Rainbow-electronics MAX5191 Manual de usuario descargar pdf (Pagina 9)

MAX5188/MAX5191

Dual, 8-Bit, 40MHz, Current/Voltage,

Alternate-Phase Output DACs

_______________________________________________________________________________________ 9

External Reference

To disable the MAX5188/MAX5191’s internal reference,

connect REN to DV

. A temperature-stable external

reference may now be applied to drive the REFO pin

(Figure 3) to set the full-scale output. Choose a refer-

ence that can supply at least 150µA to drive the bias

circuit that generates the cascode current for the cur-

rent array. For improved accuracy and drift perfor-

mance, choose a fixed output voltage reference such

as the +1.2V, 25ppm/°C MAX6520 bandgap reference.

Standby Mode

To enter the lower-power standby mode, connect digi-

tal inputs PD and DACEN to DGND. In standby, both

the reference and the control amplifier are active with

the current array inactive. To exit this condition, DACEN

must be pulled high with PD held at DGND. The

MAX5188/MAX5191 typically require 50µs to wake up

and allow both the outputs and the reference to settle.

Shutdown Mode

For lowest power consumption, the MAX5188/MAX5191

provide a power-down mode in which the reference,

control amplifier, and current array are inactive and the

DAC’s supply current is reduced to 1µA. To enter this

mode, connect PD to DV

. To return to active mode,

connect PD to DGND and DACEN to DV

. About 50µs

are required for the devices to leave shutdown mode

and settle their outputs to the values prior to shutdown.

Table 1 lists the power-down mode selection.

SET

9.6k

SET

COMP

REFR

REF

REFO

MAX4040

+1.2V

BANDGAP

REFERENCE

CURRENT-

SOURCE ARRAY

*COMPENSATION CAPACITOR (C

COMP

= 100nF) **9.6kΩ REFERENCE CURRENT SET RESISTOR

INTERNAL TO MAX5191 ONLY. USE EXTERNAL

SET

FOR MAX5188.

OPTIONAL EXTERNAL BUFFER

FOR HEAVIER LOADS

REN

MAX5188

MAX5191

REF

SET

AGND

DGND

Figure 2. Setting I

with the Internal +1.2V Reference and Control Amplifier

Table 1. Power-Down Mode Selection

X = Don’t care

MAX5191

MAX5188

MAX5191

MAX5188

1 X Shutdown

AGND

0 0 Standby

AGND

(POWER-DOWN SELECT)

DACEN

(DAC ENABLE)

POWER-DOWN

MODE

OUTPUT STATE

High-Z

0 1 Wake-Up Last state prior to standby mode

High-Z

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Comentarios a estos manuales

Sin comentarios

Rainbow-electronics MAX5191 Manual de usuario Pagina 9

Comentarios a estos manuales

Relacionado con productos y manuales para Sensores Rainbow-electronics MAX5191