AD5380_15 datasheet(24/40 Pages) AD

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AD5380

Data Sheet

Table 14. Control Register Contents

MSB

LSB

CR13

CR12

CR11

CR10

CR9

CR8

CR7

CR6

CR5

CR4

CR3

CR2

CR1

CR0

Control Register Write/Read

REG1 = REG0 = 0, A5 to A0 = 001100, R/W status determines

if the operation is a write (R/W = 0) or a read (R/W = 1). DB13

to DB0 contains the control register data.

Control Register Contents

CR13: Power-Down Status. This bit is used to configure the

output amplifier state in power down.

CR13 = 1. Amplifier output is high impedance (default on

power-up).

CR13 = 0. Amplifier output is 100 kΩ to ground.

CR12: REF Select. This bit selects the operating internal

reference for the AD5380. CR12 is programmed as follows:

CR12 = 1: Internal reference is 2.5 V (AD5380-5 default),

the recommended operating reference for AD5380-5.

CR12 = 0: Internal reference is 1.25 V (AD5380-3 default),

the recommended operating reference for AD5380-3.

CR11: Current Boost Control. This bit is used to boost the

current in the output amplifier, thereby altering its slew rate.

This bit is configured as follows:

CR11 = 1: Boost Mode On. This maximizes the bias current

in the output amplifier, optimizing its slew rate but increasing

the power dissipation.

CR11 = 0: Boost Mode Off (default on power-up). This

reduces the bias current in the output amplifier and reduces

the overall power consumption.

CR10: Internal/External Reference. This bit determines if the

DAC uses its internal reference or an externally applied

reference.

CR10 = 1: Internal Reference Enabled. The reference output

depends on data loaded to CR12.

CR10 = 0: External Reference Selected (default on power-up).

CR9: Channel Monitor Enable (see Channel Monitor Function).

CR9 = 1: Monitor Enabled. This enables the channel monitor

function. After a write to the monitor channel in the SFR

MON_OUT pin. VOUT39 operates as the MON_OUT pin.

CR9 = 0: Monitor Disabled (default on power-up). When the

monitor is disabled, the MON_OUT pin assumes its normal

DAC output function.

CR8: Thermal Monitor Function. This function is used to

monitor the AD5380’s internal die temperature when enabled.

The thermal monitor powers down the output amplifiers when

the temperature exceeds 130°C. This function can be used to

protect the device in cases where power dissipation may be

exceeded if a number of output channels are simultaneously

short-circuited. A soft power-up will re-enable the output

amplifiers if the die temperature has dropped below 130°C.

CR8 = 1: Thermal Monitor Enabled.

CR8 = 0: Thermal Monitor Disabled (default on power-up).

CR7: Don’t Care.

CR6 to CR2: Toggle Function Enable. This function allows the

user to toggle the output between two codes loaded to the A

and B registers for each DAC. Control Register Bits CR6 to CR2

are used to enable individual groups of eight channels for

operation in toggle mode. A Logic 1 written to any bit enables

a group of channels; a Logic 0 disables a group. LDAC is used to

toggle between the two registers. Table 15 shows the decoding

for toggle mode operation. For example, CR6 controls Group w,

which contains Channel 32 to Channel 39, CR6 = 1 enables

these channels.

CR1 and CR0: Don’t Care.

Table 15.

CR Bit

Group

Channels

CR6

32–39

CR5

24–31

CR4

16–23

CR3

8–15

CR2

0–7

Channel Monitor Function

REG1 = REG0 = 0, A5 to A0 = 001010

DB13 to DB8 = Contain data to address the monitored channel.

A channel monitor function is provided on the AD5380. This

feature, which consists of a multiplexer addressed via the inter-

face, allows any channel output to be routed to the MON_OUT

pin for monitoring using an external ADC. In channel monitor

mode, VOUT39 becomes the MON_OUT pin, to which all

monitored pins are routed. The channel monitor function must

be enabled in the control register before any channels are routed

to MON_OUT. On the AD5380, DB13 to DB8 contain the

channel address for the monitored channel. Selecting Channel

Address 63 three-states MON_OUT.

Rev. D | Page 24 of 40

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