AD5378

32-Channel, 14-Bit, Parallel and Serial Input, Bipolar Voltage Output DAC Preliminary Technical Data FEATURES 32-channel DAC in 13 mm × 13 mm 108-lead CSPBGA Guaranteed monotonic to 14 bits Buffered voltage outputs Output voltage span of 3.5 V × VREF(+) Maximum output voltage span of 17.5 V System calibration function allowing user-programmable offset and gain Pseudo differential outputs relative to REFGND Clear function to user-defined REFGND (CLR pin) Simultaneous update of DAC outputs (LDAC pin) DAC increment/decrement mode Channel grouping and addressing features AD5378 Interface options Parallel interface DSP/microcontroller-compatible 3-wire serial interface 2.5 V to 5.5 V JEDEC-compliant digital levels SDO daisy-chaining option Power-on reset Digital reset (RESET pin and soft reset function) APPLICATIONS Level setting in automatic test equipment (ATE) Variable optical attenuators (VOAs) Optical switches Industrial control systems FUNCTIONAL BLOCK DIAGRAM VCC POWER-ON RESET RESET DCEN/WR SYNC/CS REG0 REG1 DB13 SCLK/DB12 DIN/DB11 14 VDD VSS AGND DGND LDAC VBIAS VREF1(+) VREF1(–) REFGND A1 VBIAS CLR AD5378 / INPUT 14 REG 0–1 14 / m REG0–1 c REG0–1 14 / DAC 14 REG 0–1 / DAC 0–1 VOUT 0 VOUT 1 / STATE MACHINE 14 INTERFACE DB0 A7 / INPUT 14 REG 2 14 / m REG2 c REG2 14 / DAC 14 REG 2 / DAC 2 VOUT 2 14 / 14 / VOUT 3 A0 SER/PAR DIN SCLK SDO FIFOEN REFGND B1 REFGND B2 REFGND C1 REFGND C2 REFGND D1 REFGND D2 BUSY 14 14 / INPUT 14 REG 5 14 / m REG7 c REG7 14 / DAC 14 REG 5 VOUT 4 / DAC 5 VOUT 5 / / / INPUT 14 REG 6–7 14 / DAC 14 REG 6–7 / DAC 6–7 VOUT 6 VOUT 7 VOUT 8 VOUT 31 05292-001 / m REG8–9 c REG8–9 ×4 VREF2(+) VREF2(–) REFGND A2 Figure 1. Protected by U.S. Patent No. 5,969,657 and 6,823,416; other patents pending. Rev. PrA Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 © 2005 Analog Devices, Inc. All rights reserved. AD5378 TABLE OF CONTENTS General Description ..........................................................................3 Specifications......................................................................................4 AC Characteristics........................................................................ 5 Timing Characteristics......................................................................6 Serial Interface .............................................................................. 6 Parallel Interface ........................................................................... 9 Absolute Maximum Ratings...........................................................11 ESD Caution ................................................................................ 11 Pin Configuration and Function Descriptions ............................12 Typical Performance Characteristics ............................................15 Terminology .....................................................................................17 Functional Description ...................................................................18 DAC Architecture—General ..................................................... 18 Channel Groups .......................................................................... 18 Transfer Function ....................................................................... 18 VBIAS Function ............................................................................. 19 Reference Selection .................................................................... 19 Calibration ................................................................................... 20 Preliminary Technical Data Clear Function ............................................................................ 20 BUSY and LDAC Functions...................................................... 20 FIFO vs. Non-FIFO Operation................................................. 21 BUSY Input Function ................................................................ 21 Power-On Reset Function ......................................................... 21 RESET Input Function .............................................................. 21 Increment/Decrement Function .............................................. 21 Interfaces...........................................................................................22 Parallel Interface ......................................................................... 22 Serial Interface ............................................................................ 22 Data Decoding .................................................................................24 Address Decoding ...........................................................................25 Power Supply Decoupling ..............................................................26 Power-On .................................................................................... 26 Typical Application Circuit ............................................................27 Outline Dimensions ........................................................................28 Ordering Guide .......................................................................... 28 REVISION HISTORY 1/05—Revision PrA: Preliminary Version Rev. PrA | Page 2 of 28 Preliminary Technical Data GENERAL DESCRIPTION The AD5378 contains 32 14-bit DACs in one CSPBGA package. The AD5378 provides a bipolar output range determined by the voltages applied to the VREF(+) and VREF(−) inputs. The maximum output voltage span is 17.5 V, corresponding to a bipolar output range of −8.75 V to +8.75 V, and is achieved with reference voltages of VREF(−) = −3.5 V and VREF(+) = +5 V. The AD5378 guarantees operation over a wide VSS/VDD supply range from ±11.4 V to ±16.5 V. The output amplifier headroom requirement is 2.5 V operating with a load current of 1.5 mA, and 2 V operating with a load current of 0.5 mA. The AD5378 contains a double-buffered parallel interface in which 14 data bits are loaded into one of the input registers under the control of the WR, CS, and DAC channel address pins, A0 to A7. It also has a 3-wire serial interface, which is compatible with SPI®, QSPI™, MICROWIRE™, and DSP interface standards and can handle clock speeds of up to 50 MHz. Table 1. 40-Channel, Bipolar, Voltage Output DAC Model AD5379ABC Resolution 14 Bits Analog Supplies ±11.4 V to ±16.5 V Output Channels 40 Linearity Error (LSB) ±3 Package Description 108-Lead CSPBGA AD5378 The DAC outputs are updated when the DAC registers receive new data. All the outputs can be updated simultaneously by taking the LDAC input low. Each channel has a programmable gain and an offset adjust register. Each DAC output is gained and buffered on-chip with respect to an external REFGND input. The DAC outputs can also be switched to REFGND via the CLR pin. Table 1 and Table 2 show the product portfolio for high channel count bipolar and unipolar voltage output DACs. Package Option BC-108 Table 2. High Channel Count, Low Voltage, Single-Supply DACs Model AD5380BST-5 AD5380BST-3 AD5381BST-5 AD5381BST-3 AD5384BBC-5 AD5384BBC-3 AD5382BST-5 AD5382BST-3 AD5383BST-5 AD5383BST-3 AD5390BST-5 AD5390BCP-5 AD5390BST-3 AD5390BCP-3 AD5391BST-5 AD5391BCP-5 AD5391BST-3 AD5391BCP-3 AD5392BST-5 AD5392BCP-5 AD5392BST-3 AD5392BCP-3 Resolution 14 Bits 14 Bits 12 Bits 12 Bits 14 Bits 14 Bits 14 Bits 14 Bits 12 Bits 12 Bits 14 Bits 14 Bits 14 Bits 14 Bits 12 Bits 12 Bits 12 Bits 12 Bits 14 Bits 14 Bits 14 Bits 14 Bits AVDD Range 4.5 V to 5.5 V 2.7 V to 3.6 V 4.5 V to 5.5 V 2.7 V to 3.6 V 4.5 V to 5.5 V 2.7 V to 3.6 V 4.5 V to 5.5 V 2.7 V to 3.6 V 4.5 V to 5.5 V 2.7 V to 3.6 V 4.5 V to 5.5 V 4.5 V to 5.5 V 2.7 