MISCELLANEOUS

I2S BUS SELECT

S23, S24, S26, S27 – I2S Bus select. Toggles between on-board and external I2S (whether on-board SPDIF receiver is used).

All jumpers must be set the same. Jumpers on top two pins selects external bus (JP19). Jumpers on bottom two pins selects

on-board SPDIF receiver output.

HEADPHONE OUTPUT CONFIGURATION

Jumpers S1, S2, S3, and S4 are used to configure the headphone outputs for either cap-coupled outputs or output capacitorless

(OCL) mode in addition to the register control internal to the LM4934 for this feature. Jumpers S1 and S3 bypass the output DC

blocking capacitors when OCL mode is required. S2 connects the center amplifer HPCOUT to the headphone ring when in OCL

mode. S4 connects the center ring to GND when cap-coupled mode is desired. S4 must be removed for OCL mode to function

properly. Jumper settings for each mode:

OCL

S1=ON

S2=ON

S3=ON

S4 = OFF

Cap-Coupled

S1 = OFF

S2 = OFF

S3 = OFF

S4=ON

PLL FILTER CONFIGURATION

The LM4934 demo board comes with a simple filter setup by connecting jumpers S5 and S6. Removing these and connecting

jumpers S7 and S8 will allow for an alternate PLL filter configuration to be used at R2 and C23.

ON-BOARD SPDIF RECEIVER

The SPDIF receiver present on the LM4934 demo board allows quick demonstration of the capabilities of the LM4934 by using

the common SPDIF output found on most CD/DVD players today. There are some limitations in its useage, as the receiver will

not work with digital supplies of less than 3V and analog supplies of less than 4V. This means low analog supply voltage testing

of the LM4934 must be done on the external digital bus.

The choice of using on-board or external digital bus is made usign jumpers S23, S24, S26, and S27 as described above.

S25 selects whether the Toslink or Coaxial SPDIF input is used. The top two pins connects the toslink, the bottom two connect

the coaxial input.

Power on the digital side is routed through S20 (connecting to the other digital supplies), while on the analog side it is interrupted

by S21. Both jumpers must be in place for the receiver to function. The part is already configured for I2S standard outputs. Jumper

S28 allows the DATA output to be pulled either high or low. Default is high (jumper on right two pins).

It may be necessary to quickly toggle S29 to reset the receiver and start it working upon initial power up.. A quick short across

S29 should clear this condition.

LM4934 I

Convenient graphical user interface software is available for demonstration purposes of the LM4934. It allows for either SPI or I

control via either USB or parallel port connections to a Windows computer. Control options include all mode and output settings,

volume controls, PLL and DAC setup, FIR setting and on-the-fly adjustment by an easy to use graphical interface. An advanced

option is also present to allow direct, register-level commands. Software is available from www.national.com and is compatible

with Windows operating systems of Windows 98 or more (with USB support) with the latest .NET updates from Microsoft.

www.national.com

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