SPT1018
8-BIT, HIGH SPEED D/A CONVERTER
FEATURES
• 275 MWPS Conversion Rate - Version A
• 165 MWPS Conversion Rate - Version B
• Compatible with TDC1018 and HDAC10180
with Improved Performance
• RS-343-A Compatible
• Complete Video Controls: Sync, Blank, Bright
and Reference White (Force High)
• 10KH, 100K ECL Compatible
• Single Power Supply
• Registered Data and Video Controls
• Differential Current Outputs
• ESD Protected Data and Control Inputs
APPLICATIONS
• High Resolution Color or Monochrome Raster
Graphics Displays
• Medical Electronics: CAT, PET, MR Imaging Displays
• CAD/CAE Workstations
• Solids Modeling
• General Purpose High-Speed D/A Conversion
• Digital Synthesizers
• Automated Test Equipment
• Digital Transmitters/Modulators
GENERAL DESCRIPTION
The SPT1018 is a monolithic 8-bit digital-to-analog converter
capable of accepting video data at a 165 or 275 MWPS rate.
Complete with video controls (Sync, Blank, Reference White
[Force High], Bright), the SPT1018 directly drives doubly-
terminated 50 or 75 ohm loads to standard composite video
levels. The standard set-up level is 7.5 IRE. The SPT1018 is
pin-compatible with the HDAC10180 and the TDC1018, with
improved performance. The SPT1018 contains data and
control input registers, video control logic, reference buffer,
and current switches.
The SPT1018 is available in a 24-lead PDIP package in the
industrial temperature range. Contact the factory for military
temperature and /883 versions.
BLOCK DIAGRAM
Sync, Blank, Bright, Ref - High
Video Controls In
D0 - D3
Video Data In
4
4
4
4
Out +
Register
Video Data In
D4 - D7
(MSBs)
4
Output
Current
Switches
Out -
4 To 15
Decode
Feedthrough
Convert
2
Ref+
Ref-
Ref
Buffer
Comp
Signal Processing Technologies, Inc.
4755 Forge Road, Colorado Springs, Colorado 80907, USA
Phone: (719) 528-2300 FAX: (719) 528-2370
ABSOLUTE MAXIMUM RATING (Beyond which damage may occur)
1
Supply Voltages
V
EE
(measured to V
CC
) ............................... -7.0 to 0.5 V
Input Voltages
CONV, Data, and Controls .......................... V
EE
to 0.5 V
(measured to V
CC
)
Ref+ (measured to V
CC
) .............................. V
EE
to 0.5 V
Ref- (measured to V
CC
) ............................... V
EE
to 0.5 V
Temperature
Operating,
ambient ................................ -25 to +85
°C
junction ......................................... +175
°C
Lead, Soldering (10 seconds) ............................. +300
°C
Storage ..................................................... -60 to +150
°C
Note:
1. Operation at any Absolute Maximum Ratings is not implied. See Electrical Specifications for proper nominal applied
conditions in typical applications.
ELECTRICAL SPECIFICATIONS
V
CC
=ground, V
EE
= -5.2 V
±0.3
V, T
A
=T
MIN
to T
MAX
, C
C
= 0 pF, I
Set
= 1.105 mA, unless otherwise specified.
PARAMETERS
TEST
CONDITIONS
TEST
LEVEL
MIN
TYP
MAX
UNITS
DC ELECTRICAL CHARACTERISTICS
Integral Linearity Error
Differential Linearity Error
Gain Error
Gain Error Tempco
Input Capacitance, REF+, REF-
Compliance Voltage, +Output
Compliance Voltage, -Output
Equivalent Output Resistance
Output Capacitance
Maximum Current, + Output
Maximum Current, - Output
Output Offset Current
Input Voltage, Logic HIGH
Input Voltage, Logic LOW
Convert Voltage,
Common Mode Range (V
ICM
)
Convert Voltage, Differential (V
IDF
)
Input Current, Logic LOW,
Data and Controls
Input Current, Logic HIGH,
Data and Controls
Input Current, Convert
1.0 mA<I
Set
<1.3 mA
1.0 mA<I
Set
<1.3 mA
VI
VI
VI
V
V
VI
VI
VI
V
IV
IV
VI
VI
VI
IV
IV
VI
VI
VI
-0.5
0.4
35
40
2
-1.0
-1.5
-2.5
1.2
120
120
60
45
45
0.05
0.5
-1.2
-1.2
20
12
-.37
-.95
-0.2
-0.5
-6.5
150
5
1.5
1.5
+.37
+.95
+0.2
+0.5
+6.5
% Full Scale
LSB
% Full Scale
LSB
% Full Scale
PPM/°C
pF
V
V
kΩ
pF
mA
mA
LSB
V
V
V
V
µA
µA
µA
SPT
SPT1018
2
5/14/97
ELECTRICAL SPECIFICATIONS
V
CC
=ground, V
EE
= -5.2 V
±0.3
V, T
A
=T
MIN
to T
MAX
, C
C
= 0 pF, I
Set
= 1.105 mA, unless otherwise specified.