V to 3.6 V 2.7 V to 3.6 V 4.5 V to 5.5 V 4.5 V to 5.5 V 2.7 V to 3.6 V 2.7 V to 3.6 V 4.5 V to 5.5 V 4.5 V to 5.5 V 2.7 V to 3.6 V 2.7 V to 3.6 V Output Channels 40 40 40 40 40 40 32 32 32 32 16 16 16 16 16 16 16 16 8 8 8 8 Linearity Error (LSB) ±4 ±4 ±1 ±1 ±4 ±4 ±4 ±4 ±1 ±1 ±3 ±3 ±4 ±4 ±1 ±1 ±1 ±1 ±3 ±3 ±4 ±4 Package Description 100-Lead LQFP 100-Lead LQFP 100-Lead LQFP 100-Lead LQFP 100-Lead CSPBGA 100-Lead CSPBGA 100-Lead LQFP 100-Lead LQFP 100-Lead LQFP 100-Lead LQFP 52-Lead LQFP 64-Lead LFCSP 52-Lead LQFP 64-Lead LFCSP 52-Lead LQFP 64-Lead LFCSP 52-Lead LQFP 64-Lead LFCSP 52-Lead LQFP 64-Lead LFCSP 52-Lead LQFP 64-Lead LFCSP Package Option ST-100 ST-100 ST-100 ST-100 BC-100 BC-100 ST-100 ST-100 ST-100 ST-100 ST-52 CP-64 ST-52 CP-64 ST-52 CP-64 ST-52 CP-64 ST-52 CP-64 ST-52 CP-64 Rev. PrA | Page 3 of 28 AD5378 SPECIFICATIONS VCC = 2.7 V to 5.5 V; VDD = 11.4 V to 16.5 V; VSS = −11.4 V to −16.5 V; VREF(+) = +5 V; VREF(−) = −3.5 V; AGND = DGND = REFGND = 0 V; VBIAS = 5 V; CL = 200 pF to GND; RL = 11 kΩ to 3 V; gain = 1; offset = 0 V; all specifications TMIN to TMAX, unless otherwise noted. Table 3. Parameter ACCURACY Resolution Relative Accuracy Differential Nonlinearity Zero-Scale Error Full-Scale Error Gain Error VOUT Temperature Coefficient DC Crosstalk2 REFERENCE INPUTS2 VREF(+) DC Input Impedance VREF(−) DC Input Impedance VREF(+) Input Current VREF(+) Range VREF(−) Range REFGND INPUTS2 DC Input Impedance Input Range OUTPUT CHARACTERISTICS2 Output Voltage Range Short-Circuit Current Load Current Capacitive Load DC Output Impedance DIGITAL INPUTS Input High Voltage Input Low Voltage Input Current (with pull-up/pull-down) Input Current (no pull-up/pull-down) Input Capacitance2 DIGITAL OUTPUTS (BUSY, SDO) Output Low Voltage Output High Voltage (SDO) High Impedance Leakage Current High Impedance Output Capacitance2 A Version1 14 ±3 ±2.5 −1/+1.5 ±12 ±5 ±12 ±8 ±8 ±1/±5 5 0.5 1 8 ±10 1.5/5 −3.5/0 80 ±0.5 VSS + 2/VSS + 2.5 VDD − 2/VDD − 2.5 15 ±1.5 2200 1 1.7 2.0 0.8 ±8 ±1 10 0.5 VCC − 0.5 −70 10 Unit Bits LSB max LSB max LSB max mV max mV max mV max mV max mV max mV typ/max ppm FSR/°C typ mV max MΩ min kΩ min µA max V min/max V min/max kΩ min V min/max V min V max mA max mA max pF max Ω max V min V min V max µA max µA max pF max V max V min µA max pF typ Test Conditions/Comments −40°C to +85°C 0°C to 70°C Guaranteed monotonic by design over temperature −40°C to +85°C 0°C to 70°C −40°C to +85°C 0°C to 70°C −40°C to +85°C 0°C to 70°C Includes linearity, offset, and gain drift; see Figure 11 Typically 100 µV Typically 100 MΩ Typically 12 kΩ Per input; typically ±30 nA ±2% for specified operation ±2% for specified operation Typically 120 kΩ ILOAD = ±0.5 mA/±1.5 mA ILOAD = ±0.5 mA/±1.5 mA JEDEC-compliant VCC = 2.7 V to 3.6 V VCC = 3.6 V to 5.5 V VCC = 2.7 V to 5.5 V SER/PAR, FIFOEN, and RESET pins only All other digital input pins Sinking 200 µA Sourcing 200 µA SDO only Rev. PrA | Page 4 of 28 Preliminary Technical Data Parameter POWER REQUIREMENTS VCC VDD VSS Power Supply Sensitivity2 ∆ Full Scale/∆ VDD ∆ Full Scale/∆ VSS ∆ Full Scale/∆ VCC ICC IDD ISS Power Dissipation Power Dissipation Unloaded (P) Power Dissipation Loaded (PTOTAL) Junction Temperature A Version1 2.7/5.5 8.5/16.5 −3/−16.5 −75 −75 −90 5 28 23 850 2000 130 Unit V min/max V min/max V min/max dB typ dB typ dB typ mA max mA max mA max mW max mW max °C max Test Conditions/Comments AD5378 VCC = 5.5 V, VIH = VCC, VIL = GND Outputs unloaded; typically 20 mA Outputs unloaded; typically 15 mA VDD = 16.5 V, VSS = −16.5 V PTOTAL = P + Σ(VDD − VO) × ISOURCE + Σ(VO − VSS) × ISINK TJ = TA + PTOTAL × θJ3 1 2 Temperature range for the A version: −40°C to +85°C. Typical specifications are at 25°C. Guaranteed by design and characterization; not production tested. 3 Where θJ represents the package thermal impedance. AC CHARACTERISTICS VCC = 2.7 V to 5.5 V; VDD = 11.4 V to 16.5 V; VSS = −11.4 V to −16.5 V; VREF(+) = +5 V; VREF(−) = −3.5 V; AGND = DGND = REFGND = 0 V; VBIAS = 5 V; CL = 220 pF; RL = 11 kΩ to 3 V; gain = 1; offset = 0 V. Table 4. Parameter DYNAMIC PERFORMANCE Output Voltage Settling Time A Version1 20 30 1 20 15 100 40 10 0.1 1 350 Unit µs typ µs max V/µs typ nV-s typ mV max dB typ nV-s typ nV-s typ nV-s typ nV-s typ nV/(Hz)1/2 typ Test Conditions/Comments Full-scale change to ±1/2 LSB DAC latch contents alternately loaded with all 0s and all 1s Slew Rate Digital-to-Analog Glitch Energy Glitch Impulse Peak Amplitude Channel-to-Channel Isolation DAC-to-DAC Crosstalk VREF(+) = 2 V p-p, (1 VBIAS) 1 kHz, VREF(−) = −1 V See the Terminology section; between DACs inside a group Between DACs from different groups Effect of input bus activity on DAC output under test VREF(+) = VREF(−) = 0 V Digital Crosstalk Digital Feedthrough Output Noise Spectral Density @ 1 kHz 1 Guaranteed by design and characterization; not production tested. Rev. PrA | Page 5 of 28 AD5378 TIMING CHARACTERISTICS SERIAL INTERFACE VCC = 2.7 V to 5.5 V; VDD = 11.4 V to 16.5 V; VSS = −11.4 V to −16.5 V; VREF(+) = +5 V; VREF(−) = −3.5 V; AGND = DGND = REFGND = 0 V; VBIAS = 5 V, FIFOEN = 0 V; all specifications TMIN to TMAX, unless other wise noted. Table 5. Parameter1, 2, 3 t1 t2 t3 t4 t54 t64 t7 t8 t9 t104, 5 t11 t124 t13 t14 t15 t16 t17 t18 t19 t206, 7 t217 t227 t237 t245 t25 t26 Limit at TMIN, TMAX 20 8 8 10 15 25 10 5 4.5 30 330 20 20 150 0 100 20/30 10 350 25 5 5 20 30 10 120 Unit ns min ns min ns min ns min ns min ns min ns min ns min ns min ns max ns max ns min ns min ns typ ns min ns min µs typ/max ns min ns max ns max ns min ns min ns min ns min ns min µs max Description SCLK Cycle Time. SCLK High Time. SCLK Low Time. SYNC Falling Edge to SCLK Falling Edge Setup Time. 24th SCLK Falling Edge to SYNC Falling Edge. Minimum SYNC Low Time. Minimum SYNC High Time. Data Setup Time. Data Hold Time. 24th SCLK Falling Edge to BUSY Falling Edge. BUSY Pulse Width Low (Single-Channel Update). See Table 11. 24th SCLK Falling Edge to LDAC Falling Edge. LDAC Pulse Width Low. BUSY Rising Edge to DAC Output Response Time. BUSY Rising Edge to LDAC Falling Edge. LDAC Falling Edge to DAC Output Response Time. DAC Output Settling Time. CLR Pulse Width Low. CLR/RESET Pulse Activation Time. SCLK Rising Edge to SDO Valid. SCLK Falling Edge to SYNC Rising Edge. SYNC Rising Edge to SCLK Rising Edge. SYNC Rising Edge to LDAC Falling Edge. SYNC Rising Edge to BUSY Falling Edge. RESET Pulse Width Low. RESET Time Indicated by BUSY Low. 1 2 3 Guaranteed by design and characterization; not production tested. All input signals are specified with tr = tf = 2 ns (10% to 90% of VCC) and timed from a voltage level of 1.2 V. See Figure 4 and Figure 5. 4 Standalone mode only. 5 This is measured with the load circuit of Figure 2. 6 This is measured with the load circuit of Figure 3. 