WM2630 Octal 12-bit, Serial Input, Voltage Output DAC with Internal Reference Production Data, February 2001, Rev 1.1 FEATURES • • • • • • • • • DESCRIPTION Eight 12-bit DACs in one package Dual supply 2.7V to 5.5V operation DNL ±0.5 LSBs, INL ±2.0 LSBs typ. Programmable settling time / power (1.0µs typ. in fast mode) Internal programmable Voltage Reference Microcontroller compatible Serial Interface Power Down Mode ( < 0.1µA) Monotonic over Temperature Data Output for Daisy Chaining The WM2630 is an octal, 12-bit, resistor string digital-toanalogue converter. The eight individual DACs contained in the IC can be switched in pairs between fast and slow (low power) operation modes, or powered down, under software control. Alternatively, the whole device can be powered down, reducing current consumption to less than 0.1µA. The DAC outputs are buffered by a rail-to-rail amplifier with a gain of two, which is configurable as Class A (fast mode) or Class AB (for low-power mode). The WM2630 has been designed to interface directly to industry standard microprocessors and DSPs, and can operate on two separate analogue and digital power supplies. It is programmed with a 16-bit serial word comprising 4 address bits and up to 12 DAC or control register data bits. All eight DACs can be simultaneously forced to a preset value using a preset input pin. APPLICATIONS • • • • • • • • Battery powered test instruments Digital offset and gain adjustment Battery operated / remote industrial controls Programmable Loop Controllers CNC Machine Tools Machine and motion control devices Wireless telephone and communication systems Robotics A daisy-chain data output makes it possible to control several of Wolfson’s octal DACs from the same interface, without increasing the number of control lines. The device is available in a 20-pin TSSOP package. Commercial temperature (0° to 70°C) and Industrial temperature (-40° to 85°C) variants are supported. ORDERING INFORMATION DEVICE TEMP. RANGE PACKAGE WM2630CDT 0° to 70°C 20-pin TSSOP WM2630IDT -40° to 85°C 20-pin TSSOP BLOCK DIAGRAM TYPICAL PERFORMANCE REF (16) AVDD (11) DVDD (20) 1.024V / 2.048V SELECTABLE REFERENCE 1 DAC A DIN (2) RESISTOR STRING SCLK (3) FS (4) MODE (17) PREB (5) SERIAL INTERFACE AND CONTROL LOGIC (12) OUT A LATCH POWER/SPEED CONTROL DOUT (19) REF DACs B, C, D, E, F, G, H as DAC A (6-9, 13-15) OUT B to H Differential Non-Linearity (LSBs) 0.75 0.5 0.25 0 -0.25 -0.5 -0.75 -1 0 LOADB (18) AGND (10) DGND (1) WOLFSON MICROELECTRONICS LTD Bernard Terrace, Edinburgh, EH8 9NX, UK Tel: +44 (0) 131 667 9386 Fax: +44 (0) 131 667 5176 Email: [email protected] www.wolfsonmicro.co.uk 512 1024 1536 2048 2560 3072 3584 4096 DIGITAL CODE Production Data datasheets contain final specifications current on publication date. Supply of products conforms to Wolfson Microelectronics’ Terms and Conditions. 2001 Wolfson Microelectronics Ltd. WM2630 Production Data PIN CONFIGURATION DGND 1 20 DVDD DIN 2 19 DOUT SCLK 3 18 LOADB FS 4 17 MODE PREB 5 16 REF OUTE 6 15 OUTD OUTF 7 14 OUTC OUTG 8 13 OUTB OUTH 9 12 OUTA AGND 10 11 AVDD PIN DESCRIPTION PIN NO NAME TYPE 1 DGND Supply DESCRIPTION Digital Ground 2 DIN Digital input Digital serial data input 3 SCLK Digital input Serial clock input 4 FS Digital input Frame sync input 5 PREB Digital input Preset input 6 OUTE Analogue output DAC Output E 7 OUTF Analogue output DAC Output F 8 OUTG Analogue output DAC Output G 9 OUTH Analogue output 10 AGND Supply Analogue Ground Analogue positive power supply DAC Output H 11 AVDD Supply 12 OUTA Analogue output DAC Output A 13 OUTB Analogue output DAC Output B 14 OUTC Analogue output DAC Output C 15 OUTD Analogue output 16 REF Analogue I/O DAC Output D Voltage reference input / output 17 MODE Digital input Input mode 18 LOADB Digital input Load DAC 19 DOUT Digital output 20 DVDD Supply WOLFSON MICROELECTRONICS LTD Data serial data output Digital positive power supply PD Rev 1.1 February 2001 2 WM2630 Production Data ABSOLUTE MAXIMUM RATINGS Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical Characteristics at the test conditions specified. ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage of this device. CONDITION MIN MAX Digital supply voltages, AVDD or DVDD to GND 7V Reference input voltage -0.3V AVDD + 0.3V Digital input voltage range to GND -0.3V DVDD + 0.3V WM2630CDT 0°C 70°C WM2630IDT -40°C 85°C -65°C 150°C Operating temperature range, TA Storage temperature Soldering lead temperature, 1.6mm (1/16 inch) from package body for 10 seconds 260°C RECOMMENDED OPERATING CONDITIONS PARAMETER SYMBOL Supply voltage AVDD, TEST CONDITIONS MIN TYP 2.7 MAX UNIT 5.5 V DVDD High-level digital input voltage VIH See Note Low-level digital input voltage VIL See Note VREF AVDD = 5V GND 2.048 AVDD AVDD = 3V GND 1.024 AVDD Reference voltage to REF Output Load Resistance RL Load capacitance CL Operating free-air temperature TA 2 V 0.8 2 V V kΩ 100 pF WM2630CDT 0 70 °C WM2630IDT -40 85 °C Note: Reference input voltages greater than AVDD/2 will cause saturation for large DAC codes. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 3 WM2630 Production Data ELECTRICAL CHARACTERISTICS Test Characteristics: RL = 10kΩ, CL = 100pF AVDD = DVDD = 5V ± 10%, VREF = 2.048V and AVDD = DVDD = 3V ± 10%, VREF = 1.024V over recommended operating free-air temperature range (unless noted otherwise). PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT ±6 LSB Static DAC Specifications Resolution 12 bits Integral non-linearity INL Code 40 to 4095 (see Note 1) ±2 Differential non-linearity DNL Code 40 to 4095 (see Note 2) ±0.5 ±1 LSB Zero code error ZCE See Note 3 ±30 mV Gain error GE See Note 4 ±0.6 % FSR DC power supply rejection ratio See Note 5 -50 dB Zero code error temperature coefficient PSRR See Note 6 30 µV/°C Gain error temperature coefficient See Note 6 10 ppm/°C DAC Output Specifications Output voltage range 10kΩ Load Output load regulation 2kΩ to 10kΩ load 0 AVDD-0.4 V ±0.3 % Full Scale See Note 7 Power Supplies Active supply current IDD No load, VIH=DVDD, VIL=0V AVDD = DVDD = 5V, VREF = 2.048V Slow 6 8 mA Fast 16 21 mA See Note 8 Power down supply current No load, all inputs 0V or DVDD 0.1 µA Dynamic DAC Specifications Slew rate DAC code 10%-90% Load = 10kΩ, 100pF Fast 4 10 V/µs Slow 1 3 V/µs See Note 9 Settling time DAC code 10%-90% Load = 10kΩ, 100pF Fast 1 3 µs Slow 3 7 µs See Note 10 Glitch energy Channel Crosstalk WOLFSON MICROELECTRONICS LTD Code 2047 to code 2048 4 nV-s 10kHz sine wave, 4V pk-pk -90 dB PD Rev 1.1 February 2001 4 WM2630 Production Data Test Characteristics: RL = 10kΩ, CL = 100pF AVDD = DVDD = 5V ± 10%, VREF = 2.048V and AVDD = DVDD = 3V ± 10%, VREF = 1.024V over recommended operating free-air temperature range (unless noted otherwise). PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Reference Configured as Input Reference input resistance RREF 50 kΩ Reference input capacitance CREF 10 pF -84 dB Slow 1.9 MHz Fast 2.2 MHz Reference feedthrough VREF=2VPP at 1kHz + 2.048V DC, DAC code 0 Reference input bandwidth VREF= 0.4VPP + 2.048V DC, DAC code 2048 Reference Configured as Output Low reference voltage VREFOUTL High reference voltage VREFOUTH Output source current IREFSRC Output sink current IREFSNK Load Capacitance VDD > 4.75V 1.010 1.024 1.040 2.020 2.048 2.096 V 1 mA -1 in parallel with 100nF cap. 1 PSRR V mA 10 µF 60 dB Digital Inputs High level input current IIH Input voltage = DVDD Low level input current IIL Input voltage = 0V Input capacitance CI 1 µA µA -1 8 pF Notes: 1. Integral non-linearity (INL) is the maximum deviation of the output from the line between zero and full scale excluding the effects of zero code and full scale errors). 2. Differential non-linearity (DNL) is the difference between the measured and ideal 1LSB amplitude change of any adjacent two codes. A guarantee of monotonicity means the output voltage changes in the same direction (or remains constant) as a change in digital input code. 3. Zero code error is the voltage output when the DAC input code is zero. 4. Gain error is the deviation from the ideal full-scale output excluding the effects of zero code error. 5. Power supply rejection ratio is measured by varying AVDD from 4.5V to 5.5V and measuring the proportion of this signal imposed on the zero code error and the gain error. 