DA C7 716 DAC7716 DA C7 716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 Quad, 12-Bit, High-Accuracy, ±16V Output, Serial Input DIGITAL-TO-ANALOG CONVERTER FEATURES DESCRIPTION 1 • • • • • 2345 • • • • • • • • • Bipolar Output: Up to ±16V Unipolar Output: 0V to +20V 12-Bit Monotonic Relative Accuracy: 1 LSB Max Low Zero and Gain Errors – Before User Calibration: 0.5 LSB – After User Calibration: 0.0078 LSB Zero Error, 0.0625 LSB Gain Error Low Noise: 60nV/√Hz Settling Time: 6µs Configurable Gain: x2/x4 Analog Output Monitor Power-Down Mode SPI™: Up to 50MHz, 1.8V/3V/5V Logic Daisy-Chain Mode Operating Temperature: –40°C to +105°C Packages: QFN-40 (6x6mm), TQFP-48 (7x7mm) APPLICATIONS • • • • Automatic Test Equipment Instrumentation Industrial Process Control Communications IOVDD DGND DVDD AGND AVDD AVSS REF-A REFGND-A DAC7716 Command Register Reference Buffer A Analog Monitor CS SCLK SDI SPI Shift Register Input Control Logic Zero Register 0 Gain Register 0 12-Bit DAC Zero Register 1 Gain Register 1 RST RFB1-2 RFB2-2 VOUT-2 SGND-2 UNI/BIP-A 12-Bit DAC DAC Register 2 UNI/BIP-B LDAC GPIO-0 GPIO-1 Zero Register 2 Gain Register 2 Control Logic RFB1-3 RFB2-3 VOUT-3 SGND-3 12-Bit DAC DAC Register 3 Zero Register 3 Gain Register 3 Reference Buffer B The DAC7716 is pin-compatible with the DAC8734 (16-bit) and the DAC8234 (14-bit). RFB1-1 RFB2-1 VOUT-1 SGND-1 SDO DAC Register 1 The DAC7716 has integrated reference buffers and output buffers. It features a standard high-speed 1.8V, 3V, or 5V serial peripheral interface (SPI) that operates at clock rates of up to 50MHz to communicate with a DSP or microprocessor. The four DAC channels and the auxiliary registers are addressed with four address bits. The device features double-buffered interface logic for simultaneous updates of all DACs. An asynchronous load input (LDAC) transfers data from the input data register to the DAC latch, and the contents of the DAC latch set the output voltage. The asynchronous RST input sets the output of all four DACs to 0V. The VMON pin is an analog monitor output that multiplexes the individual DAC outputs or the AIN pin. RFB1-0 RFB2-0 VOUT-0 SGND-0 12-Bit DAC DAC Register 0 VMON The DAC7716 is a high-accuracy, quad-channel, 12-bit digital-to-analog converter (DAC) that operates from supply voltages of ±5V to ±18V in bipolar output mode, and from ±5V to +24V/–12V in unipolar mode. With a 5V reference, the DAC7716 can be configured to output ±10V, ±5V, 0V to 20V, or 0V to 10V. The DAC7716 provides 12-bit monotonicity, excellent integral nonlinearity (INL) error of ±1 LSB, low glitch, and low noise over the operating temperature range of –40°C to +105°C. This device is trimmed in production for very low zero and gain errors. In addition, the DAC7716 implements a user-programmable system-level calibration function to achieve ±0.0078 LSB zero error and ±0.0625 LSB gain error. Power-Down Control Logic AIN REF-B REFGND-B 1 2 3 4 5 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. DSP is a trademark of Texas Instruments. SPI, QSPI are trademarks of Motorola Inc. Microwire is a trademark of National Semiconductor. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2009, Texas Instruments Incorporated DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. PACKAGE/ORDERING INFORMATION (1) PRODUCT RELATIVE ACCURACY (LSB) DIFFERENTIAL LINEARITY (LSB) ±1 ±1 DAC7716 (1) PACKAGELEAD PACKAGE DESIGNATOR SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ±1 QFN-40 RHA –40°C to +105°C DAC7716 ±1 TQFP-48 PFB –40°C to +105°C DAC7716 For the most current package and ordering information, see the Package Option Addendum at the end of this data sheet, or see the TI website at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range (unless otherwise noted). AVDD to AVSS (2) DAC7716 UNIT –0.3 to 38 V AVDD to AGND (2) –0.3 to 25 V AVSS to AGND, DGND (2) –19 to 0.3 V DVDD to DGND –0.3 to 6 V IOVDD to DGND –0.3 to DVDD + 0.3 V Digital input voltage to DGND –0.3 to IOVDD + 0.3 V SDO to DGND –0.3 to IOVDD + 0.3 V SGND-x, REFGND-x, AGND to DGND VOUT-x, RFB1-x, RFB2-x, VMON, AIN to AVSS REF-x to REFGND-x, AGND GPIO-x to DGND –0.3 to +0.3 V –0.3 to AVDD + 0.3 V –0.3 to min(AVDD/2, –AVSS/2) V –0.3 to 6 V 5 mA Operating temperature range –40 to +105 °C Storage temperature range –65 to +150 °C GPIO-x input current Maximum junction temperature (TJ max) ESD ratings +150 °C Human body model (HBM) 4 kV Charged device model (CDM) 1 kV TQFP 57 °C/W QFN 32 °C/W TQFP 35 °C/W 20 °C/W (TJ max – TA) / θJA W Junction-to-ambient, θJA Thermal impedance Junction-to-case, θJC QFN Power dissipation (3) (1) (2) (3) 2 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to absolute maximum conditions for extended periods may affect device reliability. AVSS must be < –3.5V if AVDD ≥ 1V. TA is the ambient temperature. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS All specifications at TA = TMIN to TMAX, AVDD = +11V to +18V, AVSS = –11V to –18V, VREF = REF-A = REF-B = +5V, DVDD = +5V, IOVDD = +1.8V to DVDD, AGND = DGND = REFGND-A = REFGND-B = SGND-x = 0V, and DAC gain = 4, unless otherwise noted. DAC7716 PARAMETER CONDITIONS MIN TYP MAX UNIT ±1 LSB ±1 LSB ±0.5 LSB STATIC PERFORMANCE Bipolar Output Resolution 12 Bits Linearity error, INL Differential linearity error, DNL TA = +25°C, before user calibration Bipolar zero error (1) Bipolar zero error TC Gain error TA = +25°C, after user calibration (2) ±0.0078 (2) ±0.5 TA = +25°C, before user calibration (1) LSB ppm FSR/°C ±0.5 TA = +25°C, after user calibration (2) Gain error TC (2) LSB ±0.5 DC crosstalk (2) (3) LSB ±0.0625 Output unloaded ppm FSR/°C ±0.1 LSB Unipolar Output Resolution 12 Bits Linearity error, INL AVDD = +21V, AVSS = –11V ±1 LSB Differential linearity error, DNL AVDD = +21V, AVSS = –11V ±1 LSB ±0.5 LSB AVDD = +21V, AVSS = –11V, TA = +25°C, before user calibration Zero error Zero error TC AVDD = +21V, AVSS = –11V, TA = +25°C, after user calibration (2) (2) ±0.0078 AVDD = +21V, AVSS = –11V ±0.2 AVDD = +21V, AVSS = –11V, TA = +25°C, before user calibration Gain error AVDD = +21V, AVSS = –11V DC crosstalk (2) (3) AVDD = +21V, AVSS = –11V, output unloaded ppm FSR/°C ±0.5 AVDD = +21V, AVSS = –11V, TA = +25°C, after user calibration (2) Gain error TC (2) LSB LSB ±0.0625 LSB ±0.5 ppm FSR/°C ±0.1 LSB ANALOG OUTPUT (VOUT-0 to VOUT-3) Bipolar voltage output (4) Unipolar voltage output (4) Output voltage drift vs time Output impedance (2) AVDD = +16.5V, AVSS = –16.5V, VREF = +7.5V, gain = 4 –15 +15 V VREF = +5V, gain = 4 –10 +10 V 0 +20 V AVDD = +21V, AVSS = –11V, VREF = +5V, gain = 4 Operating for 500 hours at +25°C 2 ppm of FSR Operating for 1000 hours at +25°C 3 ppm of FSR ±3mA load current Short-circuit current (2) (5) Load current (4) 10 Output changes no more than ±1 LSB Power-supply rejection (1) (2) (3) (4) (5) mA ±3 Capacitive load stability (2) (2) (4) Ω 0.005 mA 700 AVDD = +5V to +18V, AVSS = –5V to –18V, DVDD = 5V ±10%, VREF = 2V ±0.1 pF LSB See the User Calibration for Zero-Code Error and Gain Error section for details. Specified by design and characterization. DC crosstalk is the dc change in the output of one channel as a result of a full-scale code change and subsequent output change on another channel. The DAC outputs are buffered by op amps that share common AVDD and AVSS power supplies. Multiple VDD and VSS terminals are provided to minimize dc crosstalk. The analog output must not be greater than (AVDD – 1.0V) and must not be less than (AVSS + 1.0V). When the output current is greater than the specification, the current is clamped at the specified maximum value. