TLV5604

2.7-V TO 5.5-V 10-BIT 3-

µS QUADRUPLE DIGITAL-TO-ANALOG CONVERTERS

WITH POWER DOWN

SLAS176A – DECEMBER 1997 – REVISED SEPTEMBER 1998

14

POST OFFICE BOX 655303

APPLICATION INFORMATION

In power down mode, all amplifiers within the TLV5604 are disabled. A particular DAC (A, B, C, D) of the

TLV5604 is selected by A1 and A0 within the input word.

A1

A0

DAC

0

0

A

0

1

B

1

0

C

1

1

D

TLV5604 interfaced to TMS320C203 DSP

Hardware interfacing

Figure 17 shows an example of how to connect the TLV5604 to a TMS320C203 DSP. The serial port is

configured in burst mode, with FSX generated by the TMS320C203 to provide the Frame Sync (FS) input to

the TLV5604. Data is transmitted on the DX line, with the serial clock input on the CLKX line. The

general-purpose input/output port bits IO0 and IO1 are used to generate the Chip Select ( CS) and DAC Latch

Update ( LDAC) inputs to the TLV5604. The active low Power Down ( PD) is pulled high all the time to ensure

the DACs are enabled.

DX

CLKX

FSX

I/O 0

I/O 1

TMS320C203

SDIN

SCLK

FS

CS

LDAC

REF

VDD

PD

VOUTA

VOUTB

VOUTC

VOUTD

VSS

TLV5604

REFINAB

REFINCD

Figure 17. TLV5604 Interfaced with TMS320C203

Software

The application example generates a differential in-phase (sine) signal between the VOUTA and VOUTB pins,

and it is quadrature (cosine) signal as the differential signal between VOUTC and VOUTD.

The on-chip timer is used to generate interrupts at a fixed frequency. The related interrupt service routine pulses

LDAC low to update all 4 DACs simultaneously, then fetches and writes the next sample to all 4 DACs. The

samples are stored in a look-up table, which describes two full periods of a sine wave.

The synchronous serial port of the DSP is used in burst mode. In this mode, the processor generates an FS

pulse preceding the MSB of every data word. If multiple, contiguous words are transmitted, a violation of the

tsu(C16-FS) timing requirement will occur. To avoid this, the program waits until the transmission of the previous

word has been completed.