REV. M

Page 4

September 1998

AS3502

Pin Description (continued)

Pin #

Name

Type

Function

19

SCLK

DI

Serial PCM Shift Clock Input

This pin acts as shift clock input signal for the externally provided signal for serial

PCM data transfer. The frequency may vary from 128 kHz to 4.096 MHz in 8 kHz

increments and should be synchronized to MCLK. In the receive direction the

bitstream is latched with the falling edge of this clock. In the transmit direction the

bitstream is shifted out with the rising edges of this clock.

20

MCLK

DI

Master Clock Input

This signal is the timing reference for all internal operations. The clock frequency

must be a integer multiple of 2.048 MHz with a maximum of 18.432MHz and must

be synchronized to SCLK. The required master clock dividing ratio is selected by

setting the DIV3 -DIV0 bits in the Digital Control Register.

21

GND

SI

Digital Negative Supply Voltage Input

22

23

TR+

TR-

DO

DO

Differential Toneringer Outputs

These digital outputs provide square or sine wave signal for driving transducers

directly. TRO+ and TRO- are operating in push/pull mode providing peak to peak

voltage swing of 2 x VDD.The output volume is programmable and is

accomplished either through pulse density modulation or through pulse width

modulation.

24

25

EP-

EP+

AO

AO

Differential Earpiece Outputs

These two pins are the outputs of the differential earpiece amplifier driving either

dynamic earpieces with 150

Ω impedance or ceramic transducers with up to 50nF

directly. The signal reference on both pins is DC referenced to the internally gen-

erated Analogue Ground which is appr. 1/2 VDD.

26

AVSS

SI

Analogue Negative Supply Voltage Input

27

28

SP+

SP-

AO

AO

Differential Loudspeaker Outputs

These two pins are the outputs of the differential loudspeaker amplifier that is ca-

pable driving dynamic speakers with 50

Ω impedance directly. The maximum

output power is 50mW. The signal reference on both pins is DC referenced to the

internally generated Analogue Ground which is appr. 1/2 VDD.

AI:

Analogue Input

AO:

Analogue Output

DI:

Digital Input

DO: Digital Output

DI/O: Digital Input/Output

SI:

Supply Input