7 Daisy-chain mode only. VCC 200µA TO OUTPUT PIN 05292-002 IOL RL TO OUTPUT PIN 2.2kΩ VOH(min) + VOL(max) CL 50pF 200µA IOH 2 05292-003 VOL CL 50pF Figure 2. Load Circuit for BUSY Timing Diagram Figure 3. Load Circuit for SDO Timing Diagram (Serial Interface, Daisy-Chain Mode) Rev. PrA | Page 6 of 28 Preliminary Technical Data t1 SCLK 1 2 24 24 AD5378 t3 t4 SYNC t2 t5 t7 t6 t8 t9 DIN DB23 DB0 t10 t11 BUSY t12 LDAC1 t13 t17 t14 VOUT1 t15 LDAC2 t13 VOUT2 t16 t17 t18 CLR t19 VOUT 1LDAC 2LDAC ACTIVE DURING BUSY. ACTIVE AFTER BUSY. t25 RESET VOUT t19 t26 05292-004 BUSY Figure 4. Serial Interface Timing Diagram (Standalone Mode) Rev. PrA | Page 7 of 28 AD5378 t1 SCLK 24 48 t7 t4 SYNC t3 t2 t21 t22 t8 DIN D23 t9 D0 D23' D0' INPUT WORD FOR DAC N INPUT WORD FOR DAC N+1 t20 SDO D23 D0 UNDEFINED INPUT WORD FOR DAC N t23 LDAC t13 t24 BUSY t11 Figure 5. Serial Interface Timing Diagram (Daisy-Chain Mode) Rev. PrA | Page 8 of 28 05292-005 Preliminary Technical Data PARALLEL INTERFACE VCC = 2.7 V to 5.5 V; VDD = 11.4 V to 16.5 V; VSS = −11.4 V to −16.5 V; AGND = DGND = DUTGND = 0 V; VREF(+) = +5 V; VREF(−) = −3.5 V, FIFOEN = 0 V; all specifications TMIN to TMAX, unless otherwise noted. Table 6. Parameter1, 2, 3 t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t104 t114 t12 t13 t14 t154 t16 t17 t18 t19 t20 t21 t22 t23 Limit at TMIN to TMAX 4.5 4.5 10 10 0 0 4.5 4.5 20 240 0/30 330 0 30 20 150 20 0 100 20/30 10 350 10 120 Unit ns min ns min ns min ns min ns min ns min ns min ns min ns min ns min ns min/max ns max ns min ns min ns min ns typ ns min ns min ns typ µs typ/ max ns min ns max ns min µs max AD5378 Description REG0, REG1, Address to WR Rising Edge Setup Time. REG0, REG1, Address to WR Rising Edge Hold Time. CS Pulse Width Low. WR Pulse Width Low. CS to WR Falling Edge Setup Time. WR to CS Rising Edge Hold Time. Data to WR Rising Edge Setup Time. Data to WR Rising Edge Hold Time. WR Pulse Width High. Minimum WR Cycle Time (Single-Channel Write). WR Rising Edge to BUSY Falling Edge. BUSY Pulse Width Low (Single-Channel Update). See Table 11. BUSY Rising Edge to WR Rising Edge. WR Rising Edge to LDAC Falling Edge. LDAC Pulse Width Low. BUSY Rising Edge to DAC Output Response Time. LDAC Rising Edge to WR Rising Edge. BUSY Rising Edge to LDAC Falling Edge. LDAC Falling Edge to DAC Output Response Time. DAC Output Settling Time. CLR Pulse Width Low. CLR/RESET Pulse Activation Time. RESET Pulse Width Low. RESET Time Indicated by BUSY Low. 1 2 Guaranteed by design and characterization; not production tested. All input signals are specified with tr = tf = 2 ns (10% to 90% of VCC) and timed from a voltage level of 1.2 V. 3 See Figure 6. 4 Measured with load circuit in Figure 2. Rev. PrA | Page 9 of 28 AD5378 t0 REG0, REG1, A7–A02 t1 t4 CS t5 t2 t9 WR t3 t8 t6 t7 t16 t12 t10 t11 DB12–DB0 BUSY t13 LDAC1 VOUT1 t14 t19 t15 t17 t14 LDAC2 VOUT2 t18 t20 t19 CLR t21 VOUT 1LDAC 2LDAC ACTIVE DURING BUSY. ACTIVE AFTER BUSY. t22 RESET VOUT t21 t23 05292-006 BUSY Figure 6. Parallel Interface Timing Diagram Rev. PrA | Page 10 of 28 Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless other wise noted. Transient currents of up to 100 mA do not cause SCR latch-up. Table 7. Parameter VDD to AGND VSS to AGND VCC to DGND Digital Inputs to DGND Digital Outputs to DGND VREF1(+), VREF2(+) to AGND VREF1(−), VREF2(−) to AGND VBIAS to AGND VOUT0–VOUT31 to AGND REFGND to AGND AGND to DGND Operating Temperature Range (TA) Industrial (A Version) Storage Temperature Range Junction Temperature (TJ max) 108-Lead CSPBGA Package θJA Thermal Impedance θJC Thermal Impedance Reflow Soldering Peak Temperature Time at Peak Temperature Rating −0.3 V to +17 V −17 V to +0.3 V −0.3 V to +7 V −0.3 V to VCC + 0.3 V −0.3 V to VCC + 0.3 V −0.3 V to +7 V VSS − 0.3 V to VDD + 0.3 V −0.3 V to +7 V VSS − 0.3 V to VDD + 0.3 V VSS − 0.3 V to VDD + 0.3 V −0.3 V to +0.3 V −40°C to +85°C −65°C to +150°C 150°C 37.5°C/W 8.5°C/W 230°C 10 sec to 40 sec AD5378 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only ; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Only one absolute maximum rating may be applied at any one time. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. PrA | Page 11 of 28 AD5378 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 1 A B C D E F G H J K L M 1 2 3 4 5 6 7 8 9 10 11 12 2 3 4 5 6 7 8 9 10 11 12 A B C D E AD5378 TOP VIEW F G H J K L 05292-007 M Figure 7. Pin Configuration Table 8. 108-Lead CSPBGA Ball Configuration CSPBGA No. A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 C1 C2 C3 Ball Name REG0 VCC3 DB10 AGND4 VBIAS VOUT5 AGND3 REFGNDA1 VDD5 VSS5 VSS4 VDD4 REG1 DGND4 DB9 CLR AGND AGND VOUT0 VOUT1 VOUT2 VOUT25 REFGNDD1 VOUT24 DB13 DB12/SCLK DB11/DIN CSPBGA No. C4 C5 C6 C7 C8 C9 C10 C11 C12 D1 D2 D3 D10 D11 D12 E1 E2 E3 E10 E11 E12 F1 F2 F3 F10 F11 F12 Ball Name SER/PAR1 CSPBGA No. G1 G2 G3 G10 G11 G12 H1 H2 H3 H10 H11 H12 J1 J2 J3 J10 J11 J12 K1 K2 K3 K4 K5 K6 K7 K8 K9 Ball Name DB1 DB0 BUSY VSS3 VOUT23 REFGNDC2 WR/DCEN SDO3 CS/SYNC VOUT22 AGND AGND A0 A1 A2 VOUT15 VOUT20 VOUT21 A4 A5 A3 DGND2 REFGNDA2 VREF2(−) VOUT10 VOUT11 AGND CSPBGA No. K10 K11 K12 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 L12 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 Ball Name VOUT14 VOUT18 VOUT19 A7 A6 N/C2 RESET3 AGND AGND2 VOUT12 VOUT8 VDD1 VREF2(+) VOUT16 VOUT17 DGND3 VCC2 FIFOEN1 AGND1 VOUT13 VOUT9 REFGNDB1 VREF1(+) VSS1 VSS2 VDD2 REFGNDC1 LDAC VOUT6 VOUT3 VOUT4 VOUT7 VOUT28 VOUT26 VOUT27 DB7 DB8 DGND1 VREF1(−) VOUT29 AGND DB5 DB6 VCC1 REFGNDB2 AGND VOUT30 DB4 DB3 DB2 VDD3 REFGNDD2 VOUT31 _________________________ 1 Internal 1 MΩ pull-down device on this logic input. Therefore, it can be left floating, and it defaults to a logic low condition. 2 N/C—Do not connect to this pin. Internal active pull-up device on these logic inputs. They default to a logic high condition. 3 Internal 1 MΩ pull-up device on this logic input. Therefore, it can be left floating, and it defaults to a logic high condition. Rev. PrA | Page 12 of 28 Preliminary Technical Data Table 9. Pin Function Descriptions Pin VCC(1–3) VSS(1–5) VDD(1–5) AGND(1–4) DGND(1–4) VREF1(+), VREF1(−) VREF2(+), VREF2(−) VBIAS AD5378 VOUT0 to VOUT31 SER/PAR SYNC1 SCLK1 DIN1 SDO1 DCEN1 CS WR DB13 to DB0 A0 to A7 REG0 REG1 CLR BUSY LDAC Description Logic Power Supply. 2.7 V to 5.5 V. These pins should be decoupled with 0.1 µF ceramic capacitors and 10 µF tantalum capacitors. Negative Analog Power Supply. −11.4 V to −16.5 V for specified performance. These pins should be decoupled with 0.1 µF ceramic capacitors and 10 µF tantalum capacitors. Positive Analog Power Supply. +11.4 V to +16.5 V for specified performance. These pins should be decoupled with 0.1 µF ceramic capacitors and 10 µF tantalum capacitors. Ground for All Analog Circuitry. All AGND pins should be connected to the AGND plane. Ground for All Digital Circuitry. All DGND pins should be connected to the DGND plane. Reference Inputs for DACs 0 to 5, 8 to 13, 16 to 21, and 24 to 30. These voltages are referred to AGND. Reference Inputs for DACs 6, 7, 14, 15, 22, 23, 30, and 31. These reference voltages are referred to AGND. DAC Bias Voltage Input/Output. This pin provides an access to the on-chip voltage generator voltage. It is provided for bypassing and overdriving purposes only. If VREF(+) > 4.25 V, VBIAS must be pulled high externally to an equal or higher potential, for example, 5 V. If VREF(+) < 4.25 V, the on-chip bias generator can be used. In this case, the VBIAS pin should be decoupled with a 10 nF capacitor to AGND. DAC Outputs. Buffered analog outputs for each of the 32 DAC channels. Each analog output can drive an output load of 5 kΩ to ground. Typical output impedance of these amplifiers is 1 Ω. Interface Select Input. This pin allows the user to select whether the serial or parallel interface is used. This pin has an internal 1 MΩ pull-down resistor, meaning that the default state at power-on is parallel mode. If this pin is tied high, the serial interface is used. Active Low Input. This is the frame synchronization signal for the serial interface. Serial Clock Input. Data is clocked into the shift register on the falling edge of SCLK. This pin operates at clock speeds up to 50 MHz. Serial Data Input. Data must be valid on the falling edge of SCLK. Serial Data Output. CMOS output. SDO can be used for daisy-chaining several devices together. Data is clocked out on SDO on the rising