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 3 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com ELECTRICAL CHARACTERISTICS (continued) All specifications at TA = TMIN to TMAX, AVDD = +11V to +18V, AVSS = –11V to –18V, VREF = REF-A = REF-B = +5V, DVDD = +5V, IOVDD = +1.8V to DVDD, AGND = DGND = REFGND-A = REFGND-B = SGND-x = 0V, and DAC gain = 4, unless otherwise noted. DAC7716 PARAMETER CONDITIONS MIN TYP MAX UNIT AC PERFORMANCE (6) To 0.1% of FS, CL = 200pF, RL= 10kΩ, output changes from –10V to +10V or +10V to –10V 6 µs To 1 LSB, CL = 200pF, RL = 10kΩ, output changes from –10V to +10V or +10V to –10V 7 µs To 1 LSB, CL = 200pF, RL = 10kΩ, code changes 512 LSBs 3 µs Slew rate (7) CL = 200pF, RL = 10kΩ 5 V/µs Recovery time from power-down mode Delay from clearing bit PD-x to when DAC returns to normal operation 50 µs Digital-to-analog glitch (8) 1 LSB code change around midscale 8 nV-s Glitch impulse peak amplitude 1 LSB code change around midscale 15 mV Settling time Channel-to-channel isolation (9) –80 dB DAC-to-DAC crosstalk (10) 2 nV-s Digital crosstalk (11) 2 nV-s Digital feedthrough (12) 2 nV-s 1 µVRMS 40 µVRMS 0.1Hz to 10Hz, ±10V output range, gain = 4, midscale code Output noise 0.1Hz to 100kHz, ±10V output range, gain = 4, midscale code 1/f corner frequency Output noise spectral density MONITOR PIN (VMON) 500 Hz TA = +25°C, at 10kHz, ±10V output range, gain = 4, midscale code 60 nV/√Hz TA = +25°C, at 10kHz, 0V to +10V output range, gain = 2, midscale code 45 nV/√Hz (6) Output impedance Ω 2200 High-impedance leakage current 100 nA Continuous current limit 0.5 mA REFERENCE INPUT Reference input voltage range 1 Reference input dc impedance 10 Reference input capacitance (6) 8 V 100 MΩ 20 pF (6) (7) (8) Specified by design and characterization. Slew rate is measured from 10% to 90% of the transition when the output changes from negative full-scale to positive full-scale. Digital-to-analog glitch is defined as the amount of energy injected into the analog output at the major code transition. It is specified as the area of the glitch in nV-s. It is measured by toggling the DAC register data between 000h and FFFh in twos complement format. (9) Channel-to-channel isolation refers to the ratio of the signal amplitude at the output of one DAC channel to the amplitude of the sinusoidal signal on the reference input of another DAC channel. It is expressed in dB and measured at midscale. (10) DAC-to-DAC crosstalk is the glitch impulse that appears at the output of one DAC as a result of both the full-scale digital code and subsequent analog output change at another DAC. It is measured with LDAC tied low and expressed in nV-s. (11) Digital crosstalk is the glitch impulse transferred to the output of one converter as a result of a full-scale code change in the DAC input register of another converter. It is measured when the DAC output is not updated, and is expressed in nV-s. (12) Digital feedthrough is the glitch impulse injected to the output of a DAC as a result of a digital code change in the DAC input register of the same DAC. It is measured with the full-scale digital code change without updating the DAC output, and is expressed in nV-s. 4 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS (continued) All specifications at TA = TMIN to TMAX, AVDD = +11V to +18V, AVSS = –11V to –18V, VREF = REF-A = REF-B = +5V, DVDD = +5V, IOVDD = +1.8V to DVDD, AGND = DGND = REFGND-A = REFGND-B = SGND-x = 0V, and DAC gain = 4, unless otherwise noted. DAC7716 PARAMETER CONDITIONS MIN TYP MAX UNIT DIGITAL INPUTS (13) (SDI, CS, SCLK, RST, UNI/BIP-A, UNI/BIP-B, LDAC, GPIO-x) High-level input voltage, VIH Low-level input voltage, VIL IOVDD = 4.5V to 5.5V 2.5 IOVDD + 0.3 V IOVDD = 2.7V to 3.3V 2.1 IOVDD + 0.3 V IOVDD = +1.8V 1.6 IOVDD + 0.3 V IOVDD = 4.5V to 5.5V –0.3 0.8 V IOVDD = 2.7V to 3.3V –0.3 0.6 V IOVDD = +1.8V –0.3 0.2 V 1 µA Input current Input capacitance 5 pF DIGITAL OUTPUTS (13) (SDO, GPIO-x) SDO high-level output voltage, VOH IOVDD = 2.7V to 5.5V, sourcing 1mA SDO low-level output voltage, VOL IOVDD = 2.7V to 5.5V, sinking 1mA 0.4 IOVDD = +1.8V, sinking 200µA 0.2 V 1 µA IOVDD = +1.8V, sourcing 200µA IOVDD – 0.4 V 1.6 V SDO high-impedance leakage SDO high-impedance output capacitance GPIO low-level output voltage, VOL GPIO open-drain high-level output leakage current V 10 pF IOVDD = 2.7V to 5.5V, sinking 1mA 0 0.4 V IOVDD = +1.8V, sinking 1mA 0 0.4 V 1 µA GPIO in Hi-Z and configured as output POWER SUPPLY AVDD (14) +4.75 +24 V AVSS (15) –18 –4.75 V DVDD +2.7 +5.5 V IOVDD +1.7 DVDD AIDD (normal operation) ±10V output range, no loading current, VOUT = 0V 2.7 ±10V output range, no loading current, VOUT = 0V 3.3 AIDD (power-down) AISS (normal operation) AISS (power-down) 3.4 V mA/Channel 100 µA 4.0 mA/Channel 100 µA DIDD Static current through the DVDD pin with VIH = IOVDD and VIL = DGND 25 50 µA IOIDD VIH = IOVDD, VIL = DGND ±1 ±10 µA Power dissipation (normal operation) ±12V power, no loading current, VOUT = 0V 290 mW TEMPERATURE RANGE Specified performance –40 +105 °C (13) Specified by design and characterization. (14) AVDD should not be greater than +24V or less than +4.75V. Also, AVDD should not be less than ( 2 × VREF + 1V) for bipolar output mode and should not be less than (Gain × VREF + 1V) for unipolar output mode. In any case, (AVDD – AVSS) ≤ +36V. (15) AVSS should not be greater than –4.75V or less than –18V. Also, AVSS should not be greater than (–2 × VREF – 1V). In any case, (AVDD – AVSS) ≤ +36V. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 5 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com FUNCTIONAL BLOCK DIAGRAM IOVDD DGND DVDD AGND AVDD AVSS REF-A REFGND-A AIN RFB1-0 RFB1-1 RFB1-2 RFB1-3 Reference Buffer A SCLK SDI SDO Command Register SPI Shift Register CS To DAC-0, DAC-1 RFB1-0 RFB2 RFB2-0 User Calibration: Zero Register 0 Gain Register 0 LDAC GPIO-0 GPIO-1 Control Logic RST UNI/BIP-B VMON RFB1 DAC-0 Input Data Register 0 UNI/BIP-A Mux Analog Monitor DAC7716 VOUT-0 Latch-0 LDAC Power-On/ Power-Down Control SGND-0 RFB1-1 RFB2-1 DAC-1 VOUT-1 SGND-1 AIN RFB1-2 RFB2-2 DAC-2 VOUT-2 SGND-2 RFB1-3 RFB2-3 DAC-3 VOUT-3 Internal Trimming Zero, Gain, INL SGND-3 To DAC-2, DAC-3 (Same Function Blocks for All Channels) REF-B 6 Power-On/ Power-Down Control Reference Buffer B REFGND-B Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 PIN CONFIGURATIONS 29 2 SCLK AVDD VMON SDI 3 28 AVSS SDO 4 27 REFGND-B 38 VOUT-3 37 NC 39 RFB2-3 41 SGND-3 40 RFB1-3 43 SGND-2 42 NC 45 RFB2-2 44 RFB1-2 47 AIN 46 VOUT-2 VOUT-3 31 30 1 CS 48 UNI/BIP-B RFB2-3 32 SGND-2 SGND-3 RFB1-2 35 RFB1-3 RFB2-2 36 34 VOUT-2 38 37 PFB PACKAGE TQFP-48 (TOP VIEW) 33 UNI/BIP-B AIN 40 39 RHA PACKAGE(1) QFN-40 (TOP VIEW) NC 1 36 CS 2 35 AVDD SCLK 3 34 VMON NC SDI 4 33 AVSS SDO 5 32 REFGND-B LDAC 6 31 REF-B RST 7 30 REF-A LDAC 5 26 REF-B RST 6 25 REF-A GPIO-0 7 24 REFGND-A GPIO-0 8 29 REFGND-A AVSS GPIO-1 9 28 AVSS UNI/BIP-A 10 27 AGND DGND 11 26 AVDD NC 12 25 NC (1) 24 NC NC RFB2-1 22 18 19 SGND-0 VOUT-1 23 17 RFB1-0 RFB1-1 21 16 RFB2-0 SGND-1 20 15 20 VOUT-1 IOVDD 19 SGND-0 RFB2-1 16 RFB1-0 17 15 RFB2-0 18 14 VOUT-0 RFB1-1 13 DVDD SGND-1 11 12 IOVDD AVDD 13 21 10 DGND AGND VOUT-0 22 9 UNI/BIP-A 14 23 8 GPIO-1 DAC7716 DVDD DAC7716 The thermal pad is internally connected to the substrate. This pad can be connected to AVSS or left floating. PIN DESCRIPTIONS PIN NO. PIN NAME QFN-40 TQFP-48 I/O CS 1 2 I SPI bus chip select input (active low). Data are not clocked into the SPI shift register unless CS is low. When CS is high, SDO is in a high-impedance state. SCLK 2 3 I SPI bus clock SDI 3 4 I SPI bus input data SDO 4 5 O SPI output data LDAC 5 6 I Load DAC latch control input (active low). When LDAC is low, the DAC latch is transparent and the contents of the Input Data Register are transferred to it. The DAC output changes to the corresponding level simultaneously when the DAC latch is updated. RST 6 7 I Reset input (active low). Logic low on this pin resets the input registers and DACs to the values defined by the UNI/BIP pins, and sets the Gain Register and Zero Register to default values. GPIO-0 7 8 I/O General-purpose digital input/output 0. This pin is a bidirectional, digital input/output, and has an open-drain output. A 10kΩ pull-up resistor to IOVDD is needed when this pin is used as an output. See the GPIO Pins section for details. GPIO-1 8 9 I/O General-purpose digital input/output 1. This pin is a bidirectional, digital input/output, and has an open-drain output. A 10kΩ pull-up resistor to IOVDD is needed when this pin is used as an output. See the GPIO Pins section for details. UNI/BIP-A 9 10 I Output mode selection of group A (DAC-0 and DAC-1). When UNI/BIP-A is tied to IOVDD, group A is in unipolar output mode; when tied to DGND, group A is in bipolar output mode. The input data written to the DAC are straight binary for unipolar output mode and twos complement for bipolar output mode. DGND 10 11 I Digital ground IOVDD 11 13 I Interface power DVDD 12 14 I Digital power VOUT-0 13 15 O DAC-0 output DESCRIPTION Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 7 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com PIN DESCRIPTIONS (continued) PIN NAME QFN-40 TQFP-48 I/O RFB2-0 (1) 14 16 O DAC-0 RFB2 feedback RFB1-0 (1) 15 17 O DAC-0 RFB1 feedback SGND-0 16 18 I DAC-0 signal ground. Connected to REFGND-A. SGND-1 17 20 I DAC-1 signal ground. Connected to REFGND-A. (1) 18 21 O DAC-1 RFB1 feedback RFB2-1 (1) 19 22 O DAC-1 RFB2 feedback VOUT-1 20 23 O DAC-1 output AVDD 21, 30 26, 35 I Positive analog power supply AGND 22 27 I Analog ground AVSS 23, 28 28, 33 I Negative analog power supply REFGND-A 24 29 I Reference REF-A ground. Connect to AGND. REF-A 25 30 I Group A (DAC-0, DAC-1) reference input REF-B 26 31 I Group B (DAC-2, DAC-3) reference input REFGND-B 27 32 I Reference REF-B ground. Connect to AGND. VMON 29 34 O Analog monitor output. This pin is