TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 features D D D D D D D PACKAGE (TOP VIEW) Dual 8-Bit Voltage Output DAC Programmable Internal Reference Programmable Settling Time: 0.8 µs in Fast Mode , 2.8 µs in Slow Mode Compatible With TMS320 and SPI Serial Ports Differential Nonlinearity <0.1 LSB Typ Monotonic Over Temperature DIN SCLK CS OUTA 1 8 2 7 3 6 4 5 VDD OUTB REF AGND applications D D D D D Digital Servo Control Loops Digital Offset and Gain Adjustment Industrial Process Control Machine and Motion Control Devices Mass Storage Devices description The TLV5626 is a dual 8-bit voltage output DAC with a flexible 3-wire serial interface.The serial interface allows glueless interface to TMS320 and SPI, QSPI, and Microwire serial ports. It is programmed with a 16-bit serial string containing 2 control and 8 data bits. The resistor string output voltage is buffered by a x2 gain rail-to-rail output buffer. The buffer features a Class AB output stage to improve stability and reduce settling time. The programmable settling time of the DAC allows the designer to optimize speed versus power dissipation. With its on-chip programmable precision voltage reference, the TLV5626 simplifies overall system design. Because of its ability to source up to 1 mA, the reference can also be used as a system reference. Implemented with a CMOS process, the device is designed for single supply operation from 2.7 V to 5.5 V. It is available in an 8-pin SOIC package to reduce board space in standard commercial and industrial temperature ranges. AVAILABLE OPTIONS PACKAGE TA SOIC (D) 0°C to 70°C TLV5626CD – 40°C to 85°C TLV5626ID 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. SPI and QSPI are trademarks of Motorola, Inc. Microwire is a trademark of National Semiconductor Corporation. Copyright 1999, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 functional block diagram REF AGND VDD PGA With Output Enable Voltage Bandgap Power-On Reset Power and Speed Control 2 2 2-Bit Control Latch x2 OUTA x2 OUTB DIN 8-Bit DAC A Latch 8 SCLK Serial Interface and Control CS 8 8 Buffer 8 8-Bit DAC B Latch 8 Terminal Functions TERMINAL NAME NO. I/O/P DESCRIPTION AGND 5 P Ground CS 3 I Chip select. Digital input active low, used to enable/disable inputs DIN 1 I Digital serial data input OUTA 4 I DAC A analog voltage output OUTB 7 O DAC B analog voltage output REF 6 I/O Analog reference voltage input/output SCLK 2 I Digital serial clock input VDD 8 P Positive power supply 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage (VDD to AGND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Reference input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to VDD + 0.3 V Digital input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to VDD + 0.3 V Operating free-air temperature range, TA: TLV5626C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C TLV5626I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 85°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. recommended operating conditions Supply voltage voltage, VDD VDD = 5 V VDD = 3 V Power on threshold voltage, POR High-level digital input voltage, VIH Low-level digital input voltage, VIL Reference voltage, Vref to REF terminal Reference voltage, Vref to REF terminal MIN NOM MAX 4.5 5 5.5 V 2.7 3 3.3 V 2 V 0.55 VDD = 2.7 V to 5.5 V VDD = 2.7 V to 5.5 V 2 VDD = 5 V (see Note 1) VDD = 3 V (see Note 1) Load resistance, RL UNIT V AGND 2.048 AGND 1.024 0.8 V VDD –1.5 VDD – 1.5 V 2 V kΩ Load capacitance, CL 100 pF Clock frequency, fCLK 20 MHz Operating free-air free air temperature, temperature TA TLV5626C TLV5626I 0 70 –40 85 °C NOTE 1: Due to the x2 output buffer, a reference input voltage ≥ (VDD – 0.4 V)/2 causes clipping of the transfer function. The output buffer of the internal reference must be disabled, if an external reference is used. