a 2.5 V to 5.5 V, 500 A, Quad Voltage Output 8-/10-/12-Bit DACs in 10-Lead microSOIC AD5304/AD5314/AD5324* FEATURES AD5304 Four Buffered 8-Bit DACs in 10-Lead microSOIC AD5314 Four Buffered 10-Bit DACs in 10-Lead microSOIC AD5324 Four Buffered 12-Bit DACs in 10-Lead microSOIC Low Power Operation: 500 A @ 3 V, 600 A @ 5 V 2.5 V to 5.5 V Power Supply Guaranteed Monotonic By Design Over All Codes Power-Down to 80 nA @ 3 V, 200 nA @ 5 V Double-Buffered Input Logic Output Range: 0–V REF Power-On-Reset to Zero Volts Simultaneous Update of Outputs (LDAC Function) Low Power, SPI™, QSPI™, MICROWIRE™, and DSP-Compatible 3-Wire Serial Interface On-Chip Rail-to-Rail Output Buffer Amplifiers Temperature Range –40ⴗC to +105ⴗC APPLICATIONS Portable Battery-Powered Instruments Digital Gain and Offset Adjustment Programmable Voltage and Current Sources Programmable Attenuators Industrial Process Control GENERAL DESCRIPTION The AD5304/AD5314/AD5324 are quad 8-, 10- and 12-bit buffered voltage output DACs in a 10-lead microSOIC package that operate from a single 2.5 V to 5.5 V supply consuming 500 µA at 3 V. Their on-chip output amplifiers allow rail-torail output swing to be achieved with a slew rate of 0.7 V/µs. A 3-wire serial interface is used which operates at clock rates up to 30 MHz and is compatible with standard SPI, QSPI, MICROWIRE and DSP interface standards. The references for the four DACs are derived from one reference pin. The outputs of all DACs may be updated simultaneously using the software LDAC function. The parts incorporate a power-on-reset circuit that ensures that the DAC outputs power up to zero volts and remain there until a valid write takes place to the device. The parts contain a power-down feature that reduces the current consumption of the device to 200 nA @ 5 V (80 nA @ 3 V). The low power consumption of these parts in normal operation makes them ideally suited to portable battery-operated equipment. The power consumption is 3 mW at 5 V, 1.5 mW at 3 V, reducing to 1 µW in power-down mode. FUNCTIONAL BLOCK DIAGRAM VDD REFIN LDAC SCLK SYNC INPUT REGISTER DAC REGISTER STRING DAC A BUFFER VOUTA INPUT REGISTER DAC REGISTER STRING DAC B BUFFER VOUTB INPUT REGISTER DAC REGISTER STRING DAC C BUFFER VOUTC INPUT REGISTER DAC REGISTER STRING DAC D BUFFER VOUTD INTERFACE LOGIC DIN POWER-ON RESET AD5304/AD5314/AD5324 POWER-DOWN LOGIC GND *Protected by U.S. Patent No. 5,969,657; other patents pending. SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corporation. REV. B 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2000 AD5304/AD5314/AD5324–SPECIFICATIONS (V DD = 2.5 V to 5.5 V; VREF = 2 V; RL = 2 k⍀ to GND; CL = 200 pF to GND; All specifications TMIN to TMAX unless otherwise noted.) Parameter1 Min B Version2 Typ Max Unit Conditions/Comments 8 ± 0.15 ± 0.02 ±1 ± 0.25 Bits LSB LSB Guaranteed Monotonic by Design Over All Codes 10 ± 0.5 ± 0.05 ±4 ± 0.5 Bits LSB LSB Guaranteed Monotonic by Design Over All Codes 3, 4 DC PERFORMANCE AD5304 Resolution Relative Accuracy Differential Nonlinearity AD5314 Resolution Relative Accuracy Differential Nonlinearity AD5324 Resolution Relative Accuracy Differential Nonlinearity Offset Error Gain Error Lower Deadband Offset Error Drift5 Gain Error Drift5 DC Power Supply Rejection Ratio5 DC Crosstalk5 DAC REFERENCE INPUTS5 VREF Input Range VREF Input Impedance 12 ±2 ± 0.2 ± 0.4 ± 0.15 20 –12 –5 –60 200 0.25 37 Reference Feedthrough OUTPUT CHARACTERISTICS5 Minimum Output Voltage6 Maximum Output Voltage6 DC Output Impedance Short Circuit Current Power-Up Time VDD V kΩ MΩ dB 0.001 VDD – 0.001 0.5 25 16 2.5 5 V V Ω mA mA µs µs ±1 0.8 0.6 0.5 2.4 2.1 2.0 Pin Capacitance POWER REQUIREMENTS VDD IDD (Normal Mode)7 VDD = 4.5 V to 5.5 V VDD = 2.5 V to 3.6 V IDD (Power-Down Mode) VDD = 4.5 V to 5.5 V VDD = 2.5 V to 3.6 V Bits LSB LSB % of FSR % of FSR mV ppm of FSR/°C ppm of FSR/°C dB µV 45 >10 –90 LOGIC INPUTS5 Input Current VIL, Input Low Voltage VIH, Input High Voltage ± 16 ±1 ±3 ±1 60 3 2.5 µA V V V V V V pF Guaranteed Monotonic by Design Over All Codes See Figures 2 and 3 See Figures 2 and 3 Lower Deadband Exists Only If Offset Error Is Negative ∆VDD = ± 10% RL = 2 kΩ to GND or VDD Normal Operation Power-Down Mode Frequency = 10 kHz This is a measure of the minimum and maximum drive capability of the output amplifier. VDD = 5 V VDD = 3 V Coming Out of Power-Down Mode. VDD = 5 V Coming Out of Power-Down Mode. VDD = 3 V VDD = 5 V ± VDD = 3 V ± VDD = 2.5 V VDD = 5 V ± VDD = 3 V ± VDD = 2.5 V 10% 10% 10% 10% 5.5 V 600 500 900 700 µA µA VIH = VDD and VIL = GND VIH = VDD and VIL = GND 0.2 0.08 1 1 µA µA VIH = VDD and VIL = GND VIH = VDD and VIL = GND NOTES 1 See Terminology. 2 Temperature range: B Version: –40°C to +105°C; typical at 25°C. 3 DC specifications tested with the outputs unloaded. 