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Data Pack H
Issued November 1985 006-109
Data Sheet
The 3410 is a 10-bit multiplying digital to analogue converter IC Complete 10-bit accuracy is achieved without laser trimming and monotonicity is guaranteed over the operating temperature range. This device when used in conjunction with an output buffer amplifier and reference performs the full 10-bit conversion.
10-bit digital to analogue converter IC 3410
RS stock number 631-389
Absolute maximum ratings
VCC Supply voltage___________________________+7V VEE Supply voltage___________________________-18V VI Digital input voltage _______________________+15V VO Applied output voltage ________________0.5, -5.0V IREF Reference current_______________________2.5mA VREF Reference amplifier inputs _____________VCC, VEE VREF (D) Reference amplifier differential inputs ____________________________0.7V Operating temperature range__________0C to +70C Junction temperature ______________________+150C
Features q 10-bit resolution and accuracy q Guaranteed monotonicity over full temperature range q Fast settling time 250ns typ. q TTL and CMOS compatible digital inputs q Reference amplifier internally compensated. Pin connections
006-109 Electrical characteristics VCC = +5.0V dc, VEE = -15V dc, VREF = 2.0mA, all digital inputs at high logic level
TA = 0 to +70C, unless otherwise noted.
Symbol and parameter Er TCEr Relative accuracy (Error relative to full scale IO) Relative accuracy drift (Relative to full scale IO) Monotonicity Settling time to within 1/2 LSB (all bits low to high) Propagation delay time Output full scale current drift Digital input logic levels (All bits) High level, logic '1' Low level, logic '0' Digital input current (All bits) High level, VIH = 5.5V Low level, VIL = 0.8V Reference input bias current (Pin 15) Output current range Output current (All bits high) Output current (All bits low) Output voltage compliance Reference amplifier slew rate Reference amplifier settling time Output current power supply sensitivity Output capacitance Digital input capacitance (All bits high) Power supply current (All bits low) Power supply voltage range Power consumption (All bits low) (All bits high) TA = 25C +4.75 -14.25 0 to 4.0mA, 0.1% VREF = 2.000V, R16 = 1000 TA = 25C TA = 25C 20 2.0 0.003 VO = 0 25 4.0 +18 -20 +5.25 -15.75 380 0.01 3.8 Over temperature TA = 25C TA = 25C 10 250 35 20 60 Test conditions TA = 25C 2.5
R16
Min
Typ
Max 0.05 1/4
Unit % LSB p.p.m./C Bits ns ns p.p.m./C Vdc
tS tPLH tPHL TCIO
VIH
2.0 0.8 +0.4 -0.4 -5.0 5.0 4.2 2.0 -2.5 +0.2
IIH IIL IREF(15) IOR IOH IOL VO SR IREF ST IREF PSRR(-) CO CI ICC IEE VCC VEE
mA A mA mA A Vdc mA/s s %/% pF pF mA Vdc mW
-0.05 -1.0 4.0 3.996 0
-11.4 +5.0 -15 220 200
2
006-109 Performance characteristics
Figure 1 Output current vs. output compliance voltage Figure 4 Reference amplifier frequency response
Figure 5 Block diagram Figure 2 Maximum output compliance voltage vs. temperature
Figure 3 Power supply current vs. temperature
Circuit description
The 3410 consists of four segment current sources which generate the 2 Most Significant Bits (MSBs), and an R/2R DAC implemented with ion implanted resistors for scaling the remaining 8 Least Significant Bits (LSBs). (Figure 6.) This approach provides complete 10-bit accuracy without trimming. The individual bit currents are switched ON or OFF by fully differential current switches. The switches use current steering for speed. An on-chip high-slew reference current amplifier drives the R/2R ladder and segment decoder. The currents are scaled in such a way that, with all bits on, the maximum output current is two times 1023/1024 of the reference amplifier current, or nominally 3.996mA for a 2.000mA reference input current. The reference amplifier allows the user to provide a voltage input. Out-board resistor R16 (Figure 7) converts this voltage to a usable current. A current mirror doubles this reference current and feeds it to the segment decoder and resistor ladder. Thus, for a reference voltage of 2.0 volts and a 1k resistor tied to Pin 16, the full scale 3
006-109
current is approximately 4.0mA. This relationship will remain regardless of the reference voltage polarity. Connections for a positive reference voltage are shown in Figure 7a. For negative reference voltage inputs, or for bipolar reference voltage inputs in the multiplying mode., R15 can be tied to a negative voltage corresponding to the minimum input level. For a negative reference input, R16 should be grounded (Figure 7b). In addition, the negative voltage reference must be at least 3V above the VEE supply voltage for best operation. Bipolar input Figure 6 3410 equivalent circuit signals may be handled by connecting R16 to a positive 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 5.0V supply, which drives logic, is to be used as the reference, R16 should be decoupled by connecting it to the +5.0V logic supply through another resistor and bypassing the junction of the two resistors with a 0.1F capacitor to ground.
