DAC5675

SLAS352C − DECEMBER 2001 − REVISED AUGUST 2004

5

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detailed description

Figure 1 shows a simplified block diagram of the current steering DAC5675. The DAC5675 consists of a

segmented array of non-transistor current sources, capable of delivering a full-scale output current up to 20 mA.

Differential current switches direct the current of each current source to either one of the complementary output

nodes IOUT1 or IOUT2. The complementary current output thus enables differential operation, canceling out

common mode noise sources (digital feed-through, on-chip and PCB noise), dc offsets, even order distortion

components, thereby doubling signal output power.

The full-scale output current is set using an external resistor (RBIAS) in combination with an on-chip bandgap

voltage reference source (1.2 V) and control amplifier. The current (IBIAS) through resistor RBIAS is mirrored

internally to provide a full-scale output current equal to 16 times IBIAS. The full-scale current is adjustable from

20 mA down to 2 mA by using the appropriate bias resistor value.

EXTIO

Current

Source

Array

BIASJ

−

+

Control Amp

SLEEP

Output

Current

Switches

DAC

Latch

+

Drivers

LVDS

Input

Interface

Input

Latches

D[13:0]B

14

14

Decoder

Bandgap

Reference

1.2 V

CLK

CLKC

+

−

IBIAS

IOUT1

IOUT2

AVDD(4x)

AGND(4x)

DLL

DLLOFF

DAC5675

D[13:0]A

DVDD(2x)

DGND(2x)

50

Ω

100

Ω

3.3 V

(AVDD)

50

Ω

3.3 V

(AVDD)

RLOAD

50

Ω

Output

1:1

3.3 V

(AVDD)

RT

200

Ω

1:4

Clock

Input

RBIAS

1 k

Ω

1 k

Ω

0.1

µF

CEXT

0.1

µF

3.3 V

3.3 V

Figure 1. Application Schematic