LTC1590 查看數據表（PDF） - Linear Technology

零件编号

产品描述 (功能)

生产厂家

LTC1590

Dual Serial 12-Bit Multiplying DAC

Linear Technology 

TIMING DIAGRAMS

TIMING DIAGRAM

t8

t7

CLK

1

t1 t2

2

3

t4

t3

DIN

D11 A

MSB

D10 A

D9 A

23

D1 B

t6

24

D0 B

LSB

LTC1590

CS/LD

DOUT

t9

D11 A

PREVIOUS WORD

D10 A

D9 A

PREVIOUS WORD PREVIOUS WORD

t5

D0 B

PREVIOUS WORD

D11 A

CURRENT WORD

1590 TD02

APPLICATIONS INFORMATION

Description

The LTC1590 is a dual 12-bit multiplying DAC that has

serial inputs and current outputs. It uses precision R/2R

resistor ladder technology to provide exceptional linearity

and stability. The device operates from a single 5V supply

and provides a ±10V reference input and voltage output

range when used with an external op amp.

Serial I/O

The LTC1590 has a 3-wire SPI/MICROWIRETM compatible

serial port that accepts 24-bit serial words. Data is loaded

MSB first with the first 12 bits controlling DAC A and the

second 12 bits controlling DAC B. Data is shifted into the

DIN input on the rising edge of CLK. The CS/LD input must

be taken low before transferring data to enable the CLK

input. After transferring data, CS/LD is pulled high to load

data from the shift register to the DAC registers which

updates both DACs.

The buffered output of the 24-bit shift register is available

on the DOUT pin. Multiple DACs can be daisy-chained on

one 3-wire interface by connecting the DOUT pin to the DIN

pin of the next DAC (see the Timing Diagrams section).

MICROWIRE is a trademark of National Semiconductor Corporation.

Equivalent Circuit

Figure 1 shows an equivalent analog circuit for the LTC1590

DACs. R is the reference input, RREF, which is nominally

11k. The DAC output is represented by the Thevinin

equivalent current source with a value of:

(Code/4096)(VREF/R)

The current source ILKG models the junction leakage of the

DAC output switches. ILKG is typically less than 5nA at

85°C and decreases by roughly two times for every 10°C

reduction in temperature. COUT is the output capacitance,

and it also comes from the DAC output switches and varies

from 30pF at zero scale to 60pF at full scale. RO is the

equivalent output resistance, which varies with digital

input code (see Op Amp Selection section).

VREF A

VREF B

R

R

( )( ) CODE VREF

4096 R

ILKG

RO

RFB A

RFB B

OUT1 A

OUT1 B

COUT

OUT2 A

OUT2 B

Figure 1. Equivalent Circuit

AGND

1590 F01

7

Share Link: