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Fully Accurate 16-Bit UnBuffered VOUT DAC SPI Interface 2.7 V to 5.5 V in a TSSOP
Preliminary Technical Data
FEATURES
Low power Quad 16 bit DAC, 1LSB INL Individual reference pins 2.7 V to 5.5 V power supply Unbuffered voltage output capable of driving 60K Fast Settling time of 4 us typically Power-on reset to zero scale or mid-scale Per channel power-down 3 power-down functions Low glitch on power up Hardware LDAC with LDAC override function CLR Function to programmable code Small 16 lead TSSOP
AD5066
FUNCTIONAL BLOCK DIAGRAMS
Figure 1.AD5066
APPLICATIONS
Process control Data acquisition systems Portable battery-powered instruments Digital gain and offset adjustment Programmable voltage and current sources Programmable attenuators
Table 1. Related Devices
Part No. AD5666 AD5065/45/25 AD5064/44/24 AD5063/62 AD5061 AD5060/40 Description Quad,16-bit buffered D/A,16 LSB INL, TSSOP Quad,16-bit buffered D/A,1 LSB INL, TSSOP Quad 16-bit nanoDAC, 1 LSB INL, TSSOP 16-bit nanoDAC, 1 LSB INL, MSOP 16-/14bit nanoDAC, 4 LSB INL, SOT-23 16-/14bit nanoDAC, 1 LSB INL, SOT-23
GENERAL DESCRIPTION
The AD5066 is a low power, 16-bit quad-channel, unbuffered voltage-out DAC offering relative accuracy specs of 1LSB INL with individual reference pin and can operate from a single 2.7V to 5.5V. The AD5066 parts also offer a differential accuracy specification of 1 LSB. Reference buffers are also provided on-chip. The parts use a versatile 3-wire, low power Schmitt trigger serial interface that operates at clock rates up to 50 MHz and is compatible with standard SPI(R), QSPITM, MICROWIRETM, and DSP interface standards. The AD5066 incorporates a power-on reset circuit that ensures the DAC output powers up zero scale or midscale and remains there until a valid write takes place to the device. The AD5066 contain a power-down feature that reduces the current consumption of the device to typically 330 nA at 5 V and provides software selectable output loads while in power-down mode. The part can be placed into power-down mode over the serial interface. Total unadjusted error for the part is <0.8 mV. Both parts exhibit very low glitch on power-up.
Rev. PrB
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
The outputs of all DACs can be updated simultaneously using the LDAC function, with the added functionality of user-selectable DAC channels to simultaneously update. There is also an asynchronous CLR that clears all DACs to a software-selectable code - 0 V, midscale, or full scale.
PRODUCT HIGHLIGHTS
1. 2. 3. 4. 5. 6. 7. Quad channel available in 16-lead TSSOP package. Individual voltage reference pins 16 bit accurate, 1 LSB INL. Low glitch on power-up. High speed serial interface with clock speeds up to 50 MHz. Three power-down modes available to the user. Reset to known output voltage (zero scale).
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c) 2007 Analog Devices, Inc. All rights reserved.
AD5066 TABLE OF CONTENTS
Preliminary Technical Data
REVISION HISTORY
Rev. PrB | Page 2 of 20
Preliminary Technical Data SPECIFICATIONS
AD5066
VDD = 2.7 V to 5.5 V, RL = 2 k to GND, CL = 200 pF to GND, 2.2V VREFIN . VDD unless otherwise specified. All specifications TMIN to TMAX, unless otherwise noted. Table 2.
A Grade 1 2 Parameter STATIC PERFORMANCE 3 Resolution Relative Accuracy Differential Nonlinearity Total Unadjusted Error (TUE) Offset Error Offset Error Temperature Coefficient Full-Scale Error Min 16 0.5 0.5 0.5 0.5 500 500 0.05 0.5 500 500 0.01 -80 0.5 4 4 1 1 800 800 0.1 Typ Max Min 16 0.5 0.5 0.5 0.5 500 500 0.05 0.5 500 500 0.01 -80 0.5 1 1.5 1 1 800 800 0.1 B Grade1 Typ Max Unit Bits LSB LSB V V mV V/C V V % FSR ppm dB LSB Conditions/Comments AD5066 AD5066 AD5066 AD5066 AD5066 AD5066
TA = -40C to +105C TA = -40C to +125C TA = -40C to +105C TA = -40C to +125C TA = -40C to +105C
AD5066 TA = -40C to +125C All 0s loaded to DAC register
800 800 0.02 1
800 800 0.02 1
TA = -40C to +105C All 1s loaded to DAC register TA = -40C to +125C Ppm Of FSR/C VDD 10% Due to single-channel full-scale output change, RL = 2 k to GND or VDD Due to load current change Due to powering down (per channel)
