DAC0808/DAC0807/DAC0806 8-Bit D/A Converters General Description The DAC0808 series is an 8-bit monolithic digital-to-analog converter (DAC) featuring a full scale output current settling time of 150 ns while dissipating only 33 mW with g 5V supplies. No reference current (IREF) trimming is required for most applications since the full scale output current is typically g 1 LSB of 255 IREF/ 256. Relative accuracies of better than g 0.19% assure 8-bit monotonicity and linearity while zero level output current of less than 4 mA provides 8-bit zero accuracy for IREFt2 mA. The power supply currents of the DAC0808 series are independent of bit codes, and exhibits essentially constant device characteristics over the entire supply voltage range. The DAC0808 will interface directly with popular TTL, DTL or CMOS logic levels, and is a direct replacement for the MC1508/MC1408. For higher speed applications, see DAC0800 data sheet. Features Y Y Y Y Y Y Y Y Relative accuracy: g 0.19% error maximum (DAC0808) Full scale current match: g 1 LSB typ 7 and 6-bit accuracy available (DAC0807, DAC0806) Fast settling time: 150 ns typ Noninverting digital inputs are TTL and CMOS compatible High speed multiplying input slew rate: 8 mA/ms Power supply voltage range: g 4.5V to g 18V Low power consumption: 33 mW @ g 5V Block and Connection Diagrams Dual-In-Line Package Order Number DAC0808, DAC0807, or DAC0806 See NS Package Number J16A, M16A or N16A TL/H/5687 – 2 TL/H/5687 – 1 Small-Outline Package TL/H/5687 – 13 Top View Ordering Information ACCURACY 7-bit 6-bit OPERATING TEMPERATURE RANGE 0§ CsTAs a 75§ C 0§ CsTAs a 75§ C ORDER NUMBERS N PACKAGE (N16A)* SO PACKAGE (M16A) DAC0808LCN MC1408P8 DAC0808LCM DAC0807LCJ MC1408L7 DAC0807LCN MC1408P7 DAC0807LCM DAC0806LCJ MC1408L6 DAC0806LCN MC1408P6 DAC0806LCM J PACKAGE (J16A)* *Note. Devices may be ordered by using either order number. C1995 National Semiconductor Corporation TL/H/5687 RRD-B30M115/Printed in U. S. A. DAC0808/DAC0807/DAC0806 8-Bit D/A Converters January 1995 Absolute Maximum Ratings (Note 1) Storage Temperature Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. b 65§ C to a 150§ C Lead Temp. (Soldering, 10 seconds) Dual-In-Line Package (Plastic) Dual-In-Line Package (Ceramic) Surface Mount Package Vapor Phase (60 seconds) Infrared (15 seconds) Power Supply Voltage a 18 VDC VCC b 18 VDC VEE b 10 VDC to a 18 VDC Digital Input Voltage, V5–V12 b 11 VDC to a 18 VDC Applied Output Voltage, VO Reference Current, I14 5 mA Reference Amplifier Inputs, V14, V15 VCC, VEE Power Dissipation (Note 3) 1000 mW ESD Susceptibility (Note 4) TBD 260§ C 300§ C 215§ C 220§ C Operating Ratings Temperature Range DAC0808LC Series TMIN s TA s TMAX 0 sTA s a 75§ C Electrical Characteristics (VCC e 5V, VEE e b15 VDC, VREF/R14 e 2 mA, DAC0808: TA e b55§ C to a 125§ C, DAC0808C, DAC0807C, DAC0806C, TA e 0§ C to a 75§ C, and all digital inputs at high logic level unless otherwise noted.) Symbol Parameter Conditions Relative Accuracy (Error Relative to Full Scale IO) DAC0808LC (LM1408-8) DAC0807LC (LM1408-7), (Note 5) DAC0806LC (LM1408-6), (Note 5) Settling Time to Within (/2 LSB (Includes tPLH) (Figure 4) tPLH, tPHL Propagation Delay Time TA e 25§ C, (Figure 5) TCIO Output Full Scale Current Drift MSB VIH VIL Digital Input Logic Levels High Level, Logic ‘‘1’’ Low Level, Logic ‘‘0’’ (Figure 3) MSB Digital Input Current High Level Low Level (Figure 3) VIH e 5V VIL e 0.8V Reference Input Bias Current (Figure 3) Output Current Range (Figure 3) VEE e b5V VEE e b15V, TA e 25§ C Er I15 IO Output Current Output Current, All Bits Low Output Voltage Compliance (Note 