edge of SCLK and is valid on the falling edge of SCLK. Daisy-Chain Select Input. Level sensitive, active high. When high, this signal is used in conjunction with SER/PAR high to enable serial interface daisy-chain mode. Parallel Interface Chip Select Input. Level sensitive, active low. When this pin is low, the device is selected. Parallel Interface Write Input. Edge sensitive. The rising edge of WR is used in conjunction with CS low and the address bus inputs to write to the selected AD5378 registers. Parallel Data Inputs. The AD5378 can accept a straight 14-bit parallel word on DB0 to DB13, where DB13 is the MSB and DB0 is the LSB. Parallel Address Inputs. A7 to A4 are decoded to select one group or multiple groups of registers (input registers, gain registers (m), or offset registers (c)) for a data transfer. This pin is used in conjunction with the REG1 and REG0 pins to determine the destination register for the input data. See the Parallel Interface section for details of the address decoding. Parallel Interface Register Select Input. This pin is used together with REG1 to select data registers, gain registers, offset registers, increment/decrement mode, or the soft reset function. See Table 12. Parallel Interface Register Select Input. This pin is used together with REG0 to select data registers, gain registers, offset registers, increment/decrement mode, or the soft reset function. See Table 12. Asynchronous Clear Input. Level sensitive, active low. When CLR is low, the input to each of the DAC output buffer stages, VOUT0 to VOUT31, is switched to the externally set potential on the relevant REFGND pin. While CLR is low, all LDAC pulses are ignored. When CLR is taken high again, the DAC outputs remain cleared until LDAC is taken low. The contents of input registers and DAC Registers 0 to 31 are not affected by taking CLR low. Digital Input/Open-Drain Output. This pin must be pulled high with a pull-up resistor for correct operation. BUSY goes low during internal calculations of x2. During this time, the user can continue writing new data to additional ×1, c, and m registers (these are stored in a FIFO), but no further updates to the DAC registers and DAC outputs can take place. If LDAC is taken low while BUSY is low, this event is stored. Because BUSY is bidirectional, it can be pulled low externally to delay LDAC action. BUSY also goes low during power-on reset or when the RESET pin is low. During a RESET operation, the parallel interface is disabled and any events on LDAC are ignored. Load DAC Logic Input. Active low. If LDAC is taken low while BUSY is inactive (high), the contents of the input registers are transferred to the DAC registers, and the DAC outputs are updated. If LDAC is taken low while BUSY is active and internal calculations are taking place, the LDAC event is stored and the DAC registers are updated when BUSY goes inactive. However, any events on LDAC during power-on reset or RESET are ignored. Rev. PrA | Page 13 of 28 AD5378 Pin FIFOEN Description FIFO Enable. Level sensitive, active high. When connected to DVDD, the internal FIFO is enabled, allowing the user to write to the device at full speed. FIFO is available in both serial and parallel modes. The FIFOEN pin has an internal 1 MΩ pull-down resistor connected to ground, meaning that the FIFO is disabled by default. Asynchronous Digital Reset Input. Falling edge sensitive. If unused, RESET can be left unconnected; an internal pullup resistor (1 MΩ) ensures that the RESET input is held high. The function of this pin is equivalent to that of the power-on reset generator. When this pin is taken low, the AD5378 state machine initiates a reset sequence to digitally reset the x1, m, c, and x2 registers to their default power-on values. This sequence takes 100 µs (typ). Furthermore, the input to each of the DAC output buffer stages, VOUT0 to VOUT31, is switched to the externally set potential on the relevant REFGND pin. During RESET, BUSY goes low and the parallel interface is disabled. All LDAC pulses are ignored until BUSY goes high. When RESET goes high again, the DAC ouputs remain at REFGND until LDAC is taken low. Reference Ground for DACs 0 to 5. VOUT0 to VOUT5 are referenced to this voltage. Reference Ground for DACs 6 and 7. VOUT6 and VOUT7 are referenced to this voltage. Reference Ground for DACs 8 to 13. VOUT8 to VOUT13 are referenced to this voltage. Reference Ground for DACs 14 and 15. VOUT14 and VOUT15 are referenced to this voltage. Reference Ground for DACs 16 to 21. VOUT16 to VOUT21 are referenced to this voltage. Reference Ground for DACs 22 and 23. VOUT22 and VOUT23 are referenced to this voltage. Reference Ground for DACs 24 to 29. VOUT24 to VOUT29 are referenced to this voltage. Reference Ground for DACs 30 and 31. VOUT30 and VOUT31 are referenced to this voltage. RESET REFGNDA1 REFGNDA2 REFGNDB1 REFGNDB2 REFGNDC1 REFGNDC2 REFGNDD1 REFGNDD2 1 These serial interface signals do not require separate pins, but share parallel interface pins. Rev. PrA | Page 14 of 28 Preliminary Technical Data TYPICAL PERFORMANCE CHARACTERISTICS 1.5 3 1.0 2 AD5378 VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V TMAX = 85°C FS 1 0.5 ERROR (mV) INL (LSBs) 0 0 –1 ZC –0.5 VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V TA = 25°C 05292-008 –2 –1.0 –3 –4 –40 –1.5 0 2 4 6 8 10 12 14 16 AD5378 CODE (103) –20 0 20 40 60 80 TEMPERATURE (°C) Figure 8. Typical INL Plot Figure 11. Typical Full-Scale and Zero-Scale Errors vs. Temperature 1400 VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V 19.0 18.9 18.8 +85°C 18.7 VDD = +12V VREF(+) = +5V VSS = –12V VREF(–) = –3.5V 1200 1000 FREQUENCY IDD (mA) 800 18.6 +25°C 18.5 18.4 600 400 18.3 –40°C 200 0 –3 –2 –1 0 INL ERROR (LSB) 1 2 3 18.2 18.1 10.0 05292-009 10.5 11.0 11.5 12.0 12.5 VDD (V) 13.0 13.5 14.0 14.5 15.0 Figure 9. INL Error Distribution (−40°C, +25°C, +85°C Superimposed) –14.6 Figure 12. IDD vs. VDD over Temperature 3 VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V TMAX = 85°C VDD = +12V VREF(+) = +5V VSS = –12V VREF(–) = –3.5V –40°C 2 –14.8 INL ERROR (LSB) 1 –15.0 ISS (mA) 0 –15.2 +25°C –15.4 –1 –2 –15.6 +85°C 10.5 11.0 11.5 12.0 12.5 VDD (V) 13.0 13.5 14.0 14.5 15.0 05292-013 –20 0 20 40 60 80 TEMPERATURE (°C) Figure 10. Typical INL Error vs. Temperature 05292-010 –3 –40 –15.8 10.0 Figure 13. ISS vs. VDD over Temperature Rev. PrA | Page 15 of 28 05292-012 05292-011 AD5378 3.5 VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V 3.0 VOUT TA = 25°C VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V 2.5 2.0 ICC (mA) 1.5 +85°C 1.0 –40°C 0.5 0 2.5 +25°C 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) Figure 14. ICC vs. Supply 05292-014 Figure 17. DAC-to-DAC Crosstalk –0.208 TA = 25°C VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V 1.75 1.70 1.65 1.60 TA = 25°C VDD = +12V VSS = –12V VREF(+) = +5V VREF(–) = –3.5V VCC = +3.3V –0.211 AMPLITUDE (V) –0.214 ICC (mA) 1.55 1.50 1.45 –0.217 –0.220 1.40 1.35 05292-015 –0.223 0 4 8 TIME (µs) 12 16 20 1.30 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 INPUT VOLTAGE (V) 05292-018 Figure 15. Major Code Transition Glitch Energy Figure 18. Supply Current vs. Digital Input Voltage –0.208 TA = 25°C VSS = –12V VREF(–) = –3.5V VDD = +12V VREF(+) = +5V AMPLITUDE (V) –0.209 –0.210 0 1.4 2.8 TIME (µs) 4.2 5.6 6.0 Figure 16. Digital Feedthrough Rev. PrA | Page 16 of 28 05292-016 –0.211 05292-017 10V 5mV Preliminary Technical Data TERMINOLOGY Relative Accuracy Relative accuracy or endpoint linearity is a measurement of the maximum deviation from a straight line passing through the