either in Hi-Z status, or connected to one of the four DAC outputs or AIN, depending on the content of the Monitor Register. RFB1-1 (1) 8 PIN NO. DESCRIPTION VOUT-3 31 38 O DAC-3 output RFB2-3 (1) 32 39 O DAC-3 RFB2 feedback RFB1-3 (1) 33 40 O DAC-3 RFB1 feedback SGND-3 34 41 I DAC-3 signal ground. Connected to REFGND-B. SGND-2 35 43 I DAC-2 signal ground. Connected to REFGND-B. RFB1-2 (1) 36 44 O DAC-2 RFB1 feedback RFB2-2 (1) 37 45 O DAC-2 RFB2 feedback VOUT-2 38 46 O DAC-2 output AIN 39 47 I Auxiliary analog input. Connected to the analog monitor mux. UNI/BIP-B 40 48 I Output mode selection of group B (DAC-2 and DAC-3). When UNI/BIP-A is tied to IOVDD, group B is in unipolar output mode; when tied to DGND, group B is in bipolar output mode. The input data written to the DAC are straight binary for unipolar output mode, and twos complement for bipolar output mode. NC — 1, 12, 19, 24, 25, 36, 37, 42 Not connected To set the DAC-x gain = 2, connect RFB1-x and RFB2-x to VOUT-x, and set the corresponding GAIN bit in the Command Register to '0'. To set the DAC-x gain = 4, connect RFB1-x to VOUT-x, keep RFB2-x open, and set the corresponding GAIN bit in the Command Register to '1'. After power-on reset or user reset, the GAIN bits are set to '1' by default; for gain = 2, the gain bits must be cleared to '0'. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 TIMING DIAGRAMS Case 1: Stand-alone mode, LDAC tied low. t8 t4 CS t1 SCLK Input Data Register and DAC Latch Updated(1) tF t5 LDAC tR t3 t2 t6 BIT 23 (MSB) SDI t7 BIT 22 BIT 1 BIT 0 Low Case 2: Stand-alone mode, LDAC active high. t8 t4 CS t1 SCLK BIT 22 BIT 1 BIT 0 Input Word To Write the Data to the Selected DAC High Input Data Register Updated but DAC Latch is Not Updated tF t6 BIT 23 (MSB) SDI LDAC tR t3 t2 t5 t7 t9 t10 DAC Latch Updated = Don’t Care Bit 23 = MSB Bit 0 = LSB Figure 1. SPI Timing for Stand-Alone Mode TIMING CHARACTERISTICS For Figure 1 (1) (2) (3) At TA = –40°C to +105°C, unless otherwise noted. 2.7V ≤ DVDD ≤ 5.5V, IOVDD = 1.8V PARAMETER MIN 2.7V ≤ DVDD ≤ 3.6V, 2.7V ≤ IOVDD ≤ DVDD MAX MIN MAX MIN 40 MAX UNIT 50 MHz fSCLK Clock frequency t1 SCLK cycle time 33 25 20 ns t2 SCLK high time 16 12 10 ns t3 SCLK low time 16 12 10 ns t4 CS falling edge to SCLK falling edge (4) 11 9 7 ns t5 Input data setup time 5 5 5 ns t6 Input data hold time 5 5 5 ns t7 SCLK falling edge to CS rising edge 15 12 10 ns t8 CS high time 60 50 30 ns t9 CS rising edge to LDAC falling edge 30 25 20 ns t10 LDAC pulse width 25 20 15 ns RST pulse width 25 20 15 ns (1) (2) (3) (4) 30 3.6V < DVDD ≤ 5.5V, 2.7V ≤ IOVDD ≤ DVDD Specified by design and characterization. Sample tested during the initial release and after any redesign or process changes that may affect these parameters. All input signals are specified with tR = tF = 2ns (10% to 90% of IOVDD) and timed from a voltage level of IOVDD/2. The first SCLK edge after CS goes low must be a falling edge. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 9 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com Case 3: Daisy-Chain mode, LDAC tied low. t8 t4 CS t1 SCLK tR t3 t2 t6 BIT 23 (N) BIT 22 (N) BIT 0 (N) BIT 23 (N+1) t11 BIT 0 (N+1) t12 BIT 23 (N) SDO LDAC Input Data Register and DAC Latch Updated(1) tF t5 SDI t7 BIT 0 (N) Low Case 4: Daisy-Chain mode, LDAC active. t8 t4 CS t1 SCLK t6 BIT 23 (N) BIT 22 (N) BIT 0 (N) BIT 23 (N+1) t11 BIT 0 (N+1) t12 BIT 23 (N) SDO LDAC Input Data Register Updated but DAC Latch is Not Updated tF t5 SDI tR t3 t2 t7 BIT 0 (N) t9 High t10 DAC Latch Updated = Don’t Care Bit 23 = MSB Bit 0 = LSB Figure 2. SPI Timing for Daisy-Chain Mode 10 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 Case 5: Readback for Stand-alone mode. t4 t8 t7 CS SCLK Input Data Register Updated tR t1 t2 t3 t5 t6 tF BIT 23 SDI BIT 0 BIT 22 BIT 23 Input Word Specifies Register to be Read t13 SDO LDAC BIT 22 t11 BIT 23 BIT 1 t12 BIT 22 BIT 0 Write NOP Command BIT 1 BIT 0 Data from the Selected Register Low = Don’t Care Bit 23 = MSB Bit 0 = LSB Figure 3. SPI Timing for Readback Operation in Stand-Alone Mode TIMING CHARACTERISTICS For Figure 2 to Figure 3 (1) (2) (3) At TA = –40°C to +105°C, unless otherwise noted. 2.7V ≤ DVDD ≤ 5.5V, IOVDD = 1.8V PARAMETER MIN 2.7V ≤ DVDD ≤ 3.6V, 2.7V ≤ IOVDD ≤ DVDD MAX MIN MIN UNIT 25 MHz Clock frequency t1 SCLK cycle time 66 50 40 ns t2 SCLK high time 33 25 20 ns t3 SCLK low time 33 25 20 ns t4 CS falling edge to SCLK falling edge (4) 25 22 17 ns t5 Input data setup time 5 5 5 ns t6 Input data hold time 5 5 5 ns t7 SCLK falling edge to CS rising edge 15 12 10 ns t8 CS high time 60 50 30 ns t9 CS rising edge to LDAC falling edge 30 25 20 ns t10 LDAC pulse width 25 t11 SDO data valid from SCLK rising edge t12 SDO data hold time from SCLK falling edge t13 SDO data valid from CS falling edge (1) (2) (3) (4) 20 MAX fSCLK RST pulse width 15 MAX 3.6V < DVDD ≤ 5.5V, 2.7V ≤ IOVDD ≤ DVDD 20 25 30 15 20 25 20 25 20 17 20 ns 15 ns ns 12 15 ns ns Specified by design and characterization. Sample tested during the initial release and after any redesign or process changes that may affect these parameters. All input signals are specified with tR = tF = 2ns (10% to 90% of IOVDD) and timed from a voltage level of IOVDD/2. The first SCLK edge after CS goes low must be a falling edge. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 11 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 INL Error (LSB) 0.6 0.4 0.2 0 -0.2 -0.4 1.0 0.6 0.2 0 -0.2 -0.4 -0.6 -0.8 -0.8 -1.0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 0 1024 1536 2048 2560 Digital Input Code 3072 3584 Figure 5. LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) DIFFERENTIAL LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) 1.0 TA = +105°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 0.6 0.4 0.2 0 -0.2 -0.4 1.0 4095 TA = +105°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 -1.0 -1.0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 Figure 6. Figure 7. LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) DIFFERENTIAL LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) 1.0 TA = -40°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 0.6 0.4 0.2 0 -0.2 -0.4 1.0 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 -1.0 4095 TA = -40°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 DNL Error (LSB) 0 -1.0 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 0 Figure 8. 12 512 Figure 4. DNL Error (LSB) 0 INL Error (LSB) 0.4 -0.6 -1.0 INL Error (LSB) TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.8 DNL Error (LSB) 1.0 DIFFERENTIAL LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 Figure 9. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) LINEARITY ERROR vs DIGITAL INPUT CODE (All Channels, Bipolar Operation) 1.0 Channel 0 Channel 1 Channel 2 Channel 3 0.8 INL Error (LSB) 0.6 0.4 0.2 0 -0.2 TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V -0.4 -0.6 -0.8 -1.0 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 Figure 10. LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) TA = +25°C Gain = 4 VREF = 5V AVDD = +12V AVSS = -12V 0.8 INL Error (LSB) 0.6 0.4 0.2 0 -0.2 -0.4 1.0 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 -1.0 -1.0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 Figure 11. Figure 12. LINEARITY ERROR vs DIGITAL INPUT CODE (Unipolar 0V to 20V Operation) DIFFERENTIAL LINEARITY ERROR vs DIGITAL INPUT CODE (Unipolar 0V to 20V Operation) 1.0 TA = +25°C Gain = 4 VREF = 5V AVDD = +24V AVSS = -12V 0.8 0.6 0.4 0.2 0 -0.2 -0.4 1.0 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 -1.0 4095 TA = +25°C Gain = 4 VREF = 5V AVDD = +24V AVSS = -12V 0.8 DNL Error (LSB) 0 INL Error (LSB) TA = +25°C Gain = 4 VREF = 5V AVDD = +12V AVSS = -12V 0.8 DNL Error (LSB) 1.0 DIFFERENTIAL LINEARITY ERROR vs DIGITAL INPUT CODE (Bipolar Operation) -1.0 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 0 Figure 13. 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 Figure 14. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 13 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS (continued) LINEARITY ERROR vs TEMPERATURE (Bipolar Operation) DIFFERENTIAL LINEARITY ERROR vs TEMPERATURE (Bipolar Operation) 0.4 0.4 Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V INL Error (LSB) 0.2 INL Max 0.2 0.1 0 -0.1 INL Min -0.1 -0.3 -0.3 DNL Min -0.4 5 20 35 50 65 Temperature (°C) 80 95 110 125 -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 110 125 Figure 15. Figure 16. LINEARITY ERROR vs REFERENCE VOLTAGE (Bipolar Operation) DIFFERENTIAL LINEARITY ERROR vs REFERENCE VOLTAGE (Bipolar Operation) 0.4 0.4 TA = +25°C Gain = 4 AVDD = +18V AVSS = -18V 0.2 INL Max 0.2 0.1 0 -0.1 TA = +25°C Gain = 4 AVDD = +18V AVSS = -18V 0.3 DNL Error (LSB) 0.3 INL Error (LSB) 0 -0.2 -40 -25 -10 INL Min DNL Max 0.1 0 -0.1 -0.2 -0.2 -0.3 -0.3 -0.4 DNL Min -0.4 1 2 3 4 5 VREF (V) 6 7 8 1 3 4 5 VREF (V) 6 7 Figure 18. LINEARITY ERROR vs SUPPLY VOLTAGE (Bipolar Operation) DIFFERENTIAL LINEARITY ERROR vs SUPPLY VOLTAGE (Bipolar Operation) 0.4 TA = +25°C Gain = 4 VREF = 2V 0.3 0.2 0.1 0 INL Min 0.2 DNL Max 0.1 0 -0.1 -0.2 -0.2 -0.3 -0.3 -0.4 8 TA = +25°C Gain = 4 VREF = 2V 0.3 DNL Error (LSB) INL Max -0.1 2 Figure 17. 