Gain Error Gain Temperature Coefficient DC Power Supply Rejection Ratio DC Crosstalk (External Reference)
0.5 0.5 OUTPUT CHARACTERISTICS 4 Output Voltage Range DC Output Impedance (Normal mode) DC Output Impedance (output connected to 100k network) (output connected to 1k network) Power-Up Time DC PSRR Wideband SFDR REFERENCE INPUTS Reference Input Range Reference Current Reference Input Impedance LOGIC INPUTS4 Input Current 5 Input Low Voltage, VINL Input High Voltage, VINH 0 8 VDD 0
0.5 0.5 VDD 8
LSB/m A LSB V k
Output impedance tolerance 10% DAC in Power Down mode Output impedance tolerance 20k Output impedance tolerance 400 All DACs coming out of power-down mode VDD = 5 V VDD10%, DAC = full scale Output frequency = 10Khz
100 1 4.5 -92 -67 2 40 120 VDD 50 2 40 120 4.5 -92 -67 VDD 50
k k s dB dB V A K
Per DAC channel Per DAC channel
3 0.8 2 2
3 0.8
A V V
All digital inputs VDD = 5 V VDD = 5 V
Rev. PrB | Page 3 of 20
AD5066
A Grade 1 2 Parameter Pin Capacitance POWER REQUIREMENTS VDD IDD (Normal Mode) 6 VDD = 4.5 V to 5.5 V IDD (All Power-Down Modes) 7 VDD = 4.5 V to 5.5 V
1 2 3
Preliminary Technical Data
B Grade1 Max Min Typ 4 Max Unit pF V Conditions/Comments Min Typ 4
2.7
5.5
2.7
5.5
All digital inputs at 0 or VDD DAC active, excludes load current VIH = VDD and VIL = GND
3 0.4
4 1
3 0.4
4 1
mA A VIH = VDD and VIL = GND
Temperature range is -40C to +105C, typical at 25C. A grade offered in AD5064 only Linearity calculated using a reduced code range of 512 to 65,024. Output unloaded. 4 Guaranteed by design and characterization; not production tested. 5 Total current flowing into all pins. 6 . Interface inactive. All DACs active. DAC outputs unloaded 7 . All four DACs powered down
Rev. PrB | Page 4 of 20
Preliminary Technical Data
AC CHARACTERISTICS
AD5066
VDD = 2.7 V to 5.5 V, RL = 2 k to GND, CL = 200 pF to GND, VREFIN = 4.096 unless otherwise specified. All specifications TMIN to TMAX, unless otherwise noted. Table 3.
Parameter 1, 2 Output Voltage Settling Time Output Voltage Settling Time Slew Rate Digital-to-Analog Glitch Impulse Reference Feedthrough Digital Feedthrough Digital Crosstalk Analog Crosstalk DAC-to-DAC Crosstalk AC Crosstalk AC PSRR Multiplying Bandwidth Total Harmonic Distortion Output Noise Spectral Density Output Noise
1 2
Min
Typ 5 14 1.5 4 -90 0.1 0.5 6 6.5 6 TBD 340 -80 64 60 6
Max
Unit s s V/s nV-s dB nV-s nV-s nV-s nV-s nV-s kHz dB nV/Hz nV/Hz V p-p
Conditions/Comments 3 1/4 to 3/4 scale settling to 1 LSB,RL = 5k single channel update including DAC calibration sequence 1/4 to 3/4 scale settling to 1 LSB,RL = 5k all channel update including DAC calibration sequence 1 LSB change around major carry VREF = 2 V 0.1 V p-p, frequency = 10 Hz to 20 MHz
VREF = 2 V 0.2 V p-p VREF = 2 V 0.1 V p-p, frequency = 10 kHz DAC code = 0x8400, 1 kHz DAC code = 0x8400, 10 kHz 0.1 Hz to 10 Hz
Guaranteed by design and characterization; not production tested. See the Terminology section. 3 Temperature range is -40C to + 105C, typical at 25C.
Rev. PrB | Page 5 of 20
AD5066
TIMING CHARACTERISTICS
Preliminary Technical Data
All input signals are specified with tr = tf = 1 ns/V (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. See Figure 3 and Figure 4. VDD = 2.7 V to 5.5 V. All specifications TMIN to TMAX, unless otherwise noted. Table 4.
Parameter t1 1 t2 t3 t4 t5 t6 t7 t8 t8 t9 t10 t11 t12 t13 t14 t15
1
Limit at TMIN, TMAX VDD = 2.7 V to 5.5 V 20 10 10 16.5 5 5 0 1.9 10.5 16.5 0 20 20 10 10 10.6
Unit ns min ns min ns min ns min ns min ns min ns min us min us min ns min ns min ns min ns min ns min ns min us min
Conditions/Comments SCLK cycle time SCLK high time SCLK low time SYNC to SCLK falling edge set-up time Data set-up time Data hold time SCLK falling edge to SYNC rising edge Minimum SYNC high time (single channel update) Minimum SYNC high time ( all channel update) SYNC rising edge to SCLK fall ignore SCLK falling edge to SYNC fall ignore LDAC pulse width low SCLK falling edge to LDAC rising edge CLR pulse width low SCLK falling edge to LDAC falling edge CLR pulse activation time
Maximum SCLK frequency is 50 MHz at VDD = 2.7 V to 5.5 V. Guaranteed by design and characterization; not production tested.