endpoints of the DAC transfer function. It is measured after adjusting for zero-scale error and full-scale error and is expressed in least significant bits (LSB). Differential Nonlinearity Differential nonlinearity 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. Zero-Scale Error Zero-scale error is the error in the DAC output voltage when all 0s are loaded into the DAC register. Ideally, with all 0s loaded to the DAC and m is all 1s, c is 10 0000 0000 0000: VOUT(zero-scale) = 2.5 × VREF(−) − AGND) + REFGND Zero-scale error is a measurement of the difference between VOUT (actual) and VOUT (ideal) expressed in mV. Zero-scale error is mainly due to offsets in the output amplifier. Full-Scale Error Full-scale error is the error in DAC output voltage when all 1s are loaded into the DAC register. Ideally, with all 1s loaded to the DAC and m is all 1s, c is 10 0000 0000 0000: VOUT(full-scale) = 3.5 × (VREF(+) − AGND) + 2.5 × (VREF(−)− AGND) + REFGND Full-scale error is a measurement of the difference between VOUT (actual) and VOUT (ideal) expressed in mV. It does not include zero-scale error. Gain Error Gain error is the difference between full-scale error and zeroscale error. It is expressed in mV. Gain Error = Full-Scale Error − Zero-Scale Error VOUT Temperature Coefficient This includes output error contributions from linearity, offset, and gain drift. DC Output Impedance DC output impedance is the effective output source resistance. It is dominated by package lead resistance. AD5378 DC Crosstalk The 32 DAC outputs are buffered by op amps that share common VDD and VSS power supplies. If the dc load current changes in one channel (due to an update), this can result in a further dc change in one or more channel outputs. This effect is more significant at high load currents and reduces as the load currents are reduced. With high impedance loads, the effect is virtually unmeasurable. Multiple VDD and VSS terminals are provided to minimize dc crosstalk. Output Voltage Settling Time This is the amount of time it takes for the output of a DAC to settle to a specified level for a full-scale input change. Digital-to-Analog Glitch Energy This is 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 0x1FFF and 0x2000. Channel-to-Channel Isolation Channel-to-channel isolation refers to the proportion of input signal from one DAC’s reference input that appears at the output of another DAC operating from another reference. It is expressed in dB and measured at midscale. DAC-to-DAC Crosstalk DAC-to-DAC crosstalk is the glitch impulse that appears at the output of one converter due to both the digital change and subsequent analog output change at another converter. It is specified in nV-s. Digital Crosstalk The glitch impulse transferred to the output of one converter due to a change in the DAC register code of another converter is defined as the digital crosstalk and is specified in nV-s. Digital Feedthrough When the device is not selected, high frequency logic activity on the device’s digital inputs can be capacitively coupled both across and through the device to show up as noise on the VOUT pins. It can also be coupled along the supply and ground lines. This noise is digital feedthrough. Output Noise Spectral Density This is a measurement of internally generated random noise. Random noise is characterized as a spectral density (voltage per √Hz). It is measured by loading all DACs to midscale and measuring noise at the output. It is measurement in nV/(Hz)1/2. Rev. PrA | Page 17 of 28 AD5378 FUNCTIONAL DESCRIPTION DAC ARCHITECTURE—GENERAL The AD5378 contains 32 DAC channels and 32 output amplifiers in a single package. The architecture of a single DAC channel consists of a 14-bit resistor-string DAC followed by an output buffer amplifier. The resistor-string section is simply a string of resistors, each of value R, from VREF(+) to AGND. This type of architecture guarantees DAC monotonicity. The 14-bit binar y digital code loaded to the DAC register determines at which node on the string the voltage is tapped off before being fed into the output amplifier. The output amplifier translates the output of the DAC to a wider range. The DAC output is gained up by a factor of 3.5 and offset by the voltage on the VREF(−) pin. See the Transfer Function section. Figure 19 shows a single DAC channel and its associated registers. The power-on values for the m and c registers are full scale and 0x2000, respectively. The user can individually adjust the voltage range on each DAC channel by over writing the power-on values of m and c. The AD5378 has digital overflow and underflow detection circuitr y to clamp the DAC output at full scale or at zero scale when the values chosen for x1, m, and c result in x2 being out of range. LDAC DAC VREF(+) x1 INPUT REG INPUT DATA x2 m REG x2 REG DAC REG DAC VDAC CHANNEL GROUPS The 32 DAC channels on the AD5378 are arranged into four groups (A, B, C, D) of eight channels. In each group, six channels are connected to VREF1(+) and VREF1(−); the remaining two channels are connected to VREF2(+) and VREF2(−). Each group has two individual REFGND pins. For example, in Group A, six channels are connected to REFGNDA1, and the remaining two channels are connected to REFGNDA2. In addition to an input register (x1) and a DAC register (x2), each channel has a gain register (m) and an offset register (c). See Table 18. Including these registers allows the user to calibrate out errors in the complete signal chain, including the DAC errors. Table 10 shows the reference and REFGND inputs, and the m and c registers for Group A. Groups B, C, and D are similar. Table 10. Inputs and Registers for Group A Channel 0…5 6…7 Reference VREF1(+), VREF1(−) VREF2(+), VREF2(−) REFGND REFGNDA1 REFGNDA2 m, c Registers m REG0…5 c REG0…5 m REG6…7 c REG6…7 c REG 05292-019 AGND Figure 19. Single DAC Channel The complete transfer function for the AD5378 can be represented as VOUT = 3.5 × ((VREF(+)− AGND) × x2/214) + 2.5 × (VREF(−)− AGND) + REFGND where: x2 is the data-word loaded to the resistor string DAC. VREF(+) is the voltage at the positive reference pin. VREF(−) is the voltage at the negative reference pin. Figure 20 shows the output amplifier stage of a single channel. VDAC is the voltage output from the resistor string DAC. The nominal range of VDAC is 1 LSB to full scale. TRANSFER FUNCTION The digital input transfer function for each DAC can be represented as x2 = [(m + 1)/213 × x1] + (c − 2n−1) where: x2 is the data-word loaded to the resistor string DAC. The default is 10 0000 0000 0000. x1 is the 14-bit data-word written to the DAC input register. The default is 10 0000 0000 0000. m is the 13-bit gain coefficient. The default is 1 1111 1111 1111. c is the 14-bit offset coefficient. The default is 10 0000 0000 0000. n is the DAC resolution. n = 14. REFGND 2.5R VREF(–) R R VDAC VOUT 2.5R R AGND Figure 20. Output Amplifier Stage Rev. PrA | Page 18 of 28 05292-020 Preliminary Technical Data VBIAS FUNCTION The AD5378 on-chip voltage generator provides a bias voltage of 4.25 V (min). The VBIAS pin is provided for bypassing and overdriving purposes only. It is not intended to be used as a supply or a reference. If VREF(+) > 4.25 V, VBIAS must be pulled high externally to an equal or higher potential such as 5 V. The external voltage source should be capable of driving a 50 µA (typical) current sink load. AD5378 If this offset error too large to calibrated out, it is possible to adjust the negative reference value to account for this by using the following equation: VREF(−)NEW = VREF(−)A − VOFFSET/2.625 