MC1408P8 - National Semiconductor

TL/H/5687

DAC0808/DAC0807/DAC0806 8-Bit D/A Converters

January 1995

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 g5V sup-

plies. No reference current (IREF) trimming is required for

most applications since the full scale output current is typi-

cally g1 LSB of 255 IREF/ 256. Relative accuracies of bet-

ter than g0.19% 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 cur-

rents 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

YRelative accuracy: g0.19% error maximum (DAC0808)

YFull scale current match: g1 LSB typ

Y7 and 6-bit accuracy available (DAC0807, DAC0806)

YFast settling time: 150 ns typ

YNoninverting digital inputs are TTL and CMOS compati-

ble

YHigh speed multiplying input slew rate: 8 mA/ms

YPower supply voltage range: g4.5V to g18V

YLow power consumption: 33 mW @g5V

Block and Connection Diagrams

TL/H/5687–1

Dual-In-Line Package

TL/H/5687–2

Small-Outline Package

TL/H/5687–13

Top View

Ordering Information

ACCURACY OPERATING TEMPERATURE ORDER NUMBERS

RANGE J PACKAGE (J16A)*N PACKAGE (N16A)*SO PACKAGE (M16A)

DAC0808LCN MC1408P8 DAC0808LCM

7-bit 0§CsTAsa75§C DAC0807LCJ MC1408L7 DAC0807LCN MC1408P7 DAC0807LCM

6-bit 0§CsTAsa75§C DAC0806LCJ MC1408L6 DAC0806LCN MC1408P6 DAC0806LCM

*Note. Devices may be ordered by using either order number.

Order Number

DAC0808, DAC0807,

or DAC0806

See NS Package

Number J16A,

M16A or N16A

C1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

Power Supply Voltage

VCC a18 VDC

VEE b18 VDC

Digital Input Voltage, V5– V12 b10 VDC to a18 VDC

Applied Output Voltage, VOb11 VDC to a18 VDC

Reference Current, I14 5mA

Reference Amplifier Inputs, V14, V15 VCC,V

Power Dissipation (Note 3) 1000 mW

ESD Susceptibility (Note 4) TBD

Storage Temperature Range b65§Ctoa

150§C

Lead Temp. (Soldering, 10 seconds)

Dual-In-Line Package (Plastic) 260§C

Dual-In-Line Package (Ceramic) 300§C

Surface Mount Package

Vapor Phase (60 seconds) 215§C

Infrared (15 seconds) 220§C

Operating Ratings

Temperature Range TMIN sTAsTMAX

DAC0808LC Series 0 sTAsa75§C

Electrical Characteristics

(VCC e5V, VEE eb

15 VDC,V

REF/R14 e2 mA, DAC0808: TAeb

55§Ctoa

125§C, DAC0808C, DAC0807C, DAC0806C, TA

e0§Ctoa

75§C, and all digital inputs at high logic level unless otherwise noted.)

Symbol Parameter Conditions Min Typ Max Units

ErRelative Accuracy (Error Relative

(Figure 4)

to Full Scale IO)

DAC0808LC (LM1408-8) g0.19 %

DAC0807LC (LM1408-7), (Note 5) g0.39 %

DAC0806LC (LM1408-6), (Note 5) g0.78 %

Settling Time to Within (/2 LSB TAe25§C (Note 6), 150 ns

(Includes tPLH)

(Figure 5)

tPLH,t

PHL Propagation Delay Time TAe25§C,

(Figure 5)

30 100 ns

TCIOOutput Full Scale Current Drift g20 ppm/§C

MSB Digital Input Logic Levels

(Figure 3)

VIH High Level, Logic ‘‘1’’ 2 VDC

VIL Low Level, Logic ‘‘0’’ 0.8 VDC

MSB Digital Input Current

(Figure 3)

High Level VIH e5V 0 0.040 mA

Low Level VIL e0.8V b0.003 b0.8 mA

I15 Reference Input Bias Current

(Figure 3)

b1b3mA

Output Current Range

(Figure 3)

VEE eb

5V 0 2.0 2.1 mA

VEE eb

15V, TAe25§C 0 2.0 4.2 mA

IOOutput Current VREF e2.000V,

R14 e1000X,

(Figure 3)

1.9 1.99 2.1 mA

Output Current, All Bits Low

(Figure 3)

04mA

Output Voltage Compliance (Note 2) Ers0.19%, TAe25§C

VEEeb5V, IREFe1mA b

0.55, a0.4 VDC

VEE Below b10V b5.0, a0.4 VDC

Electrical Characteristics (Continued)

(VCC e5V, VEE eb

15 VDC,V

REF/R14 e2 mA, DAC0808: TAeb

55§Ctoa

125§C, DAC0808C, DAC0807C, DAC0806C, TA

e0§Ctoa

75§C, and all digital inputs at high logic level unless otherwise noted.)

