Sipex HS3160C-3Q 16-bit multiplying dac Datasheet

SP7516 and HS3160
Corporation
SIGNAL PROCESSING EXCELLENCE
16-Bit Multiplying DACs
■ Monolithic Construction
■ 16–Bit Resolution
■ 0.003% Non-Linearity
■ Four-Quadrant Multiplication
■ Latch-up Protected
■ Low Power - 30mW
■ Single +15V Power Supply
DESCRIPTION…
The SP7516 and HS3160 are precision 16-bit multiplying DACs, that provide four-quadrant
multiplication. Both parts accept both AC and DC reference voltages. The SP7516 is available
for use in commercial and industrial temperature ranges, packaged in a 24-pin SOIC. The
HS3160 is available in commercial and military temperature ranges, packaged in a 22-pin
side-brazed DIP.
VREF Force
23
VREF Sense
22
GND
VDD
2
3
1
4
21
IOUT2 Sense
IOUT2 Force
IOUT1
SP7516
5
6
7
BIT1 BIT2 BIT3
(MSB)
8
20
BIT4
BIT16
(LSB)
24
RFEEDBACK
Switches shown in high state.
VREF
21
2
GND
VDD
IOUT2
3
1
20
IOUT1
HS3160
4
5
6
BIT1 BIT2 BIT3
(MSB)
7
19
BIT4
BIT16
(LSB)
22
RFEEDBACK
Switches shown in high state.
Corporation
SIGNAL PROCESSING EXCELLENCE
127
SPECIFICATIONS
(Typical @ 25°C, nominal power supply, VREF = +10V, unipolar unless otherwise noted)
PARAMETER
DIGITAL INPUT
Resolution
2–Quad, Unipolar Coding
4–Quad, Bipolar Coding
Logic Compatibility
Input Current
REFERENCE INPUT
Voltage Range
Input Impedance
ANALOG OUTPUT
Scale Factor
Scale Factor Accuracy
Output Leakage
Output Capacitance
COUT 1, all inputs high
COUT 1, all inputs low
COUT 2, all inputs high
COUT 2, all inputs low
STATIC PERFORMANCE
Integral Linearity
SP7516KN/BN, HS3160–4
SP7516JN/AN, HS3160–3
Differential Linearity
SP7516KN/BN, HS3160–4
SP7516JN/AN, HS3160–3
Monotonicity
SP7516KN/BN, HS3160–4
SP7516JN/AN, HS3160–3
STABILITY
Scale Factor
Integral Linearity
Differential Linearity
Monotonicity Temp. Range
SP7516JN/KN, HS3160C
SP7516AN/BN
HS3160B–_
DYNAMIC PERFORMANCE
Digital Small Signal Settling
Digital Full Scale Settling
Reference Feedthrough Error
@ 1kHz
@ 10kHz
Reference Input Bandwidth
POWER SUPPLY (VDD)
Operating Voltage
Voltage Range
Current
Rejection Ratio
128
MIN.
TYP.
MAX.
16
UNITS
CONDITIONS
Bits
Binary
Offset Binary
CMOS, TTL
3.25
75
±1
µA
±25
9.75
V
KOhms
225
±1
10
µA/VREF
%
nA
100
50
50
100
Note 1
Note 2
Note 3
Note 4
pF
pF
pF
pF
Note 5
±0.003
±0.006
±0.006
±0.012
% FSR
% FSR
±0.003
±0.006
±0.006
±0.012
%FSR
% FSR
Note 6
Guaranteed to 14 bits
Guaranteed to 13 bits
4
0.5
0.5
0
–40
–55
1.0
1.0
+70
+85
+125
ppm FSR/°C
ppm FSR/°C
ppm FSR/°C
°C
°C
°C
1.0
2.0
µS
µS
200
2
1
µV
mV
MHz
+15 ±5%
+8
+18
2.0
0.005
(TMIN to TMAX)
Note 7 and 8
V
V
mA
%/%
(VREF = 20Vpp)
Note 9
Corporation
SIGNAL PROCESSING EXCELLENCE
SPECIFICATIONS (continued)
(Typical @ 25°C, nominal power supply, VREF = +10V, unipolar unless otherwise noted)
PARAMETER
MIN.
TYP.
MAX.