4 Linearity is tested using a reduced code range: AD5304 (Code 8 to 248); AD5314 (Code 28 to 995); AD5324 (Code 115 to 3981). 5 Guaranteed by design and characterization, not production tested. 6 In order for the amplifier output to reach its minimum voltage, Offset Error must be negative. In order for the amplifier output to reach its maximum voltage, VREF = VDD and “Offset plus Gain” Error must be positive. 7 IDD specification is valid for all DAC codes. Interface inactive. All DACs active. Load currents excluded. Specifications subject to change without notice. –2– REV. B AD5304/AD5314/AD5324 AC CHARACTERISTICS1 (VDD = 2.5 V to 5.5 V; RL = 2 k⍀ to GND; CL = 200 pF to GND; all specifications TMIN to TMAX unless otherwise noted.) 2 Parameter B Version3 Min Typ Max Unit 6 7 8 0.7 12 1 1 3 200 –70 µs µs µs V/µs nV-s nV-s nV-s nV-s kHz dB Output Voltage Settling Time AD5304 AD5314 AD5324 Slew Rate Major-Code Transition Glitch Energy Digital Feedthrough Digital Crosstalk DAC-to-DAC Crosstalk Multiplying Bandwidth Total Harmonic Distortion 8 9 10 Conditions/Comments VREF = VDD = 5 V 1/4 Scale to 3/4 Scale Change (40 Hex to C0 Hex) 1/4 Scale to 3/4 Scale Change (100 Hex to 300 Hex) 1/4 Scale to 3/4 Scale Change (400 Hex to C00 Hex) 1 LSB Change Around Major Carry VREF = 2 V ± 0.1 V p-p VREF = 2.5 V ± 0.1 V p-p. Frequency = 10 kHz NOTES 1 Guaranteed by design and characterization, not production tested. 2 See Terminology. 3 Temperature range: B Version: –40°C to +105°C; typical at 25°C. Specifications subject to change without notice. TIMING CHARACTERISTICS1, 2, 3 (V DD = 2.5 V to 5.5 V. All specifications TMIN to TMAX unless otherwise noted) Parameter Limit at TMIN, TMAX VDD = 2.5 V to 3.6 V VDD = 3.6 V to 5.5 V Unit Conditions/Comments t1 t2 t3 t4 t5 t6 t7 t8 40 16 16 0 5 4.5 0 80 ns min ns min ns min ns min ns min ns min ns min ns min SCLK Cycle Time SCLK High Time SCLK Low Time SYNC to SCLK Rising Edge Setup Time Data Setup Time Data Hold Time SCLK Falling Edge to SYNC Rising Edge Minimum SYNC High Time 33 13 13 0 5 4.5 0 33 NOTES 1 Guaranteed by design and characterization, not production tested. 2 All input signals are specified with tr = tf = 5 ns (10% to 90% of V DD) and timed from a voltage level of (V IL + VIH)/2. 3 See Figure 1. Specifications subject to change without notice. t1 SCLK t8 t3 t2 t7 t4 SYNC t6 t5 DIN DB15 DB0 Figure 1. Serial Interface Timing Diagram REV. B –3– AD5304/AD5314/AD5324 ABSOLUTE MAXIMUM RATINGS1, 2 PIN CONFIGURATION (TA = 25°C unless otherwise noted) VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V Digital Input Voltage to GND . . . . . . . –0.3 V to VDD + 0.3 V Reference Input Voltage to GND . . . . –0.3 V to VDD + 0.3 V VOUTA–D to GND . . . . . . . . . . . . . . . . –0.3 V to VDD + 0.3 V Operating Temperature Range Industrial (B Version) . . . . . . . . . . . . . . . –40°C to +105°C Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C Junction Temperature (TJ max) . . . . . . . . . . . . . . . . . . 150°C 10-Lead microSOIC Package Power Dissipation . . . . . . . . . . . . . . . . . . (TJ max – TA)/θJA θJA Thermal Impedance . . . . . . . . . . . . . . . . . . . . 206°C/W θJC Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 44°C/W Reflow Soldering Peak Temperature . . . . . . . . . . . . . . . . . . . . . 220 +5/–0°C Time at Peak Temperature . . . . . . . . . . . . 10 sec to 40 sec 10 SYNC VDD 1 AD5304/ AD5314/ AD5324 VOUTA 2 VOUTB 3 VOUTC 4 REFIN 5 TOP VIEW (Not to Scale) 9 SCLK 8 DIN 7 GND 6 VOUTD NOTES 1 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; and functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 Transient currents of up to 100 mA will not cause SCR latch-up. PIN FUNCTION DESCRIPTIONS Pin No. Mnemonic 1 2 3 4 5 6 7 8 VDD VOUTA VOUTB VOUTC REFIN VOUTD GND DIN 9 SCLK 10 SYNC Function Power Supply Input. These parts can be operated from 2.5 V to 5.5 V and the supply should be decoupled to GND. Buffered Analog Output Voltage from DAC A. The output amplifier has rail-to-rail operation. Buffered Analog Output Voltage from DAC B. The output amplifier has rail-to-rail operation. Buffered Analog Output Voltage from DAC C. The output amplifier has rail-to-rail operation. Reference Input Pin for All Four DACs. It has an input range from 0.25 V to VDD. Buffered Analog Output Voltage from DAC D. The output amplifier has rail-to-rail operation. Ground Reference Point for All Circuitry on the Part. Serial Data Input. This device has a 16-bit shift register. Data is clocked into the register on the falling edge of the serial clock input. The DIN input buffer is powered down after each write cycle. 