2) VEE eb5V, IREF e 1 mA VEE Below b10V Min Typ Max Units % g 0.19 g 0.39 g 0.78 TA e 25§ C (Note 6), (Figure 5) 150 30 100 g 20 ns ppm/§ C 2 VREF e 2.000V, R14 e 1000X, (Figure 3) (Figure 3) % % % ns 0.8 VDC VDC b 0.003 0.040 b 0.8 mA mA b1 b3 mA 0 0 2.0 2.0 2.1 4.2 mA mA 1.9 1.99 0 2.1 4 mA mA b 0.55, a 0.4 b 5.0, a 0.4 VDC VDC 0 Er s 0.19%, TA e 25§ C 2 Electrical Characteristics (Continued) (VCC e 5V, VEE e b15 VDC, VREF/R14 e 2 mA, DAC0808: TA e b55§ C to a 125§ C, DAC0808C, DAC0807C, DAC0806C, TA e 0§ C to a 75§ C, and all digital inputs at high logic level unless otherwise noted.) Symbol Parameter SRIREF Reference Current Slew Rate (Figure 6) Conditions Output Current Power Supply Sensitivity b 5V s VEE s b 16.5V Power Supply Current (All Bits Low) (Figure 3) Min Typ 4 8 Power Supply Voltage Range All Bits High 2.7 mA/V 2.3 22 b 4.3 b 13 mA mA TA e 25§ C, (Figure 3) VCC VEE Power Dissipation All Bits Low Units mA/ms 0.05 ICC IEE Max VCC VCC VCC VCC e e e e 4.5 5.0 5.5 b 4.5 b 15 b 16.5 33 106 90 160 170 305 5V, VEE e b5V 5V, VEE e b15V 15V, VEE e b5V 15V, VEE e b15V VDC VDC mW mW mW mW Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its specified operating conditions. Note 2: Range control is not required. Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, iJA, and the ambient temperature, TA. The maximum allowable power dissipation at any temperature is PD e (TJMAX b TA)/iJA or the number given in the Absolute Maixmum Ratings, whichever is lower. For this device, TJMAX e 125§ C, and the typical junction-to-ambient thermal resistance of the dual-in-line J package when the board mounted is 100§ C/W. For the dual-inline N package, this number increases to 175§ C/W and for the small outline M package this number is 100§ C/W. Note 4: Human body model, 100 pF discharged through a 1.5 kX resistor. Note 5: All current switches are tested to guarantee at least 50% of rated current. Note 6: All bits switched. Note 7: Pin-out numbers for the DAL080X represent the dual-in-line package. The small outline package pinout differs from the dual-in-line package. Typical Application VO e 10V #2 A1 a A2 A8 a. . . 4 256 J TL/H/5687 – 3 FIGURE 1. a 10V Output Digital to Analog Converter (Note 7) 3 Typical Performance Characteristics VCC e 5V, VEE e b15V, TA e 25§ C, unless otherwise noted Logic Input Current vs Input Voltage Bit Transfer Characteristics Logic Threshold Voltage vs Temperature Output Current vs Output Voltage (Output Voltage Compliance) Output Voltage Compliance vs Temperature Typical Power Supply Current vs Temperature Typical Power Supply Current vs VEE Typical Power Supply Current vs VCC Reference Input Frequency Response TL/H/5687 – 5 Unless otherwise specified: R14 e R15 e 1 kX, C e 15 pF, pin 16 to VEE; RL e 50X, pin 4 to ground. Curve A: Large Signal Bandwidth Method of Figure 7 , VREF e 2 Vp-p offset 1 V above ground. Curve B: Small Signal Bandwidth Method of Figure 7 , RL e 250X, VREF e 50 mVp-p offset 200 mV above ground. Curve C: Large and Small Signal Bandwidth Method of Figure 9 (no op amp, RL e 50X), RS e 50X, VREF e 2V, VS e 100 mVp-p centered at 0V. 4 5 FIGURE 2. Equivalent Circuit of the DAC0808 Series (Note 7) TL/H/5687 – 4 Test Circuits VI and I1 apply to inputs A1 – A8. The resistor tied to pin 15 is to temperature compensate the bias current and may not be necessary for all applications. IO e K #2 A1 a A2 A3 A4 A5 A6 A7 A8 a a a a a a 4 8 16 32 64 128 256 VREF where K j R14 and AN e ‘‘1’’ if AN is at high level AN e ‘‘0’’ if AN is at low level J TL/H/5687–6 FIGURE 3. Notation Definitions Test Circuit (Note 7) TL/H/5687 – 7 FIGURE 