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 3 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 electrical characteristics over recommended operating conditions (unless otherwise noted) power supply PARAMETER IDD TEST CONDITIONS No load, All inputs = AGND or VDD, DAC latch = 0x800 Power supply current TYP MAX VDD = 5 V, Int. ref. Fast MIN 4.2 5 mA Slow 2 2.5 mA VDD = 3 V, Int. ref. Fast 3.7 4.6 mA Slow 1.7 2.2 mA VDD = 5 V, Ext. ref. Fast 3.8 4.6 mA Slow 1.7 2.1 mA VDD = 3 V, Ext. ref. Fast 3.4 4.2 mA Slow 1.4 1.8 mA Power-down supply current PSRR µA 1 Power supply rejection ratio Zero scale, See Note 2 –65 Full scale, –65 See Note 3 UNIT dB NOTES: 2. Power supply rejection ratio at zero scale is measured by varying VDD and is given by: PSRR = 20 log [(EZS(VDDmax) – EZS(VDDmin))/VDDmax] 3. Power supply rejection ratio at full scale is measured by varying VDD and is given by: PSRR = 20 log [(EG(VDDmax) – EG(VDDmin))/VDDmax] static DAC specifications PARAMETER TEST CONDITIONS MIN Resolution TYP MAX 8 UNIT bits INL Integral nonlinearity, end point adjusted See Note 4 ± 0.4 ±1 LSB DNL Differential nonlinearity See Note 5 ± 0.1 ± 0.5 LSB EZS EZS TC Zero-scale error (offset error at zero scale) See Note 6 ±24 mV Zero-scale-error temperature coefficient See Note 7 EG Gain error See Note 8 10 ppm/°C ± 0.6 % full scale V EG TC Gain error temperature coefficient See Note 9 10 ppm/°C NOTES: 4. The relative accuracy or integral nonlinearity (INL) sometimes referred to as linearity error, 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. 5. The differential nonlinearity (DNL) sometimes referred to as differential error, is the difference between the measured and ideal 1 LSB amplitude change of any two adjacent codes. Monotonic means the output voltage changes in the same direction (or remains constant) as a change in the digital input code. 6. Zero-scale error is the deviation from zero voltage output when the digital input code is zero. 7. Zero-scale-error temperature coefficient is given by: EZS TC = [EZS (Tmax) – EZS (Tmin)]/Vref × 106/(Tmax – Tmin). 8. Gain error is the deviation from the ideal output (2Vref – 1 LSB) with an output load of 10 k excluding the effects of the zero-error. 9. Gain temperature coefficient is given by: EG TC = [EG(Tmax) – EG (Tmin)]/Vref × 106/(Tmax – Tmin). output specifications PARAMETER VO Output voltage Output load regulation accuracy 4 TEST CONDITIONS RL = 10 kΩ 0 VO = 4.096 V, 2.048 V, POST OFFICE BOX 655303 MIN RL = 2 kΩ vs 10 k • DALLAS, TEXAS 75265 TYP MAX VDD–0.4 ± 0.25 UNIT V % full scale V TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 electrical characteristics over recommended operating conditions (unless otherwise noted) (Continued) reference pin configured as output (REF) PARAMETER Vref(OUTL) Vref(OUTH) Low reference voltage Iref(source) Iref(sink) Output source current TEST CONDITIONS High reference voltage VDD > 4.75 V MIN TYP MAX UNIT 1.003 1.024 1.045 V 2.027 2.048 2.069 1 Output sink current –1 mA Load capacitance PSRR 100 Power supply rejection ratio V mA –65 pF dB reference pin configured as input (REF) PARAMETER VI RI Input voltage CI Input capacitance TEST CONDITIONS MIN TYP 0 VDD–1.5 Input resistance Reference input bandwidth REF = 0.2 0 2 Vpp + 1.024 1 024 V dc Reference feedthrough REF = 1 Vpp at 1 kHz + 1.024 V dc (see Note 10) MAX UNIT V 10 MΩ 5 pF Fast 1.3 MHz Slow 525 kHz – 80 dB NOTE 10: Reference feedthrough is measured at the DAC output with an input code = 0x000. digital inputs PARAMETER IIH IIL High-level digital input current Ci Input capacitance TEST CONDITIONS VI = VDD VI = 0 V Low-level digital input current MIN TYP MAX 1 UNIT µA µA –1 8 pF analog output dynamic performance PARAMETER TEST CONDITIONS CL = 100 pF,, TYP MAX Fast MIN 0.8 2.4 Slow 2.8 5.5 Fast 0.4 1.2 Slow 0.8 1.6 Fast 12 Slow 1.8 ts(FS) (FS) time full scale Output settling time, RL = 10 kΩ,, See Note 11 ts(CC) (CC) Output settling time time, code to code RL = 10 kΩ,, See Note 12 CL = 100 pF,, SR Slew rate RL = 10 kΩ,, See Note 13 CL = 100 pF,, Glitch energy DIN = 0 to 1, CS = VDD fCLK = 100 kHz, Signal-to-noise ratio 53 57 S/(N+D) Signal-to-noise + distortion 48 47 THD Total harmonic distortion SFDR Spurious free dynamic range fs = 480 kSPS,, fout = 1 kHz,, RL = 10 kΩ, CL = 100 pF –50 50 µs µs V/µs 5 SNR UNIT nV–S –48 dB 62 NOTES: 11. Settling time is the time for the output signal to remain within ± 0.5 LSB of the final measured value for a digital input code change of 0x020 to 0xFD0 or 0xFD0 to 0x020 respectively. Not tested, assured by design. 12. Settling time is the time for the output signal to remain within ± 0.5 LSB of the final measured value for a digital input code change of one count. Not tested, assured by design. 