0.4 INL Error (LSB) DNL Max 0.1 -0.2 -0.4 DNL Min -0.4 4.5 6.0 7.5 9.0 10.5 12.0 13.5 +AVDD , -AVSS (V) 15.0 16.5 18.0 4.5 Figure 19. 14 Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 0.3 DNL Error (LSB) 0.3 6.0 7.5 9.0 10.5 12.0 13.5 +AVDD , -AVSS (V) 15.0 16.5 18.0 Figure 20. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) 0.5 1.5 0.4 Bipolar Zero Error (mV) 2.0 1.0 0.5 0 -0.5 TA = +25°C Gain = 4 AVDD = +18V AVSS = -18V -1.0 -1.5 -2.0 1 Bipolar Gain Error (mV) BIPOLAR ZERO ERROR vs REFERENCE VOLTAGE (10 Units, 40 Channels Total) 2 3 4 5 6 Reference Voltage (V) 7 0.2 0.1 0 -0.1 -0.2 TA = +25°C Gain = 4 AVDD = +18V AVSS = -18V -0.3 -0.4 8 1 2 3 4 5 6 Reference Voltage (V) 7 Figure 21. Figure 22. BIPOLAR GAIN ERROR vs TEMPERATURE (10 Units, 40 Channels Total) BIPOLAR ZERO ERROR vs TEMPERATURE (10 Units, 40 Channels Total) 2.0 1.0 1.5 0.8 1.0 0.5 0 -0.5 Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V -1.0 -1.5 8 0.6 0.4 0.2 0 -0.2 -0.4 Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V -0.6 -0.8 -1.0 -2.0 -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 110 125 -40 -25 -10 5 20 35 50 65 Temperature (°C) 80 95 Figure 23. Figure 24. UNIPOLAR ZERO ERROR vs REFERENCE VOLTAGE (10 Units, 40 Channels Total) UNIPOLAR ZERO ERROR vs TEMPERATURE (10 Units, 40 Channels Total) TA = +25°C Gain = 4 AVDD = +24V AVSS = -12V 0.05 0 -0.05 -0.10 -0.15 0.3 0.2 0.1 0 -0.1 Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V -0.2 -0.3 -0.20 110 125 0.4 Unipolar Zero Error (mV) 0.10 Unipolar Zero Error (mV) 0.3 -0.5 Bipolar Zero Error (mV) Bipolar Gain Error (mV) BIPOLAR GAIN ERROR vs REFERENCE VOLTAGE (10 Units, 40 Channels Total) -0.4 1.0 1.5 2.0 2.5 3.0 3.5 Reference Voltage (V) 4.0 4.5 5.0 -40 -25 -10 Figure 25. 5 20 35 50 65 Temperature (°C) 80 95 110 125 Figure 26. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 15 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS (continued) DELTA OUTPUT VOLTAGE vs SOURCE/SINK CURRENT (Bipolar Operation) TOTAL SUPPLY CURRENT vs DIGITAL INPUT CODE 14 6 TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V Code Change for One Channel All Other Channel Outputs = 0V 12 11 10 9 BTC 7FFh 4 DVOUT (mV) AIDD, AISS (mA) 13 TA = +25°C Gain = 4 VREF = 5V AVDD = +12V AVSS = -12V BTC 800h |AISS| BTC C00h 2 BTC 400h +1 LSB 0 -1 LSB -2 -4 |AIDD| 8 -6 0 512 1024 1536 2048 2560 Digital Input Code 3072 3584 4095 -12 -10 -8 -4 -2 0 2 ILOAD (mA) 4 6 Figure 27. Figure 28. MAJOR CARRY GLITCH MAJOR CARRY GLITCH BTC Code Change: 000h to FFFh 2mV/div -6 VOUT VOUT 5V/div LDAC 10 12 TA = +25°C Gain = 4 VREF = 5V DVDD = 5V AVDD = +15V AVSS = -15V BTC Code Change: FFFh to 000h TA = +25°C Gain = 4 VREF = 5V DVDD = 5V AVDD = +15V AVSS = -15V 8 2mV/div 5V/div Time (0.5ms/div) LDAC Time (0.5ms/div) Figure 29. Figure 30. SETTLING TIME (+10V to –10V Transition) SETTLING TIME (–10V to +10V Transition) Small-Signal Error 4.8mV/div 5V/div Large-Signal Output 5V/div Large-Signal Output TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 10kW || 200pF LDAC TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 10kW || 200pF 5V/div 5V/div LDAC Time (5ms/div) Time (5ms/div) Figure 31. 16 4.8mV/div Small-Signal Error Figure 32. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS (continued) 0.1Hz TO 10Hz NOISE (Bipolar Operation) IOVDD SUPPLY CURRENT vs LOGIC INPUT VOLTAGE IOVDD Supply Current (mA) Noise (2mV/div) 1.2 TA = +25°C Gain = 4 VREF = 0V AVDD = +15V AVSS = -15V Midscale Code TA = +25°C AVDD = +15V AVSS = -15V 1.0 IOVDD = 5V 0.8 0.6 0.4 0.2 IOVDD = 2.7V 0 Time (1s/div) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Logic Input Voltage (V) Figure 33. AIDD PRODUCTION DISTRIBUTION 5.0 AISS PRODUCTION DISTRIBUTION 30 AIDD (mA/Channel) AISS (mA/Channel) Figure 35. Figure 36. BIPOLAR GAIN ERROR PRODUCTION DISTRIBUTION 4.00 3.80 3.90 3.60 3.70 3.40 3.50 3.20 3.30 3.00 3.10 3.40 3.30 3.10 3.20 2.90 3.00 2.70 2.80 2.60 2.50 2.40 0 2.30 0 2.10 5 2.20 5 2.80 10 2.90 10 15 2.60 15 20 2.70 20 TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V VOUT = 0V 25 Population (%) TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V VOUT = 0V 25 Population (%) 4.5 Figure 34. 30 BIPOLAR ZERO ERROR PRODUCTION DISTRIBUTION 25 70 15 10 TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 60 50 Population (%) TA = +25°C Gain = 4 VREF = 5V AVDD = +15V AVSS = -15V 20 Population (%) 4.0 40 30 20 5 Bipolar Zero Error (LSB) Figure 37. Figure 38. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 0.5000 0.0500 0.0625 0.0250 Bipolar Gain Error (LSB) 0.0375 0.0125 0 -0.0125 -0.0250 -0.0375 -0.0500 -0.0625 0 -0.5000 0.5000 0.0625 0.0375 0.0500 0.0125 0.0250 0 -0.0125 -0.0250 -0.0375 -0.0500 -0.0625 0 -0.5000 10 17 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com TYPICAL CHARACTERISTICS (continued) UNIPOLAR GAIN ERROR PRODUCTION DISTRIBUTION UNIPOLAR ZERO ERROR PRODUCTION DISTRIBUTION 25 90 Population (%) 20 15 10 TA = +25°C Gain = 4 VREF = 5V AVDD = +24V AVSS = -12V 80 70 Population (%) TA = +25°C Gain = 4 VREF = 5V AVDD = +24V AVSS = -12V 60 50 40 30 20 5 18 Unipolar Zero Error (LSB) Figure 39. Figure 40. Submit Documentation Feedback 0.5000 0.0500 0.0625 0.0250 Unipolar Gain Error (LSB) 0.0375 0.0125 0 -0.0125 -0.0250 -0.0375 -0.0500 -0.0625 0 -0.5000 0.5000 0.0625 0.0375 0.0500 0.0125 0.0250 0 -0.0125 -0.0250 -0.0375 -0.0500 -0.0625 -0.5000 10 0 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 THEORY OF OPERATION DAC ARCHITECTURE The DAC7716 is a highly-integrated, quad-channel, 12-bit, voltage-output DAC with internal reference buffers and output buffers. Each channel consists of an R-2R ladder configuration with the three MSBs segmented, followed by an operational amplifier, as shown in Figure 41. The DAC7716 has a high-impedance, buffered reference input; the output of the reference buffers drives the R-2R ladders. The output buffer is designed to allow user-configurable adjustments, giving the DAC7716 four different output voltage range settings. With the production trim process, this device has excellent dc accuracy and ac performance. R From Reference Buffer Output 2R 2R 2R S15 S14 S10 2R S9 R 2R S8 R 2R S7 R 2R S6 2R S0 2R RFB VOUT Three MSBs Decoded Into Seven Equal Segments 9-Bit R-2R Ladder SGND Figure 41. DAC7716 Architecture CHANNEL GROUPS The four DAC channels are arranged into two groups (A and B) with two channels per group. Group A consists of DAC-0 and DAC-1, and Group B consists of DAC-2 and DAC-3. The two DAC channels of Group A derive their reference voltage from REF-A, and those of Group B from REF-B. USER-CALIBRATION FOR ZERO ERROR AND GAIN ERROR The DAC7716 implements a user-calibration function that allows for trimming the system gain and zero errors. Each DAC channel has a Gain Register and Zero Register and the DAC output is calibrated according to the value of the corresponding registers. The range of gain adjustment is typically ±0.195% of full-scale with 0.0625 LSB per step. The zero code adjustment is typically ±0.0488% of full-scale with 0.0078 LSB per step. The input data format of the Gain and Zero registers is twos complement. Refer to Table 9 and Table 10 for more details. If the system-level calibration is not needed, these registers should be left at the respective default values (0000h) at power-on. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 19 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com TRANSFER FUNCTION FOR THE ANALOG OUTPUTS (VOUT-0 to VOUT-3) For bipolar output: VOUT = Gain ´ VREF ´ INPUT_CODE ZERO_CODE + 128 ´ 4096 4096 ´ INPUT_CODE ZERO_CODE + 128 ´ 4096 4096 ´ 1+ GAIN_CODE 32 ´ 4096 (1) For unipolar output: VOUT = Gain ´ VREF ´ 1+ GAIN_CODE 16 ´ 4096 (2) Where: GAIN is the DAC gain, which can be set to x2 or x4 and is determined by the connection of pins RFB1-x and RFB2-x to VOUT-x, and the GAIN bit in the Command Register. INPUT_CODE is the decimal equivalent value of the code written into the DAC input register. ZERO_CODE is the decimal equivalent value of the code written into the Zero Register. GAIN_CODE is the decimal equivalent value of the code written into the Gain Register. Note that the output voltage must not be greater than (AVDD – 1.0V) or less than (AVSS + 1.0V); otherwise, the output may be saturated. Input Data Format For bipolar output operation, INPUT_CODE is always twos complement, and can accept values between –2048 to 2047. For unipolar output operation, INPUT_CODE is always straight binary, and can accept values between 0 to 4095. GAIN_CODE is always in twos complement format, and can accept values between –128 and +127. ZERO_CODE is always in twos complement format and can accept values between –256 and +255. The data written to the Command and Monitor registers are written as specified in the definitions. For read operations, the read-back data format is the same as the format used to write to the device. Refer to the Internal Registers section for more details. OUTPUT RANGE Each channel of the DAC7716 implements an output amplifier that provides a unipolar output or a bipolar output with a gain of 2 or 4. The output span equals the gain times the reference voltage. For a 5V reference, the output range can be configured as ±10V, ±5V, 0V to 20V, or 0V to 10V. The status of the UNI/BIP pin determines the output mode (unipolar or bipolar) of each group. When the UNI/BIP-A pin is high, the outputs of Group A (DAC-0 and DAC-1) are unipolar; when the pin is low, the outputs of Group A are bipolar. Similarly, the UNI/BIP-B pin defines the output mode of Group B (DAC-2 and DAC-3). Each individual DAC can be configured with a gain of 4 or a gain of 2. To set the gain = 4, connect RFB1-x to VOUT-x with RFB2-x left open, and set the gain bit for that channel to '1' in the Command Register. To set the gain = 2, connect both RFB1-x and RFB2-x to VOUT-x, and set the gain bit for that channel to '0'. The gain bits in the Command Register are set to '1' by default at power-on or reset, and must be cleared to '0' for gain = 2. Note that the power supplies must meet the following requirements: • AVDD must not be greater than 24V or less than 4.75V, and AVSS must not be greater than –4.75V or less than –18V. In any case, (AVDD – AVSS) ≤ 36V. • For bipolar mode: AVDD ≥ 2 × VREF + 1V, and AVSS ≤ –2 × VREF – 1V. • For unipolar mode: AVDD ≥ Gain × VREF + 1V, and AVSS ≤ –2 × VREF – 1V. For example, for a 5V reference in bipolar operation, the minimum supplies must be at least ±11V, regardless of whether the output range is ±5V or ±10V. For unipolar operation with the same reference, the supplies must be at least ±11V for a 0V to 10V operation, and +21V/–11V for a 0V to +20V operation. 20 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 UPDATING THE DAC OUTPUTS The DAC7716 has a double-buffered interface that consists of two register banks for every channel: the input register and the DAC latch. The digital code is transferred from the SPI shift register to the addressed channel input register upon completion of a valid write sequence. The DAC latch contains the digital code used by the resistor R-2R ladder. The contents of the DAC latch define the output from the DAC. The DAC outputs can be updated individually or simultaneously. The DAC7716 updates the DAC latch only if it has been accessed since the last time the LDAC pin was brought low or the LD bit in the Command Register was set to '1', thereby eliminating any unnecessary glitch. The DAC channels that were not accessed are not reloaded, and the output values remain unchanged. Individual DAC Channel Update In this mode, the LDAC pin is held low while the CS pin is low and the data are clocked into the SPI shift register. At the end of the data transfer into the shift register, the CS pin is brought high. This action updates both the addressed input data register and the corresponding DAC latch register. The DAC latch register controls the R-2R switches; thus, an update on the DAC latch register updates the corresponding DAC channel analog output. Simultaneous Update of Multiple DAC Channels In this mode, the LDAC pin is held high while the CS pin is low and data are clocked into the SPI shift register. At the end of the data transfer into the shift register, the CS pin is brought high. This action updates only the addressed input data register; it does not update the DAC latch register or change the output. The DAC latch and the analog output are updated only when the LDAC pin goes low, or when the LD bit in the Command Register is set to '1' at anytime after the input data register is written. HARDWARE RESET When the RST pin is low, the device is in hardware reset. All the analog outputs (VOUT-0 to VOUT-3), the input registers, and the DAC latches are set to the reset values shown in Table 1. All registers are loaded with default values. Communication is disabled, and the signals on the SDI, CS, and SCLK pins are ignored. On the rising edge of the RST pin, the analog outputs (VOUT-0 to VOUT-3) maintain the reset value (0V) until a new value is programmed. After the RST pin goes high, the device returns to normal operation. Note that the default values of the gain bits in the Command Register are '1' after a reset. For gain = 2, the gain bits must be cleared to '0'. Table 1. Reset Values UNI/BIP PIN OUTPUT MODE INPUT FORMAT VALUE OF INPUT REGISTER AND DAC LATCH VOUT DGND Bipolar Twos Complement 0000h 0V IOVDD Unipolar Straight Binary 0000h 0V Setting the RST bit in the Command Register to '1' performs a software reset, which is functionally the same as a hardware reset. After reset completes, the RST bit returns to '0' automatically. POWER-ON RESET On power-on, the input data registers and DAC latches are loaded with the value defined by the UNI/BIP pins (see Table 1). All other registers are loaded with default values. After power-on, the outputs of the VOUT pins are set to 0V. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 21 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com ANALOG OUTPUT MONITOR PIN (VMON) The VMON pin is the analog output monitor. The analog output monitor function consists of an analog multiplexer addressed via the serial interface, allowing one of the four channel outputs or the AIN input to be routed to this pin for monitoring. The monitor function is controlled by the Monitor Register, which allows the monitored output to be enabled or disabled. When all multiplexer channels are disabled, the monitor output is high impedance; therefore, several monitor outputs can be connected in parallel with only one enabled at a time. Table 5 shows the settings relevant to the monitor function. Note that the multiplexer is implemented as a series of analog switches. Care should be taken to ensure the maximum current from the VMON pin must not be greater than the given specification because such a condition could conceivably cause a large amount of current to flow from the input of the multiplexer (that is, from VOUT-x or AIN) to the output of the multiplexer (VMON). Also, the VMON pin output impedance is approximately 2.2kΩ; therefore, VMON should be measured with a high-impedance input. POWER-DOWN MODE The DAC7716 implements a group power-down feature to reduce power consumption in case some channels are idle. When the power-down bit (PD-A and/or PD-B) in the Command Register is set to '1', the corresponding group goes into a power-down state. During power-down, the reference buffer and output buffers of that group are powered down and the corresponding analog outputs are set to 0V through an internal 10kΩ resistor to AGND. The contents of the internal registers do not change, and the bus interface remains active in order to continue communication and receive commands from the host controller. Any internal register can be read from or written to. The host controller can wake the device from power-down mode and return to normal operating mode by clearing the power-down bit (PD-A and/or PD-B) in the Command Register. Recovery completes in approximately 50µs. POWER-SUPPLY SEQUENCING In order to ensure proper initialization of the DAC7716, the digital supplies (DVDD and IOVDD) and logic inputs (UNI/BIP-x) must be applied before AVSS and AVDD. Additionally, AVSS must be applied before AVDD unless both can ramp up at the same time. REF-x should be applied after AVDD comes up in order to make sure the ESD protection circuitry does not turn on. GENERAL-PURPOSE INPUT/OUTPUT PINS (GPIO-0, -1) The GPIO-0 and GPIO-1 pins are general-purpose, bidirectional, digital input/output (I/O) signals, as Figure 42 shows. These pins can receive an input or produce an output. When the GPIO-n pin acts as an output, it has an open-drain, and the status is determined by the corresponding GPIO-n bit of the Command Register. The output status is high impedance when the GPIO-n bit is set to '1', and is logic low when the GPIO-n bit is cleared ('0'). Note that a 10kΩ pullup resistor is required when using the GPIO-n pin as an output. To use the GPIO-n pin as an input, the GPIO-n bits in the Command Register must be set to '1'. When the GPIO-n pin