TLV5614

2.7-V TO 5.5-V 12-BIT 3-

µS QUADRUPLE DIGITAL-TO-ANALOG CONVERTERS

WITH POWER DOWN

SLAS188 – SEPTEMBER 1998

13

POST OFFICE BOX 655303

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 sixteenth positive 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

t

t

wL(min)

+ 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:

(D15 . . . D12)

(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