TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 D D D D D D D D D D Programmable Settling Time to 0.5 LSB 2.5 µs or 12.5 µs Typ Two 10-Bit CMOS Voltage Output DACs in an 8 Pin Package Simultaneous Updates for DAC A and DAC B Single Supply Operation 3-Wire Serial Interface High-Impedance Reference Inputs Voltage Output Range . . . 2 Times the Reference Input Voltage Software Power Down Mode Internal Power-On Reset TMS320 and SPI Compatible D D D Low Power Consumption: – 3 mW Typ in Slow Mode – 8 mW Typ in Fast Mode Input Data Update Rate of 1.21 MHz Monotonic Over Temperature applications D D D D D Battery Powered Test Instruments Digital Offset and Gain Adjustment Battery Operated/Remote Industrial Controls Machine and Motion Control Devices Cellular Telephones D PACKAGE (TOP VIEW) The TLC5617 and TLC5617A are dual 10-bit voltage output digital-to-analog converters (DAC) with buffered reference inputs (high impedance). The DACs have an output voltage range that is two times the reference voltage, and the DACs are monotonic. The devices are simple to use, running from a single supply of 5 V. A power-on reset function is incorporated to ensure repeatable start-up conditions. DIN SCLK CS OUT A 1 8 2 7 3 6 4 5 VDD OUT B REFIN AGND Digital control of the TLC5617 is over a 3-wire CMOS compatible serial bus. The device receives a 16-bit word for programming and producing the analog output. The digital inputs feature Schmitt triggers for high noise immunity. Digital communication protocols include the SPI, QSPI, and Microwire standards. Two versions of this device are available. The TLC5617 does not have any internal state machine and is dependent on all external timing signals. The TLC5617A has an internal state machine that will count the number of clocks from the falling edge of CS and then updates and disables the device from accepting further data inputs. The TLC5617A is recommended for TMS320 and SPI processors and the TLC5617 is recommended only for use in SPI or 3-wire serial port processors. The TLC5617A is backward compatible and designed to work in TLC5617 designed systems. The 8-terminal small-outline D package allows digital control of analog functions in space-critical applications. The TLC5617C is characterized for operation from 0°C to 70°C. The TLC5617I is characterized for operation from – 40°C to 85°C. 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 2000, 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 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 AVAILABLE OPTIONS PACKAGE TA SMALL OUTLINE† (D) 0°C to 70°C TLC5617CD TLC5617ACD – 40°C to 85°C TLC5617ID TLC5617AID † Available in tape and reel as the TLC5617CDR and the TLC5617IDR DEVICE COMPATIBILITY TLC5617 SPI, QSPI, and Microwire TLC5617A TMS320Cxx, SPI, QSPI, and Microwire functional block diagram 6 REFIN AGND _ DAC A + DAC + _ 7 ×2 5 Power-Up Reset R OUT A (Voltage Output) R 10-Bit DAC Register Latch A CS SCLK DIN 3 Control Logic (LSB) 2 1 (MSB) 12 Data Bits 4 Program Bits 16-Bit Shift Register Double Buffer Latch 10-Bit DAC Register Latch B _ + DAC DACB R 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 4 + _ ×2 R OUT B (Voltage Output) TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION AGND 5 Analog ground CS 3 I Chip select, active low DIN 1 I Serial data input OUT A 4 O DAC A analog output OUT B 7 O DAC B analog output REFIN 6 I Reference voltage input SCLK 2 I Serial clock input VDD 8 Positive power supply absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage (VDD to AGND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Digital input voltage range to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to VDD + 0.3 V Reference input voltage range to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to VDD + 0.3 V Output voltage at OUT from external source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VDD + 0.3 V Continuous current at any terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 20 mA Operating free-air temperature range, TA: TLC5617C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C TLC5617I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 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, VDD High-level digital input voltage, VIH Low-level digital