13. Slew rate determines the time it takes for a change of the DAC output from 10% to 90% full-scale voltage. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 digital input timing requirements MIN NOM MAX UNIT tsu(CS–CK) tsu(C16-CS) Setup time, CS low before first negative SCLK edge Setup time, 16th negative SCLK edge (when D0 is sampled) before CS rising edge 10 ns 10 ns twH twL SCLK pulse width high 25 ns SCLK pulse width low 25 ns tsu(D) th(D) Setup time, data ready before SCLK falling edge 10 ns Hold time, data held valid after SCLK falling edge 5 ns PARAMETER MEASUREMENT INFORMATION twL SCLK X 1 2 tsu(D) DIN X twH 3 4 5 15 X 16 th(D) D15 D14 D13 D12 D1 D0 X tsu(C16-CS) tsu(CS-CK) CS Figure 1. Timing Diagram 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 TYPICAL CHARACTERISTICS SUPPLY CURRENT vs FREE-AIR TEMPERATURE SUPPLY CURRENT vs FREE-AIR TEMPERATURE 4.5 4.5 4 Fast Mode I DD – Supply Current – mA I DD – Supply Current – mA 4 3.5 3 2.5 2 Slow Mode 1.5 Fast Mode 3.5 3 2.5 2 Slow Mode 1.5 VDD = 5 V Vref = Int. 2 V Input Code = 1023 (Both DACs) 1 VDD = 3 V Vref = Int. 1 V Input Code = 1023 (Both DACs) 1 0.5 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 TA – Free-Air Temperature – °C 0.5 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 TA – Free-Air Temperature – °C Figure 2 Figure 3 POWER DOWN SUPPLY CURRENT vs TIME OUTPUT VOLTAGE vs LOAD CURRENT 2.064 2.4 VDD = 3 V Vref = Int. 1 V Input Code = 4095 Fast Mode 2.2 2.062 2 VO – Output Voltage – V I DD – Power Down Supply Current – mA 2.6 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 2.06 Slow Mode 2.058 2.056 2.054 2.052 0.2 0 0 10 20 50 30 40 t – Time – µs 60 70 80 2.05 0 0.5 1 1.5 2 2.5 3 3.5 4 Source Current – mA Figure 4 Figure 5 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 TYPICAL CHARACTERISTICS OUTPUT VOLTAGE vs LOAD CURRENT OUTPUT VOLTAGE vs LOAD CURRENT 3 4.128 VDD = 5 V Vref = Int. 2 V Input Code = 4095 Fast Mode 2.5 VO – Output Voltage – V VO – Output Voltage – V 4.126 VDD = 3 V Vref = Int. 1 V Input Code = 0 4.124 Slow Mode 4.122 4.12 4.118 Fast Mode 2 1.5 1 0.5 4.116 Slow Mode 0 4.114 0 0.5 1 1.5 2 2.5 3 3.5 0 4 0.5 Figure 6 THD+N – Total Harmonic Distortion and Noise – dB VDD = 5 V Vref = Int. 2 V Input Code = 0 VO – Output Voltage – V 4 3.5 Fast Mode 3 2.5 2 1.5 1 Slow Mode 0 0.5 1 3 3.5 4 1.5 2 2.5 Sink Current – mA 3 3.5 4 0 –10 VDD = 5 V Vref = 1 V dc + 1 V p/p Sinewave Output Full Scale –20 –30 –40 –50 –60 Slow Mode –70 Fast Mode –80 –90 –100 100 1000 10000 f – Frequency – Hz Figure 8 8 2.5 TOTAL HARMONIC DISTORTION AND NOISE vs FREQUENCY 5 0 2 Figure 7 OUTPUT VOLTAGE vs LOAD CURRENT 0.5 1.5 Sink Current – mA Source Current – mA 4.5 1 Figure 9 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 100000 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 TYPICAL CHARACTERISTICS TOTAL HARMONIC DISTORTION vs FREQUENCY THD – Total Harmonic Distortion – dB 0 –10 VDD = 5 V Vref = 1 V dc + 1 V p/p Sinewave Output Full Scale –20 –30 –40 –50 –60 –70 Slow Mode –80 Fast Mode –90 –100 100 1000 10000 100000 f – Frequency – Hz Figure 10 DNL – Differential Nonlinearity – LSB DIFFERENTIAL NONLINEARITY vs DIGITAL OUTPUT CODE 0.20 0.15 0.10 0.05 –0.00 –0.05 –0.10 –0.15 –0.2 0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256 Digital Output Code Figure 11 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 9 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 TYPICAL CHARACTERISTICS INL – Integral Nonlinearity – LSB INTEGRAL NONLINEARITY vs DIGITAL OUTPUT CODE 1.0 0.8 0.6 0.4 0.2 –0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256 Digital Output Code Figure 12 APPLICATION INFORMATION general function The TLV5626 is a dual 8-bit, single supply DAC, based on a resistor string architecture. It consists of a serial interface, a speed and power-down control logic, a programmable internal reference, a resistor string, and a rail-to-rail output buffer. The output voltage (full scale determined by reference) is given by: 2 REF CODE [V] 0x1000 Where REF is the reference voltage and CODE is the digital input value in the range 0x000 to 0xFF0.Bits 3 to 0 must be set to zero. A power on reset initially puts the internal latches to a defined state (all bits zero). serial interface A falling edge of CS starts shifting the data bit-per-bit (starting with the MSB) to the internal register on