AD5757 Analog Devices, AD5757 Datasheet - Page 27

• Manufacturer Part Number: AD5757
• Description: Quad Channel, 16-Bit, Serial Input, 4-20mA Output DAC, Dynamic Power Control, HART Connectivity
• Manufacturer: Analog Devices

Specifications of AD5757

• Resolution (bits): 16bit
• Dac Update Rate: 60kSPS
• Dac Settling Time: 15µs
• Max Pos Supply (v): +33V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: SPI

Data Sheet
DATA REGISTERS
The input register is 24 bits wide. When PEC is enabled, the
input register is 32 bits wide, with the last eight bits correspond-
ing to the PEC code (see the Packet Error Checking section for
more information on PEC). When writing to a data register, the
format in Table 7 must be used.
Table 7. Writing to a Data Register
MSB
D23
R/W
Table 8. Input Register Decode
Bit
R/W
DUT_AD1, DUT_AD0
DREG2, DREG1, DREG0
DAC_AD1, DAC_AD0
Table 9. Programming the DAC Data Registers
MSB
D23
R/W
D22
DUT_AD1
D22
DUT_AD1
D21
DUT_AD0
Description
Indicates a read from or a write to the addressed register.
Used in association with the external pins, AD1 and AD0, to determine which AD5757 device is being addressed
by the system controller.
DUT_AD1
0
0
1
1
Selects whether a data register or a control register is written to. If a control register is selected, a further decode
of CREG bits (see Table 16) is required to select the particular control register, as follows.
DREG2
0
0
0
1
1
1
1
These bits are used to decode the DAC channel.
DAC_AD1
0
0
1
1
X
D21
DUT_AD0
DUT_AD0
0
1
0
1
DREG1
0
1
1
0
0
1
1
DAC_AD0
0
1
0
1
X
D20
DREG2
D20
DREG2
D19
DREG1
D19
DREG1
Function
Addresses part with Pin AD1 = 0, Pin AD0 = 0
Addresses part with Pin AD1 = 0, Pin AD0 = 1
Addresses part with Pin AD1 = 1, Pin AD0 = 0
Addresses part with Pin AD1 = 1, Pin AD0 = 1
DREG0
0
0
1
0
1
0
1
DAC Channel/Register Address
DAC A
DAC B
DAC C
DAC D
These are don’t cares if they are not relevant to the operation being performed.
Rev. B | Page 27 of 44
D18
DREG0
Function
Write to DAC data register (individual channel write)
Write to gain register
Write to gain register (all DACs)
Write to offset register
Write to offset register (all DACs)
Write to clear code register
Write to a control register
D18
DREG0
DAC Data Register
When writing to the AD5757 DAC data registers, D15 to D0 are
used for the DAC data bits. Table 9 shows the register format
and Table 8 describes the function of Bit D23 to Bit D16.
D17
DAC_AD1
D17
DAC_AD1
D16
DAC_AD0
D16
DAC_AD0
LSB
D15 to D0
Data
LSB
D15 to D0
DAC data
AD5757