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 clock speeds up to 30 MHz. The SCLK input buffer is powered down after each write cycle. Active Low Control Input. This is the frame synchronization signal for the input data. When SYNC goes low, it enables the input shift register and data is transferred in on the falling edges of the following 16 clocks. If SYNC is taken high before the sixteenth falling edge of SCLK, the rising edge of SYNC acts as an interrupt and the write sequence is ignored by the device. ORDERING GUIDE Model Temperature Range Package Description Package Option Branding Information AD5304BRM AD5314BRM AD5324BRM –40°C to +105°C –40°C to +105°C –40°C to +105°C 10-Lead microSOIC 10-Lead microSOIC 10-Lead microSOIC RM-10 RM-10 RM-10 DBB DCB DDB 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 the AD5304/AD5314/AD5324 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. –4– WARNING! ESD SENSITIVE DEVICE REV. B AD5304/AD5314/AD5324 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. Typical INL versus Code plots can be seen in Figures 4, 5, and 6. DIGITAL CROSSTALK This 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 and vice versa) in the input register of another DAC. It is expressed in nV-secs. DAC-TO-DAC CROSSTALK 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. Typical DNL versus Code plots can be seen in Figures 7, 8, and 9. This 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 and vice versa) with the LDAC bit set low and monitoring the output of another DAC. The energy of the glitch is expressed in nV-secs. OFFSET ERROR MULTIPLYING BANDWIDTH This is a measure of the offset error of the DAC and the output amplifier. It is expressed as a percentage of the full-scale range. 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. GAIN ERROR This is a measure of the span error of the DAC. It is the deviation in slope of the actual DAC transfer characteristic from the ideal expressed as a percentage of the full-scale range. OFFSET ERROR DRIFT This is a measure of the change in offset error with changes in temperature. It is expressed in (ppm of full-scale range)/°C. TOTAL HARMONIC DISTORTION This 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 dBs. GAIN ERROR DRIFT OUTPUT VOLTAGE This is a measure of the change in gain error with changes in temperature. It is expressed in (ppm of full-scale range)/°C. GAIN ERROR PLUS OFFSET ERROR IDEAL ACTUAL POWER-SUPPLY REJECTION RATIO (PSRR) This 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 dBs. VREF is held at 2 V and VDD is varied ± 10%. NEGATIVE OFFSET ERROR DAC CODE DEADBAND CODES DC CROSSTALK AMPLIFIER FOOTROOM (1mV) This is the dc change in the output level of one DAC at midscale in response to a full-scale code change (all 0s to all 1s and vice versa) and output change of another DAC. It is expressed in µV. NEGATIVE OFFSET ERROR REFERENCE FEEDTHROUGH This 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. It is expressed in dBs. Figure 2. Transfer Function with Negative Offset MAJOR-CODE TRANSITION GLITCH ENERGY Major-code transition glitch energy is the energy of the impulse injected into the analog output when the code in the DAC register changes state. It is normally specified as the area of the glitch in nV-secs and is measured when the digital code is changed by 1 LSB at the major carry transition (011 . . . 11 to 100 . . . 00 or 100 . . . 00 to 011 . . . 11). ACTUAL GAIN ERROR PLUS OFFSET ERROR OUTPUT VOLTAGE IDEAL DIGITAL FEEDTHROUGH Digital feedthrough is a measure of the impulse injected into the analog output of the DAC from the digital input pins of the device when the DAC output is not being written to (SYNC held high). It is specified in nV-secs and is measured with a worst-case change on the digital input pins, e.g., from all 0s to all 1s or vice versa. REV. B POSITIVE OFFSET DAC CODE Figure 3. Transfer Function with Positive Offset –5– AD5304/AD5314/AD5324 12 3 1.0 TA = 25ⴗC VDD = 5V TA = 25ⴗC VDD = 5V TA = 25ⴗC VDD = 5V 8 2 0 INL ERROR – LSBs INL ERROR – LSBs INL ERROR – LSBs 0.5 1 0 –1 4 0 –4 –0.5 –8 –2 0 50 100 150 CODE 200 –3 250 Figure 4. AD5304 Typical INL Plot 400 600 CODE 800 1000 0 1000 2000 CODE 3000 4000 Figure 6. AD5324 Typical INL Plot 1 0.6 TA = 25ⴗC VDD = 5V TA = 25ⴗC VDD = 5V TA = 25ⴗC VDD = 5V 0.4 DNL ERROR – LSBs DNL ERROR – LSBs 200 Figure 5. AD5314 Typical INL Plot 0.3 0.2 –12 0 0.1 0 –0.1 DNL ERROR – LSBs –1.0 0.2 0 –0.2 0.5 0 –0.5 –0.2 –0.3 –0.4 0 50 100 150 CODE 200 Figure 7. AD5304 Typical DNL Plot –1 –0.6 250 0 800 400 600 CODE 200 Figure 8. AD5314 Typical DNL Plot 0.5 0 1000 0.4 MAX INL 0.3 3000 4000 1 VDD = 5V VREF = 3V VDD = 5V VREF = 2V MAX INL 0.5 MAX DNL 0 MIN DNL 0.2 MAX DNL 0.1 ERROR – % ERROR – LSBs 0.25 ERROR – LSBs 2000 CODE Figure 9. AD5324 Typical DNL Plot 0.5 VDD = 5V TA = 25ⴗC 1000 0 –0.1 MIN DNL GAIN ERROR 0 OFFSET ERROR –0.2 –0.25 –0.5 –0.3 MIN INL MIN INL –0.4 –0.5 0 1 2 3 VREF – V 4 5 Figure 10. AD5304 INL and DNL Error vs. VREF –0.5 ⴚ40 0 40 80 TEMPERATURE – ⴰC Figure 11. AD5304 INL Error and DNL Error