6. Zero code error and Gain error temperature coefficients are normalised to full-scale voltage. 7. Output load regulation is the difference between the output voltage at full scale with a 10kΩ load and 2kΩ load. It is expressed as a percentage of the full scale output voltage with a 10kΩ load. 8. IDD is measured while continuously writing code 2048 to the DAC. For VIH < DVDD - 0.7V and VIL > 0.7V supply current will increase. 9. Slew rate results are for the lower value of the rising and falling edge slew rates. 10. Settling time is the time taken for the signal to settle to within 0.5LSB of the final measured value for both rising and falling edges. Limits are ensured by design and characterisation, but are not production tested. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 5 WM2630 Production Data SERIAL INTERFACE tWL SCLK X 1 2 tSUD tWH 3 4 16 X tHD DIN X D15 D14 D13 DOUT X D15 * D14 * D13 * tWHFS tSUFSCLK FS (µC MODE) 2 D12 * D1 D0 X D1 * D0 * X tSUC16-FS * DIN data from previous word (delayed by 16 clock cycles) tWLFS FS (DSP MODE) No high to low transitions Figure 1 Timing Diagram SYMBOL TEST MIN TYP MAX UNIT CONDITIONS tSUFSCLK Setup time, FS pin low before first falling edge of SCLK th 8 ns tC16-FS Setup time, 16 falling clock edge after FS low to rising edge of FS (only used in microcontroller mode) 10 ns tWLOADB Pulse duration, LOADB low 10 ns tWH Pulse duration, SCLK high 16 ns tWL Pulse duration, SCLK low 16 ns tSUD Setup time, data ready before SCLK falling edge 8 ns tHD Hold time, data held valid after SCLK falling edge 5 ns tWHFS Pulse duration, FS high 10 ns tWLFS Pulse duration, FS low 10 ns ts DAC Output settling time WOLFSON MICROELECTRONICS LTD see Dynamic DAC Specifications PD Rev 1.1 February 2001 6 WM2630 Production Data TYPICAL PERFORMANCE GRAPHS 4 Integral Non-Linearity (LSBs) 3 2 1 0 -1 -2 -3 -4 0 512 1024 1536 2048 2560 3072 3584 4096 DIGITAL CODE Figure 2 Integral Non-Linearity 1 1 VDD = 3.3V VREF = 1.024V Input Code = 0 VDD = 5V VREF = 2.048V Input Code = 0 Slow Fast Output Voltage (V) Output Voltage (V) Slow Fast 0.8 0.8 0.6 0.4 0.2 0.6 0.4 0.2 0 0 0 0.5 1 1.5 2 0 0.2 0.4 0.6 Figure 3 Output Load Regulation (Sink) AVDD = 3V 1 1.2 1.4 1.6 1.8 2 Figure 4 Output Load Regulation (Sink) AVDD = 5V 2.1 4.15 VDD=3V VREF =1.024V Input Code = 4095 VDD=5V V REF=2.048V Input Code = 4095 Slow Fast 2.08 Slow Fast 4.13 DACA (Volts) DACA (Volts) 0.8 Sink Current (mA) Sink Current (mA) 2.06 2.04 4.11 4.09 4.07 2.02 4.05 2 0 -0.5 -1 -1.5 -2 -2.5 -3 -3.5 Sourcing Current (mA) Figure 5 Output Load Regulation (Source) AVDD = 3V WOLFSON MICROELECTRONICS LTD -4 0 -0.5 -1 -1.5 -2 -2.5 -3 -3.5 -4 Sourcing Current (mA) Figure 6 Output Load Regulation (Source) AVDD = 5V PD Rev 1.1 February 2001 7 WM2630 Production Data DEVICE DESCRIPTION GENERAL FUNCTION The WM2630 is an octal 12-bit, voltage output DAC. It contains a serial interface, control logic for speed and power down, a programmable voltage reference, and eight digital to analogue converters. Each converter uses a resistor string network buffered with an op amp to convert 12-bit digital data to analogue voltage levels (see Block Diagram). The output voltage is determined by the reference input voltage and the input code according to the following relationship: ( Output voltage = 2 VREF ) CODE 4096 INPUT 1111 1111 OUTPUT 1111 ( 2 VREF : 1000 0000 4096 : 0001 ( 2 VREF 1000 0000 0000 ( 2 VREF 0111 1111 1111 ) 2048 = V REF 4096 ( : 0000 0000 ) 2047 4096 : 0001 ( 2 VREF 0000 ) 2049 4096 2 VREF 0000 ) 4095 0000 ) 1 4096 0V Table 1 Binary Code Table (0V to 2VREF Output), Gain = 2 POWER ON RESET An internal power-on-reset circuit resets the DAC register to all 0s on power-up. BUFFER AMPLIFIER The output buffer has a near rail-to-rail output with short circuit protection and can reliably drive a 2kΩ load with a 100pF load capacitance. PROGRAMMABLE REFERENCE The DAC reference can be sourced internally or externally under software control. If an external reference voltage is applied to the REF pin, the device must be configured to accept this. If an internal reference is selected, a voltage of 1.024V or 2.048 is available. The internal reference can source up to 1mA and can therefore be used as an external system reference. