TLV5637

2.7 V TO 5.5 V LOW POWER DUAL 10-BIT DIGITAL-TO-ANALOG

CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN

SLAS224 –JUNE 1999

10

POST OFFICE BOX 655303

TYPICAL CHARACTERISTICS

–0.1

–0.2

0

256

512

0

0.15

Digital Code

DIFFERENTIAL NONLINEARITY ERROR

0.2

768

1024

0.1

0.05

–0.05

–0.15

Figure 12

APPLICATION INFORMATION

general function

The TLV5637 is a dual 10-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 reference) is given by:

2REF

CODE

0x1000

[V]

Where REF is the reference voltage and CODE is the digital input value in the range 0x000 to 0xFFF. Because

it is a 10-bit DAC, only D11 to D2 are used. D0 and D1 are ignored. A power on reset initially puts the internal

latches to a defined state (all bits zero).

serial interface

A falling edge of CS starts shifting the data bit-per-bit (starting with the MSB) to the internal register on the falling

edges of SCLK. After 16 bits have been transferred or CS rises, the content of the shift register is moved to the

target latches (DAC A, DAC B, BUFFER, CONTROL), depending on the control bits within the data word.

Figure 13 shows examples of how to connect the TLV5637 to TMS320, SPI

™, and Microwire™.

TMS320

DSP FSX

CLKX

DX

TLV5637

SCLK

DIN

CS

SPI

I/O

SCK

MOSI

TLV5637

SCLK

DIN

CS

Microwire

I/O

SK

SO

TLV5637

SCLK

DIN

CS

Figure 13. 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 CS. If the word width is 8 bits (SPI

™ and Microwire™), two write

operations must be performed to program the TLV5637. After the write operation(s), the holding registers or the