2mA
IOL
TO OUTPUT PIN
CL 50pF 2mA IOH
VOH (MIN)
Figure 2. Load Circuit for Digital Output (SDO) Timing Specifications
Rev. PrB | Page 6 of 20
05298-002
Preliminary Technical Data
t10
SCLK
AD5066
t1 t9
t8
SYNC
t4
t3
t2
t7
t5
DIN DB23
t6
DB0
t14
LDAC1
t11
t12
LDAC2 CLR
t13 t15
05858-002
VOUT
1ASYNCHRONOUS LDAC UPDATE MODE. 2SYNCHRONOUS LDAC UPDATE MODE.
Figure 3. Serial Write Operation
Rev. PrB | Page 7 of 20
AD5066 ABSOLUTE MAXIMUM RATINGS
TA = 25C, unless otherwise noted. Table 5.
Parameter VDD to GND Digital Input Voltage to GND VOUT to GND VREF to GND Operating Temperature Range Industrial Storage Temperature Range Junction Temperature (TJ MAX) TSSOP Package Power Dissipation JA Thermal Impedance Reflow Soldering Peak Temperature SnPb Pb Free Rating -0.3 V to +7 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -40C to +125C -65C to +150C +150C (TJ MAX - TA)/JA 150.4C/W 240C 260C
Preliminary Technical Data
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. PrB | Page 8 of 20
Preliminary Technical Data PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
AD5066
Figure 4. 16-Lead TSSOP (RU-16)
Table 6. Pin Function Descriptions
Pin No. 1 2 Mnemonic LDAC SYNC Description Pulsing this pin low allows any or all DAC registers to be updated if the input registers have new data. This allows all DAC outputs to simultaneously update. Alternatively, this pin can be tied permanently low. Active Low Control Input. This is the frame synchronization signal for the input data. When SYNC goes low, it powers on the SCLK and DIN buffers and enables the input shift register. Data is transferred in on the falling edges of the next 32 clocks. If SYNC is taken high before the 32nd falling edge, the rising edge of SYNC acts as an interrupt and the write sequence is ignored by the device. Power Supply Input. These parts can be operated from 2.7 V to 5.5 V, and the supply should be decoupled with a 10 F capacitor in parallel with a 0.1 F capacitor to GND. Dac B reference input .This is the reference voltage input pin for Dac B. Dac A reference input .This is the reference voltage input pin for Dac A. Unbuffered analog output voltage from DAC A. Unbuffered analog output voltage from DAC C. Power-on Reset Pin. Tying this pin to GND powers up the part to 0 V. Tying this pin to VDD powers up the part to midscale. Dac B reference input .This is the reference voltage input pin for Dac C. Asynchronous Clear Input. The CLR input is falling edge sensitive. When CLR is low, all LDAC pulses are ignored. When CLR is activated, the input register and the DAC register are updated with the data contained in the CLR code register--zero, midscale, or full scale. Default setting clears the output to 0 V. Dac A reference input .This is the reference voltage input pin for Dac D. Unbuffered analog output voltage from DAC D. Unbuffered analog output voltage from DAC B. Ground Reference Point for All Circuitry on the Part. Serial Data Input. This device has a 32-bit shift register. Data is clocked into the register on the falling edge of the serial clock input. Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock input. Data can be transferred at rates of up to 50 MHz.
3 4 5 6 7 8 9 10
VDD VREFB VREFA VOUTA VOUTC POR VREFC CLR
11 12 13 14 15 16
VREFD VOUTD VOUTB GND DIN SCLK
Rev. PrB | Page 9 of 20
AD5066 TERMINOLOGY
Relative Accuracy For the DAC, relative accuracy, or integral nonlinearity (INL), is a measure of the maximum deviation in LSBs from a straight line passing through the endpoints of the DAC transfer function. Error! Reference source not found. shows a plot of typical INL vs. code. Differential Nonlinearity Differential nonlinearity (DNL) is the difference between the measured change and the ideal 1 LSB change between any two adjacent codes. A specified differential nonlinearity of 1 LSB maximum ensures monotonicity. This DAC is guaranteed monotonic by design. Error! Reference source not found. shows a plot of typical DNL vs. code. Offset Error Offset error is a measure of the difference between the actual VOUT and the ideal VOUT, expressed in millivolts in the linear region of the transfer function. Offset error is measured on the AD5066 with Code xxx loaded into the DAC register. It can be negative or positive and is expressed in millivolts. Zero-Code Error Zero-code error is a measure of the output error when zero code (0x0000) is loaded into the DAC register. Ideally, the output should be 0 V. The zero-code error is always positive in the AD5066, because the output of the DAC cannot go below 0 V. It is due to a combination of the offset errors in the DAC and output amplifier. Zero-code error is expressed in millivolts. Error! Reference source not found. shows a plot of typical zero-code error vs. Supply. Gain Error Gain error is a measure of the span error of the DAC. It is the deviation in slope of the DAC transfer characteristic from the ideal, expressed as a percentage of the full-scale range. Zero-Code Error Drift Zero-code error drift is a measure of the change in zero-code error with a change in temperature. It is expressed in V/C. Gain Error Drift Gain error drift is a measure of the change in gain error with changes in temperature. It is expressed in (ppm of full-scale range)/C.
