Datasheet

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APPLICATION INFORMATION
GENERAL FUNCTION
2 REF
CODE
2
n
[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:
where REF is the reference voltage and CODE is the digital input value within the range of 0
10
to 2
n-1
, where
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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