Reference Selection Example Nominal Output Range = 10 V; (−2 V to +8 V) Offset Error = ±100 mV Gain Error = ±3% REFGND = AGND = 0 V 1. Gain Error = ±3%; => Maximum Positive Gain Error = +3% => Output Range including Gain Error = 10 + 0.03 (10) = 10.3 V Offset Error = ±100 mV; => Maximum Offset Error Span = 2(100) mV = 0.2 V => Output Range including Gain Error and Offset Error = 10.3 + 0.2 = 10.5 V VREF(+) and VREF(−) Calculation: Actual Output Range = 10.5 V, that is, −2.25 V to +8.25 V (centered); => VREF(+) = (8.25 + 2.25)/3.5 = 3 V and VREF(−) = −2.25/2.5 = −0.9 V REFERENCE SELECTION The voltages applied to VREF(+) and VREF(−) determine the output voltage range and span on VOUT0 to VOUT31. If the offset and gain features are not used (m and c are left at their power-on values), the reference levels required can be calculated as follows: VREF(+)min = (VOUTmax − VOUTmin)/3.5 VREF(−)max = (AGND + VOUTmin)/2.5 If the offset and gain features of the AD5378 are used, the output range required is slightly different. The output range chosen should take into account the offset and gain errors that need to be trimmed out. Therefore, the output range should be larger than the actual required range. The reference levels required can be calculated as follows: 1. 2. 3. 4. Identify the nominal output range on VOUT. Identify the maximum offset span and the maximum gain required on the full output signal range. Calculate the new maximum output range on VOUT, including the maximum offset and gain errors expected. Choose the new VOUTmax and VOUTmin required, keeping the new VOUT limits centered on the nominal values and assuming REFGND is 0 V (or equal to AGND). VDD and VSS must provide sufficient headroom. Calculate the values of VREF(+) and VREF(−) as follows: VREF(+)min = (VOUTmax − VOUTmin)/3.5 VREF(−)max = (AGND + VOUTmin)/2.5 In addition, when using reference values other than those suggested (VREF(+) = 5 V and VREF(−) = −3.5 V), the expected offset error component changes as follows: VOFFSET = 0.125 × (VREF(−)A + 0.7 × VREF(+)A) where: VREF(−)A is the new negative reference value. VREF(+)A is the new positive reference value. 2. 3. If the solution yields inconvenient reference levels, the user can adopt one of these approaches: • • Use a resistor divider to divide down a convenient, higher reference level to the required level. Select convenient reference levels above VREF(+)min or below VREF(−)max. Modify the gain and offset registers to downsize the references digitally. In this way, the user can use almost any convenient reference level, but can reduce performance by overcompaction of the transfer function. Use a combination of these two approaches. 5. • Rev. PrA | Page 19 of 28 AD5378 CALIBRATION The user can perform a system calibration by overwriting the default values in the m and c registers for any individual DAC channel as follows: 1. 2. Calculate the nominal offset and gain coefficients for the new output range (see the revious example). Calculate the new m and c values for each channel based on the specified offset and gain errors. Software Clear Loading a clear code to the x1 registers also enables the user to set VOUT0 to VOUT31 to the REFGND level. The default clear code corresponds to m at full scale and c at midscale (x2 = x1). Default Clear Code = 214 × (−Output Offset)/(Output Range) = 214 × 2.5 × (AGND − VREF(−))/(3.5 × (VREF(+)− AGND)) The more general expression for the clear code is as follows: Clear Code = (214)/(m + 1) × (Default Clear Code − c) Calibration Example Nominal Offset Coefficient = 0 Nominal Gain Coefficient = 10/10.5 × 8191 = 0.95238 × 8191 = 7801 Example 1: Channel 0, Gain Error = 3%, Offset Error = 100 mV 1. 2. Gain Error (3%) Calibration: 7801 × 1.03 = 8035 => Load Code 1 1111 0110 0011 to m Register 0 Offset Error (100 mV) Calibration: LSB Size = 10.5 / 16384 = 641 µV; Offset Coefficient for 100 mV Offset = 100 / 0.64 = 156 LSBs => Load 10 0000 1001 1100 to c Register 0 BUSY AND LDAC FUNCTIONS The value of x2 is calculated each time the user writes new data to the corresponding x1, c, or m registers. During the calculation of x2, the BUSY output goes low. While BUSY is low, the user can continue writing new data to the x1, m, or c registers, but no DAC output updates can take place. The DAC outputs are updated by taking the LDAC input low. If LDAC goes low while BUSY is active, the LDAC event is stored and the DAC outputs update immediately after BUSY goes high. A user can also hold the LDAC input permanently low. In this case, the DAC outputs update immediately after BUSY goes high. Table 11. BUSY Pulse Width BUSY Pulse Width (ns max) Action Loading x1, c, or m to 1 channel Loading x1, c, or m to 2 channels Loading x1, c, or m to 3 channels Loading x1, c, or m to 4 channels Loading x1, c, or m to all 32 channels FIFO Enabled 530 700 900 1050 5500 FIFO Disabled 330 500 700 850 5300 Example 2: Channel 1, Gain Error = −3%, Offset Error = −100 mV 1. 2. Gain Error (−3%) Calibration: 7801 × 0.97 = 7567 => Load Code 1 1110 1000 1111 to m Register 1 Offset Error (−100 mV) Calibration: LSB Size = 10.5 / 16384 = 641 µV; Offset Coefficient for −100 mV Offset = −100 / 0.64 = −156 LSBs => Load 01 1111 0110 0100 to c Register 1 CLEAR FUNCTION The clear function on the AD5378 can be implemented in hardware or software. Hardware Clear Bringing the CLR pin low switches the outputs, VOUT0 to VOUT31, to the externally set potential on the REFGND pin. This is achieved by switching in REFGND and reconfiguring the output amplifier stages into unity gain buffer mode, thus ensuring that VOUT is equal to REFGND. The contents of the input registers and DAC registers are not affected by taking CLR low. When CLR is brought high, the DAC outputs remain cleared until LDAC is taken low. While CLR is low, the value of LDAC is ignored. The value of x2 for a single channel or group of channels is recalculated each time there is a write to any x1 register(s), c register(s), or m register(s). During the calculation of x2, BUSY goes low. The duration of this BUSY pulse depends on the number of channels being updated. For example, if x1, c, or m data is written to one DAC channel, BUSY goes low for 550 ns (max). However, if data is written to two DAC channels, BUSY goes low for 700 ns (max). There are approximately 200 ns of overhead due to FIFO access. See Table 11. The AD5378 contains an additional feature whereby a DAC register is not updated unless its x2 register is written to since the last time LDAC was brought low. Normally, when LDAC is brought low, the DAC registers are filled with the contents of the x2 registers. However, the AD5378 updates the DAC register only if the x2 data changes, thereby removing unnecessary digital crosstalk. Rev. PrA | Page 20 of 28 Preliminary Technical Data FIFO VS. NON-FIFO OPERATION Data can be loaded to the AD5378 registers with FIFO disabled or enabled. Operation with FIFO disabled is optimum for single writes to the device. If the system requires significant data transfers to the AD5378, however, operation with FIFO enabled is more efficient. When FIFO is enabled, the AD5378 uses an internal FIFO memory to allow high speed successive writes in both serial and parallel modes. This optimizes the interface speed and efficiency, minimizes the total conversion time due to internal digital efficiencies, and minimizes the overhead on the master controller when managing the data transfers. The BUSY signal goes low while instructions in the state machine are being executed. Table 11 compares operation with FIFO enabled and FIFO disabled for different