CXA1550 Sony Corporation, CXA1550 Datasheet - Page 9

• Manufacturer Part Number: CXA1550
• Description: Dolby B type Noise Reduction System
• Manufacturer: Sony Corporation

Notes on Applications
1) Power supply
2) Double speed ( 2)
3) Operational mode control
4) Reference levels
The CXA1550 series is designed to operate on either single or split power supply. The ripple rejection
performance is excellent for either supply. VCT (Pin 4) is a reference voltage of the V
With single power supply operation, internally generated V
capacitor has to be connected between the pin and ground. On split power supply operation, the VCT (Pin
4) pin has to be connected to ground, and V
The CXA1550 series provides double speed encode/decode modes, which offer high speed dubbing
function. On double speed mode, the frequency response shifts twice as the normal B type.
The CXA1550 series provides fully electronic switching circuits. The functions are controlled by DC voltage
of the two control pins of REC/PB (Pin 12) and ON/OFF/ 2 (Pin 5). The switching truth tables are shown in
Table 1.
It is desirable to provide CR time constant circuits at the mode control pins with time constant from 100
msec to 1 sec, which will reduce switching clicks effectively.
Characteristics and specifications of the Dolby noise reduction processor are defined as the levels and
measured with reference to the Dolby level. This particular level in these devices is –10 dBm (245 mVrms),
and is measured at the recording output (REC OUT) in the NR off mode.
The reference levels of the recording input (REC IN), playback input (PB IN) and line output (LINE OUT)
are defined as the levels which provide the Dolby level at the recording output in the NR off mode.
The CXA1550 series has a common silicon die, and has different internal connection (AL pattern). The
series provides four different line output levels for various applications. Other reference levels, recording
input level, playback input level and recording output level (=Dolby level) are identical in all devices.
The reference levels are as follows
Recording output level (=Dolby level)
Recording input level
Playback input level
Line output level
Pin 12
Pin 5
Pin
PB (Decode)
REC (Encode)
NR
NR OFF
NR ON
Function
2
CXA1550
CXA1551
CXA1552
CXA1553
V
CC
0.5 V ≥ V ≥ 0 V
0.5 V ≥ V ≥ 0 V
–2.5 ≥ V ≥ 2.5 V
V
V
Single Supply
EE
CC
CC
–10 dBm (245 mVrms)
–30 dBm (24.5 mVrms)
–30 dBm (24.5 mVrms)
–10 dBm (245 mVrms)
(negative power supply) is supplied to the GND (Pin 15) pin.
–3 dBm (548 mVrms)
–6 dBm (388 mVrms)
≥ V ≥ 2.5 V
≥ V ≥ V
Table 1.
0 dBm (775 mVrms)
—9—
CC
–0.5 V
CC
/2 voltage appears at the pin, and a bypass
CXA1550P, CXA1551M/P, CXA1552M/P, CXA1553M/P
V
V
V
CC
EE
EE
+0.5 V ≥ V ≥ V
–2.5 V ≥ V ≥ V
+0.5 V ≥ V ≥ V
V
V
CC
CC
Split Supply
≥ V ≥ V
≥ V ≥ V
CC
EE
EE
CC
EE
EE
/2 buffer amplifier.
+2.5 V
+2.5 V
–0.5 V