input voltage, VIL VDD = 5 V VDD = 5 V MIN NOM MAX 4.5 5 5.5 0.7 VDD 1 Load resistance, RL 2 Operating free-air free air temperature, temperature TA TLC5617C TLC5617I POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 V V 0.3 VDD Reference voltage, Vref to REFIN terminal UNIT 2.048 VDD – 1.1 V V kΩ 0 70 °C – 40 85 °C 3 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 electrical characteristics over recommended operating free-air temperature range, VDD = 5 V ± 5%, Vref (REFIN)= 2.048 V (unless otherwise noted) static DAC specifications PARAMETER TEST CONDITIONS MIN Resolution Differential nonlinearity (DNL) Zero-scale error (offset error at zero scale) Zero-scale-error temperature coefficient EG Gain error Gain error temperature coefficient Vref(REFIN) = 2.048 V, Vref(REFIN) = 2.048 V, See Note 1 Power-supply Power-su ly rejection ratio UNIT ±1 LSB ± 0.5 LSB Vref(REFIN) = 2.048 V, Vref(REFIN) = 2.048 V, See Note 3 Vref(REFIN) = 2.048 V, Vref(REFIN) = 2.048 V, See Note 5 ±3 See Note 4 3 LSB ppm/°C ±3 See Note 6 1 LSB ppm/°C 80 Slow Gain bits ± 0.1 See Note 2 Zero scale PSRR MAX 10 Integral nonlinearity (INL), end point adjusted EZS TYP 80 See Notes 7 and 8 Zero scale dB 80 Fast Gain 80 NOTES: 1. 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. 2. 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. 3. Zero-scale error is the deviation from zero voltage output when the digital input code is zero. 4. Zero-scale-error temperature coefficient is given by: EZS TC = [EZS (Tmax) – EZS (Tmin)]/Vref × 106/(Tmax – Tmin). 5. Gain error is the deviation from the ideal output (Vref – 1 LSB) with an output load of 10 kΩ excluding the effects of the zero-error. 6. Gain temperature coefficient is given by: EG TC = [EG(Tmax) – EG (Tmin)]/Vref × 106/(Tmax – Tmin). 7. Zero-scale-error rejection ratio (EZS-RR) is measured by varying the VDD from 4.5 V to 5.5 V dc and measuring the proportion of this signal imposed on the zero-code output voltage. 8. Gain-error rejection ratio (EG-RR) is measured by varying the VDD from 4.5 V to 5.5 V dc and measuring the proportion of this signal imposed on the full-scale output voltage after subtracting the zero scale change. OUT A and OUT B output specifications PARAMETER VO TEST CONDITIONS Voltage output RL = 10 kΩ Output load regulation accuracy VO(OUT) = 2V, RL from 10 kΩ to 2 kΩ VO(OUT A) or VO(OUT B) to VDD or AGND IOSC Output short circuit current IO(sink) IO(source) Output sink current Output source current MIN TYP 0 VO(OUT) > 0.25 V VO(OUT) < 4.75 V MAX UNIT VDD –0.4 0.5 V LSB 20 mA 5 mA 5 mA reference input (REFIN) PARAMETER VI Ri Input voltage Ci Input capacitance TEST CONDITIONS MIN TYP 0 Input resistance MAX VDD – 2 10 UNIT V MΩ 5 pF dB Reference feedthrough REFIN = 1 Vpp at 1 kHz + 1.024 V dc (see Note 9) – 80 Reference input in ut bandwidth (f–3dB) REFIN = 0.2 0 2 Vpp + 1.024 1 024 V dc Slow 0.5 Fast 1 MHz NOTE 9: Reference feedthrough is measured at the DAC output with an input code = 00 hex and a Vref(REFIN) input = 1.024 V dc + 1 Vpp at 1 kHz. 4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 electrical characteristics over recommended operating free-air temperature range, VDD = 5 V ± 5%, Vref (REFIN)= 2.048 V (unless otherwise noted) (continued) digital inputs (DIN, SCLK, CS) PARAMETER IIH IIL High-level digital input current Ci Input capacitance TEST CONDITIONS MIN TYP VI = VDD VI = 0 V Low-level digital input current MAX UNIT ±1 µA ±1 µA 8 pF power supply PARAMETER TEST CONDITIONS MIN TYP MAX 4.5 5 5.5 Slow 0.6 1 Fast 1.6 2.5 Supply voltage, VDD IDD VDD = 5.5 V, No load load, All inputs = 0 V or VDD Power supply current Power down supply current UNIT V mA D13 = 0 (see Table 3) µA 1 operating characteristics over recommended operating free-air temperature range, VDD = 5 V ± 5%, Vref(REFIN) = 2.048 V (unless otherwise noted) analog output dynamic performance PARAMETER SR Output slew rate TEST CONDITIONS CL = 100 pF, RL = 10 kΩ, kΩ Code 32 to Code 1024, Vref(REFIN) = 2.048 V, TA = 25°C 25°C, VO from 10% to 90% MIN TYP Slow 0.3 0.5 Fast 2.4 3 UNIT V/µs ts Output settling time To ± 0.5 LSB,, RL = 10 kΩ, CL = 100 pF, See Note 10 Slow 12.5 Fast 2.5 ts(c) ( ) Output settling g time,, code to code To ± 0.5 LSB,, RL = 10 kΩ, CL = 100 pF, See Note 11 Slow 2 Fast 2 Glitch energy DIN = All 0s to all 1s, f(SCLK) = 100 kHz CS = VDD, Signal to noise + distortion Vref(REFIN) ( ) = 1 Vpp at 1 kHz and 10 kHz + 1.024 V dc, Input code = 10 0000 0000 S/(N+D) MAX µs µs 5 Slow 78 Fast 81 nV–s dB NOTES: 10. 