Symbol Parameter Conditions Min Typ Max Units

SRIREF Reference Current Slew Rate

(Figure 6)

4 8 mA/ms

Output Current Power Supply b5V sVEE sb16.5V 0.05 2.7 mA/V

Sensitivity

Power Supply Current (All Bits

(Figure 3)

Low)

ICC 2.3 22 mA

IEE b4.3 b13 mA

Power Supply Voltage Range TAe25§C,

(Figure 3)

VCC 4.5 5.0 5.5 VDC

VEE b4.5 b15 b16.5 VDC

Power Dissipation

All Bits Low VCC e5V, VEE eb

5V 33 170 mW

VCC e5V, VEE eb

15V 106 305 mW

All Bits High VCC e15V, VEE eb

5V 90 mW

VCC e15V, VEE eb

15V 160 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 PDe(TJMAX bTA)/iJA or the number given in the Absolute Maixmum Ratings, whichever is lower. For this

device, TJMAX e125§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-in-

line 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 kXresistor.

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

VOe10V #A1

2aA2

4a...A8

256 J

TL/H/5687–3

FIGURE 1. a10V Output Digital to Analog Converter (Note 7)

Typical Performance Characteristics

VCC e5V, VEE eb

15V, TAe25§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

Unless otherwise specified: R14 e

R15 e1kX,Ce15 pF, pin 16 to

VEE;R

Le50X, pin 4 to ground.

Curve A: Large Signal Bandwidth

Method of

Figure 7

REF e2 Vp-p

offset 1 V above ground.

Curve B: Small Signal Bandwidth

Method of

Figure 7

Le250X,V

REF

e50 mVp-p offset 200 mV above

ground.

Curve C: Large and Small Signal

Bandwidth Method of

Figure 9

(no op

amp, RLe50X), RSe50X,V

REF e

2V, VSe100 mVp-p centered at 0V.

TL/H/5687–5

TL/H/5687–4

FIGURE 2. Equivalent Circuit of the DAC0808 Series (Note 7)

Test Circuits

TL/H/5687–6

VIand I1apply 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.

IOeK#A1

2aA2

4aA3

8aA4

16 aA5

32 aA6

64 aA7

128 aA8

256 J

where K jVREF

R14

and ANe‘‘1’’ if ANis at high level

ANe‘‘0’’ if ANis at low level

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)

Test Circuits (Continued)

TL/H/5687–9

FIGURE 6. Reference Current Slew Rate Measurement (Note 7)

TL/H/5687–10

FIGURE 7. Positive VREF (Note 7)

TL/H/5687–11

FIGURE 8. Negative VREF (Note 7)

Application Hints

REFERENCE AMPLIFIER DRIVE AND COMPENSATION

The reference amplifier provides a voltage at pin 14 for con-

verting 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,

TL/H/5687–12

FIGURE 9. Programmable Gain Amplifier or

Digital Attenuator Circuit (Note 7)

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.

Application Hints (Continued)

A negative reference voltage may be used if R14 is ground-

ed 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 neg-

ative 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 posi-

tive input level at pin 15.

When a DC reference voltage is used, capacitive bypass to

ground is recommended. The 5V logic supply is not recom-

mended as a reference voltage. If a well regulated 5V sup-

ply 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, de-

creasing the overall bandwidth.

OUTPUT VOLTAGE RANGE

The voltage on pin 4 is restricted to a range of b0.55 to

0.4V when VEE eb

5V due to the current switching meth-

ods 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 kXbetween pin 4 and ground will

yield a voltage output of 256 levels between 0 and

b4.980V. 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 volt-

age swing. Values of RLup to 500Xdo not significantly

affect performance, but a 2.5 kXload 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.

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

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 cur-

rent. However, the DAC0808 has a very low full-scale cur-

rent 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 corre-

sponds 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 12-

bit converter is calibrated for a full-scale output current of

1.992 mA. This is an optional step since the DAC0808 accu-

racy 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 g0.00076%,

which is much more accurate than the g0.019% specifica-

tion provided by the DAC0808.

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 con-

tributions are less than 1.6 mA. This is well within 8-bit accu-

racy 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 RLs500Xand COs25 pF.

Extra care must be taken in board layout since this is usually

the dominant factor in satisfactory test results when mea-

suring settling time. Short leads, 100 mF supply bypassing

for low frequencies, and minimum scope lead length are all

mandatory.

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

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

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failure to perform, when properly used in accordance support device or system, or to affect its safety or

with instructions for use provided in the labeling, can effectiveness.

be reasonably expected to result in a significant injury

to the user.

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