THAT4305 Datasheet, PDF (17/20 Pages) List of Unclassifed Manufacturers – Pre-trimmed Analog Engine® IC

Document 600067 Rev 00
i _R3
=
RMSOut
R₃
, and
i _R12
=
RMSOut
R₁₂
We'll choose a point about 4dB above the mini-
mum input level which is -56dBV.
Page 17
V_In
=
10⁽
−52dBV
20
)
=
3.16mV_RMS
.
Therefore,
0.00316mV
8.87 kΩ
=
( −23.6 −( −52)) ⋅0.0062
R₃
,
And
R3
=
( −23.6 −( −52)) ⋅0.0062
0. 00316 mV
=
459kΩ
≈
464 kΩ
8. 87 kΩ
The same is true for R12.
Encode In
Signal Path
Pre-emphasis
C7
R3
U2
3n3 ^2k32
C1
R1
Op-Amp
1u
21k0
U1A
11 ^THAT4305
EC+
15 _{VCA In VCA Out} ¹³
EC-
12
C5
22p
R2
84k5
U3
Op-Amp
R6
R5
C8
Encode Out
Vcc
C4
22u
464k
4k02
RMS
3n3
RMS Out
5
RMS In 2
Pre-emphasis
C2
R4
U1B
CT
THAT4305
4
8k87
1u
C3
10u
Figure 20. 4305 hi-fi 2:1 encoder circuit
Decode In
U4
Op-Amp
RMS Pre-emphasis
C18 _R11
3n3 ^4k02
C12
R10
1u
8k87
V+
C14 _C13
22u _10u
C11
R8
1u
84k5
R13
5k1
C21
220p
R12
464k
U3B
THAT4305
2
RMS In
RMS Out
5
CT
4
U3A
THAT4305
11
EC+
15
13
VCA In VCA Out
EC-
12
Signal Path
De-emphasis
R9 ^C17
2k32 _3n3
R7
21k0 C15
U5 22p
Decode Out
Op-Amp
Figure 21. 4305 hi-fi 2:1 decoder circuit
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com