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 020 hex to 3FF hex or 3FF hex to 020 hex. 11. Setting 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. digital input timing requirements MIN NOM MAX UNIT tsu(DS) th(DH) Setup time, DIN before SCLK low 5 ns Hold time, DIN valid after SCLK low 5 ns tsu(CSS) tsu(CS1) Setup time, CS low to SCLK low tsu(CS2) tw(CL) Setup time, SCLK ↑ to CS ↓, start of next write cycle tw(CH) 5 ns 10 ns 5 ns Pulse duration, SCLK low 25 ns Pulse duration, SCLK high 25 ns Setup time, SCLK ↑ to CS ↑, external end-of-write POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 PARAMETER MEASUREMENT INFORMATION CS tsu(CSS) tsu(CS1) tw(CL) tw(CH) tsu(CS2) SCLK (see Note A) ÎÎÎ ÎÎÎ tsu(DS) DIN ÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎ ÏÏÏÏ ÏÏ ÏÏÏÏ ÏÏ th(DH) D15 D14 D13 D12 ÏÏÏÏÏÏ ÏÏÏÏÏÏ D11 DAC Data Bits (12) Program Bits (4) DAC OUT A/B D0 ts ≤ Final Value ±0.5 LSB NOTE A: SCLK must go high after the 16th falling clock edge. Figure 1. Timing Diagram for the TLC5617A PARAMETER MEASUREMENT INFORMATION OUTPUT SINK CURRENT (FAST MODE) vs OUTPUT LOAD VOLTAGE OUTPUT SOURCE CURRENT (FAST MODE) vs OUTPUT LOAD VOLTAGE 40 –60 VDD = 5 V, Input Code = 4095 35 Output Source Current – mA Output Sink Current – mA –50 30 25 20 15 10 5 –5 0 0.5 1 1.5 2 2.5 3 3.5 4 –30 –20 –10 VCC = 5 V, Input Code = 0 0 –40 4.5 0 0 0.5 Output Load Voltage – V 1.5 2 2.5 Figure 3 POST OFFICE BOX 655303 3 3.5 Output Load Voltage – V Figure 2 6 1 • DALLAS, TEXAS 75265 4 4.5 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 TYPICAL CHARACTERISTICS OUTPUT SOURCE CURRENT (SLOW MODE) vs OUTPUT LOAD VOLTAGE 25 –30 20 –25 Output Source Current – mA Output Sink Current – mA OUTPUT SINK CURRENT (SLOW MODE) vs OUTPUT LOAD VOLTAGE 15 10 5 0 –20 –15 –10 –5 VDD = 5 V, Input Code = 0 –0 0 0.5 1 1.5 2 2.5 3 3.5 4 VDD = 5 V, Input Code = 4095 0 4.5 0 0.5 Output Load Voltage – V 2 2.5 3 3.5 4 4.5 Figure 5 SUPPLY CURRENT vs TEMPERATURE RELATIVE GAIN (FAST MODE) vs FREQUENCY 5 1.4 VDD = 5 V, VREFIN = 2.048 V, TA = 25°C 0 Fast Mode 1 –5 Relative Gain – dB Supply Current – mA 1.5 Output Load Voltage – V Figure 4 1.2 1 0.8 0.6 0.4 –15 –20 Slow Mode –25 0.2 0 – 60 – 40 – 20 –10 0 20 40 60 80 Temperature – °C 100 120 140 VCC = 5 V, VREFIN = 0.2 VPP + 2.048 Vdc, TA = 25°C –30 100 1000 10 K f – Frequency – kHz Figure 6 Figure 7 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 TYPICAL CHARACTERISTICS RELATIVE GAIN (SLOW MODE) vs FREQUENCY TOTAL HARMONIC DISTORTION (SLOW MODE) vs FREQUENCY 5 95 THD – Total Harmonic Distortion – dB 0 Relative Gain – dB –5 –10 –15 –20 –25 –30 VCC = 5 V, VREFIN = 0.2 VPP + 2.048 Vdc, TA = 25°C –35 –40 100 85 80 75 70 65 10 K 1000 90 1 10 f – Frequency – kHz Figure 8 Figure 9 SIGNAL-TO-NOISE RATIO (SLOW MODE) vs FREQUENCY 85 85 SNR – Signal-To-Noise Ratio – dB THD+N – Total Harmonic Distortion + Noise – dB TOTAL HARMONIC DISTORTION + NOISE (SLOW MODE) vs FREQUENCY 80 75 70 65 60 1 100 10 80 75 70 65 1 f – Frequency– kHz 10 f – Frequency– kHz Figure 10 8 100 f – Frequency – kHz Figure 11 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 100 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 TYPICAL CHARACTERISTICS TOTAL HARMONIC DISTORTION (FAST MODE) vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE (FAST MODE) vs FREQUENCY THD+N – Total Harmonic Distortion + Noise – dB 90 85 80 75 1 100 10 85 80 75 70 65 1 10 f – Frequency – kHz f – Frequency – kHz Figure 12 Figure 13 100 SIGNAL-TO-NOISE RATIO (FAST MODE) vs FREQUENCY 85 SNR – Signal-To-Noise Ratio – dB THD – Total Harmonic Distortion – dB 95 80 75 70 65 1 10 100 f – Frequency – kHz Figure 14 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 9 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 DNL – Differential Nonlinearity – LSB TYPICAL CHARACTERISTICS 0.2 0.15 0.1 0.05 0 –0.05 –0.1 –0.15 –0.2 0 255 511 767 1023 Input Code INL – Integral Nonlinearity – LSB Figure 15. Differential Nonlinearity With Input Code 1 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1 