Datasheet

TLV5614
2.7-V TO 5.5-V 12-BIT 3-µS QUADRUPLE DIGITAL-TO-ANALOG CONVERTERS
WITH POWER DOWN
SLAS188B – SEPTEMBER 1998 – REVISED APRIL 2003
13
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
serial interface (continued)
If there is no need to have more than one device on the serial bus, then CS can be tied low. Figure 16 shows
an example of how to connect the TLV5614 to a TMS320, SPI, or Microwire port using only three pins.
TMS320
DSP
FSX
DX
CLKX
TLV5614
FS
DIN
SCLK
CS
SPI
SS
MOSI
SCLK
TLV5614
FS
DIN
SCLK
CS
Microwire
I/O
SO
SK
TLV5614
FS
DIN
SCLK
CS
Figure 16. Three-Wire Interface
Notes on SPI and Microwire: Before the controller starts the data transfer, the software has to generate a falling
edge on the I/O pin connected to FS. If the word width is 8 bits (SPI and Microwire), two write operations must
be performed to program the TLV5614. After the write operation(s), the DAC output is updated automatically
on the next positive clock edge following the sixteenth falling clock edge.
serial clock frequency and update rate
The maximum serial clock frequency is given by:
f
SCLKmax
+
1
t
wH(min)
) t
wL(min)
+ 20 MHz
The maximum update rate is:
f
UPDATEmax
+
1
16
ǒ
t
wH(min)
) t
wL(min)
Ǔ
+ 1.25 MHz
Note that the maximum update rate is a theoretical value for the serial interface since the settling time of the
TLV5614 has to be considered also.
data format
The 16-bit data word for the TLV5614 consists of two parts:
D Control bits (D15 . . . D12)
D New DAC value (D11 ...D0)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
A1 A0 PWR SPD New DAC value (12 bits)
X: don’t care
SPD: Speed control bit. 1 → fast mode 0 → slow mode
PWR: Power control bit. 1 → power down 0 → normal operation