Preliminary Technical Data
Full-Scale Error Full-scale error is a measure of the output error when full-scale code (0xFFFF) is loaded into the DAC register. Ideally, the output should be VDD - 1 LSB. Full-scale error is expressed as a percentage of the full-scale range. Digital-to-Analog Glitch Impulse Digital-to-analog glitch impulse is the impulse injected into the analog output when the input code in the DAC register changes state. It is normally specified as the area of the glitch in nV-s and is measured when the digital input code is changed by 1 LSB at the major carry transition (0x7FFF to 0x8000). See Error! Reference source not found. and Error! Reference source not found.. DC Power Supply Rejection Ratio (PSRR) PSRR indicates how the output of the DAC is affected by changes in the supply voltage. PSRR is the ratio of the change in VOUT to a change in VDD for full-scale output of the DAC. It is measured in decibels. VREF is held at 2 V, and VDD is varied 10%. DC Crosstalk DC crosstalk is the dc change in the output level of one DAC in response to a change in the output of another DAC. It is measured with a full-scale output change on one DAC (or soft power-down and power-up) while monitoring another DAC kept at midscale. It is expressed in microvolts. DC crosstalk due to load current change is a measure of the impact that a change in load current on one DAC has to another DAC kept at midscale. It is expressed in microvolts per milliamp. Reference Feedthrough Reference feedthrough is the ratio of the amplitude of the signal at the DAC output to the reference input when the DAC output is not being updated (that is, LDAC is high). It is expressed in decibels. Digital Feedthrough Digital feedthrough is a measure of the impulse injected into the analog output of a DAC from the digital input pins of the device, but is measured when the DAC is not being written to (SYNC held high). It is specified in nV-s and measured with a full-scale change on the digital input pins, that is, from all 0s to all 1s or vice versa.
Rev. PrB | Page 10 of 20
Preliminary Technical Data
Digital Crosstalk Digital crosstalk is the glitch impulse transferred to the output of one DAC at midscale in response to a full-scale code change (all 0s to all 1s or vice versa) in the input register of another DAC. It is measured in standalone mode and is expressed in nV-s. Analog Crosstalk Analog crosstalk is the glitch impulse transferred to the output of one DAC due to a change in the output of another DAC. It is measured by loading one of the input registers with a full-scale code change (all 0s to all 1s or vice versa) while keeping LDAC high, and then pulsing LDAC low and monitoring the output of the DAC whose digital code has not changed. The area of the glitch is expressed in nV-s. DAC-to-DAC Crosstalk DAC-to-DAC crosstalk is the glitch impulse transferred to the output of one DAC due to a digital code change and subsequent output change of another DAC. This includes both digital and analog crosstalk. It is measured by loading one of the DACs with a full-scale code change (all 0s to all 1s or vice versa) with LDAC low and monitoring the output of another DAC. The energy of the glitch is expressed in nV-s.
AD5066
Multiplying Bandwidth The amplifiers within the DAC have a finite bandwidth. The multiplying bandwidth is a measure of this. A sine wave on the reference (with full-scale code loaded to the DAC) appears on the output. The multiplying bandwidth is the frequency at which the output amplitude falls to 3 dB below the input. Total Harmonic Distortion (THD) Total harmonic distortion is the difference between an ideal sine wave and its attenuated version using the DAC. The sine wave is used as the reference for the DAC, and the THD is a measure of the harmonics present on the DAC output. It is measured in decibels.
Rev. PrB | Page 11 of 20
AD5066 THEORY OF OPERATION
D/A SECTION
The AD5066 are Quad 16-bit, serial input, voltage output DACs. The parts operate from supply voltages of 2.7 V to 5.5 V. Data is written to the AD5066 in a 32-bit word format via a 3wire serial interface. The AD5066 incorporates a power-on reset circuit that ensures the DAC output powers up to a known output state (midscale or zero-scale, see the Ordering Guide). The devices also have a software power-down mode that reduces the typical current consumption to less than 1 a. Because the input coding to the DAC is straight binary, the ideal output voltage when using an external reference is given by
R
Preliminary Technical Data
R
R
TO OUTPUT AMPLIFIER
R
The ideal output voltage when using and internal reference is given by D VOUT = 2 x V REFOUT x N 2 where: D = decimal equivalent of the binary code that is loaded to the DAC register. 0 to 65,535 for AD5066 (16 bits).N = the DAC resolution.
Figure 7. Resistor String
SERIAL INTERFACE
The AD5066 has a 3-wire serial interface (SYNC, SCLK, and DIN) that is compatible with SPI, QSPI, and MICROWIRE interface standards as well as most DSPs. See Figure 3 for a timing diagram of a typical write sequence.
DAC ARCHITECTURE
The DAC architecture of the AD5066 consists of two matched DAC sections. A simplified circuit diagram is shown in Figure 5. The four MSBs of the 16-bit data word are decoded to drive 15 switches, E1 to E15. Each of these switches connects one of 15 matched resistors to either GND or VREF buffer output. The remaining 12 bits of the data word drive switches S0 to S11 of a 12-bit voltage mode R-2R ladder network.
