that1512 THAT Corporation, that1512 Datasheet - Page 4

• Manufacturer Part Number: that1512
• Description: Low Noise, High Performance Audio Preamplifier Ic
• Manufacturer: THAT Corporation

Page 4
Gain Setting
and RG2 pins is all that is needed to set the gain of
the THAT 1510/1512, according to the formulae:
R
For the 1510, gain is 0dB when R
This is the minimum gain for the 1510. At infinite
R
mum gain for the 1512. With R
reaches 0dB gain.
R
connected to pins R
(R
typical initial accuracy (at room temperature) of
±0.5%, and are typically stable with temperature to
within ±200 ppm/°C. Gain will drift with tempera-
ture based on the mismatch between the temperature
coefficient of the external R
resistors R
racy is important, THAT recommends using discrete,
switched resistors for R
G
G
G
A
, the 1512 reaches -6dB gain; This is the mini-
required varies drastically between the two parts.
and the accuracy of the internal thin-film resistors
A single external resistor (R
for the 1510:
for the 1512:
A
Either part may reach unity gain, but the value of
Overall gain accuracy depends on the tolerance of
For variable-gain applications where gain accu-
& R
V
is the voltage gain of the part.
B
in Figure 1). These internal resistors have a
A
& R
B
.
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
A
A
-In
+In
V
V
G1
= +
=
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
G
1
and R
0 5
. Where continuous control
.
G
10 W
+
R
and that of the internal
k
G
5
R
G2
k
C2
470p
G
C1
470p
47p
G
W
C3
) between the RG1
G
G
in the 1510/1512
=10kW, the 1512
where
or
is infinite (open);
Copyright © 2007, THAT Corporation
Figure 2. Basic 1510 / 1512 Circuit
1k
R1
Applications
1k
R2
RG
is required, or where gain accuracy is less critical, a
potentiometer may be used. In such applications, de-
signers should take care in specifying the element
construction to avoid excess noise. The potentiome-
ter taper will set the circuit’s characteristic of gain vs.
pot rotation. Typically, reverse log (audio) taper ele-
ments offer the desired behavior in which gain in-
creases with clockwise rotation (and lower values for
R
potentiometer taper and gain for the 1510 and 1512
compared to similar parts from other manufacturers.
Noise Performance
mance of ~1 nV/ÖHz at high gains. With ~2 pA/ÖHz
current noise, they are optimized for relatively low
source impedance applications, such as dynamic mi-
crophones with typically a few hundred ohm output
impedances. But, because they have different inter-
nal gain structures, the 1510 has higher equivalent
input noise at 0dB gain (~57 nV/ÖHz) than the 1512,
which runs 4.5 dB lower at ~34 nV/ÖHz. The un-
usual and superior topology of the THAT 1512
makes it’s noise performance comparable to some of
the better discrete designs currently available.
Inputs
Simple Configurations
protection diodes at all pins except V+ and V-. These
diodes reduce the likelihood that accidental electro-
-In
+In
RG1
RG2
G
). See THAT Design Note 138 for a discussion of
Both parts exhibit excellent voltage noise perfor-
As shown in Figure 1, the 1510/1512 includes
+15
-15
V+
V-
100n
100n
Ref
C6
C9
THAT 1510 / 1512 Audio Preamplifier IC
Out
THAT
1510/1512
U1
Out