ENVIRONMENTAL AND MECHANICAL
Operating Temperature
SP7516JN/KN
0
+70
SP7516AN/BN
–40
+85
HS3160–C
0
+70
HS3160–B
–55
+125
HS3160–B/883
–55
+125
Storage Temperature
–65
+150
Package
SP7516_N
24-pin SOIC
HS3160
22–pin Side–Brazed DIP
UNITS
CONDITIONS
°C
°C
°C
°C
°C
°C
Notes:
1.
Digital input voltage must not exceed supply voltage or go below –0.5V ; “0” <0.8V; 2.4V < “1” ≤VDD.
2.
AC or DC; use R6758–1 for fixed reference applications
3.
Using the internal feedback resistor and an external op amp. The Scale Factor can be adjusted externally by variable resistors in series with the
reference input and/or in series to the internal feedback resistor. Please refer to the Applications Information section.
4.
At 25°C; the output leakage current will create an offset voltage at the external op amps output. It doubles every 10°C temperature increase.
5.
Integral Linearity is measured as the arithmetic mean value of the magnitudes of the greatest positive deviation and the greatest negative deviation from
the theoretical value for any given input combination.
6.
Differential Linearity is the deviation of an output step form the theoretical value of 1LSB for any two adjacent digital input codes.
7.
At 25°C, the output leakage current will create an offset voltage output. It doubles every 10°C temperature increase.
8.
Using the internal feedback resistor and an external op amp.
9.
Use series 470ohm resistor to limit startup current.
CHARACTERISTIC CURVES
0.048
50
LINEARITY ERROR - PPM
INTEGRAL LINEARITY ERROR - %
(Typical @ + 25°C, V DD = + 15VDC, VREF = + 10VDC, unless otherwise noted.)
0.024
0.012
0.006
0.003
0.01
0.1
1
10
V REF -VOLTS
40
2 LSB
30
20
1 LSB
10
1/2 LSB @ 16 BITS
Integral Linearity Error vs. Reference Voltage
0
0.048%
0
10
20
30
40
50
LINEARITY - %
VOS-mV
Additional Linearity Error vs. Output-Amplifier
Offset-Voltage (VREF = + 10V)
0.024%
0.012%
0.01
0.006%
0.003%
6
4
8
10
12
14
16
18
0.008
GAIN CHANGE - %
V DD -VOLTS
Linearity vs. Supply Voltage
2.5
I DD -mA
2.0
0.006
0.004
0.002
1.5
0
4
1.0
4
6
8
10
12
V
-VOLTS
DD
14
16
18
10
6
8
10
12
V
-VOLTS
DD
14
16
18
Gain Change vs. Supply Voltage
Power Supply Current vs. Voltage
Corporation
SIGNAL PROCESSING EXCELLENCE
129
PIN ASSIGNMENTS
HS3160 22–PIN
Pin 1 – IO1 – Current Output 1.
Pin 2 – IO2 – Current Output 2.
Pin 3 – GND – Ground.
Pin 4 – DB15 – MSB, Data Bit 1.
Pin 5 – DB14 – Data Bit 2.
Pin 6 – DB13 – Data Bit 3.
Pin 7 – DB12 – Data Bit 4.
Pin 8 – DB11 – Data Bit 5.
Pin 9 – DB10 – Data Bit 6.
Pin 10 – DB9 – Data Bit 7.
Pin 11 – DB8 – Data Bit 8.
Pin 12 – DB7 – Data Bit 9.
Pin 13 – DB6 – Data Bit 10.
Pin 14 – DB5 – Data Bit 11.
Pin 15 – DB4 – Data Bit 12.
Pin 16 – DB3 – Data Bit 13.
Pin 17 – DB2 – Data Bit 14.
Pin 18 – DB1 – Data Bit 15.
Pin 19 – DB0 – LSB, Data Bit 16.
Pin 20 – VDD – Positive Supply Voltage.
Pin 21 – VREF – Reference Voltage Input.
Pin 22 – RFB – Feedback Resistor.
SP7516 24–PIN
Pin 1 – IO1 – Current Output 1.
Pin 2 – IO2 Sense – Current Output 2.
Pin 3 – IO3 Force – Current Output 3.
Pin 4 – GND – Ground.
Pin 5 – DB15 – MSB, Data Bit 1.
Pin 6 – DB14 – Data Bit 2.
Pin 7 – DB13 – Data Bit 3.
Pin 8 – DB12 – Data Bit 4.
Pin 9 – DB11 – Data Bit 5.
Pin 10 – DB10 – Data Bit 6.