4. Relative Accuracy Test Circuit (Note 7) TL/H/5687 – 8 FIGURE 5. Transient Response and Settling Time (Note 7) 6 Test Circuits (Continued) TL/H/5687 – 10 TL/H/5687 – 9 FIGURE 7. Positive VREF (Note 7) FIGURE 6. Reference Current Slew Rate Measurement (Note 7) TL/H/5687 – 11 FIGURE 8. Negative VREF (Note 7) TL/H/5687 – 12 FIGURE 9. Programmable Gain Amplifier or Digital Attenuator Circuit (Note 7) Application Hints REFERENCE AMPLIFIER DRIVE AND COMPENSATION The reference amplifier provides a voltage at pin 14 for converting the reference voltage to a current, and a turn-around circuit or current mirror for feeding the ladder. The reference amplifier input currrent, I14, must always flow into pin 14, regardless of the set-up method or reference voltage polarity. Connections for a positive voltage are shown in Figure 7 . The reference voltage source supplies the full current I14. For bipolar reference signals, as in the multiplying mode, R15 can be tied to a negative voltage corresponding to the minimum input level. It is possible to eliminate R15 with only a small sacrifice in accuracy and temperature drift. The compensation capacitor value must be increased with increases in R14 to maintain proper phase margin; for R14 values of 1, 2.5 and 5 kX, minimum capacitor values are 15, 37 and 75 pF. The capacitor may be tied to either VEE or ground, but using VEE increases negative supply rejection. 7 Application Hints (Continued) the excellent temperature tracking of the monolithic resistor ladder. The reference current may drift with temperature, causing a change in the absolute accuracy of output current. However, the DAC0808 has a very low full-scale current drift with temperature. The DAC0808 series is guaranteed accurate to within g (/2 LSB at a full-scale output current of 1.992 mA. This corresponds to a reference amplifier output current drive to the ladder network of 2 mA, with the loss of 1 LSB (8 mA) which is the ladder remainder shunted to ground. The input current to pin 14 has a guaranteed value of between 1.9 and 2.1 mA, allowing some mismatch in the NPN current source pair. The accuracy test circuit is shown in Figure 4 . The 12bit converter is calibrated for a full-scale output current of 1.992 mA. This is an optional step since the DAC0808 accuracy is essentially the same between 1.5 and 2.5 mA. Then the DAC0808 circuits’ full-scale current is trimmed to the same value with R14 so that a zero value appears at the error amplifier output. The counter is activated and the error band may be displayed on an oscilloscope, detected by comparators, or stored in a peak detector. Two 8-bit D-to-A converters may not be used to construct a 16-bit accuracy D-to-A converter. 16-bit accuracy implies a total error of g (/2 of one part in 65,536 or g 0.00076%, which is much more accurate than the g 0.019% specification provided by the DAC0808. A negative reference voltage may be used if R14 is grounded and the reference voltage is applied to R15 as shown in Figure 8 . A high input impedance is the main advantage of this method. Compensation involves a capacitor to VEE on pin 16, using the values of the previous paragraph. The negative reference voltage must be at least 4V above the VEE supply. Bipolar input signals may be handled by connecting R14 to a positive reference voltage equal to the peak positive input level at pin 15. When a DC reference voltage is used, capacitive bypass to ground is recommended. The 5V logic supply is not recommended as a reference voltage. If a well regulated 5V supply which drives logic is to be used as the reference, R14 should be decoupled