Datasheet

AD5390/AD5391/AD5392 Data Sheet
Rev. E | Page 34 of 44
Table 27 shows the control register contents of the AD5391. Table 28 provides bit descriptions. Note that REG1 = REG0 = 0,
A3 to A0 = 1100, and DB13 to DB0 contain the control register data.
Table 27. AD5391 Control Register Contents
MSB LSB
CR11 CR10 CR9 CR8 CR7 CR6 CR5 CR4 CR3 CR2 CR1 CR0
Table 28. AD5391 Bit Descriptions
Bit Description
CR11 Power-Down Status. This bit is used to configure the output amplifier state in power-down mode.
CR11 = 1: Amplifier output is high impedance (default on power-up).
CR11 = 0: Amplifier output is 100 kΩ to ground.
CR10 REF Select. This bit selects the operating internal reference for the AD5391. CR10 is programmed as follows:
CR10 = 1: Internal reference is 2.5 V (AD5391-5 default). Recommended operating reference for AD5391-5.
CR10 = 0: Internal reference is 1.25 V (AD5391-3 default). Recommended operating reference for AD5391-3.
CR9 Current Boost Control. This bit is used to boost the current in the output amplifier, thus altering its slew rate. This bit is
configured as follows:
CR9 = 1: Boost mode on. This maximizes the bias current in the output amplifier, optimizing its slew rate but increasing
the power dissipation.
CR9 = 0: Boost mode off (default on power-up). This reduces the bias current in the output amplifier and reduces the overall
power consumption.
CR8 Internal/External Reference. This bits determines if the DAC uses its internal reference or an external reference.
CR8 = 1: Internal reference enabled. Reference output depends on data loaded to CR10.
CR8 = 0: External reference selected (default on power-up).
CR7 Channel Monitor Enable (see Table 24).
CR7 = 1: Monitor enabled. This enables the channel monitor function. Following a write to the monitor channel in
the SFR register, the selected channel output is routed to the MON_OUT pin.
CR7 = 0: Monitor disabled (default on power-up). When monitor is disabled, the MON_OUT pin is three-stated.
CR6 Thermal Monitor Function. When enabled, this function is used to monitor the internal die temperature of the AD5391,
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 the power dissipation of the device may be exceeded, if a number of
output channels are simultaneously short circuited. A soft power-up re-enables the output amplifiers if the die temperature
has dropped below 130°C.
CR6 = 1: Thermal monitor enabled.
CR6 = 0: Thermal monitor disabled (default on power-up).
CR5 to CR2 Don’t Care.
CR1 to CR0 Toggle Function Enable. This function lets the user toggle the output between two codes loaded to the A and B register for
each DAC. Control Register Bit CR1 and Bit CR0 are used to enable individual groups of eight channels for operation in
toggle mode on the AD5391, as follows:
CR1 Group 1 Channel 8 to Channel 15
CR0 Group 0 Channel 0 to Channel 7
Logic 1 written to any bit enables a group of channels and Logic 0 disables a group.
LDAC
is used to toggle between the two
registers.