0 255 511 767 Input Code Figure 16. Integral Nonlinearity With Input Code 10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1023 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION general function The TLC5617 uses a resistor string network buffered with an op amp to convert 10-bit digital data to analog voltage levels (see functional block diagram and Figure 17). The output of the TLC5617 is the same polarity as the reference input (see Table 1). ǒ The output code is given by: 2 V Ǔ CODE REFIN 1024 An internal circuit resets the DAC register to all 0s on power up. + _ REFIN Resistor String DAC DIN CS + _ ×2 OUT R SCLK R AGND VDD 5V 0.1 µF Figure 17. TLC5617 Typical Operating Circuit Table 1. Binary Code Table (0 V to 2 VREFIN Output), Gain = 2 INPUT† 1111 1111 11(00) : 1000 0000 01(00) 1000 0000 00(00) 0111 1111 11(00) : 0000 0000 01(00) 0000 0000 00(00) ǒ ǒ 2 V Ǔ Ǔ OUTPUT 1023 REFIN 1024 : 513 2 V REFIN 1024 512 V 2 V REFIN 1024 REFIN ǒ ǒ 2 V ǒ Ǔ + Ǔ 511 REFIN 1024 2 V Ǔ : 1 REFIN 1024 0V † A 10-bit data word with two sub-LSB 0s must be written since the DAC input latch is 12 bits wide. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 11 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION buffer amplifier The output buffer has a rail-to-rail output with short circuit protection and can drive a 2-kΩ load with a 100-pF load capacitance. Settling time is a software selectable 12.5 µs or 2.5 µs typical to within ±0.5 LSB of the final value. external reference The reference voltage input is buffered which makes the DAC input resistance not code dependent. Therefore, the REFIN input resistance is 10 MΩ and the REFIN input capacitance is typically 5 pF, independent of input code. The reference voltage determines the DAC full-scale output. logic interface The logic inputs function with CMOS logic levels. Most of the standard high-speed CMOS logic families may be used. serial clock and update rate Figure 1 shows the TLC5617 timing. The maximum serial clock rate is f(SCLK)max +t 1 + 20 MHz ) t ǒ Ǔ w CL min wǒCHǓmin ǒ ǒ Ǔ ǒ ǓǓ The digital update rate is limited by the chip-select period, which is tp(CS) + 16 t w CH ) tw CL ) tsuǒCS1Ǔ This equals 820-ns or 1.21-MHz update rate. However, the DAC settling time to 10 bits limits the update rate for full-scale input step transitions. 12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION serial interface When chip select (CS) is low, the input data is read into a 16-bit shift register with the input data clocked in most significant bit first. The falling edge of the SCLK input shifts the data into the input register. The rising edge of CS then transfers the data to the DAC register. All CS transitions should occur when the SCLK input is low. The 16 bits of data can be transferred with the sequence shown in Figure 18. 16 Bits Program Bits D15 D14 Fill Bits† Data Bits D13 D12 D11 MSB (Input Word) 10 Data Bits MSB (Data) D2 D1 = x LSB (Data) D0 = x LSB (Input Word) † Two extra (sub-LSB) bits (can be don’t care) Figure 18. Input Data Word Format Table 2 shows the function of program bits D15 – D12. Table 2. Program Bits D15 – D12 Function PROGRAM BIT DEVICE FUNCTION D15 D14 D13 D12 1 X X X Write to latch A with serial interface register g data and latch B updated with buffer latch data 0 X X 0 Write to latch B and double buffer latch 0 X X 1 Write to double buffer latch only X 1 X X 12.5 µs settling time X 0 X X 2.5 µs settling time X X 0 X Powered-up operation X X 1 X Powered-down mode function of the latch control bits (D15 and D12) Three data transfers are possible. All transfers occur immediately after CS goes high and are described in the following sections. latch A write, latch B update (D15 = high, D12 = X) The serial interface register (SIR) data are written to latch A and the double buffer latch contents are written to latch B. The double buffer contents are unaffected. This control bit condition allows simultaneous output updates of both DACs. Serial Interface Register D12 = X D15 = High Double Buffer Latch Latch A To DAC A Latch B To DAC B Figure 19. Latch A Write, Latch B Update POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 13 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION latch B and double-buffer 