vs. Temperature –6– 120 –1 ⴚ40 0 40 80 120 TEMPERATURE – ⴰC Figure 12. AD5304 Offset Error and Gain Error vs. Temperature REV. B AD5304/AD5314/AD5324 5 0.2 TA = 25ⴰC VREF = 2V 0.1 5V SOURCE 500 3V SOURCE 400 4 0 –0.2 –0.3 3 IDD – A –0.1 2 OFFSET ERROR 1 3V SINK 100 5V SINK –0.5 0 1 2 4 3 VDD – Volts 5 0 6 Figure 13. Offset Error and Gain Error vs. VDD 0 2 5 1 3 4 SINK/SOURCE CURRENT – mA Figure 15. Supply Current vs. DAC Code 0.5 1000 TA = 25ⴗC 500 900 0.4 +25ⴰC +105ⴰC 800 300 0.3 IDD – A IDD – A 400 ⴚ40ⴰC 0.2 ⴙ25ⴰC 200 700 VDD = 5V 600 0.1 100 500 VDD = 3V ⴙ105ⴰC 0 2.5 3.0 3.5 4.5 4.0 VDD – Volts 5.0 0 2.5 5.5 Figure 16. Supply Current vs. Supply Voltage ⴰC TA = 25 5µs VDD = 5V VREF = 5V 400 3.0 3.5 4.0 4.5 VDD – Volts 5.0 5.5 Figure 17. Power-Down Current vs. Supply Voltage CH1 SCLK CH1 1V, CH2 5V, TIME BASE= 1s/DIV Figure 19. Half-Scale Settling (1/4 to 3/4 Scale Code Change) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VLOGIC – Volts Figure 18. Supply Current vs. Logic Input Voltage TA = 25ⴰC VDD = 5V VREF = 2V CH1 TA = 25ⴰC VDD = 5V VREF = 2V VOUTA VOUTA CH2 CH2 0 VDD VOUTA REV. B FULL – SCALE ZERO – SCALE CODE ⴚ40ⴰC IDD – A 0 6 Figure 14. VOUT Source and Sink Current Capability 600 CH1 300 200 –0.4 –0.6 TA = 25ⴰC VDD = 5V VREF = 2V GAIN ERROR VOUT – Volts ERROR – % 600 CH2 CH1 2V, CH2 200mV, TIME BASE = 200s/DIV Figure 20. Power-On Reset to 0 V –7– SCLK CH1 500mV, CH2 5V, TIME BASE= 1s/DIV Figure 21. Exiting Power-Down to Midscale AD5304/AD5314/AD5324 2.50 10 0 –10 2.49 –20 dB VDD = 5V VOUT – Volts FREQUENCY VDD = 3V –30 2.48 –40 –50 2.47 300 350 400 450 500 IDD – A 550 600 1s/DIV Figure 22. IDD Histogram with VDD = 3 V and VDD = 5 V Figure 23. AD5324 Major-Code Transition Glitch Energy –60 0.01 0.1 1 10 100 FREQUENCY – kHz 1k 10k Figure 24. Multiplying Bandwidth (Small-Signal Frequency Response) 0.02 TA = 25ⴗC 0.01 1mV/DIV FULL-SCALE ERROR – Volts VDD = 5V 0 –0.01 –0.02 0 1 2 3 4 VREF – Volts 5 Figure 25. Full-Scale Error vs. VREF 6 150ns/DIV Figure 26. DAC-to-DAC Crosstalk –8– REV. B AD5304/AD5314/AD5324 FUNCTIONAL DESCRIPTION DAC Reference Inputs The AD5304/AD5314/AD5324 are quad resistor-string DACs fabricated on a CMOS process with resolutions of 8, 10, and 12 bits respectively. Each contains four output buffer amplifiers and is written to via a 3-wire serial interface. They operate from single supplies of 2.5 V to 5.5 V and the output buffer amplifiers provide rail-to-rail output swing with a slew rate of 0.7 V/µs. The four DACs share a single reference input pin. The devices have programmable power-down modes, in which all DACs may be turned off completely with a high-impedance output. There is a single reference input pin for the four DACs. The reference input is unbuffered. The user can have a reference voltage as low as 0.25 V and as high as VDD since there is no restriction due to headroom and footroom of any reference amplifier. Digital-to-Analog Section The architecture of one DAC channel consists of a resistor-string DAC followed by an output buffer amplifier. The voltage at the REFIN pin provides the reference voltage for the DAC. Figure 27 shows a block diagram of the DAC architecture. Since the input coding to the DAC is straight binary, the ideal output voltage is given by: VOUT = VREF × D 2N It is recommended to use a buffered reference in the external circuit (e.g., REF192). The input impedance is typically 45 kΩ. Output Amplifier The output buffer amplifier is capable of generating rail-to-rail voltages on its output, which gives an output range of 0 V to VDD when the reference is VDD. It is capable of driving a load of 2 kΩ to GND or VDD, in parallel with 500 pF to GND or VDD. The source and sink capabilities of the output amplifier can be seen in the plot in Figure 14. The slew rate is 0.7 V/µs with a half-scale settling time to ± 0.5 LSB (at 8 bits) of 6 µs. POWER-ON RESET where D = decimal equivalent of the binary code, which is loaded to the DAC register; The AD5304/AD5314/AD5324 are provided with a power-on reset function, so that they power up in a defined state. The power-on state is: – Normal operation. – Output voltage set to 0 V. 0–255 for AD5304 (8 Bits) 0–1023 for AD5314 (10 Bits) 0–4095 for AD5324 (12 Bits) Both input and DAC registers are filled with zeros and remain so until a valid write sequence is made to the device. This is particularly useful in applications where it is important to know the state of the DAC outputs while the device is powering up. N = DAC resolution REFIN SERIAL INTERFACE INPUT REGISTER DAC REGISTER RESISTOR STRING VOUTA OUTPUT BUFFER AMPLIFIER Figure 27. DAC Channel Architecture Resistor String The resistor string section is shown in Figure 28. It is simply a string of resistors, each of value R. The digital code loaded to the DAC register determines at which node on the string