Pin 11 – DB9 – Data Bit 7.
Pin 12 – DB8 – Data Bit 8.
Pin 13 – DB7 – Data Bit 9.
Pin 14 – DB6 – Data Bit 10.
130
Pin 15 – DB5 – Data Bit 11.
Pin 16 – DB4 – Data Bit 12.
Pin 17 – DB3 – Data Bit 13.
Pin 18 – DB2 – Data Bit 14.
Pin 19 – DB1 – Data Bit 15.
Pin 20 – DB0 – LSB, Data Bit 16.
Pin 21 – VDD – Positive Supply Voltage.
Pin 22 – VREF Sense – Reference Voltage Input.
Pin 23 – VREF Force – Reference Voltage Input.
Pin 24 – RFB – Feedback Resistor.
FEATURES…
The SP7516 and HS3160 are precision 16-bit multiplying DACs. The DACs are implemented as a onechip CMOS circuit with a resistor ladder network.
Three output lines are provided on the DACs to allow
unipolar and bipolar output connection with a minimum of external components. The feedback resistor
is internal. The resistor ladder network termination is
externally available, thus eliminating an external resistor for the 1 LSB offset in bipolar mode.
The SP7516 is available for use in commercial and
industrial temperature ranges, packaged in a 24-pin
SOIC. The HS3160 is available in commercial
and military temperature ranges, packaged in a
24–pin side–brazed DIP. For product processed
and screened to the requirements of MIL–M–
38510 and MIL–STD–883C, please consult the
factory (HS3160B only).
PRINCIPLES OF OPERATION
The SP7516/HS3160 achieve high accuracy by using
a decoded or segmented DAC scheme to implement
this function. The following is a brief description of
this approach.
Cf
Rf
VREF
–
Ri
CO
Rp
EO
+
C
Figure 1. SP7516/HS3160 Equivalent Output Circuit
Corporation
SIGNAL PROCESSING EXCELLENCE
2 - 1 (MSB)
0
0
1
1
2
Output
-2
0
1
0
1
470Ω
400Ω
V REF
0
1/4 Full-Scale
1/2 Full-Scale
3/4 Full-Scale
V DD
200Ω
RFEEDBACK
R OS
I O1
DIGITAL
INPUTS
Table 1. Contribution of the two MSB's
The most common technique for building a D/A
converter of n bits is to use n switches to turn n current
or voltage sources on or off. The n switches and n
sources are designed so that each switch or bit contributes twice as much to the D/A converter’s output as the
preceding bit. This technique is commonly known as
binary weighting and allows an n-bit converter to
generate 2n output levels by turning on the proper
combination of bits.
In such a binary-weighted converter, the switch
with the smallest contribution (the LSB) accounts
for only 2 -n of the converter’s full-scale value.
Similarly, the switch with the largest contribution
(the MSB) accounts for 2 -1 or half of the converter’s
full-scale output. Thus it is easy to see that a given
percent change in the MSB will have a greater
effect on the converter’s output than would a
similar percent change in the LSB. For example, a
1% change in the LSB of a 10 bit converter would
only affect the output by 0.001% of full-scale. A
1% change in the MSB of the same converter
would affect the output by 0.5% of FSR.
In order to overcome the problem which results from
the large weighting of the MSB, the two MSB’s can
be decoded to three equally weighted sources. Table
1 shows that all combinations of the two MSB’s of a
converter result in four output levels. So by replacing
the two MSB’s with three bits equally weighted at 1/
4 full-scale and decoding the two MSB digital inputs
into three lines which drive the equally weighted bits,
SP7516
HS3160
A
I O2
+
GND
Figure 2. Unipolar Operation
the same functional performance can be obtained.
Thus by replacing the two MSB switches of a conventional converter with three switches properly decoded, the contribution of any switch is reduced from
1/2 to 1/4. This reduction in sensitivity also reduces the
accuracy required of any switch for a given overall
converter accuracy.
With the decoded converter described above, a 1%
change in any of the converter’s switches will affect
the output by no more than 0.25% of full-scale as
compared to 0.5% for a conventional converter. In
other words the conventional D/A converter can be
made less sensitive to the quality of its individual bits
by decoding.
In the SP7516/HS3160 the first four MSB’s are
decoded into 16 levels which drive 15 equally weighted
current sources. The sensitivity of each switch on the
output is reduced by a factor of 8. Each of the 15
sources contributes 6.25% output change rather than
an MSB change of 50% for the common approach.