VOUT 2R 2R S0 VREF
047762-027
STANDALONE MODE
The write sequence begins by bringing the SYNC line low. Data from the DIN line is clocked into the 32-bit shift register on the falling edge of SCLK. The serial clock frequency can be as high as 50 MHz, making the AD5066 compatible with high speed DSPs. On the 32nd falling clock edge, the last data bit is clocked in and the programmed function is executed, that is, a change in DAC register contents and/or a change in the mode of operation. At this stage, the SYNC line can be kept low or be brought high. In either case, it must be brought high for a minimum of 15 ns before the next write sequence so that a falling edge of SYNC can initiate the next write sequence. Because the SYNC buffer draws more current when VIN = 2 V than it does when VIN = 0.8 V, SYNC should be idled low between write sequences for even lower power operation of the part. As is mentioned previously, however, SYNC must be brought high again just before the next write sequence.
2R S1
2R S11
2R E1
2R E2
2R E15
12-BIT R-2R LADDER
FOUR MSBs DECODED INTO 15 EQUAL SEGMENTS
Figure 6. Dac Ladder Structure
REFERENCE BUFFER
The AD5066 operates with an external reference. Each of the four onboard dac's will have a dedicated voltage reference pin. In either case the reference input pin has an input range of 2 V to VDD. This input voltage is then used to provide a buffered reference for the DAC core.
Rev. PrB | Page 12 of 20
05298-024
D VOUT = VREFIN x N 2
R
Preliminary Technical Data
Table 7. Command Definitions
C3 0 0 0 0 0 0 0 0 1 1 1 Command C2 C1 0 0 0 0 0 1 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 C0 0 1 0 1 0 1 0 1 0 1 1 Description Write to Input Register n Update DAC Register n Write to Input Register n, update all (software LDAC) Write to and update DAC Channel n Power down/power up DAC Load clear code register Load LDAC register Reset (power-on reset) Set up DCEN register (Daisy chain enable) Set up DIO direction and Value Reserved
AD5066
Table 8. Address Commands
Address (n) A3 0 0 0 0 1 A2 0 0 0 0 1 A1 0 0 1 1 1 A0 0 1 0 1 1 Selected DAC Channel DAC A DAC B Reserved Reserved All DACs
Rev. PrB | Page 13 of 20
AD5066
INPUT SHIFT REGISTER
The AD5066 input shift register is 32 bits wide (see Figure 8). The first four bits are don't cares. The next four bits are the command bits, C3 to C0 (see Table 8), followed by the 4-bit DAC address bits, A3 to A0 (see Table 9) and finally the bit data-word. The data-word comprises of 16-bit input code followed by 4 don't care bits for the AD5066 (see Figure 8). These data bits are transferred to the DAC register on the 32nd falling edge of SCLK.
Preliminary Technical Data
SYNC INTERRUPT
In a normal write sequence, the SYNC line is kept low for at least 32 falling edges of SCLK, and the DAC is updated on the 32nd falling edge. However, if SYNC is brought high before the 32nd falling edge, this acts as an interrupt to the write sequence. The shift register is reset, and the write sequence is seen as invalid. Neither an update of the DAC register contents nor a change in the operating mode occurs (see Error! Reference source not found.).
DB31 (MSB) X X X X C3 C2 C1 C0 A3 A2 A1 A0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X
DB0 (LSB) X X
DATA BITS
COMMAND BITS
ADDRESS BITS
Figure 8. AD5066 Input Register Content
POWER-ON RESET
The AD5066 contains a power-on reset circuit that controls the output voltage during power-up. By connecting the POR pin low, the AD5066 output powers up to 0 V; by connecting the POR pin high, the AD5066 output powers up to midscale. The output remains powered up at this level until a valid write sequence is made to the DAC. This is useful in applications where it is important to know the state of the output of the DAC while it is in the process of powering up. There is also a software executable reset function that resets the DAC to the power-on reset code. Command 0111 is reserved for this reset function (see Table 7). Any events on LDAC or CLR during power-on reset are ignored. When both Bit DB9 and Bit DB8, in the control register are set to 0, the part works normally with its normal power consumption of TBD at 5 V. However, for the three power-down modes, the supply current falls to TBD at 5 V (TBD at 3 V). Not only does the supply current fall, but the output stage is also internally switched from the output of the Dac to a resistor network of known values. This has the advantage that the output impedance of the part is known while the part is in powerdown mode. There are three different options. The output is connected internally to GND through either a 1 k or a 100 k resistor, or it is left open-circuited (three-state). The output stage is illustrated in Figure 9. The bias generator, resistor string, and other associated linear circuitry are shut down when the power-down mode is activated. However, the contents of the DAC register are unaffected when in power-down. The time to exit power-down is typically 2.5 s for VDD = 5 V and VDD = 3 V (see Error! Reference source not found.). Any combination of DACs can be powered up by setting PD1 and PD0 to 0 (normal operation). The output powers up to the value in the input register (LDAC Low) or to the value in the DAC register before powering down (LDAC high).
POWER-DOWN MODES
The AD5066 contains four separate modes of operation. Command 0100 is reserved for the power-down function (see Table 7). These modes are software-programmable by setting two bits, Bit DB9 and Bit DB8, in the control register (refer to Table 12). Table 11 shows how the state of the bits corresponds to the mode of operation of the device. Any or all DACs (DAC A - DAC D) can be powered down to the selected mode by setting the corresponding four bits (DB3, DB2, DB1, DB0) to 1. See Table 12 for the contents of the input shift register during power-down/ power-up operation.