the voltage is tapped off to be fed into the output amplifier. The voltage is tapped off by closing one of the switches connecting the string to the amplifier. Because it is a string of resistors, it is guaranteed monotonic. R The AD5304/AD5314/AD5324 are controlled over a versatile, 3-wire serial interface, which operates at clock rates up to 30 MHz and is compatible with SPI, QSPI, MICROWIRE, and DSP interface standards. Input Shift Register The input shift register is 16 bits wide. Data is loaded into the device as a 16-bit word under the control of a serial clock input, SCLK. The timing diagram for this operation is shown in Figure 1. The 16-bit word consists of four control bits followed by 8, 10, or 12 bits of DAC data, depending on the device type. Data is loaded MSB first (Bit 15) and the first two bits determine whether the data is for DAC A, DAC B, DAC C, or DAC D. Bits 13 and 12 control the operating mode of the DAC. Bit 13 is PD, which determines whether the part is in normal or powerdown mode. Bit 12 is LDAC, which controls when DAC registers and outputs are updated. R Table I. Address Bits for the AD53x4 R TO OUTPUT AMPLIFIER R R Figure 28. Resistor String REV. B –9– A1 A0 DAC Addressed 0 0 1 1 0 1 0 1 DAC A DAC B DAC C DAC D AD5304/AD5314/AD5324 BIT0 (LSB) BIT15 (MSB) A1 A0 PD LDAC D7 D6 D5 D4 D3 D2 D1 D0 X X X X DATA BITS Figure 29. AD5304 Input Shift Register Contents BIT0 (LSB) BIT15 (MSB) A1 A0 PD LDAC D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X DATA BITS Figure 30. AD5314 Input Shift Register Contents BIT0 (LSB) BIT15 (MSB) A1 A0 PD LDAC D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 DATA BITS Figure 31. AD5324 Input Shift Register Contents Address and Control Bits Low-Power Serial Interface PD: To reduce the power consumption of the device even further, the interface only powers up fully when the device is being written to, i.e., on the falling edge of SYNC. As soon as the 16-bit control word has been written to the part, the SCLK and DIN input buffers are powered down. They only power up again following a falling edge of SYNC. 0: All four DACs go into power-down mode consuming only 200 nA @ 5 V. The DAC outputs enter a highimpedance state. 1: Normal operation. LDAC: 0: All four DAC registers and hence all DAC outputs updated simultaneously on completion of the write sequence. 1: Addressed input register only is updated. There is no change in the content of the DAC registers. Double-Buffered Interface The AD5324 uses all 12 bits of DAC data, the AD5314 uses 10 bits and ignores the two LSBs. The AD5304 uses eight bits and ignores the last four bits. The data format is straight binary, with all zeros corresponding to 0 V output and all ones corresponding to full-scale output (VREF –1 LSB). The SYNC input is a level-triggered input that acts as a frame synchronization signal and chip enable. Data can only be transferred into the device while SYNC is low. To start the serial data transfer, SYNC should be taken low, observing the minimum SYNC to SCLK active edge setup time, t4. After SYNC goes low, serial data will be shifted into the device's input shift register on the falling edges of SCLK for sixteen clock pulses. Any data and clock pulses after the sixteenth falling edge of SCLK will be ignored because the SCLK and DIN input buffers are powered down. No further serial data transfer will occur until SYNC is taken high and low again. SYNC may be taken high after the falling edge of the sixteenth SCLK pulse, observing the minimum SCLK falling edge to SYNC rising edge time, t7. After the end of serial data transfer, data will automatically be transferred from the input shift register to the input register of the selected DAC. If SYNC is taken high before the sixteenth falling edge of SCLK, the data transfer will be aborted and the DAC input registers will not be updated. When data has been transferred into three of the DAC input registers, all DAC registers and all DAC outputs may simultaneously be updated by setting LDAC low when writing to the remaining DAC input register. The AD5304/AD5314/AD5324 DACs all have double-buffered interfaces consisting of two banks of registers—input registers and DAC registers. The input register is directly connected to the input shift register and the digital code is transferred to the relevant input register on completion of a valid write sequence. The DAC register contains the digital code used by the resistor string. Access to the DAC register is controlled by the LDAC bit. When the LDAC bit is set high, the DAC register is latched and hence the input register may change state without affecting the contents of the DAC register. However, when the LDAC bit is set low, all DAC registers are updated after a complete write sequence. This is useful if the user requires simultaneous