data transfers to the AD5378. Operation with FIFO enabled is more efficient for all operations except single write operations. When using the FIFO, the user can continue writing new data to the AD5378 while write instructions are being executed. Up to 128 successive instructions can be written to the FIFO at maximum speed. When the FIFO is full, additional writes to the AD5378 are ignored. AD5378 the parallel interface is disabled, so it is not possible to write to the part. Any transitions on LDAC during the power-on period are ignored in order to reject initial LDAC pin glitching. A rising edge on BUSY indicates that power-on is complete and that the parallel interface is enabled. All DACs remain in their power-on state until LDAC is used to update the DAC outputs. RESET INPUT FUNCTION The AD5378 can be placed into the power-on reset state at any time by activating the RESET pin. The AD5378 state machine initiates a reset sequence to digitally reset the x1, m, c, and x2 registers to their default power-on values. This sequence takes 95 µs (typical), 120 µs (max), and 70 µs (min). During this sequence, BUSY goes low. While RESET is low, any transitions on LDAC are ignored. As with the CLR input, while RESET is low, the DAC outputs are switched to REFGND. The outputs remain at REFGND until an LDAC pulse is applied. This reset function can also be implemented via the parallel interface by setting the REG0 and REG1 pins low and writing all 1s to DB13 to DB0. See Table 17 for soft reset. INCREMENT/DECREMENT FUNCTION The AD5378 has a special function register that enables the user to increment or decrement the internal 14-bit input register data (x1) in steps of 0 to 127 LSBs. The increment/decrement function is selected by setting both REG1 and REG0 pins (or bits) low. Address Pins (or bits) A7 to A0 are used to select a DAC channel or group of channels. The amount by which the x1 register is incremented or decremented is determined by the DB6 to DB0 bits/pins. For example, for a 1 LSB increment or decrement, DB6...DB0 = 0000001, while for a 7 LSB increment or decrement, DB6...DB0 = 0000111. DB8 determines whether the input register data is incremented (DB8 = 1) or decremented (DB8 = 0). The maximum amount by which the user is allowed to increment or decrement the data is 127 LSBs, that is, DB6...DB0 = 1111111. The 0 LSB step is included to facilitate software loops in the user’s application. See Table 16. The AD5378 has digital overflow and underflow detection circuitry to clamp at full scale or zero scale when the values chosen for increment or decrement mode are out of range. BUSY INPUT FUNCTION Because the BUSY pin is bidirectional and open-drain (for correct operation, use a pull-up resistor to digital supply), a second AD5378 or any other device (such as a system controller), can pull BUSY low and, therefore, delay DAC update(s), if required. This is a means of delaying any LDAC action. This feature allows synchronous updates of multiple AD5378 devices in a system at maximum speed. As soon as the last device connected to the BUSY pin is ready, all DACs update automatically. Tying the BUSY pin of multiple devices together enables synchronous updating of all DACs without extra hardware. POWER-ON RESET FUNCTION The AD5378 contains a power-on reset generator and state machine. During power-on, CLR becomes active (internally), the power-on state machine resets all internal registers to their default values, and BUSY goes low. This sequence takes 8 ms (typical). The outputs, VOUT0 to VOUT31, are switched to the externally set potential on the REFGND pin. During power-on, Rev. PrA | Page 21 of 28 AD5378 INTERFACES The AD5378 contains parallel and serial interfaces. The active interface is selected via the SER/PAR pin. The AD5378 uses an internal FIFO memor y to allow high speed successive writes in both serial and parallel modes. The user can continue writing new data to the AD5378 while write instructions are being executed. The BUSY signal goes low while instructions in the FIFO are being executed. Up to 120 successive instructions can be written to the FIFO at maximum speed. When the FIFO is full, additional writes to the AD5378 are ignored. To minimize both the power consumption of the device and on-chip digital noise, the active interface powers up fully only when the device is being written to, that is, on the falling edge of WR or on the falling edge of SYNC. All digital interfaces are 2.5 V LVTTL-compatible when operating from a 2.7 V to 3.6 V VCC supply. A7 to A0 Pins Each of the 32 DAC channels can be addressed individually. In addition, several channel groupings enable the user to simultaneously write the same data to multiple DAC channels. Address Bits A7 to A4 are decoded to select one group or multiple groups of registers. Address Bits A3 to A0 select one of ten input data registers (x1), offset registers (c), or gain registers (m). See Table 18. SERIAL INTERFACE The SER/PAR pin must be tied high to enable the serial interface and disable the parallel interface. The serial interface is controlled by the following pins. SYNC, DIN, SCLK Standard 3-wire interface pins. DCEN Selects standalone mode or daisy-chain mode. PARALLEL INTERFACE A pull-down on the SER/PAR pin makes the parallel interface the default. If using the parallel interface, the SER/PAR pin can be left unconnected. Figure 6 shows the timing diagram for a parallel write to the AD5378. The parallel interface is controlled by the following pins. SDO Data out pin for daisy-chain mode. Figure 4 and Figure 5 show the timing diagrams for a serial write to the AD5378 in standalone and daisy-chain modes, respectively. The 24-bit data-word format for the serial interface is shown in Figure 21. MSB A7–A0 REG1 REG0 DB13–DB0 LSB CS Pin Active low device select pin. WR Pin On the rising edge of WR, with CS low, the address values at Pins A7 to A0 are latched and data values at Pins DB13 to DB0 are loaded into the selected AD5378 input registers. GROUP/CHANNEL REGISTER SELECT SELECT BITS BITS REGISTER DATA BITS REG1, REG0 Pins The REG1 and REG0 pins determine the destination register of the data being written to the AD5378. See Table 12. Table 12. Register Selection REG1 1 1 0 0 REG0 1 0 1 0 Register Selected Input Data Register (x1) Offset Register (c) Gain Register (m) Special Function Register Figure 21. Serial Data Format Standalone Mode By connecting the DCEN (daisy-chain enable) pin low, standalone mode is enabled. The serial interface works with both a continuous and a burst serial clock. The first falling edge of SYNC starts the write cycle and resets a counter that counts the number of serial clocks to ensure that the correct number of bits is shifted into the serial shift register. Additional edges on SYNC are ignored until 24 bits are shifted in. Once 24 bits are shifted in, the SCLK is ignored. For another serial transfer to take place, the counter must be reset by the falling edge of SYNC. DB13 to DB0 Pins The AD5378 accepts a straight 14-bit parallel word on DB0 to DB13, where DB13 is the MSB and DB0 is the LSB. See Table 13 to Table 17. Rev. PrA | Page 22 of 28 05292-021 Preliminary Technical Data Daisy-Chain Mode For systems that contain several DACs, the SDO pin can be used to daisy-chain several devices together. This daisy-chain mode can be useful in system diagnostics and in reducing the number of serial interface lines. Connecting the DCEN (daisy-chain enable) pin high enables daisy-chain mode. The first falling edge of SYNC starts the write cycle. The SCLK is continuously applied to the input