the falling edges of SCLK. After 16 bits have been transferred or CS rises, the content of the shift register is moved to the target latches (DAC A, DAC B, BUFFER, CONTROL), depending on the control bits within the data word. Figure 13 shows examples of how to connect the TLV5626 to TMS320, SPI, and Microwire. TMS320 DSP FSX DX CLKX TLV5626 CS DIN SCLK SPI I/O MOSI SCK TLV5626 CS DIN SCLK Figure 13. Three-Wire Interface 10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 Microwire I/O SO SK TLV5626 CS DIN SCLK TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 APPLICATION INFORMATION Notes on SPI and Microwire: Before the controller starts the data transfer, the software has to generate a falling edge on the I/O pin connected to CS. If the word width is 8 bits (SPI and Microwire), two write operations must be performed to program the TLV5626. After the write operation(s), the holding registers or the control register are updated automatically on the 16th positive clock edge. serial clock frequency and update rate The maximum serial clock frequency is given by: f sclkmax +t )t 1 whmin wlmin + 20 MHz The maximum update rate is: f updatemax + 16 ǒt 1 whmin )t Ǔ+ 1.25 MHz wlmin The maximum update rate is just a theoretical value for the serial interface, as the settling time of the TLV5626 has to be considered, too. data format The 16-bit data word for the TLV5626 consists of two parts: D D Program bits (D15..D12) New data (D11..D0) D15 D14 D13 D12 R1 SPD PWR R0 SPD: Speed control bit PWR: Power control bit D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 12 Data bits 1 → fast mode 1 → power down 0 → slow mode 0 → normal operation The following table lists the possible combination of the register select bits: register select bits R1 R0 REGISTER 0 0 Write data to DAC B and BUFFER 0 1 Write data to BUFFER 1 0 Write data to DAC A and update DAC B with BUFFER content 1 1 Write data to control register The meaning of the 12 data bits depends on the register. If one of the DAC registers or the BUFFER is selected, then the 12 data bits determine the new DAC value: data bits: DAC A, DAC B and BUFFER D11 D10 D9 D8 D7 D6 D5 D4 New DAC Value D3 D2 D1 D0 0 0 0 0 If control is selected, then D1, D0 of the 12 data bits are used to program the reference voltage: POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 11 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 APPLICATION INFORMATION data bits: CONTROL D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X X X X X X X X X REF1 REF0 X: don’t care REF1 and REF0 determine the reference source and, if internal reference is selected, the reference voltage. reference bits REF1 REF0 REFERENCE 0 0 External 0 1 1.024 V 1 0 2.048 V 1 1 External CAUTION: If external reference voltage is applied to the REF pin, external reference MUST be selected. examples of operation: D Set DAC A output, select fast mode, select internal reference at 2.048 V: 1. Set reference voltage to 2.048 V (CONTROL register): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 D6 D5 D4 D3 D2 D1 D0 0 0 0 0 2. Write new DAC A value and update DAC A output: D15 D14 D13 D12 1 1 0 0 D11 D10 D9 D8 D7 New DAC A output value The DAC A output is updated on the rising clock edge after D0 is sampled. To output data consecutively using the same DAC configuration, it is not necessary to program the CONTROL register again. D Set DAC B output, select fast mode, select external reference: 3. Select external reference (CONTROL register): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 D4 D3 D2 D1 D0 0 0 0 0 4. Write new DAC B value to BUFFER and update DAC B output: D15 D14 D13 D12 0 1 0 0 D11 D10 D9 D8 D7 D6 D5 New BUFFER content and DAC B output value X = Don’t care The DAC A output is updated on the rising clock edge after D0 is sampled. To output data consecutively using the same DAC configuration, it is not necessary to program the CONTROL register again. 