updating of all DAC outputs. The user may write to three of the input registers individually and then, by setting the LDAC bit low when writing to the remaining DAC input register, all outputs will update simultaneously. These parts contain an extra feature whereby the DAC register is not updated unless its input register has been updated since the last time that LDAC was brought low. Normally, when LDAC is brought low, the DAC registers are filled with the contents of the input registers. In the case of the AD5304/AD5314/AD5324, the part will only update the DAC register if the input register has been changed since the last time the DAC register was updated, thereby removing unnecessary digital crosstalk. POWER-DOWN MODE The AD5304/AD5314/AD5324 have low power consumption, dissipating only 1.5 mW with a 3 V supply and 3 mW with a 5 V supply. Power consumption can be further reduced when the DACs are not in use by putting them into power-down mode, which is selected by a zero on Bit 13 (PD) of the control word. –10– REV. B AD5304/AD5314/AD5324 When the PD bit is set to 1, all DACs work normally with a typical power consumption of 600 µA at 5 V (500 µA at 3 V). However, in power-down mode, the supply current falls to 200 nA at 5 V (80 nA at 3 V) when all DACs are powered down. Not only does the supply current drop, but the output stage is also internally switched from the output of the amplifier making it open-circuit. This has the advantage that the output is threestated while the part is in power-down mode, and provides a defined input condition for whatever is connected to the output of the DAC amplifier. The output stage is illustrated in Figure 32. AD5304/AD5314/AD5324 to 68HC11/68L11 Interface The bias generator, the output amplifier, the resistor string, and all other associated linear circuitry are all shut down when the power-down mode is activated. However, the contents of the registers are unaffected when in power-down. The time to exit power-down is typically 2.5 µs for VDD = 5 V and 5 µs when VDD = 3 V. This is the time from the falling edge of the sixteenth SCLK pulse to when the output voltage deviates from its powerdown voltage. See Figure 21 for a plot. Figure 34 shows a serial interface between the AD5304/AD5314/ AD5324 and the 68HC11/68L11 microcontroller. SCK of the 68HC11/68L11 drives the SCLK of the AD5304/AD5314/ AD5324, while the MOSI output drives the serial data line (DIN) of the DAC. 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 should be configured so that its CPOL bit is a 0 and its CPHA bit is a 1. When data is being transmitted to the DAC, the SYNC line is taken low (PC7). When the 68HC11/68L11 is configured as above, 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. In order to load data to the AD5304/ AD5314/AD5324, PC7 is left low after the first eight bits are transferred, a second serial write operation is performed to the DAC, and PC7 is taken high at the end of this procedure. AD5304/ AD5314/ AD5324* 68HC11/68L11* RESISTOR STRING DAC AMPLIFIER VOUT PC7 SYNC SCK SCLK MOSI POWER-DOWN CIRCUITRY DIN *ADDITIONAL PINS OMITTED FOR CLARITY. Figure 32. Output Stage During Power-Down MICROPROCESSOR INTERFACING AD5304/AD5314/AD5324 to ADSP-2101/ADSP-2103 Interface Figure 33 shows a serial interface between the AD5304/AD5314/ AD5324 and the ADSP-2101/ADSP-2103. The ADSP-2101/ ADSP-2103 should be set up to operate in the SPORT Transmit Alternate Framing Mode. The ADSP-2101/ADSP-2103 SPORT is programmed through the SPORT control register and should be configured as follows: Internal Clock Operation, Active-Low Framing, 16-Bit Word Length. Transmission is initiated by writing a word to the Tx register after the SPORT has been enabled. The data is clocked out on each rising edge of the DSP’s serial clock and clocked into the AD5304/AD5314/AD5324 on the falling edge of the DAC’s SCLK. AD5304/ AD5314/ AD5324* ADSP-2101/ ADSP-2103* TFS DT SCLK SYNC Figure 34. AD5304/AD5314/AD5324 to 68HC11/68L11 Interface AD5304/AD5314/AD5324 to 80C51/80L51 Interface Figure 35 shows a serial interface between the AD5304/AD5314/ AD5324 and the 80C51/80L51 microcontroller. The setup for the interface is as follows: TxD of the 80C51/80L51 drives SCLK of the AD5304/AD5314/AD5324, while 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 AD5304/AD5314/ AD5324, P3.3 is taken low. The 80C51/80L51 transmits data only in 8-bit bytes; 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 outputs the serial data in a format which has the LSB first. The AD5304/ AD5314/AD5324 requires its data with the MSB as the first bit received. The 80C51/80L51 transmit routine should take this into account. DIN SCLK AD5304/ AD5314/ AD5324* 80C51/80L51* *ADDITIONAL PINS OMITTED FOR CLARITY. Figure 33. AD5304/AD5314/AD5324 to ADSP-2101/ ADSP-2103 Interface