acts as input, the digital value on the pin is acquired by reading the GPIO-n bit. After a power-on reset or any forced hardware or software reset, all GPIO-n bits are set to '1', and the GPIO-n pin goes to a high-impedance state. +V GPIO-x Enable Bit GPIO-x (when writing) Bit GPIO-x (when reading) Figure 42. GPIO Pins 22 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 SERIAL INTERFACE The DAC7716 is controlled over a versatile, three-wire serial interface that operates at clock rates of up to 50MHz and is compatible with SPI, QSPI™, Microwire™, and DSP™ standards. SPI Shift Register The SPI Shift Register is 24 bits wide. Data are loaded into the device MSB first as a 24-bit word under the control of the serial clock input, SCLK. The falling edge of CS starts the communication cycle. Data are latched into the SPI Shift Register on the falling edge of SCLK while CS is low. When CS is high, SCLK is blocked, SDI is ignored, and the SDO line is in a high-impedance state. The contents of the SPI Shift Register are loaded into the addressed internal register on the rising edge of CS. The SPI Shift Register consists of a read/write bit, four register address bits, 12 data bits, and seven reserved bits, as shown in Table 2. The timing for this operation is shown in the Timing Diagrams section. When the device is loaded, the command is decoded, and the new data are transferred into the proper data registers. The serial interface works with both continuous and non-continuous serial clocks. A continuous SCLK source can only be used if CS is held low for the correct number of clock cycles. In gated clock mode, a burst clock containing the exact number of clock cycles must be used and CS must be taken high after the final clock in order to latch the data. Stand-Alone Operation The first falling edge of CS starts the operation cycle. Exactly 24 falling clock edges must be applied before CS is brought back high again. If CS is brought high before the 24th falling SCLK edge, then the data are ignored. If more than 24 falling SCLK edges are applied before CS is brought high, then the last 24 bits are considered. The addressed internal register is updated from the Shift Register on the rising edge of CS. In order for another serial transfer to take place, CS must be brought low again. When the data have been transferred into the chosen register of the addressed DAC, all DAC latches and analog outputs can be updated by taking the LDAC pin low or setting the LD bit in the Command Register. Daisy-Chain Operation For systems that contain more than one device, the SDO pin can be used to daisy-chain multiple devices together. Daisy-chain operation can be useful in system diagnostics and in reducing the number of serial interface lines. Note that before daisy-chain operation can begin, the SDO pin must be enabled by clearing the SDO disable bit in the Command Register (DSDO = '0'). By default, this bit is cleared after power-on or reset. The first falling edge of CS starts the operation cycle. SCLK is continuously applied to the input shift register when CS is low. If more than 24 clock pulses are applied, the data ripple out of the shift register and appear on the SDO line. These data are clocked out on the rising edge of SCLK and are valid on the falling edge. By connecting the SDO output of the first device to the SDI input of the next device in the chain, a multiple-device interface is constructed. Each device in the system requires 24 clock pulses. Therefore, the total number of clock cycles must equal 24 × N, where N is the total number of DAC7716s in the chain. When the serial transfer to all devices is complete, CS is taken high. This action latches data from the SPI shift register into the device input register of each device in the daisy-chain, and prevents any further data from being clocked in. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 23 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com Read-Back Operation The READ command is used to start read-back operation. However, before read-back operation can be initiated, the SDO pin must be enabled by clearing the DSDO bit in the Command Register (DSDO = '0'); this bit is cleared by default. Read-back operation is then started by executing a READ command (R/W bit = '1'; see Table 2). Bits A3 to A0 in the READ command select the register to be read. The remaining data in the command are don’t care bits. During the next SPI operation, the data that appear on the SDO output are from the previously addressed register. For a read of a single register, a NOP command can be used to clock out the data from the selected register on SDO. Multiple registers can be read if multiple READ commands are issued. The readback diagram in Figure 43 shows the read-back sequence. The read-back data format is the same format as what was used to write to the device. Single Reading CS SCLK DB23 SDI DB23 DB0 READ Command Specifies Register to be Read DB23 SDO DB0 NOP Command or Write Command DB23 DB0 Undefined DB0 Data from Selected Register Multiple Readings CS SCLK SDI DB23 DB0 DB23 Command to Read Register A SDO DB23 DB0 Undefined DB0 Command to Read Register B DB23 DB23 DB0 DB23 Command to Read Register C DB0 Data from Register A = Don’t Care DB23 DB0 Data from Register B DB0 NOP Command or Write Command DB23 DB0 Data from Register C DB23 = MSB DB0 = LSB Figure 43. Read-Back Operation 24 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 SPI SHIFT REGISTER The SPI Shift Register is 24 bits wide, as shown in Table 2. By default, the SPI shift register resets to 000000h at power-on or after a reset. Table 2. SPI Shift Register Format MSB (1) DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15:DB4 DB3:DB0 R/W 0 0 0 A3 A2 A1 A0 DATA Rsvd (1) Writing to a reserved bit has no effect; reading the bit returns '0'. R/W—Indicates a read from or a write to the addressed register. R/W = '0' sets a write operation and the data are written to the specified register. R/W = '1' sets a read-back operation. For read operation, bits A3 to A0 select the register to be read. The remaining are don’t care bits. During the next SPI operation, the data appearing on SDO pin are from the previously addressed register. [A3:A0]—Address bits that specify which register is accessed. DATA—12 data bits All DAC7716 registers (command registers and data registers) are 16-bit. Table 3 shows the register map. Table 3. Register Map ADDRESS BITS A3 A2 A1 A0 DATA BITS DB15 DB14 DB13 DB12 DB11 DB10 DB8 DB7 GPIO1 GPIO0 DB5: DB4 DB3: DB2 NOP GAIN Bits GAIN Bits DB1: DB0 Rsvd (1) REGISTER Command Register 0 0 0 A/B LD RST PD-A PD-B 0 0 0 1 MDAC-3 MDAC-2 MDAC-1 MDAC-0 AIN 0 1 0 0 D11:D0 Reserved (1) DAC-0 0 1 0 1 D11:D0 Reserved (1) DAC-1 0 1 1 0 D11:D0 Reserved (1) DAC-2 0 1 1 1 D11:D0 Reserved (1) DAC-3 1 0 0 0 Reserved (1) Z8:Z0 Zero Register-0 1 0 0 1 Reserved (1) Z8:Z0 Zero Register-1 1 0 1 0 Reserved (1) Z8:Z0 Zero Register-2 1 0 1 1 Reserved (1) Z8:Z0 Zero Register-3 1 1 0 0 Reserved (1) G7:G0 Gain Register-0 1 1 0 1 Reserved (1) G7:G0 Gain Register-1 1 1 1 0 Reserved (1) G7:G0 Gain Register-2 1 1 1 1 Reserved (1) G7:G0 Gain Register-3 (1) DSDO DB6 0 Others Rsvd (1) DB9 Monitor Register Reserved (1) Reserved (1) — Writing to a reserved bit has no effect; reading the bit returns '0'. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 25 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com INTERNAL REGISTERS The DAC7716 internal registers consist of the Command Register, the Monitor Register, the DAC Input Data Registers, the Zero Registers, and the Gain Registers. Command Register. Default = 033Ch. The Command Register determines the actions performed by the DAC7716. Table 4. Command Register BIT DB15 NAME A/B DEFAULT VALUE DESCRIPTION 0 A/B bit. When A/B = '0', reading DAC-x returns the value in the Input Data Register. When A/B = '1', reading DAC-x returns the value in the DAC latch. DB14 LD 0 Synchronously update DACs bit. Functions in the same manner as the LDAC pin. When LDAC is tied high, set LD = '1' at any time after the write operation and the correction process proceeds to synchronously update all DAC latches with the content of the corresponding Input Data Register, and sets VOUT to a new level. The DAC7716 updates the DAC latch only if it has been accessed since the last time LDAC was brought low or the LD bit was set to '1', thereby eliminating unnecessary glitch. Any DACs that were not accessed are not reloaded. After updating, the bit returns to '0'. Refer to the Updating Via LDAC section for details. When the LDAC pin is tied low, the LD bit is ignored. DB13 RST 0 Software reset bit. Set the RST bit to '1' to reset the device; functions the same as a hardware reset. After reset completes, the