The reference amplifier is internally compensated with a 10pF feed-forward capacitor, which gives it its high slew rate and fast settling time. Proper phase margin is maintained with all possible values of R16 and reference voltages which supply 2.0mA reference current into Pin 16. The reference current can also be supplied by a high impedance current source of 2.0mA. As R16 increases, the bandwidth of the amplifier decreases slightly and settling time increases. For a current source with a dynamic output impedance of 1.0M, the bandwidth of the reference amplifier is approximately half what it is in the case of R16 = 1.0k, and settling time is 10s. The reference amplifier phase margin decreases as the current source value decreases in the case of a current source reference, so that the minimum reference current supplied from a current source is 0.5mA for stability.
Accuracy
Absolute accuracy is a measure of each output current level with respect to its intended value. It is dependent upon relative accuracy and full scale current drift. Relative accuracy, or linearity, is the measure of each output current with respect to its intended fraction of the full scale current. The relative accuracy of the 3410 is fairly constant over temperature due to the excellent temperature tracking, of the implanted resistors. The full scale current from the reference amplifier may drift with temperature causing a change in the absolute accuracy. However, the 3410 has a low full scale current drift with temperature. The 3410 is accurate to within .05% at 25C with a reference current of 2.0mA on Pin 16.
Monotonicity
The 3410 is guaranteed monotonic over temperature. This means that for every increase in the input digital code, the output current either remains the same or increases but never decreases. In the multiplying mode, where reference input current will vary, monotonicity can be assured if the reference input current remains above 0.5mA.
Output voltage compliance
The output voltage compliance ranges from -2.5 to +0.2V. As shown in Figure 2, this compliance range is nearly constant over temperature. At the temperature extremes, however, the compliance voltage may be reduced if VEE > -15V. 4
006-109
Figure 7 Basic connections Figure 8 Settling time
a) Positive reference voltage
b) Negative reference voltage
ts - 250 ns TYPICAL TO 1.2 LSB USE RL TO GND FOR TURN-OFF MEASUREMENT FOR SETTLING TIME MEASUREMENT. (ALL BIT SWITCHED LOW TO HIGH)
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 250ns for the output to settle to within 1/2 LSB for 10-bit accuracy, and 200ns for 8-bit accuracy. The turn-off time is typically 120ns. These times apply when the output swing is limited to a small (<0.7 volt) swing and the external output capacitance is under 25pF. The major carry (MSB off-to-on, all others on-to-off) settles in approximately the same time as when all bits are switched off-to-on. If a load resistor of 625 ohms is connected to ground, allowing the output to swing to -2.5 volts, the settling time increases to 1.5s. Extra care must be taken in board layout as this is usually the dominant factor in satisfactory test results when measuring time. Short leads, 100F supply bypassing, and minimum scope lead length are all necessary. A typical test set-up for measuring settling time is shown in Figure 8. The same set-up for the most part can be used to measure the slew rate of the reference amplifier (Figure 10) by typing all data bits high, pulsing the voltage reference input between 0 and 2V, and using a 500 load resistor RL. Figure 9 Propagation delay time
FOR PROPAGATION DELAY TIME
5

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