P3.3 SYNC TxD SCLK RxD DIN *ADDITIONAL PINS OMITTED FOR CLARITY. Figure 35. AD5304/AD5314/AD5324 to 80C51/80L51 Interface REV. B –11– AD5304/AD5314/AD5324 The load regulation of the REF195 is typically 2 ppm/mA, which results in an error of 5.4 ppm (27 µV) for the 2.7 mA current drawn from it. This corresponds to a 0.0014 LSB error at 8 bits and 0.022 LSB error at 12 bits. AD5304/AD5314/AD5324 to MICROWIRE Interface Figure 36 shows an interface between the AD5304/AD5314/ AD5324 and any MICROWIRE-compatible device. Serial data is shifted out on the falling edge of the serial clock, SK and is clocked into the AD5304/AD5314/AD5324 on the rising edge of SK, which corresponds to the falling edge of the DAC’s SCLK. Bipolar Operation Using the AD5304/AD5314/AD5324 The AD5304/AD5314/AD5324 have been designed for singlesupply operation, but a bipolar output range is also possible using the circuit in Figure 38. This circuit will give 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. AD5304/ AD5314/ AD5324* MICROWIRE* CS SYNC SK SCLK SO DIN R2 = 10k⍀ +5V 5V A0 SERIAL INTERFACE Figure 38. Bipolar Operation with the AD5304 REFIN is the reference voltage input. VOUTC DIN SYNC SCLK SYNC N is the DAC resolution. VOUTB SCLK VOUTD GND DIN D is the decimal equivalent of the code loaded to the DAC. REFIN AD780/REF192 WITH VDD = 5V OR AD589 WITH VDD = 2.5V VOUTC where: VOUTA 1F 1F –5V VOUTB VOUT = [(REFIN × D/2N) × (R1+R2)/R1 – REFIN × (R2/R1)] AD5304/ AD5314/ AD5324 VIN REFIN The output voltage for any input code can be calculated as follows: VDD = 2.5V TO 5.5V 10F VOUT GND The AD5304/AD5314/AD5324 can be used with a wide range of reference voltages where the devices offer full, one-quadrant multiplying capability over a reference range of 0 V to VDD. More typically, these devices are used with a fixed, precision reference voltage. Suitable references for 5 V operation are the AD780 and REF192 (2.5 V references). For 2.5 V operation, a suitable external reference would be the AD589, a 1.23 V bandgap reference. Figure 37 shows a typical setup for the AD5304/ AD5314/AD5324 when using an external reference. EXT REF AD5304 REF195 VIN ⴞ5V VOUTA VDD APPLICATIONS Typical Application Circuit VOUT AD820/ OP295 0.1F 10F Figure 36. AD5304/AD5314/AD5324 to MICROWIRE Interface 0.1F R1 = 10k⍀ 6V TO 16V *ADDITIONAL PINS OMITTED FOR CLARITY. with: VOUTD REFIN = 5 V, R1 = R2 = 10 kΩ: GND VOUT = (10 × D/2N) – 5 V Opto-Isolated Interface for Process Control Applications SERIAL INTERFACE Figure 37. AD5304/AD5314/AD5324 Using External Reference If an output range of 0 V to VDD is required, the simplest solution is to connect the reference input to VDD. As this supply may not be very accurate and may be noisy, the AD5304/AD5314/ AD5324 may be powered from the reference voltage; for example, using a 5 V reference such as the REF195. The REF195 will output a steady supply voltage for the AD5304/AD5314/AD5324. The current required from the REF195 is 600 µA supply current and approximately 112 µA into the reference input. This is with no load on the DAC outputs. When the DAC outputs are loaded, the REF195 also needs to supply the current to the loads. The total current required (with a 10 kΩ load on each output) is: 712 µA + 4(5 V/10 kΩ) = 2.70 mA The AD5304/AD5314/AD5324 have a versatile 3-wire serial interface making them ideal for generating accurate voltages in process control and industrial applications. Due to noise, safety requirements or distance, it may be necessary to isolate the AD5304/AD5314/AD5324 from the controller. This can easily be achieved by using opto-isolators, which will provide isolation in excess of 3 kV. The actual data rate achieved may be limited by the type of optocouplers chosen. The serial loading structure of the AD5304/AD5314/ AD5324 makes them ideally suited for use in opto-isolated applications. Figure 39 shows an opto-isolated interface to the AD5304 where DIN, SCLK, and SYNC are driven from optocouplers. The power supply to the part also needs to be isolated. This 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 AD5304. –12– REV. B AD5304/AD5314/AD5324 5V REGULATOR POWER 10F 0.1F VDD 10k⍀ VDD SCLK SCLK REFIN AD5304 VDD 10k⍀ A digitally programmable upper/lower limit detector using two of the DACs in the AD5304/AD5314/AD5324 is shown in Figure 41. The upper and lower limits for the test are loaded to DACs A and B which, in turn, set the limits on the CMP04. If the signal at the VIN input is not within the programmed window, an LED will indicate the fail condition. Similarly, DACs C and D can be used for window detection on a second VIN signal. 