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 8 WM2630 Production Data SERIAL INTERFACE INTERFACE MODES The control interface can operate in two different modes: • In the microcontroller mode, FS needs to be held low until all 16 data bits have been transferred. If th FS is driven high before the 16 falling clock edge, the data transfer is cancelled. The DAC is updated after a rising edge on FS. • In DSP mode, FS only needs to stay low for 20ns, and can go high before the 16 falling clock edge. th SCLK FS DIN X D15 D14 D1 D0 X E15 E15 E14 E14 E1 E0 E0 X X X F15 F14 X F15 F14 Figure 7 Interface Timing in Microcontroller Mode SCLK FS DIN X D15 D14 D1 D0 E1 X Figure 8 Interface Timing in DSP Mode The operating mode is selected using pin 17 (MODE). MODE PIN (17) INTERFACE MODE HIGH Microcontroller LOW or unconnected DSP mode Table 2 Interface Mode Selection SERIAL CLOCK AND UPDATE RATE Figure 1 shows the interface timing. The maximum serial clock rate is: f SCLK max = 1 = 31MHz tWH min + tWL min Since a data word contains 16 bits, the sample rate is limited to f s max = 1 16(tWH min + tWL min ) = 1.95MHz However, the DAC settling time to 12 bits accuracy limits the response time of the analogue output for large input step transitions. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 9 WM2630 Production Data DAISY CHAINING MULTIPLE DEVICES OCTAL DAC #1 DIN SCLK FS LOADB DOUT DIN SCLK FS LOADB DOUT DIN SCLK FS LOADB DOUT DIN SCLK FS LOADB The DOUT output (pin 19) provides the data sampled on DIN with a delay of 16 clock cycles. This signal can be used to control another WM2630 or similar device in a daisy-chain type circuit. OCTAL DAC #2 OCTAL DAC #3 Figure 9 Daisy Chaining SOFTWARE CONFIGURATION OPTIONS DATA FORMAT The WM2630 is controlled with a 16-bit code consisting of four address bits, A0-A3, and 12 data bits. D15 D14 D13 D12 A3 A2 A1 A0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Data Table 3 Input Data Format Using the four address bits, 16 different registers can be addressed. A3 A2 A1 A0 REGISTER 0 0 0 0 DAC A Code 0 0 0 1 DAC B Code 0 0 1 0 DAC C Code 0 0 1 1 DAC D Code 0 1 0 0 DAC E Code 0 1 0 1 DAC F Code 0 1 1 0 DAC G Code 0 1 1 1 DAC H Code 1 0 0 0 Control Register 0 1 0 0 1 Control Register 1 1 0 1 0 Preset all DACs 1 0 1 1 RESERVED 1 1 0 0 DAC A and complement B 1 1 0 1 DAC C and complement D 1 1 1 0 DAC E and complement F 1 1 1 1 DAC G and complement H Table 4 Register Map WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 10 WM2630 Production Data DAC A TO H CODE REGISTERS Addresses 0 to 7 are the DAC registers. The data written to these registers is transferred to the respective DAC when the LOADB input (pin 18) is low. For instantaneous updating, LOADB can be held low permanently. CONTROL REGISTER 0 Control register 0 (address 8) is used to select functions that apply to the whole IC, such as Power Down and Data Input Format. BIT D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function X X X X X X X PD DO R1 R0 IM Default X X X X X X X 0 0 0 0 0 Table 5 Register Map BIT DESCRIPTION 0 1 PD Full device Power Down Normal Power Down DO DOUT Enable Disabled Enabled R1 Int / Ext Reference Select External Internal R0 Internal Reference Select 1.024V 2.048V IM Input Mode Straight Binary Two’s Complement X Reserved Table 6 Register Map CONTROL REGISTER 1 Control register 1 (address 9) is used to power down individual pairs of DACs and select their settling time. Powering down a pair of DACs disables their amplifiers and reduces the power consumption of the device. The settling time in fast mode is typically 1µs. In slow mode, the settling time is typically 3µs and power consumption is reduced. BIT D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function X X X X PGH PEF PCD PAB SGH SEF SCD SAB Default X X X X 0 0 0 0 0 0 0 0 Table 7 Register Map BIT DESCRIPTION 0 1 PXY Power Down DACs X and Y Normal Power Down SXY Speed Setting for DACs X and Y Slow Fast Table 8 Register Map DAC PRESET REGISTER The Preset register (address 10) makes it possible to update all eight DACs at the same time. The value stored in this register becomes the digital input to all the DACs when the asynchronous PREB input (pin 5) is driven low. If no data has previously been written to the preset register, all DACs are set to zero scale. TWO-CHANNEL REGISTERS The two-channel registers (addresses 12 to 15) provide a ‘differential output’ function where writing data to one DAC will automatically write the complement to the other DAC in the pair. For example, writing a hexadecimal value of FFFF to address 12 will set DAC A to full scale and DAC B to zero scale. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 11 WM2630 Production Data PROGRAMMABLE INTERNAL REFERENCE The reference can be sourced internally or externally under software control. If an external reference voltage is applied to the REF pin, the device must be configured to accept this. If an external reference is selected, the reference voltage input is buffered which makes the DAC input resistance independent of code. The REF pin has an input resistance of 10MΩ and an input capacitance of typically 55pF. The reference voltage determines the DAC full-scale output. If an internal reference is selected, a voltage of 1.024V or 2.048 is available. The internal reference can source up to 1mA and can therefore be used as an external system reference. REF1 REF0 REFERENCCE 0 0 External (default) 0 1 1.024V 1 0 2.048V 1 1 External Table 9 Programmable Internal Reference APPLICATIONS INFORMATION LINEARITY, OFFSET, AND GAIN ERROR Amplifiers operating from a single supply can have positive or negative voltage offsets. With a positive offset, the output voltage changes on the first code transition. However, if the offset is negative, the output voltage may not change with the first code, depending on the magnitude of the offset voltage. This is because with the most negative supply rail being ground, any attempt to drive the output amplifier below ground will clamp the output at 0 V. The output voltage then remains at zero until the input code is sufficiently high to overcome the negative offset voltage, resulting in the transfer function shown in Figure 10. Output Voltage 0V Negative Offset DAC code Figure 10 Effect of Negative Offset This offset error, not the linearity error, produces the breakpoint. The transfer function would follow the dotted line if the output buffer could drive below the ground rail. DAC linearity is measured between zero-input code (all input bits at 0) and full-scale code (all inputs at 1), disregarding offset and full-scale errors. However, due to the breakpoint in the transfer function, single supply operation does not allow for adjustment when the offset is negative. In such cases, the linearity is therefore measured between full-scale and the lowest code that produces a positive (non-zero) output voltage. POWER SUPPLY DECOUPLING AND GROUNDING Printed circuit boards with separate analogue and digital ground planes deliver the best system performance. The two ground planes should be connected together at the low impedance power supply source. Ground currents should be managed so as to minimise voltage drops across the ground planes. A 0.1µF decoupling capacitor should be connected between the positive supply and ground pins of the DAC, with short leads as close as possible to the device. Use of ferrite beads may further isolate the system analogue supply from the digital supply. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 12 WM2630 Production Data PACKAGE DIMENSIONS DT: 20 PIN TSSOP (6.5 x 4.4 x 1.0 mm) b DM008.D e 20 11 E1 E GAUGE PLANE 1 θ 10 D 0.25 c A A2 L A1 -C0.1 C SEATING PLANE Symbols A A1 A2 b c D e E E1 L θ REF: MIN ----0.05 0.80 0.19 0.09 6.40 4.30 0.45 o 0 Dimensions (mm) NOM --------1.00 --------6.50 0.65 BSC 6.4 BSC 4.40 0.60 ----- MAX 1.20 0.15 1.05 0.30 0.20 6.60 4.50 0.75 o 8 JEDEC.95, MO-153 NOTES: A. ALL LINEAR DIMENSIONS ARE IN MILLIMETERS. B. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. C. BODY DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSION, NOT TO EXCEED 0.25MM. D. MEETS JEDEC.95 MO-153, VARIATION = AC. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS. WOLFSON MICROELECTRONICS LTD PD Rev 1.1 February 2001 13