470Ω
400Ω
V REF
V DD
200Ω
R FEEDBACK
R OS1
I O1
TRANSFER FUNCTION (N=16)
DIGITAL
INPUTS
A1
+
SP7516
HS3160
BINARY INPUT UNIPOLAR OUTPUT BIPOLAR OUTPUT
111...111
–VREF (1 - 2–N)
100...001
–V REF (1/2 + 2–N)
100...000
–VREF /2
011...111
–VREF (1/2 – 2 –N)
000…001
–VREF (2(N – 1))
000...000
0
Table 2. Transfer Function
Corporation
SIGNAL PROCESSING EXCELLENCE
V OUT
4KΩ
4KΩ
–VREF (1 – 2 –(N – 1) )
–VREF (2
V OUT
I O2
)
–(N – 1)
R OS2
R OS2
VREF (2 –(N – 1))
VREF (1 – 2
R
GND
0
A2
+
)
–(N – 1)
V OUT1
A1, A2 , OP-07
VREF
Figure 3. Bipolar Operation
131
V DD
VREF
(+ 25V MAX)
D0
D1
D1
D2
D2
D3
400
D0
74273
D3
D4
D4
D5
D5
D6
D6
D7
CLK
D7
D0
D1
D2
WR
G2A
BDSEL
A2
A1
G2B
74273
A0
C
B
D3
D4
74LS138
D5
D6
CLK
D7
470 3
LSB VREF
15 + VDD
14
13
UNIPOLAR MODE
(2-QUADRANT)
200
RF
12
11
10
I 01
9
I 02
SP7516/
SP7514/
7516
HS3160
8
2
–
A
3 +1
6
VOUT
0 TO - V REF
(1-2 - N)
R 0S
7
6
5
4
3
2
MSB GND
A
ADDRESS DECODER
LATCHES
Figure 4. Microprocessor Interface to SP7514
Following the decoded section of the DAC a
standard binary weighted R-2R approach is used.
This divides each of the 16 levels (or 6.25% of
F.S.) into 4096 discrete levels (the 12 LSB’s).
Output Capacitance
The SP7516/HS3160 have very low output capacitance (CO). This is specified both with all
switches ON and all switches OFF. Output capacitance varies from 50pF to 100pF over all input
codes. This low capacitance is due in part to the
decoding technique used. Smaller switches are
used with resulting less capacitance. Three important system characteristics are affected by CO and
∆CO; namely digital feedthrough, settling time,
and bandwidth. The DAC output equivalent circuit can be represented as shown in Figure 1.
Digital feedthrough is the change in analog output
due to the toggling conditions on the converter
input data lines when the analog input VREF is at
0V. The SP7516/HS3160 very low CO and therefore will yield low digital feedthrough. Inputs to
the DAC can be buffered. This input latch with
microprocessor control is shown in Figure 4.
Settling time is directly affected by CO. In Figure
1, CO combines with Rf to add a pole to the open
loop response, reducing bandwidth and causing
excessive phase shift - which could result in
ringing and/or oscillation. A feedback capacitor, Cf must be added to restore stability. Even with
Cf, there is still a zero-pole mismatch due to RiCO
which is code dependent. This code dependent
mismatch is minimized when CORi = RfCf. However Cf must now be made larger to compensate for
worst case ∆RiCO - resulting in reduced bandwidth
and increased settling time. With the SP7516/
132
HS3160, small values for Cf must be used. Resistor Rp can be added, this will parallel Rj decreasing
the effective resistance. If Cf is reduced the bandwidth will be increased and settling time decreased.
However a system penalty for lowering Cf is to
increase noise gain. The tradeoff is noise vs. settling time. If Rp is added then a large value (1µF or
greater) non-polarized capacitor Cp should be added
in series with Rp to eliminate any DC drifts. If
settling time is not important, eliminate Rp and Cp,
and adjust Cf to prevent overshoot.
Output Offset
In most applications, the output of the DAC is fed
into an amplifier to convert the DAC’s current
output to voltage. A little known and not commonly discussed parameter is the linearity error
versus offset voltage of the output amplifier. All
CMOS DAC’s must operate into a virtual ground,
i.e., the summing junction of an op amp. Any
amplifier’s offset from the amplifier will appear as
an error at the output (which can be related to
LSB’s of error).