Rev. PrB | Page 14 of 20
05298-025
Preliminary Technical Data
Table 9. DCEN (Daisy-Chain Enable) Register
(DB1) 0 1 (DB0) 0 0 Action Standalone mode (default) DCEN mode
AD5066
Table 10. 32-Bit Input Shift Register Contents for Daisy-Chain Enable and Reference Set-Up Function
MSB DB31 to DB28 X Don't cares DB27 DB26 DB25 DB24 1 0 0 0 Command bits (C3 to C0) DB23 X DB22 DB21 DB20 X X X Address bits (A3 to A0) DB2 to DB19 X Don't cares LSB DB1 DB0 1/0 1/0 DCEN register
Table 11. Modes of Operation
DB9 0 0 1 1 DB8 0 1 0 1 Operating Mode Normal operation Power-down modes 1 k to GND 100 k to GND Three-state
Table 12. 32-Bit Input Shift Register Contents for Power-Up/Power-Down Function
MSB DB31 to DB28 X Don't cares LSB DB27 DB26 DB25 DB24 0 1 0 0 Command bits (C2 to C0) DB23 DB22 DB21 DB20 X X X X Address bits (A3 to A0)-- don't cares DB10 to DB19 X Don't cares DB9 DB8 PD1 PD0 Power-down mode DB4 to DB7 X Don't cares DB3 DB2 DB1 DB0 DAC D DAC C DAC B DAC A Power-down/power-up channel selection-- set bit to 1 to select
Figure 9. Output Stage During Power-Down
Rev. PrB | Page 15 of 20
AD5066
CLEAR CODE REGISTER
The AD5066 has a hardware CLR pin that is an asynchronous clear input. The CLR input is falling edge sensitive. Bringing the CLR line low clears the contents of the input register and the DAC registers to the data contained in the user-configurable CLR register and sets the analog outputs accordingly. (see Table 13) This function can be used in system calibration to load zero scale, midscale, or full scale to all channels together. These clear code values are user-programmable by setting two bits, Bit DB1 and Bit DB0, in the control register (see Table 13). The default setting clears the outputs to 0 V. Command 0101 is reserved for loading the clear code register (see Table 7). The part exits clear code mode on the 32nd falling edge of the next write to the part. If CLR is activated during a write sequence, the write is aborted. The CLR pulse activation time--the falling edge of CLR to when the output starts to change--is typically TBD ns. However, if outside the DAC linear region, it typically takes TBD ns after executing CLR for the output to start changing (see Error! Reference source not found.). See Table 14 for contents of the input shift register during the loading clear code register operation
Preliminary Technical Data
updates synchronously; that is, the DAC register is updated after new data is read, regardless of the state of the LDAC pin. It effectively sees the LDAC pin as being tied low. (See Table 15 for the LDAC register mode of operation.) This flexibility is useful in applications where the user wants to simultaneously update select channels while the rest of the channels are synchronously updating. Writing to the DAC using command 0110 loads the 4-bit LDAC register (DB3 to DB0). The default for each channel is 0; that is, the LDAC pin works normally. Setting the bits to 1 means the DAC channel is updated regardless of the state of the LDAC pin. See Table 16 for the contents of the input shift register during the load LDAC register mode of operation.
POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in a circuit, it is helpful to carefully consider the power supply and ground return layout on the board. The printed circuit board containing the AD5066 should have separate analog and digital sections. If the AD5066 is in a system where other devices require an AGND-to-DGND connection, the connection should be made at one point only. This ground point should be as close as possible to the AD5066. The power supply to the AD5066 should be bypassed with 10 F and 0.1 F capacitors. The capacitors should physically be as close as possible to the device, with the 0.1 F capacitor ideally right up against the device. The 10 F capacitors are the tantalum bead type. It is important that the 0.1 F capacitor has low effective series resistance (ESR) and low effective series inductance (ESI), such as is typical of common ceramic types of capacitors. This 0.1 F capacitor provides a low impedance path to ground for high frequencies caused by transient currents due to internal logic switching. The power supply line should have as large a trace as possible to provide a low impedance path and reduce glitch effects on the supply line. Clocks and other fast switching digital signals should be shielded from other parts of the board by digital ground. Avoid crossover of digital and analog signals if possible. When traces cross on opposite sides of the board, ensure that they run at right angles to each other to reduce feedthrough effects through the board. The best board layout technique is the microstrip technique, where the component side of the board is dedicated to the ground plane only and the signal traces are placed on the solder side. However, this is not always possible with a 2-layer board.
