

Page 6

... THAT 1570 IN1 10k 10 3300u IN2 R2 1k0 THAT1570 Low-Noise Differential Audio Preamplifier IC -A OUT1 V -A OUT2 V Diodes and V . These +15V C9 100n OUT+ Vcc ...

Page 7

... THAT1570 Low-Noise Differential Audio Preamplifier However, while the internal diodes are effective against ESD, they should not be relied upon to protect against excessive input voltage, which can result in significant current flow. This is a particular problem when the preamplifier includes a source of +48 V phantom power (see text below) but can be of ...

Page 8

... A/D converters require a dc offset at their inputs for proper operation. In such cases, drive circuitry should be configured to add the appropriate dc offset to the 1570 outputs in order to match the converter. As well, the 1570 has common-mode gain of unity, regardless THAT1570 Low-Noise Differential Audio Preamplifier +15V D5 THAT ...

Page 9

... THAT1570 Low-Noise Differential Audio Preamplifier PHANTOM POWER +48V R5 R6 6k81 6k81 IN+ 10 47u C1 22p C3 C5 220p R4 + IN- 10 47u C2 22p RFI PHANTOM POWER PROTECTION PROTECTION Figure 8. 1570 Typical Phantom Power Application Circuit With Dual-Gang Pot for Gain Control, AC-Coupled R Common-mode inputs are presented at the output, along with the common-mode dc offset of -610 mV ...

Page 10

... Figure 10 to provide uniform heat distribution between the top layer of the PCB to the bottom layer. For current feedback amplifiers such as the THAT1570, stray capacitance to ground or power planes results in higher gains at high frequencies. This compromises common-mode rejection at high frequencies and, in extreme cases, can even lead to oscillation ...

Page 11

... THAT1570 Low-Noise Differential Audio Preamplifier Package and Soldering Information Parameter Symbol Package Style Thermal Resistance Environmental Regulation Compliance Soldering Reflow Profile Moisture Sensitivity Level MSL Above-referenced JEDEC soldering profile BOTTOM VIEW Exposed Thermal Pad ...

Page 12

... Document 600132 Rev 01 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 © 2009, THAT Corporation; All rights reserved. Page Differential Audio Preamplifier IC Notes THAT1570 Low-Noise ...

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