PARAMETERS
Input Capacitance,
Data and Controls
Power Supply Sensitivity
Supply Current
Maximum Conversion Rate
Rise Time
Rise Time
Current Settling Time, Clocked Mode
Current Settling Time, Clocked Mode
Current Settling Time, Clocked Mode
t
SI
Clock to Output Delay, Clocked Mode
t
DSC
Data to Output Delay,
Transparent Mode t
DST
Convert Pulse Width, ( Low or High)
t
PWL
, t
PWH
Glitch Energy
Reference Bandwidth, -3 dB
Set-up Time, Data and Controls
t
S
Hold Time, Data and Controls
t
H
Slew Rate
Clock Feedthrough
TEST
CONDITIONS
LEVEL
V
VI
VI
MIN
TYP
3.0
MAX
UNITS
pF
DC ELECTRICAL CHARACTERISTICS
-120
20
155
+120
220
µA/V
mA
MWPS
MWPS
ns
ns
ns
ns
ns
ns
DYNAMIC CHARACTERISTICS (
R
L
= 37.5 ohms, C
L
= 5 pF, T
A
= 25
°C,
I
Set
= 1.105 mA)
B Grade
A Grade
10% to 90% G.S.
T
A
= T
MIN
to T
MAX
10% to 90% G.S.
R
L
= 25 ohms
To 0.2% G.S.
To 0.8% G.S.
To 0.2% G.S.
R
L
= 25
Ω
T
A
= T
MIN
to T
MAX
T
A
= T
MIN
to T
MAX
B Grade
A Grade
Area = 1/2 VT
IV
IV
IV
IV
V
V
V
V
IV
IV
IV
IV
IV
IV
V
V
IV
IV
IV
IV
IV
IV
IV
IV
165
275
1.6
2.0
1.0
7.0
5.5
4.5
2.2
3.2
3.0
1.8
4
1.0
1.0
1.0
0.5
0.5
390
325
-48
-48
4.0
4.5
6.0
6.0
T
A
= T
MIN
to T
MAX
T
A
= T
MIN
to T
MAX
20% to 80% G.S.
T
A
= T
MIN
to T
MAX
T
A
= T
MIN
to T
MAX
ns
ns
ns
ns
ns
ns
pV-s
MHz
ns
ns
ns
ns
V/µS
V/µS
dB
dB
TEST LEVEL CODES
All electrical characteristics are subject to the
following conditions: All parameters having min/
max specifications are guaranteed. The Test
Level column indicates the specific device test-
ing actually performed during production and
Quality Assurance inspection. Any blank sec-
tion in the data column indicates that the speci-
fication is not tested at the specified condition.
TEST LEVEL
I
II
III
IV
V
VI
TEST PROCEDURE
100% production tested at the specified temperature.
100% production tested at T
A
= +25
°C,
and sample
tested at the specified temperatures.
QA sample tested only at the specified temperatures.
Parameter is guaranteed (but not tested) by design
and characterization data.
Parameter is a typical value for information purposes
only.
100% production tested at T
A
= +25
°C.
Parameter is
guaranteed over specified temperature range.
SPT
SPT1018
3
5/14/97
Figure 1 - Functional Diagram
D0 - D7
8
Composite
Video Controls
CONV
CONV
Feedthrough
2
Decoding
Logic
Data
Registers
Current
Sources
And
Switches
Out +
Out -
4
Current
Source
Biasing
Amp
+
-
VEE
VCC
Ref+
Ref-
APPLICATION INFORMATION
The SPT1018 is a high speed video digital-to-analog con-
verter capable of conversion rates of up to 275 MWPS. This
makes the device suitable for driving 1500 X 1800 pixel
displays at 70 to 90 Hz update rates.
The SPT1018 is separated into different conversion rate
categories as shown in table I.
The SPT1018 has 10 KH and 100K ECL logic level compat-
ible video controls and data inputs. The complementary
analog output currents produced by the devices are propor-
tional to the product of the digital control and data inputs in
conjunction with the analog reference current. The SPT1018
is segmented so that the four MSBs of the input data are
separated into a parallel thermometer code. From here,
fifteen identical current sinks are driven to fabricate sixteen
coarse output levels. The remaining four LSBs drive four
binary weighted current switches.