LDAC FUNCTION
The outputs of all DACs can be updated simultaneously using the hardware LDAC pin. Synchronous LDAC: After new data is read, the DAC registers are updated on the falling edge of the 32nd SCLK pulse. LDAC can be permanently low or pulsed as in Figure 3 Asynchronous LDAC: The outputs are not updated at the same time that the input registers are written to. When LDAC goes low, the DAC registers are updated with the contents of the input register. Alternatively, the outputs of all DACs can be updated simultaneously using the software LDAC function by writing to Input Register n and updating all DAC registers. Command 0010 is reserved for this software LDAC function. An LDAC register gives the user extra flexibility and control over the hardware LDAC pin. This register allows the user to select which combination of channels to simultaneously update when the hardware LDAC pin is executed. Setting the LDAC bit register to 0 for a DAC channel means that this channel's update is controlled by the LDAC pin. If this bit is set to 1, this channel
Rev. PrB | Page 16 of 20
Preliminary Technical Data
Table 13. Clear Code Register
DB1 CR1 0 0 1 1 Clear Code Register DB0 CR0 0 1 0 1
AD5066
Clears to Code 0x0000 0x8000 0xFFFF No operation
Table 14. 32-Bit Input Shift Register Contents for Clear Code Function
MSB DB31 to DB28 X Don't cares DB27 DB26 DB25 DB24 0 1 0 1 Command bits (C3 to C0) DB23 X DB22 DB21 DB20 X X X Address bits (A3 to A0) DB2 to DB19 X Don't cares LSB DB1 DB0 1/0 1/0 Clear code register (CR1 to CR0)
Table 15. LDAC Overwrite Definition
Load DAC Register LDAC Bits (DB3 to DB0) LDAC Pin 0 1 1/0 X--don't care LDAC Operation Determined by LDAC pin DAC channels update, overrides the LDAC pin. DAC channels see LDAC as 0.
Table 16. 32-Bit Input Shift Register Contents for LDAC Overwrite Function
MSB DB31 to DB28 X Don't cares LSB DB4 to DB19 X Don't cares
DB27 0
DB26 DB25 DB24 1 1 0 Command bits (C3 to C0)
DB23 DB22 DB21 X X X Address bits (A3 to A0)-- don't cares
DB20 X
DB3 DB2 DB1 DB0 DAC D DAC C DAC B DAC A Setting LDAC bit to 1 override LDAC pin
Rev. PrB | Page 17 of 20
AD5066
MICROPROCESSOR INTERFACING
AD5066 to Blackfin(R) ADSP-BF53X Interface
Figure 10 shows a serial interface between the AD5066 and the Blackfin ADSP-BF53X microprocessor. The ADSP-BF53X processor family incorporates two dual-channel synchronous serial ports, SPORT1 and SPORT0, for serial and multiprocessor communications. Using SPORT0 to connect to the AD5066, the setup for the interface is as follows: DT0PRI drives the DIN pin of the AD5066, while TSCLK0 drives the SCLK of the parts. The SYNC is driven from TFS0.
ADSP-BF53x1
TFS0 DTOPRI TSCLK0
Preliminary Technical Data
AD5066 to 80C51/80L51 Interface
Figure 12 shows a serial interface between the AD5066 and the 80C51/80L51 microcontroller. The setup for the interface is as follows: TxD of the 80C51/ 80L51 drives SCLK of the AD5066, and RxD drives the serial data line of the part. The SYNC signal is again derived from a bit-programmable pin on the port. In this case, Port Line P3.3 is used. When data is to be transmitted to the AD5066, P3.3 is taken low. The 80C51/80L51 transmit data in 8-bit bytes only; thus, only eight falling clock edges occur in the transmit cycle. To load data to the DAC, P3.3 is left low after the first eight bits are transmitted, and a second write cycle is initiated to transmit the second byte of data. P3.3 is taken high following the completion of this cycle. The 80C51/80L51 output the serial data in a format that has the LSB first. The AD5066 must receive data with the MSB first. The 80C51/80L51 transmit routine should take this into account.
80C51/80L511
AD5066
SYNC DIN SCLK
1
AD5066
1 SYNC SCLK DIN
0000-052
1ADDITIONAL
0000-049
PINS OMITTED FOR CLARITY.
P3.3 TxD RxD
Figure 10. AD5066 to Blackfin ADSP-BF53X Interface
AD5066 to 68HC11/68L11 Interface
Figure 11 shows a serial interface between the AD5066 and the 68HC11/68L11 microcontroller. SCK of the 68HC11/68L11 drives the SCLK of the AD5066, and the MOSI output drives the serial data line of the DAC.
68HC11/68L111
PC7 SCK MOSI
1ADDITIONAL
PINS OMITTED FOR CLARITY.
Figure 12. AD5066 to 80C512/80L51 Interface
AD5066 to MICROWIRE Interface
AD5066
SYNC SCLK DIN
0000-050
1
Figure 13 shows an interface between the AD5066 and any MICROWIRE-compatible device. Serial data is shifted out on the falling edge of the serial clock and is clocked into the AD5025/45/65 on the rising edge of the SCLK.
MICROWIRE1
CS SK SO
1ADDITIONAL PINS OMITTED FOR CLARITY.