12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 APPLICATION INFORMATION examples of operation: (continued) D Set DAC A value, set DAC B value, update both simultaneously, select slow mode, select internal reference at 1.024 V: 1. Set reference voltage to 1.024 V (CONTROL register): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 D8 D7 D6 D5 D4 D3 D2 D1 D0 0 0 0 0 D3 D2 D1 D0 0 0 0 0 2. Write data for DAC B to BUFFER: D15 D14 D13 D12 0 0 0 1 D11 D10 D9 New DAC B value X = Don’t care 3. Write new DAC A value and update DAC A and B simultaneously: D15 D14 D13 D12 1 0 0 0 D11 D10 D9 D8 D7 D6 D5 D4 New DAC A value X = Don’t care Both outputs are updated on the rising clock edge after D0 from the DAC A data word is sampled. D Set power-down mode: D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X 1 X X X X X X X X X X X X X X = Don’t care linearity, offset, and gain error using single ended supplies When an amplifier is operated from a single supply, the voltage offset can still be either positive or negative. With a positive offset, the output voltage changes on the first code change. With a negative offset, the output voltage may not change with the first code, depending on the magnitude of the offset voltage. The output amplifier attempts to drive the output to a negative voltage. However, because the most negative supply rail is ground, the output cannot drive below ground and clamps the output at 0 V. The output voltage then remains at zero until the input code value produces a sufficient positive output voltage to overcome the negative offset voltage, resulting in the transfer function shown in Figure 14. Output Voltage 0V DAC Code Negative Offset Figure 14. Effect of Negative Offset (single supply) POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 13 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 APPLICATION INFORMATION This offset error, not the linearity error, produces this breakpoint. The transfer function would have followed the dotted line if the output buffer could drive below the ground rail. For a DAC, linearity is measured between zero-input code (all inputs 0) and full-scale code (all inputs 1) after offset and full scale are adjusted out or accounted for in some way. However, single supply operation does not allow for adjustment when the offset is negative due to the breakpoint in the transfer function. So the linearity is measured between full-scale code and the lowest code that produces a positive output voltage. definitions of specifications and terminology integral nonlinearity (INL) The relative accuracy or integral nonlinearity (INL), sometimes referred to as linearity error, 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. differential nonlinearity (DNL) The differential nonlinearity (DNL), sometimes referred to as differential error, is the difference between the measured and ideal 1 LSB amplitude change of any two adjacent codes. Monotonic means the output voltage changes in the same direction (or remains constant) as a change in the digital input code. zero-scale error (EZS) Zero-scale error is defined as the deviation of the output from 0 V at a digital input value of 0. gain error (EG) Gain error is the error in slope of the DAC transfer function. signal-to-noise ratio + distortion (S/N+D) S/N+D is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components below the Nyquist frequency, including harmonics but excluding dc. The value for S/N+D is expressed in decibels. spurious free dynamic range (SFDR) Spurious free dynamic range is the difference between the rms value of the output signal and the rms value of the spurious signal within a specified bandwidth. The value for SFDR is expressed in decibels. 14 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLV5626 2.7 V TO 5.5 V LOW POWER DUAL 8-BIT DIGITAL-TO-ANALOG CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN SLAS236 –JUNE 1999 MECHANICAL DATA D (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0.050 (1,27) 0.020 (0,51) 0.014 (0,35) 14 0.010 (0,25) M 8 0.008 (0,20) NOM 0.244 (6,20) 0.228 (5,80) 0.157 (4,00) 0.150 (3,81) Gage Plane 0.010 (0,25) 1 7 0°– 8° A 0.044 (1,12) 0.016 (0,40) Seating Plane 0.069 (1,75) MAX 0.010 (0,25) 0.004 (0,10) PINS ** 0.004 (0,10) 8 14 16 A MAX 0.197 (5,00) 0.344 (8,75) 0.394 (10,00) A MIN 0.189 (4,80) 0.337 (8,55) 0.386 (9,80) DIM 4040047 / D 10/96 NOTES: A. B. C. D. All linear dimensions are in inches (millimeters). This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15). Falls within JEDEC MS-012 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 15 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. 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