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MSM7543

Single Rail CODEC

Oki Electric Industry 

¡ Semiconductor

MSM7543/7544

PWI, AOUT+, AOUT–

PWI is connected to the inverting input of the receive driver. The receive driver output is

connected to the AOUT– pin. Therefour, the receive level can be adjusted with the pins VFRO,

PWI, and AOUT–. When the PWI pin is not used, connect the PWI pin to the AOUT– pin, and

leave open the pins AOUT– and AOUT+. The output of AOUT+ is inverted with respect to the

output of AOUT–. Since the signal from which provides differential drive of an impedance of 1.2

kW, these outputs can directly be connected to a receiver of handset using a piezoelectric

earphone. Refer to the application example.

VI

Receive Filter

VFRO R6

PWI

R7

–

SG +

AOUT–

VO ZL

–

SG +

AOUT+

R6 > 20 kW

ZL ≥ 1.2 kW

Gain = VO/VI = 2 ¥ R7/R6 £ 2

During power saving and power down modes, the outputs of AOUT+ and AOUT– are in a high

impedance state .

The electrical driving capability of the AOUT– pin and AOUT+ pin is ±1.3 V maximum. The

output load resistor has a minimum value of 0.6 kW.

If an output amplitude less than ±1.3 V is allowed, these outputs can drive a load resistance less

than that described above.

For more details, refer to SINGLE POWER SUPPLY PCM CODEC APPLICATION NOTE.

VDD

Power supply pin for +5 V.

PCMIN

PCM signal input.

A serial PCM signal input to this pin is converted to an analog signal in synchronization with the

RSYNC signal and BCLOCK signal.

The data rate of the PCM signal is equal to the frequency of the BCLOCK signal.

The PCM signal is shifted at a falling edge of the BCLOCK signal and latched into the internal

register when shifted by eight bits.

The start of the PCM data (MSD) is identified at the rising edge of RSYNC.

BCLOCK

Shift clock signal input for the PCMIN and PCMOUT signal.

The frequency, equal to the data rate, is 64, 96, 128, 192, 256, 384, 512, 768, 1024, 1536, 1544, 2048,

or 200 kHz. Setting this signal to logic "1" or "0" drives both transmit and receive circuits to the

power saving state.

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