5V VOUTA SYNC SYNC AD5304/AD5314/AD5324 as a Digitally Programmable Window Detector 0.1F VOUTB 10F VIN VOUTC VOUTD VREF VDD 1k⍀ FAIL PASS VDD REFIN VOUTA 10k⍀ DIN 1k⍀ DIN SYNC GND DIN SCLK SYNC DIN 1/2 AD5304/ AD5314/ AD5324* 1/2 CMP04 VOUTB SCLK PASS/FAIL 1/6 74HC05 GND Figure 39. AD5304 in an Opto-Isolated Interface *ADDITIONAL PINS OMITTED FOR CLARITY Decoding Multiple AD5304/AD5314/AD5324s The SYNC pin on the AD5304/AD5314/AD5324 can be used in applications to decode a number of DACs. In this application, all the DACs in the system receive the same serial clock and serial data, but the SYNC to only one of the devices will be active at any one time, allowing access to four channels in this 16channel system. The 74HC139 is used as a 2-to-4-line decoder to address any of the DACs in the system. To prevent timing errors, the enable input should be brought to its inactive state while the coded address inputs are changing state. Figure 40 shows a diagram of a typical setup for decoding multiple AD5304 devices in a system. SCLK AD5304 SYNC DIN VDD DIN SCLK VCC ENABLE CODED ADDRESS 1G 1Y0 1A 1Y1 1B 74HC139 1Y2 1Y3 VOUTA VOUTB VOUTC VOUTD AD5304 SYNC DIN SCLK DGND VOUTA VOUTB VOUTC VOUTD AD5304 SYNC DIN SCLK VOUTA VOUTB VOUTC VOUTD AD5304 SYNC DIN SCLK VOUTA VOUTB VOUTC VOUTD Figure 40. Decoding Multiple AD5304 Devices in a System REV. B Figure 41. Window Detection POWER SUPPLY BYPASSING AND GROUNDING In any circuit where accuracy is important, careful consideration of the power supply and ground return layout helps to ensure the rated performance. The printed circuit board on which the AD5304/AD5314/AD5324 is mounted should be designed so that the analog and digital sections are separated, and confined to certain areas of the board. If the AD5304/AD5314/AD5324 is in a system where multiple devices require an AGND-to-DGND connection, the connection should be made at one point only. The star ground point should be established as close as possible to the device. The AD5304/AD5314/AD5324 should have ample supply bypassing of 10 µF in parallel with 0.1 µF on the supply located as close to the package as possible, ideally right up against the device. The 10 µF capacitors are the tantalum bead type. The 0.1 µF capacitor should have low Effective Series Resistance (ESR) and Effective Series Inductance (ESI), like the common ceramic types that provide a low impedance path to ground at high frequencies, to handle transient currents due to internal logic switching. The power supply lines of the AD5304/AD5314/AD5324 should use as large a trace as possible to provide low impedance paths and reduce the effects of glitches on the power supply line. Fast switching signals such as clocks should be shielded with digital ground to avoid radiating noise to other parts of the board, and should never be run near the reference inputs. Avoid crossover of digital and analog signals. Traces on opposite sides of the board should run at right angles to each other. This reduces the effects of feedthrough through the board. A microstrip technique is by far the best, but not always possible with a double-sided board. In this technique, the component side of the board is dedicated to ground plane while signal traces are placed on the solder side. –13– AD5304/AD5314/AD5324 Table II. Overview of All AD53xx Serial Devices Resolution No. of DACs DNL Interface Settling Time Package Pins AD5300 AD5310 AD5320 8 10 12 1 1 1 ± 0.25 ± 0.5 ± 1.0 SPI SPI SPI 4 µs 6 µs 8 µs SOT-23, microSOIC SOT-23, microSOIC SOT-23, microSOIC 6, 8 6, 8 6, 8 AD5301 AD5311 AD5321 8 10 12 1 1 1 ± 0.25 ± 0.5 ± 1.0 2-Wire 2-Wire 2-Wire 6 µs 7 µs 8 µs SOT-23, microSOIC SOT-23, microSOIC SOT-23, microSOIC 6, 8 6, 8 6, 8 AD5302 AD5312 AD5322 8 10 12 2 2 2 ± 0.25 ± 0.5 ± 1.0 SPI SPI SPI 6 µs 7 µs 8 µs microSOIC microSOIC microSOIC 8 8 8 AD5303 AD5313 AD5323 8 10 12 2 2 2 ± 0.25 ± 0.5 ± 1.0 SPI SPI SPI 6 µs 7 µs 8 µs TSSOP TSSOP TSSOP 16 16 16 AD5304 AD5314 AD5324 8 10 12 4 4 4 ± 0.25 ± 0.5 ± 1.0 SPI SPI SPI 6 µs 7 µs 8 µs microSOIC microSOIC microSOIC 10 10 10 AD5305 AD5315 AD5325 8 10 12 4 4 4 ± 0.25 ± 0.5 ± 1.0 2-Wire 2-Wire 2-Wire 6 µs 7 µs 8 µs microSOIC microSOIC microSOIC 10 10 10 AD5306 AD5316 AD5326 8 10 12 4 4 4 ± 0.25 ± 0.5 ± 1.0 2-Wire 2-Wire 2-Wire 6 µs 7 µs 8 µs TSSOP TSSOP TSSOP 16 16 16 AD5307 AD5317 AD5327 8 10 12 4 4 4 ± 0.25 ± 0.5 ± 1.0 SPI SPI SPI 6 µs 7 µs 8 µs TSSOP TSSOP TSSOP 16 16 16 Part No. SINGLES DUALS QUADS Visit our web-page at http://www.analog.com/support/standard_linear/selection_guides/AD53xx.html –14– REV. B AD5304/AD5314/AD5324 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 0.122 (3.10) 0.114 (2.90) 10 6 0.199 (5.05) 0.187 (4.75) 0.122 (3.10) 0.114 (2.90) 1 5 PIN 1 0.0197 (0.50) BSC 0.037 (0.94) 0.031 (0.78) 0.120 (3.05) 0.112 (2.85) 0.120 (3.05) 0.112 (2.85) C3721a–2.5–6/00 (rev. B) 00929 10-Lead microSOIC (RM-10) 0.043 (1.10) MAX 0.028 (0.70) 0.016 (0.40) PRINTED IN U.S.A. 6ⴗ 0.006 (0.15) 0.012 (0.30) SEATING 0ⴗ PLANE 0.009 (0.23) 0.002 (0.05) 0.006 (0.15) 0.005 (0.13) REV. B –15–