by connecting it to 5V through another resistor and bypassing the junction of the 2 resistors with 0.1 mF to ground. For reference voltages greater than 5V, a clamp diode is recommended between pin 14 and ground. If pin 14 is driven by a high impedance such as a transistor current source, none of the above compensation methods apply and the amplifier must be heavily compensated, decreasing the overall bandwidth. OUTPUT VOLTAGE RANGE The voltage on pin 4 is restricted to a range of b0.55 to 0.4V when VEE e b5V due to the current switching methods employed in the DAC0808. The negative output voltage compliance of the DAC0808 is extended to b5V where the negative supply voltage is more negative than b10V. Using a full-scale current of 1.992 mA and load resistor of 2.5 kX between pin 4 and ground will yield a voltage output of 256 levels between 0 and b 4.980V. Floating pin 1 does not affect the converter speed or power dissipation. However, the value of the load resistor determines the switching time due to increased voltage swing. Values of RL up to 500X do not significantly affect performance, but a 2.5 kX load increases worst-case settling time to 1.2 ms (when all bits are switched ON). Refer to the subsequent text section on Settling Time for more details on output loading. MULTIPLYING ACCURACY The DAC0808 may be used in the multiplying mode with 8-bit accuracy when the reference current is varied over a range of 256:1. If the reference current in the multiplying mode ranges from 16 mA to 4 mA, the additional error contributions are less than 1.6 mA. This is well within 8-bit accuracy when referred to full-scale. A monotonic converter is one which supplies an increase in current for each increment in the binary word. Typically, the DAC0808 is monotonic for all values of reference current above 0.5 mA. The recommended range for operation with a DC reference current is 0.5 to 4 mA. SETTLING TIME The worst-case switching condition occurs when all bits are switched ON, which corresponds to a low-to-high transition for all bits. This time is typically 150 ns for settling to within g (/2 LSB, for 8-bit accuracy, and 100 ns to (/2 LSB for 7 and 6-bit accuracy. The turn OFF is typically under 100 ns. These times apply when RL s 500X and CO s 25 pF. Extra care must be taken in board layout since this is usually the dominant factor in satisfactory test results when measuring settling time. Short leads, 100 mF supply bypassing for low frequencies, and minimum scope lead length are all mandatory. OUTPUT CURRENT RANGE The output current maximum rating of 4.2 mA may be used only for negative supply voltages more negative than b8V, due to the increased voltage drop across the resistors in the reference current amplifier. ACCURACY Absolute accuracy is the measure of each output current level with respect to its intended value, and is dependent upon relative accuracy and full-scale current drift. Relative accuracy is the measure of each output current level as a fraction of the full-scale current. The relative accuracy of the DAC0808 is essentially constant with temperature due to 8 Physical Dimensions inches (millimeters) Dual-In-Line Package Order Number DAC0807 or DAC0806 NS Package Number J16A Small Outline Package Order Number DAC0806LCM, DAC0807LCM or DAC0808LCM NS Package Number M16A 9 DAC0808/DAC0807/DAC0806 8-Bit D/A Converters Physical Dimensions inches (millimeters) (Continued) Dual-In-Line Package Order Number DAC0808, DAC0807 or DAC0806 NS Package Number N16A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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