The MSB currents are then summed with the LSBs, which
provide a one-sixteenth of full scale contribution, to provide
the 256 distinct analog output levels.
The video control inputs drive weighted current sinks that are
added to the output current to produce composite video
output levels. These controls, Sync, Blank, Reference White
(Force High), and Bright are needed in video applications.
Another feature that similar video D/A converters do not have
is the Feedthrough Control. This pin allows registered or
unregistered operation of the video control and data inputs.
In the registered mode, the composite functions are latched
to the pixel data to prevent screen-edge distortions generally
found on unregistered video DACs.
Table I - The SPT1018 Family and Speed Designations
PART NUMBER
SPT1018A
UPDATE
275 MWPS
COMMENTS
Suitable for 1200 X 1500 to 1500 X 1800
displays at 60 to 90 Hz update rate.
Suitable for 1024 X 1280 to 1200 X 1500
displays at 60 to 90 Hz update rate.
SPT1018B
165 MWPS
SPT
SPT1018
4
5/14/97
Figure 2 - Typical Interface Circuit
Video Monitor
FT
FH
Blank
BRT
Sync
4
Out-
R3
50/75
Ω
50/75
Ω
COAX
R4
50/75
Ω
Video
Control
Inputs
4
D0 (LSB)
D1
D2
D3
Output
Current
Switches
Register
Out+
Video
Data
Inputs
NOTES:
1. V- = -1.2 V (typical) for LM113.
D4
D5
D6
D7 (MSB)
CONV
4 To 15
Decode
Clock
R1
500
Ω
R2
750
Ω
ISet
LM113/313
V-
1 kΩ
CONV
2. V+ = -1.2 V
V+
3. I
Set
=
α
T(R
1
+R
2
)
4. R
L
= R3 / / R4
5. V
Out
- = K
255-Digital Input Code
255
x I Set
R
L
+
[
K
I
x I
Set
x R
L
(Bright)
]
V+
(
ISet
*
)
Ref+
6. V
Sync
= (K x I
Set
x R
L
) + (K
2
x I
Set
x R
L
)
Ref
Buffer
K = 15.8069
K
1
= 1.7617
K
2
= 10.0392
7. FB = Ferrite bead, Fair-rite P/N 217430011 or equivalent.
VCC
VEE
COMP
Ref-
.01 µF
2 kΩ
– 5.2 V
.01 µF
8. All reference resistors 1/8 W 1% metal film
power supply decoupling 50 V ceramic disc.
9.
x
= ECL Termination
= V
CC
= AGND
See figure 8 for detail on Ref Buffer.
= DGND (digital input drivers).
FB
10 µF
10.
-5.2 V
11.
10.
TYPICAL INTERFACE CIRCUIT
GENERAL
A typical interface circuit using the SPT1018 in a color raster
application is shown in figure 2. The SPT1018 requires few
external components and is extremely easy to use. The very
high operating speeds of the SPT1018 require good circuit
layout, decoupling of supplies, and proper design of trans-
mission lines. The following considerations should be noted
to achieve best performance.
INPUT CONSIDERATIONS
Video input data and controls may be directly connected to
the SPT1018. Note that all ECL inputs are terminated as
closely to the device as possible to reduce ringing, crosstalk
and reflections. A convenient and commonly used microstrip
impedance is about 130 ohms, which is easily terminated
using a 330 ohm resistor to V
EE
and a 220 ohm resistor to
Ground. This arrangement gives a Thevenin equivalent ter-
mination of 130 ohms to -2 volts without the need for a
-2 volt supply. Standard SIP (Single Inline Package) 220/330
resistor networks are available for this purpose. It is recom-
mended that stripline or microstrip techniques be used for all
ECL interface. Printed circuit wiring of known impedance
over a solid ground plane is recommended.
OUTPUT CONSIDERATIONS
The analog outputs are designed to directly drive a dual 50 or
75 ohm load transmission system as shown. The source
impedances of the SPT1018 outputs are high impedance
current sinks. The load impedance (R
L
) must be 25
or 37.5 ohms to attain standard RS-343-A video levels. Any
deviation from this impedance will affect the resulting video
output levels proportionally. As with the data interface, it is
important that the analog transmission lines have matched
impedance throughout, including connectors and transitions
between printed wiring and coaxial cable. The combination of
matched source termination resistor R
S
and load terminator
R
L
minimizes reflections of both forward and reverse travel-
ing waves in the analog transmission system. The return path
for analog output current is V
CC
which is connected to the
source termination resistor R
S
.
SPT
SPT1018
5
5/14/97