AD5066
SYNC DIN SCLK
0000-049
Figure 11. AD5066 to 68HC11/68L11 Interface
The SYNC signal is derived from a port line (PC7). The setup conditions for correct operation of this interface are as follows: The 68HC11/68L11 is configured with its CPOL bit as 0, and its CPHA bit as 1. When data is being transmitted to the DAC, the SYNC line is taken low (PC7). When the 68HC11/ 68L11 is configured as described previously, data appearing on the MOSI output is valid on the falling edge of SCK. Serial data from the 68HC11/68L11 is transmitted in 8-bit bytes with only eight falling clock edges occurring in the transmit cycle. Data is transmitted MSB first. To load data to the AD5066, PC7 is left low after the first eight bits are transferred, and a second serial write operation is performed to the DAC. PC7 is taken high at the end of this procedure.
1ADDITIONAL
PINS OMITT ED FOR CLARITY.
Figure 13. AD5066/45/654 to MICROWIRE Interface
Rev. PrB | Page 18 of 20
Preliminary Technical Data APPLICATIONS
USING A REFERENCE AS A POWER SUPPLY FOR THE AD5066
Because the supply current required by the AD5066 is extremely low, an alternative option is to use a voltage reference to supply the required voltage to the parts (see Figure 14). This is especially useful if the power supply is quite noisy or if the system supply voltages are at some value other than 5 V or 3 V, for example, 15 V. The voltage reference outputs a steady supply voltage for the AD5066. If the low dropout REF195 is used, it must supply 500 A of current to the AD5066, with no load on the output of the DAC. When the DAC output is loaded, the REF195 also needs to supply the current to the load. The total current required (with a 5 k load on the DAC output) is 500 A + (5 V/5 k) = 1.5 mA The load regulation of the REF195 is typically 2 ppm/mA, which results in a 3 ppm (15 V) error for the 1.5 mA current drawn from it. This corresponds to a 0.196 LSB error.
15V REF195 5V
AD5066
+5 V output.
R2 = 10k +5V +5V R1 = 10k
AD820/ OP295
VDD 10F 0.1F AD5066 VOUT -5V
5V
Figure 15. Bipolar Operation with the AD5066
USING THE AD5066 WITH A GALVANICALLY ISOLATED INTERFACE
In process control applications in industrial environments, it is often necessary to use a galvanically isolated interface to protect and isolate the controlling circuitry from any hazardous common-mode voltages that can occur in the area where the DAC is functioning. iCoupler(R) provides isolation in excess of 2.5 kV. The AD5066 uses a 3-wire serial logic interface, so the ADuM1300 three-channel digital isolator provides the required isolation (see Figure 16). The power supply to the part also needs to be isolated, which is done by using a transformer. On the DAC side of the transformer, a 5 V regulator provides the 5 V supply required for the AD5066.
0000-053
THREE-WIRE SERIAL INTERFACE
SYNC SCLK DIN
VDD
AD5066
VOUT = 0V TO 5V
5V REGULATOR POWER 10F 0.1F
Figure 14. REF195 as Power Supply to the AD5025/45/65
BIPOLAR OPERATION USING THE AD5066
The AD5066 has been designed for single-supply operation, but a bipolar output range is also possible using the circuit in Figure 15. The circuit gives an output voltage range of 5 V. Rail-to-rail operation at the amplifier output is achievable using an AD820 or an OP295 as the output amplifier. The output voltage for any input code can be calculated as follows:
D R1 + R2 R2 VO = VDD x x - VDD x R1 65,536 R1
SCLK VIA VOA SCLK VDD
ADuM1300
SDI VIB VOB
AD5066
SYNC VOUT
DATA
VIC
VOC
DIN GND
0000-055
Figure 16. AD5025/45/65 with a Galvanically Isolated Interface
where D represents the input code in decimal (0 to 65,535). With VDD = 5 V, R1 = R2 = 10 k,
10 x D VO = -5V 65,536
This is an output voltage range of 5 V, with 0x0000 corresponding to a -5 V output, and 0xFFFF corresponding to a
Rev. PrB | Page 19 of 20
0000-053
THREE-WIRE SERIAL INTERFACE
AD5066
Preliminary Technical Data
OUTLINE DIMENSIONS
5.10 5.00 4.90
16
9
4.50 4.40 4.30
1 8
6.40 BSC
PIN 1 0.15 0.05 0.65 BSC 0.30 0.19 COPLANARITY 0.10 1.20 MAX
0.20 0.09
SEATING PLANE
8 0
0.75 0.60 0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AB
Figure 17. 16-Lead Thin Shrink Small Outline Package [TSSOP] (RU-16) Dimensions shown in millimeters
ORDERING GUIDE
Model AD5066BRUZ-1 1 AD5066BRUZ-1REEL7 AD5066ARUZ AD5066ARUZ-REEL7 Eval-AD5066 EBZ
1
Temperature Range -40C to +105C -40C to +105C -40C to +105C -40C to +105C
Package Description 16-Lead TSSOP 16-Lead TSSOP 16-Lead TSSOP 16-Lead TSSOP Evaluation board
Package Option RU-16 RU-16 RU-16 RU-16
Power-On Reset to Code Zero Zero Zero Zero
Accuracy 1 LSB INL 1 LSB INL 4 LSB INL 4 LSB INL
Resolution 16 bits 16 bits 16 bits 16 bits
Z = Pb-free part.
(c)2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR06845-0-6/07(PrB)
T T
Rev. PrB | Page 20 of 20

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