RST bit returns to '0'. DB12 PD-A 0 Power-down bit for Group A. Setting the PD-A bit to '1' places Group A (DAC-0 and DAC-1) into power-down operation. All output buffers are in Hi-Z and all analog outputs (VOUT-x) connect to AGND through an internal 10kΩ resistor. The interface remains active. Setting the PD-A bit to '0' returns Group A to normal operation. DB11 PD-B 0 Power-down bit for Group B. Setting the PD-B bit to '1' places Group B (DAC-2 and DAC-3) into power-down operation. All output buffers are in Hi-Z and all analog outputs (VOUT-x) connect to AGND through an internal 10kΩ resistor. The interface remains active. Setting the PD-B bit to '0' returns Group B to normal operation. DB10 Rsvd 0 Reserved. Writing to this bit has no effect; reading this bit returns '0'. DB9 GPIO-1 1 GPIO-1 status bit. Writing a '1' to the GPIO-1 bit puts the GPIO-1 pin into a Hi-Z state (default). Writing a '0' to the GPIO-1 bit forces the GPIO-1 pin low. When reading this bit, the digital value on the GPIO-1 pin is acquired. DB8 GPIO-0 1 GPIO-0 status bit. Writing a '1' to the GPIO-0 bit puts the GPIO-1 pin into a Hi-Z state (default). Writing a '0' to the GPIO-0 bit forces the GPIO-1 pin low. When reading this bit, the digital value on the GPIO-0 pin is acquired. DB7 DSDO 0 Disable SDO bit. Set the DSDO bit to '0' to enable the SDO pin (default). The SDO pin works as a normal SPI output. Set the DSDO bit to '1' to disable the SDO pin. The SDO pin is always in a Hi-Z state regardless of the status of the CS pin is. DB6 NOP 0 No operation bit. Writing '0' or '1' to this bit has no effect and the bit returns to '0' at the end of the write operation. Reading the bit always returns '0'. DB5 GAIN-3 1 DAC-3 gain bit. Set the GAIN-3 bit to '1' for a gain = 4. Set the GAIN-3 bit to '0' for a gain = 2. DB4 GAIN-2 1 DAC-2 gain bit. Set the GAIN-2 bit to '1' for a gain = 4. Set the GAIN-2 bit to '0' for a gain = 2. DB3 GAIN-1 1 DAC-1 gain bit. Set the GAIN-1 bit to '1' for a gain = 4. Set the GAIN-1 bit to '0' for a gain = 2. DB2 GAIN-0 1 DAC-0 gain bit. Set the GAIN-0 bit to '1' for a gain = 4. Set the GAIN-0 bit to '0' for a gain = 2. DB1:DB0 — 0 Reserved. Writing to these bits has no effect; reading these bits returns '0'. 26 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 Monitor Register. Default = 0000h. The Monitor Register selects one of the four DAC outputs or the external signal AIN that is to be monitored through the VMON pin. Only one bit can be set to '1' at a time. When all bits = '0', the monitor is disabled and VMON is placed in a high-impedance state. The default value after power-on or reset is 0000h. Table 5. Monitor Register DB15 DB14 DB13 DB12 DB11 DB10:DB0 0 0 0 0 1 Reserved (1) AIN 0 0 0 1 0 Reserved (1) DAC-0 0 0 1 0 0 Reserved (1) DAC-1 0 1 0 0 0 Reserved (1) DAC-2 1 0 0 0 0 Reserved (1) DAC-3 0 (1) 0 (1) 0 0 0 Reserved VMON CONNECTS TO Monitor disabled, Hi-Z (default) Writing to a reserved bit has no effect; reading the bit returns '0'. Input Data Register for DAC-n (where n = 0, 1, 2, or 3). Default = 0000h. This register stores the DAC data written to the device. When the data are loaded into the corresponding DAC latch, the DAC output changes to the new level defined by the DAC data. The default value after power-on or reset is 0000h. For bipolar operation, the input data format is always twos complement. For unipolar operation, the input data format is always straight binary. Table 6. DAC-n (n = 0, 1, 2, or 3) Input Data Register MSB DB15 D11 (1) (2) (1) LSB DB14 D10 DB13 DB12 D9 D8 DB11 D7 DB10 D6 DB9 D5 DB8 DB7 D4 D3 DB6 D2 DB5 D1 DB4 D0 DB3 DB2 DB1 Reserved DB0 (2) D11:D0 are the DAC data bits. Writing to a reserved bit has no effect; reading the bit returns '0'. Table 7. DAC Output vs Twos Complement Code for Bipolar Output Operation TWOS COMPLEMENT CODE (D11:D0) OUTPUT DESCRIPTION 0111 1111 1111 +0.5 × Gain × VREF × (2047/2048) +Full-Scale – 1 LSB ••• ••• ••• ••• ••• ••• 0000 0000 0000 +0.5 × Gain × VREF × (048) +1 LSB 0000 0000 0000 0 Zero 1111 1111 1111 –0.5 × Gain × VREF × (048) –1 LSB ••• ••• ••• ••• ••• ••• 1000 0000 0000 –0.5 × Gain × VREF × (2048/2048) –Full-Scale Table 8. DAC Output vs Straight Binary Code for Unipolar Output Operation STRAIGHT BINARY CODE (D11:D0) OUTPUT DESCRIPTION 1111 1111 1111 Gain × VREF × (4095/4096) +Full-Scale – 1 LSB ••• ••• ••• ••• ••• ••• 1000 0000 0000 Gain × VREF × (2048/4096) Full-Scale 0111 1111 1111 Gain × VREF × (2047/4096) Full-Scale – 1 LSB ••• ••• ••• ••• ••• ••• 0000 0000 0000 0 Zero Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 27 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com Zero Register n (where n = 0, 1, 2, or 3). Default = 0000h. The Zero Register stores the user-calibration data that are used to eliminate the offset error. The data are nine bits wide, 0.0078 LSB/step, and the total adjustment is typically –2 LSB to +1.9922 LSB, or ±0.0488% of full-scale range. The Zero Register uses a twos complement data format in both bipolar and unipolar modes of operation. Table 9. Zero Register (1) DB15:DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Reserved (1) Z8 Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0 Writing to a reserved bit has no effect; reading the bit returns '0'. Z8:Z0—OFFSET BITS ZERO ADJUSTMENT 011111111 +1.9922 LSB 011111110 +1.9844 LSB ••• ••• ••• ••• ••• ••• 000000001 +1.00781 LSB 000000000 0 LSB (default) 111111111 –1.00781 LSB ••• ••• ••• ••• ••• ••• 100000001 –1.9922 LSB 100000000 –2 LSB Gain Register n (where n = 0, 1, 2, or 3). Default = 0000h. The Gain Register stores the user-calibration data that are used to eliminate the gain error. The data are eight bits wide, 0.0625 LSB/step, and the total adjustment is typically –8 LSB to +7.9375 LSB, or ±0.195% of full-scale range. The Gain Register uses a twos complement data format in both bipolar and unipolar modes of operation. Table 10. Gain Register DB15:DB8 Reserved (1) 28 (1) DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 G7 G6 G5 G4 G3 G2 G1 G0 Writing to a reserved bit has no effect; reading the bit returns '0'. G7:G0—GAIN-CODE BITS GAIN ADJUSTMENT 01111111 +7.9375 LSB 01111110 +7.875 LSB ••• ••• ••• ••• ••• ••• 00000001 +0.0625 LSB 00000000 0 LSB (default) 11111111 –0.0625 LSB ••• ••• ••• ••• ••• ••• 10000001 –7.9375 LSB 10000000 –8 LSB Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 APPLICATION INFORMATION BASIC OPERATION 46 45 44 43 42 41 40 39 38 37 VOUT-2 RFB2-2 RFB1-2 SGND-2 NC SGND-3 RFB1-3 RFB2-3 VOUT-3 NC VOUT-3 47 AIN VOUT-2 48 UNI/BIP-B AIN The DAC7716 is a highly-integrated device with high-performance reference buffers and output buffers, greatly reducing the printed circuit board (PCB) area and cost. On-chip reference buffers eliminate the need for a negative external reference. Configurable on-chip output buffers support four different output modes. Figure 44 shows a basic application for the DAC7716. NC 36 AVDD 35 SCLK VMON 34 4 SDI AVSS 33 SDO 5 SDO REFGND-B 32 LDAC 6 LDAC REF-B 31 REF-B RST 7 RST REF-A 30 REF-A 8 GPIO-0 REFGND-A 29 9 GPIO-1 AVSS 28 1 NC CS 2 CS SCLK 3 SDI 0.1mF 10 UNI/BIP-A 11 DGND 12 NC 27 AVDD 26 NC 25 10mF VOUT-0 RFB2-0 RFB1-0 SGND-0 NC SGND-1 RFB1-1 RFB2-1 VOUT-1 NC 15 16 17 18 19 20 21 22 23 24 DVDD 14 0.1mF 13 10kW IOVDD 0.1mF 10kW + 10mF AVSS 0.1mF AGND 10mF VMON 0.1mF DAC7716 + + + 10mF 10mF AVDD 0.1mF + 10mF VOUT-1 DVDD VOUT-0 IOVDD + NOTES: AVDD = +15V, AVSS = -15V, DVDD = +5V, IOVDD = +1.8 to +5V, REF-A = +5V, and REF-B = +2.5V. The gain bits in the Command Register are: GAIN-0 = ‘0’, GAIN-1 = ‘1’, GAIN-2 = ‘0’, and GAIN-3 = ‘1’. The DACs are set to the following gains: DAC-0 = x2, DAC-1 = x4, DAC-2 = x2, and DAC-3 = x4. The output ranges are: VOUT-0 = -5V to +5V VOUT-1 = -10V to +10V, VOUT-2 = 0V to +5V, VOUT-3 = 0V to +10V. Figure 44. Basic Application Example Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 29 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com USER ZERO- AND GAIN-CALIBRATION The DAC7716 is trimmed during production for nominal operating conditions to have very low gain error and offset error. However, to trim the offset and gain errors introduced at other conditions of operation or by other components in the signal chain, the DAC7716 has a user zero and gain digital calibration feature for each DAC channel. Figure 45 and Figure 46 illustrate the relationship of zero and gain calibration for the DAC7716 in unipolar output and bipolar output configurations, respectively. Gain ´ VREF + Full Scale Full-Scale Range Analog Output 1LSB Gain Adjust Rotates the Transfer Function Input = 000h Input = FFFh Zero Scale Digital Input Zero Adjust Translates the Transfer Function Figure 45. Relationship of Zero and Gain Calibration for a Unipolar Output Configuration 0.5 ´ Gain ´ VREF + FullScale Analog Output Input = 800h Full-Scale Range 1LSB Gain Adjust Rotates the Transfer Function Zero Adjust Translates the Transfer Function Input = 7FFh Input = 000h - Full-Scale -0.5 ´ Gain ´ VREF Digital Input Figure 46. Relationship of Zero and Gain Calibration for a Bipolar Output Configuration 30 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 DAC7716 www.ti.com ........................................................................................................................................... SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 System Zero Adjust Example The DAC7716 zero calibration feature can minimize system offset errors to 0.00019% FSR or 38µV over a 20V output range. The total adjustment range is approximately ±0.0488% of FSR, or ±9.7mV over a 20V output span. Assuming that the DAC has been set up with a full-scale range of 20V, and the offset error to be eliminated from the signal chain is –1mV, then the step size = 0.0000019 × 20V = 38µV. -1 ´ Offset_Error Number of Steps of Zero Calibration = Step Size (3) Where Offset_Error is the value of the offset error to be corrected. For this example, the number of steps of zero calibration = 1mV / 38µV ≈ 26. Therefore, the Zero Register should be coded with the twos complement of 26 = 0 0001 1010. Suppose the offset error to be eliminated is +1mV instead; then the number of steps of zero calibration is the twos complement equivalent of –26, which is 1 1110 0110. System Gain Adjust Example The DAC7716 gain calibration feature can minimize system gain errors to 0.001525% FSR or 305µV over a 20V output range. The total adjustment range is approximately ±0.195% FSR, or –39mV to +38.7mV over a 20V output span. Assuming that the DAC has been set up with a full-scale range of 20V, and the gain error to be eliminated from the signal chain is –10mV, then the step size = 0.00001525 × 20V = 305µV. -1 ´ Gain_Error Number of Steps of Gain Calibration = Step Size (4) Where Gain_Error is the value of the gain error to be corrected. For this example, the number of steps of the gain calibration = 10mV/305µV ≈ 33. Therefore, the Gain Register should be coded with the twos complement of 33 = 0010 0001. Suppose the gain error to be eliminated is +10mV instead; then the number of steps of Gain calibration is the twos complement equivalent of –33, which is 1101 1111. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 31 DAC7716 SBAS463A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com LAYOUT AND GROUNDING Precision analog circuits require careful layout, adequate bypass capacitors, and a clean, well-regulated power supply to obtain the best possible dc and ac performance. A careful consideration of the power-supply and ground-return layout helps to ensure the rated performance. The PCB must be designed so that the analog and digital sections are separated and confined to certain areas of the board. Fast switching signals, such as clocks, must be shielded with the digital ground to avoid radiating noise to other sections of the board, and must never be run near the reference inputs. It is essential to minimize noise on the reference inputs because it couples through to the DAC output. Avoid crossover of digital and analog signals. Traces on opposite sides of the board must run at right angles to each other. This configuration reduces the effects of feedthrough on the board. A microstrip technique may be considered, but may not always be possible with a double-sided board. In this technique, the component side of the board is dedicated to the ground plane, and signal traces are placed on the solder side. DGND is the return path for digital currents and AGND is the analog power ground for the DAC. For the best ac performance, care should be taken to connect DGND and AGND with very low resistance back to the supply ground. If multiple devices require an AGND-to-DGND connection, the connection must be made at one point only. The star ground point must be established as close as possible to the device. Each DAC has a ground pin (SGND-x) that must be connected directly to the corresponding reference ground in low-impedance paths to achieve the best performance. SGND-0 and SGND-1 must be connected with REFGND-A, and SGND-2 and SGND-3 must be connected with REFGND-B. It is critical that this trace resistance be extremely small in order to prevent the voltage drops across the path from affecting device linearity and gain performance. The reference ground pins, REFGND-A and REFGND-B, must be connected to analog ground AGND. POWER-SUPPLY NOISE The DAC7716 should have ample supply bypassing of 1µF to 10µF in parallel with 0.1µF on each supply, located as close to the package as possible; ideally, placed next to the device. The 1µF to 10µF capacitors must be a tantalum-bead type. The 0.1µF capacitor must have low effective series resistance (ESR) and low effective series inductance (ESI), such as common ceramic types that provide a low-impedance path to ground at high frequencies to handle transient currents because of internal logic switching. The power-supply lines must use traces as wide as possible to provide low-impedance paths and reduce the effects of glitches on the power-supply line. Apart from these considerations, the wideband noise on the AVDD, AVSS, DVDD, and IOVDD supplies should be filtered before being fed to the DAC in order to obtain the best noise performance possible. PRECISION VOLTAGE REFERENCE SELECTION To achieve the optimum performance from the DAC7716 over its full operating temperature range, a precision voltage reference must be used. Consideration should be given to the selection of a precision voltage reference. The DAC7716 has two reference inputs, REF-A and REF-B. The voltages applied to the reference inputs are used to provide a buffered positive and negative reference for the DAC cores. Therefore, any error in the voltage reference is reflected in the outputs of the device. There are four possible sources of error to consider when choosing a voltage reference for high-accuracy applications: initial accuracy, temperature coefficient of the output voltage, long-term drift, and output voltage noise. Initial accuracy error on the output voltage of an external reference can lead to a full-scale error in the DAC. Therefore, to minimize these errors, a reference with a low initial accuracy error specification is preferred. Long-term drift is a measurement of how much the reference output voltage drifts over time. A reference with a tight, long-term drift specification ensures that the overall solution remains relatively stable over its entire lifetime. The temperature coefficient of a reference output voltage affects INL, DNL, gain error, and zero error. Choose a reference with a tight temperature coefficient specification to reduce the dependence of the DAC output voltage on ambient conditions. In high-accuracy applications that have a relatively low noise budget, reference output voltage noise must be considered. Choosing a reference with as low an output noise voltage as practical for the system resolution required is important. Precision voltage references such as the TI REF50xx (2V to 5V) and REF32xx (1.25V to 4V), provide low-drift and high-accuracy reference voltage. 32 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): DAC7716 PACKAGE OPTION ADDENDUM www.ti.com 7-Sep-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty DAC7716SPFB ACTIVE TQFP PFB 48 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR DAC7716SPFBR ACTIVE TQFP PFB 48 1000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR DAC7716SRHAR ACTIVE QFN RHA 40 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR DAC7716SRHAT ACTIVE QFN RHA 40 250 CU NIPDAU Level-2-260C-1 YEAR Green (RoHS & no Sb/Br) Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 15-Sep-2009 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant DAC7716SPFBR TQFP PFB 48 1000 330.0 16.4 9.6 9.6 1.5 12.0 16.0 Q2 DAC7716SRHAR QFN RHA 40 2500 330.0 16.4 6.3 6.3 1.5 12.0 16.0 Q2 DAC7716SRHAT QFN RHA 40 250 330.0 16.4 6.3 6.3 1.5 12.0 16.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 15-Sep-2009 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) DAC7716SPFBR TQFP PFB 48 1000 346.0 346.0 33.0 DAC7716SRHAR QFN RHA 40 2500 333.2 345.9 28.6 DAC7716SRHAT QFN RHA 40 250 333.2 345.9 28.6 Pack Materials-Page 2 MECHANICAL DATA MTQF019A – JANUARY 1995 – REVISED JANUARY 1998 PFB (S-PQFP-G48) PLASTIC QUAD FLATPACK 0,27 0,17 0,50 36 0,08 M 25 37 24 48 13 0,13 NOM 1 12 5,50 TYP 7,20 SQ 6,80 9,20 SQ 8,80 Gage Plane 0,25 0,05 MIN 0°– 7° 1,05 0,95 Seating Plane 0,75 0,45 0,08 1,20 MAX 4073176 / B 10/96 NOTES: A. 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