Most all CMOS DAC’s currently available are
implemented using an R-2R ladder network. The
formula for nonlinearity is typically 0.67mV/mVOS
(not derived here). However the SP7516 has a
coefficient of only 0.065mV/mVOS. This is due to
the decoding technique described earlier. CMOS
DAC applications notes (including this one) always show a potentiometer used to null out the
amplifier’s offset. If an amplifier is chosen having
‘pretrimmed’ offset it may be possible to eliminate
this component. Consider the following calculations:
1.
Using LF441A amplifier (low power - 741 pinout)
2.
Specified offset: 0.5mV max
3.
Temperature coefficient of input offset: 10µV/°C max
VOS max (0°C to 70°C)
= 0.5mV + (70µV)10
= 1.2mV
Add'l nonlinearity (max)
= 1.2mV x 0.065mV/mV
= 78µV (1/2 LSB @ 16 Bits!)
Where: 78µV = 1/2 LSB @ 16 Bits (10V range)
Via the above configuration, the SP7516/HS3160
can be used to divide an analog signal by digital
code (i.e. for digitally controlled gain). The transfer function is given in Table 2, where the value of
each bit is 0 or 1. Division by all “0”s is undefined
and causes the op amp to saturate.
Corporation
SIGNAL PROCESSING EXCELLENCE
Applications Information
Unipolar Operation
Figure 2 shows the interconnections for unipolar
operation. Connect IO1 and FB1 as shown in diagram. Tie IO2 (Pin 7), FB3 (Pin 3), and FB4 (Pin 1)
to Ground (Pin 8). As shown, a series resistor is
recommended in the VDD supply line to limit
current during ‘turn-on.’ To maintain specified
linearity, external amplifiers must be zeroed. Apply
an ALL “ZEROES” digital input and adjust ROS
for VOUT = 0 ± 1mV. The SP7516 and HS3160
have been used successfully with OP-07, OP-27
and LF441A. For high speed applications the
SP2525 is recommended.
Bipolar Operation
Figure 3 shows the interconnections for bipolar
operation. Connect IO1, IO2, FB1, FB3, FB4 as
shown in diagram. Tie LDTR to IO2. As shown, a
series resistor is recommended in the VDD supply
line to limit current during ‘turn-on. To maintain
specified linearity, external amplifiers must be
zeroed. This is best done with VREF set to zero and,
the DAC register loaded with 10...0 (MSB = 1). Set
R0S1 for V01 = 0. Set R0S2 for VOUT = 0. Set VREF
to +10V and adjust RB for VOUT to be 0V.
Grounding
Connect all GND pins to system analog ground
and tie this to digital ground. All unused input
pins must be grounded.
Corporation
SIGNAL PROCESSING EXCELLENCE
133
ORDERING INFORMATION
Model ................................................................ Monotonicity ................................ Temperature Range .................................... Package
16-Bit Multiplying DAC
HS3160C-3Q ............................................................ 13-Bit ............................................... 0°C to +70°C ................... 22-pin, 0.4" Side-Brazed DIP
HS3160B-3Q ............................................................ 13-Bit ......................................... -55°C to +125°C ................... 22-pin, 0.4" Side-Brazed DIP
HS3160B-3/883 ....................................................... 13-Bit ......................................... -55°C to +125°C ................... 22-pin, 0.4" Side-Brazed DIP
HS3160C-4Q ............................................................ 14-Bit ............................................... 0°C to +70°C ................... 22-pin, 0.4" Side-Brazed DIP
HS3160B-4Q ............................................................ 14-Bit ......................................... -55°C to +125°C ................... 22-pin, 0.4" Side-Brazed DIP
HS3160B-4/883 ....................................................... 14-Bit ......................................... -55°C to +125°C .................. 22-pin , 0.4" Side-Brazed DIP
SP7516JN ................................................................
SP7516KN ...............................................................
SP7516AN ...............................................................
SP7516BN ...............................................................
134
13-Bit ............................................... 0°C
14-Bit ............................................... 0°C
13-Bit .......................................... –40°C
14-Bit .......................................... –40°C
to
to
to
to
+70°C
+70°C
+85°C
+85°C
...................................... 24-pin,
...................................... 24-pin,
...................................... 24-pin,
...................................... 24-pin,
0.3"
0.3"
0.3"
0.3"
SOIC
SOIC
SOIC
SOIC
Corporation
SIGNAL PROCESSING EXCELLENCE