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Электронный компонент: IC3410

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10-bit digital to analogue
converter IC 3410
Issued November 1985
RS stock number 631-389
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.
Absolute maximum ratings
V
CC
Supply voltage___________________________+7V
V
EE
Supply voltage___________________________-18V
V
I
Digital input voltage _______________________+15V
V
O
Applied output voltage ________________0.5, -5.0V
I
REF
Reference current_______________________2.5mA
V
REF
Reference amplifier inputs _____________V
CC
, V
EE
V
REF
(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
Data Pack H
Data Sheet
006-109
2
Electrical characteristics
V
CC
= +5.0V dc, V
EE
= -15V dc,
V
REF
= 2.0mA, all digital inputs at high logic level
R16
T
A
= 0 to +70C, unless otherwise noted.
Symbol and parameter
Test conditions
Min
Typ
Max
Unit
E
r
Relative accuracy
T
A
= 25C
0.05
%
(Error relative to full scale I
O
)
1/4
LSB
TCE
r
Relative accuracy drift
2.5
p.p.m./C
(Relative to full scale I
O
)
Monotonicity
Over temperature
10
Bits
Settling time to within
T
A
= 25C
250
ns
t
S
1
/
2
LSB (all bits low to high)
t
PLH
Propagation delay time
T
A
= 25C
35
ns
t
PHL
20
TCI
O
Output full scale current drift
60
p.p.m./C
Digital input logic levels
(All bits)
V
IH
High level, logic '1'
2.0
Vdc
Low level, logic '0'
0.8
Digital input current (All bits)
I
IH
High level, V
IH
= 5.5V
+0.4
mA
I
IL
Low level, V
IL
= 0.8V
-0.05
-0.4
Reference input bias current
I
REF(15)
(Pin 15)
-1.0
-5.0
A
I
OR
Output current range
4.0
5.0
mA
I
OH
Output current (All bits high)
V
REF
= 2.000V,
3.8
3.996
4.2
mA
R
16
= 1000
I
OL
Output current (All bits low)
T
A
= 25C
0
2.0
A
V
O
Output voltage compliance
T
A
= 25C
-2.5
Vdc
+0.2
SR I
REF
Reference amplifier slew rate
20
mA/s
ST I
REF
Reference amplifier settling time
0 to 4.0mA, 0.1%
2.0
s
Output current power supply
PSRR(-)
sensitivity
0.003
0.01
%/%
C
O
Output capacitance
V
O
= 0
25
pF
Digital input capacitance
C
I
(All bits high)
4.0
pF
I
CC
Power supply current
+18
I
EE
(All bits low)
-11.4
-20
mA
V
CC
+4.75
+5.0
+5.25
V
EE
Power supply voltage range
T
A
= 25C
-14.25
-15
-15.75
Vdc
Power consumption
(All bits low)
220
380
mW
(All bits high)
200
006-109
3
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 Signifi-
cant 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
006-109
4
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 V
EE
supply voltage for best operation. Bipolar input
Figure 6 3410 equivalent circuit
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 band-
width 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.
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 V
EE
> -15V.
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.
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 cur-
rent drift with temperature.
The 3410 is accurate to within .05% at 25C with a ref-
erence 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.
006-109
5
Figure 7 Basic connections
a) Positive reference voltage
b) Negative reference voltage
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 typi-
cally 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) set-
tles 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 usu-
ally 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, puls-
ing the voltage reference input between 0 and 2V, and
using a 500
load resistor R
L
.
Figure 8 Settling time
t
s
- 250 ns TYPICAL
TO 1.2 LSB
USE R
L
TO GND FOR TURN-OFF MEASUREMENT
FOR SETTLING TIME
MEASUREMENT.
(ALL BIT SWITCHED
LOW TO HIGH)
Figure 9 Propagation delay time
FOR PROPAGATION
DELAY TIME