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APPLICATION INFORMATION

GENERAL FUNCTION

2 REF

CODE

[V]

SERIAL INTERFACE

TMS320

DSP

XF0

CLKX

DX

FSX

XF1

TLV5636

CS

FS

DIN SCLK

TLV5636

CS

FS

DIN

SCLK

TLV5636

SLAS223C – JUNE 1999 – REVISED APRIL 2004

The TLV5636 is a 12-bit, single supply DAC, based on a resistor string architecture. It consists of a serial

interface, a speed and power-down control logic, a programmable internal reference, a resistor string, and a

rail-to-rail output buffer.

The output voltage (full scale determined by external reference) for each channel is given by:

n = 12 (bits). The 16-bit data word, consisting of control bits and the new DAC value, is illustrated in the data

format section. A power-on reset initially resets the internal latches to a defined state (all bits zero).

The device has to be enabled with CS set to low. A falling edge of FS starts shifting the data bit-per-bit (starting

with the MSB) to the internal register on high-low transitions of SCLK. After 16 bits have been transferred or FS

rises, the content of the shift register is moved to the DAC latch, which updates the voltage output to the new

level.

The serial interface of the TLV5636 can be used in two basic modes:

•

Four wire (with chip select)

•

Three wire (without chip select)

Using chip select (four-wire mode), it is possible to have more than one device connected to the serial port of the

data source (DSP or microcontroller). Figure 13 shows an example with two TLV5636s connected directly to a

TMS320 DSP.

Figure 13. TMS320 Interface

If there is no need to have more than one device on the serial bus, then CS can be tied low. Figure 14 shows an

example of how to connect the TLV5636 to TMS320, SPI™ or Microwire™ using only three pins.

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