shift register when SYNC is low. If more than 24 clock pulses are applied, the data ripples out of the shift register and appears on the SDO line. This data is clocked out on the rising edge of SCLK and is valid on the falling edge. By connecting this line to the DIN input on the next device in the chain, a multidevice interface is constructed. For each AD5378 in the system, 24 clock pulses are required. Therefore, the total number of AD5378 clock cycles must equal 24N, where N is the total number of AD5378 devices in the chain. If fewer than 24 clocks are applied, the write sequence is ignored. When the serial transfer to all devices is complete, SYNC should be taken high. This latches the input data in each device in the daisy chain and prevents any additional data from being clocked into the input shift register. A continuous SCLK source can be used if SYNC is held low for the correct number of clock cycles. Alternatively, a burst clock containing the exact number of clock cycles can be used and SYNC taken high after the final clock to latch the data. When the transfer to all input registers is complete, a common LDAC signal updates all DAC registers, and all analog outputs are updated simultaneously. Rev. PrA | Page 23 of 28 AD5378 DATA DECODING The AD5378 contains a 14-bit data bus, DB13 to DB0. Depending on the value of REG1 and REG0, this data is loaded into the addressed DAC input register(s), offset (c) register(s), gain (m) register(s), or the special function register. Table 13. DAC Data Format (REG1 = 1, REG0 = 1) DB13 to DB0 11 1111 1111 1111 11 1111 1111 1110 10 0000 0000 0001 10 0000 0000 0000 01 1111 1111 1111 00 0000 0000 0001 00 0000 0000 0000 DAC Output (16383/16384) VREF(+) V (16382/16384) VREF(+) V (8193/16384) VREF(+) V (8192/16384) VREF(+) V (8191/16384) VREF(+) V (1/16384) VREF(+) V 0V Table 15. Gain Data Format (REG1 = 0, REG0 = 1) DB12 to DB1 1 1111 1111 1111 1 1111 1111 1110 1 0000 0000 0001 1 0000 0000 0000 0 1111 1111 1111 0 0000 0000 0001 0 0000 0000 0000 Gain 8192/8192 8191/8192 4098/8192 4097/8192 4096/8192 2/8192 1/8192 Table 16. Special Function Data Format (REG1 = 0, REG0 = 0) DB13 to DB0 00000 10 1111111 00000 10 0000111 00000 10 0000001 00000 X0 0000000 00000 00 0000001 00000 00 0000111 00000 00 1111111 Increment/Decrement Step (LSB) +127 +7 +1 0 −1 −7 −128 Table 14. Offset Data Format (REG1 = 1, REG0 = 0) DB13 to DB0 11 1111 1111 1111 11 1111 1111 1110 10 0000 0000 0001 10 0000 0000 0000 01 1111 1111 1111 00 0000 0000 0001 00 0000 0000 0000 Offset (LSB) +8191 +8190 +1 +0 −1 −8191 −8192 Table 17. Soft Reset (REG1 = 0, REG0 = 0) DB13 to DB0 11 1111 1111 1111 DAC Output REFGND Rev. PrA | Page 24 of 28 Preliminary Technical Data ADDRESS DECODING The AD5378 contains an 8-bit address bus, A7 to A0. This address bus allows each DAC input register (x1), each offset (c) register, and each gain (m) register to be individually updated. AD5378 The REG1 and REG0 bits in the special function register (SFR) (see Table 10) show the decoding for data, offset, and gain registers. When all 32 DAC channels are selected, Address Bits A[3:0] are ignored. Table 18. DAC Group Addressing A7 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 A6 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 A5 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 A4 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Group All 32 DACs Group A Group B Groups A, B Group C Groups A, C Groups B, C Groups A, B, C Group D Groups A, D Groups B, D Groups A, B, D Groups C, D Groups A, C, D Groups B, C, D Groups A, B, C, D A3 0 0 0 0 0 0 1 1 A2 0 0 0 0 1 1 0 0 A1 0 0 1 1 0 0 0 0 A0 0 1 0 1 0 1 0 1 Data/Offset/Gain/INC-DEC Register Register 0 Register 1 Register 2 Register 3 Register 4 Register 5 Register 6 Register 7 Rev. PrA | Page 25 of 28 AD5378 POWER SUPPLY DECOUPLING 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 AD5378 is mounted should be designed so that the analog and digital sections are separated and confined to certain areas of the board. If the AD5378 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. For supplies with multiple pins (VSS, VDD, VCC), it is recommended to tie these pins together and to decouple each supply once. The AD5378 should have ample supply decoupling of 10 µF in parallel with 0.1 µF on each 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), such as the common ceramic types that provide a low impedance path to ground at high frequencies, to handle transient currents due to internal logic switching. Digital lines running under the device should be avoided, because these couple noise onto the device. The analog ground plane should be allowed to run under the AD5378 to avoid noise coupling. The power supply lines of the AD5378 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 digital signals 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. It is essential to minimize noise on all VREF(+) and VREF(−) lines. The VBIAS pin should be decoupled with a 10 nF capacitor to AGND. 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. As for all thin packages, care must be taken to avoid flexing the CSPBGA package and to avoid a point load on the surface of this package during the assembly process. POWER-ON An on-chip power supply monitor makes the AD5378 robust to power sequencing. The supply monitor powers up the analog section after (VDD − VSS) is greater than 7 V (typical). The output buffers power up in CLR mode forced to the DUTGND potential, even if VCC remains at 0 V. After VSS is applied, the analog circuitry powers up and the buffered DAC output level settles linearly within the supply range. Rev. PrA | Page 26 of 28 Preliminary Technical Data TYPICAL APPLICATION CIRCUIT The high channel count of the AD5378 makes it wellsuited to applications requiring high levels of integration such as optical and automatic test equipment (ATE) systems. Figure 22 shows the AD5378 as it is used in an ATE system. Shown here is one pin of a typical logic tester. It is apparent that a number of discrete levels are required for the pin driver, active load circuit, parametric measurement unit, comparators, and clamps. AD5378 In addition to the DAC levels required in the ATE system shown, drivers, loads, comparators, and parametric measurement unit functions are also required. Analog Devices provides solutions for all these functions. DRIVEN SHIELD DAC CENTRAL PMU ADC GUARD AMP VCH ADC DAC PPMU DAC DAC TIMING DATA MEMORY DAC TIMING GENERATOR DLL LOGIC VTERM VH RELAYS 50Ω COAX FORMATTER DE-SKEW DRIVER DAC VL DAC DAC VTH COMPARE MEMORY FORMATTER DE-SKEW COMP DAC ACTIVE LOAD DAC IOL ADC VTL DAC DEVICE POWER SUPPLY VCL GND SENSE DUT DAC VCOM DAC Figure 22. Typical Application Circuit for Logic Tester Rev. PrA | Page 27 of 28 05292-022 IOH AD5378 OUTLINE DIMENSIONS 13.00 BSC SQ A1 CORNER INDEX AREA 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H J K L M BALL A1 INDICATOR 11.00 BSC SQ BOTTOM VIEW TOP VIEW 1.00 BSC *1.85 1.70 1.55 DETAIL A DETAIL A 1.05 1.00 0.90 0.75 0.70 0.65 *0.64 TYP BALL DIAMETER *COMPLIANT WITH JEDEC STANDARDS MO-192-AAD-1 WITH THE EXCEPTION OF PACKAGE HEIGHT AND BALL DIAMETER. SEATING PLANE 0.12 MAX COPLANARITY Figure 23. 108-Lead Chip Scale Ball Grid Array [CSPBGA] (BC-108-2) Dimensions shown in millimeters ORDERING GUIDE Model AD5378ABC AD5378ABCZ1 Temperature Range −40°C to +85°C −40°C to +85°C Linearity Error (LSBs) ±3 ±3 Package Description 108-Lead CSPBGA 108-Lead CSPBGA Package Option BC-108-2 BC-108-2 1 Z = Pb-free part. © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR05292–0–1/05(PrA) Rev. PrA | Page 28 of 28