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CXA1563M/S

Application Note

The CXA1563M/S is a dual channel Dolby B-C type NR IC with a built-in S type (CXA1417S/Q) switch. By

using the CXA1563M/S in conjunction with two sets of the CXA1417S/Q encoder unit, a stereo Dolby B-C-S

type NR system can be achieved.

1) Power Supply

The CXA1563M/S is designed to operate on either single or dual power supply.

VCT (Pin 28). Connect a by-pass capacitor between this pin and GND.

The operating voltage range is ±3.5 to ±8.0V (7.0 to 16V), which satisfies the signal handling of 12dB

specified by the Dolby Laboratories.

2) Supply Voltage of the CXA1417S/Q and the CXA1563M/S

(1) When both have split power supply

Set within the respective specified ranges.

CXA1417S/Q: ±AV

CXA1563M/S: ±BV

(2) When both have single power supply

Set at the same potential with the range specified for the CXA1417S/Q (9 to 13V).

CXA1417S/Q: AV

CXA1563M/S: BV

(3) Single and dual power supplies can not be used together.

3) Operation Mode Control

The CXA1563M/S has built-in electronic switches. The operations are controlled by the DC voltages of SSW

(Pin 12), NRSW (Pin 13) and MODE (Pin 16) control pins. Table 1 shows the switching truth tables.

For single power supply, VH, VM, and VL correspond to Vcc, Vcc/2 and GND, respectively.

Refer to "threshold" on the characteristics graph for the thresholds of the control voltages. NRSW (Pin 13)

and MODE (Pin 16) control pins are connected to VCT via a 50k

Ω resistor, so when the pin is open, VM

condition results. SSW (Pin 12) control pin is of PNP base input, so the pin can be used as VH when it is

open.

SSW is taken precedence over NRSW, and NRSW is invalid when SSW is at Low.

Table 1

VH

VM

VL

SSW

NRSW

MODE

B-C type

C type

MPX ON

REC

(Encode)

—

B type

MPX OFF

REC

(Encode)

S type

NR OFF

PB

(Decode)