1 write (D15 = low, D12 = low) The SIR data are written to both latch B and the double buffer. Latch A is unaffected. Serial Interface Register D12 = Low D15 = Low Double Buffer Latch Latch A To DAC A Latch B To DAC B Figure 20. Latch B and Double-Buffer Write double-buffer-only write (D15 = low, D12 = high) The SIR data are written to the double buffer only. Latch A and B contents are unaffected. Serial Interface Register D12 = High D15 = Low Double Buffer Latch A To DAC A Latch B To DAC B Figure 21. Double-Buffer-Only Write purpose and use of the buffer Normally only one DAC output can change after a write. The double buffer allows both DAC outputs to change after a single write. This is achieved by the two following steps. 1. A double-buffer-only write is executed to store the new DAC B data without changing the DAC A and B outputs. 2. Following the previous step a write to latch A is executed. This writes the SIR data to latch A and also writes the double-buffer contents to latch B. Thus both DACs receive their new data at the same time and so both DAC outputs begin to change at the same time. Unless a double-buffer-only write is issued, the latch B and double-buffer contents are identical. Thus, following a write to latch A or B with another write to latch A does not change the latch B contents. 14 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION operational examples changing the latch A data from zero to full code Assuming that latch A starts at zero code (e.g., after power up), the latch can be filled with 1s by writing (bit D15 on the left, D0 on the right) 1X0X 1111 1111 11XX to the serial interface. Bit D14 can be zero to select slow mode or one to select fast mode. The other Xs can be zero or one (don’t care). The latch B contents and the DAC B output are not changed by this write unless the double-buffer contents are different from the latch B contents. This can only be true if the last write was a double-buffer-only write. changing the latch B data from zero to full code Assuming that latch B starts at zero code (e.g., after power-up), the latch can be filled with 1s by writing (bit D15 on the left, D0 on the right). 0X00 1111 1111 11XX to the serial interface. Bit D14 can be zero to select slow mode or one to select fast mode. The other Xs can be zero or one (don’t care). The data (bits D0 to D11) are written to both the double buffer and latch B. The latch A contents and the DAC A output are not changed by this write. double-buffered change of both DAC outputs Assuming that DACs A and B start at zero code (e.g., after power-up), if DAC A is to be driven to mid-scale and DAC B to full-scale, and if the outputs are to begin rising at the same time, this can be achieved as follows: First, 0d01 1111 1111 11XX is written (bit D15 on the left, D0 on the right) to the serial interface. This loads the full-scale code into the double buffer latch but does not change the latch B contents and the DAC B output voltage. The latch A contents and the DAC A output are also unaffected by this write operation. Changing from fast to slow mode or slow to fast mode changes the supply current which can glitch the outputs, and so D14 (designated by d in the data word) should be set to maintain the speed made set by the previous write. The other Xs can be ones or zeros (don’t care). Next, 1X0X 1000 0000 00XX is written (bit D15 on the left, D0 on the right) to the serial interface. Bit D14 can be zero to select slow mode or one to select fast mode. The other Xs can be zero or one (don’t care). This writes the mid-scale code (1000000000XX) to latch A and also copies the full-scale code from the double buffer to latch B. Both DAC outputs thus begin to rise after the second write. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 15 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION DSP serial interface Utilizing a simple 3-wire serial interface, the TLC5617A can be interfaced to TMS320 compatible serial ports. The 5617A has an internal state machine that counts 16 clocks after receiving a falling edge of CS and then disable further clocking in of data until the next falling edge is received on CS. Therefore the CS can be connected directly to the FS pins of the serial port and only the leading falling edge of the DSP will be used to start the write process. The TLC5617A is designed to be used with the TMS320Cxx DSP in burst mode serial port transmit operation. VCC FSR FSX CS Analog Output OUT A TLC5617 Analog Output OUT B CLKX SCLK TMS320C32 DSP CLKR DX DIN REFIN 2.5 V dc GND To Source Ground Figure 22. Interfacing The TLC5617 To TMS320C32 DSP SPI serial interface Both the TLC5617 and TLC5617A are compatible with SPI, QSPI, or Microwire serial standards. The hardware connections are shown in Figure 23 and Figure 24. The TLC5617A has an internal state machine that counts 16 clocks after the falling edge of CS and then internally disables the device. The internal edge is ORed together with CS so that the rising edge can be provided to CS prior to the occurrence of the internal edge to also disable the device. general serial interface The TLC5617 3-wire interface is compatible with the SPI, QSPI, and Microwire serial standards. The hardware connections are shown in Figure 23 and Figure 24. The SPI and Microwire interfaces transfer data in 8-bit bytes, therefore, two write cycles are required to input data to the DAC. The QSPI interface, which has a variable input data length from 8 to 16 bits, can load the DAC input register in one write cycle. 16 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION general serial interface (continued) SK SCLK SO Microwire Port DIN TLC5617 I/O CS Figure 23. Microwire Connection SCK SCLK MOSI SPI/QSPI Port I/O DIN TLC5617 CS CPOL = 1, CPHA = 0 Figure 24. SPI/QSPI Connection linearity, offset, and gain error using single-end 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 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 25. Output Voltage 0V DAC Code Negative Offset Figure 25. Effect of Negative Offset (Single Supply) 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. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 17 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 APPLICATION INFORMATION linearity, offset, and gain error using single end supplies (continued) 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. For the TLC5617, the zero-scale (offset) error is plus or minus 3 LSB maximum. The code is calculated from the maximum specification for the negative offset. power-supply bypassing and ground management Printed-circuit boards that use separate analog and digital ground planes offer the best system performance. Wire-wrap boards do not perform well and should not be used. The two ground planes should be connected together at the low-impedance power-supply source. The best ground connection may be achieved by connecting the DAC AGND terminal to the system analog ground plane, making sure that analog ground currents are well managed. A 0.1-µF ceramic bypass capacitor should be connected between VDD and AGND and mounted with short leads as close as possible to the device. Use of ferrite beads may further isolate the system analog and digital power supplies. Figures 26 shows the ground plane layout and bypassing technique. Analog Ground Plane 1 8 2 7 3 6 4 5 0.1 µF Figure 26. Power-Supply Bypassing saving power Setting the DAC register to all 0s minimizes power consumption by the reference resistor array and the output load when the system is not using the DAC. ac considerations/analog feedthrough Higher frequency analog input signals may couple to the output through internal stray capacitance. Analog feedthrough is tested by holding CS high, setting the DAC code to all 0s, sweeping the frequency applied to REFIN, and monitoring the DAC output. 18 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TLC5617, TLC5617A PROGRAMMABLE DUAL 10-BIT DIGITAL-TO-ANALOG CONVERTERS SLAS151B – JULY 1997 – REVISED MARCH 2000 MECHANICAL DATA D (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PIN SHOWN PINS ** 0.050 (1,27) 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 0.020 (0,51) 0.014 (0,35) 14 0.010 (0,25) M 8 0.244 (6,20) 0.228 (5,80) 0.008 (0,20) NOM 0.157 (4,00) 0.150 (3,81) 1 Gage Plane 7 A 0.010 (0,25) 0°– 8° 0.044 (1,12) 0.016 (0,40) Seating Plane 0.069 (1,75) MAX 0.010 (0,25) 0.004 (0,10) 0.004 (0,10) 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). 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