FAIRCHILD TDC1044AR4C

www.fairchildsemi.com
TDC1044A
Monolithic Video A/D Converter
4-Bit, 25 Msps
Features
Description
•
•
•
•
•
•
The TDC1044A is a 25 Msps (Megasample per second) fullparallel analog-to-digital converter, capable of converting an
analog signal with full-power frequency components up to
12.5 MHz into 4-bit digital words. Use of a sample-and-hold
circuit is not necessary for operation of the TDC1044A. All
digital inputs and outputs are TTL compatible.
4-bit resolution
1/4 LSB non-linearity
Sample-and-hold circuit not required
25 Msps conversion rate
Selectable output format
16-lead DIP and 20-lead PLCC packages
The TDC1044A consists of 15 latching comparators, encoding logic, and an output register. A single convert signal
controls the conversion operation. Output formats are
true/inverted binary or true/inverted offset two’s complement
codes.
Applications
•
•
•
•
Digital communications
Video special effects
Radar data conversion
Medical imaging
Block Diagram
NMINV
NLINV
CONV
VIN
RT
R1
1
R
2
R
R
8
RM
15 TO 4
DECODER
LATCH
D1–D4
4
R
R
14
65-1044A-01
R
15
R/2
RB
REFERENCE
RESISTOR
CHAIN
DIFFERENTIAL
COMPARATORS
(15)
Rev. 1.1.2
TDC1044A
Functional Description
General Information
The TDC1044A has three functional sections: a comparator
array, encoding logic, and an output register. The comparator
array compares the input signal with 15 reference voltages to
produce an N-of-15 thermometer code. All the comparators
referred to voltages more positive than the input signal will
be off, and those referred to voltages more negative than the
input signal will be on. Encoding logic converts the N-of-15
code into binary or two’s complement coding and can invert
either output code. This coding function is controlled by DC
signals on pins NMINV and NLINV. The output register
holds the output constant between updates.
Power
The TDC1044A operates from two power supply voltages,
+5.0V and -5.2V. The return for ICC (the current drawn from
the +5.0V supply) is DGND. The return for IEE (the current
drawn from the -5.2V supply) is AGND. All power and
ground pins must be connected.
Reference
The TDC1044A converts analog signals in the range
VRB £ VIN £ VRB into digital form. VRB (the voltage
applied to RB at the bottom of the reference resistor chain)
and VRT (the voltage applied to RB at the top of the reference resistor chain) should be between +0.1V and -1.1V.
VRT should be more positive than VRB within that range.
The voltage applied across the reference resistor chain
(VRT – VRB) must be between 0.4V and 1.3V.
Nominal voltages are VRT = 0.00V and VRB = -1.00V. These
voltages may be varied dynamically up to 10MHz. Due to
slight variation in the reference currents with clock and input
signals, RT and RB should be low-impedance points. For circuits in which the reference is not varied, a bypass capacitor
to ground is recommended. If the reference inputs are varied
dynamically (as in an Automatic Gain Control circuit), a
low-impedance reference source is required.
A reference middle, RM, is also provided; this may be used
as an input to adjust the mid-scale point in order to improve
integral linearity. This point may also be used as a tap to supply a mid-scale voltage to offset the analog input. If VRM is
used as an output, it must be connected to a high input
impedance device which has small input current. Noise at
this point may adversely affect the performance of this
device.
2
PRODUCT SPECIFICATION
Controls
Two function control pins, NMINV and NLINV, set the output format to be either straight binary or offset two’s complement, in either true or inverted sense, according to Table 1.
These pins are active LOW as signified by the prefix "N" in
the signal name. They may be tied to VCC for a logic "1" and
DGND for a logic "0."
NMINV controls the MSB, D1; NLINV controls the three
LSBs: D2, D3 and D4.
Convert
The TDC1044A requires a CONVert (CONV) signal. A sample is taken (the comparators are latched) within tSTO after a
rising edge of CONV. The coded result is translated to the
output latches on the next rising edge. The outputs hold the
previous data a minimum time (tHO) after the rising edge of
the CONV signal. New data becomes valid after a maximum
delay time, tD.
Analog Input
The TDC1044A uses latching comparators which cause the
input impedance to vary slightly with the signal level. For
optimal performance, the source impedance of the driving
circuit must less than 25 Ohms. Within the range of VEE to
+0.5V, the input signal will not damage the device. If the
input signal is at a voltage between VRT and VRB, the output
will be a binary code between 0 and 15 inclusive. A signal
outside this range will indicate either full-scale positive or
full-scale negative, depending on whether the signal is offscale in the positive or negative direction.
Outputs
TDC1044A outputs are TTL compatible, and capable of
driving four low-power Schottky TTL (54/74 LS) unit loads.
The outputs hold the previous data a minimum time (tHO)
after the rising edge of the CONV signal. Data becomes
valid after a maximum delay time (tD) after the rising edge
of CONV. For optimum performance, 2.2 kOhm pull-up
resistors are recommended.
No Connects
Pin 3 of the TDC1044A is labeled No Connect (NC), and has
no connection to the chip. Connect this pin to AGND for best
noise performance.
PRODUCT SPECIFICATION
TDC1044A
Table 1. Output Coding1
Binary
Range
-1.00V FS
Offset Two’s Complement
True
Inverted
True
Inverted
NMINV = 1
0
0
1
NLINV = 1
0
1
0
0.000V
0000
1111
1000
0111
-0.067V
0001
1110
1001
0110
-0.133V
0010
1101
1010
0101
-0.200V
0011
1100
1011
0100
-0.267V
0100
1011
1100
0011
-0.333V
0101
1010
1101
0010
-0.400V
0110
1001
1110
0001
-0.467V
0111
1000
1111
0000
-0.533V
1000
0111
0000
1111
-0.600V
1001
0110
0001
1110
-0.667V
1010
0101
0010
1101
-0.733V
1011
0100
0011
1100
-0.800V
1100
0011
0100
1011
-0.867V
1101
0010
0101
1010
-0.933V
1110
0001
0110
1001
-1.000V
1111
0000
0111
1000
Note:
1. Input voltages are at code centers.
D3
D2
D1 (MSB)
DGND
17
16
15
14
19
D4 (LSB)
NC
18
Pin Assignments
13
VCC
CONV
20
12
NMINV
AGND
1
11
RM
VIN
2
10
NLINV
9
4
5
6
7
8
NC
NC
RB
VEE
3
RT
NC
20 Lead PLCC
NC
65-1044A-02
AGND
1
16
CONV
VIN
NC
2
15
3
14
RT
RB
VEE
NLINV
RM
4
13
5
12
6
11
7
10
8
9
D4 (LSB)
D3
D2
D1 (MSB)
DGND
VCC
NMINV
65-1044A-03
16 Lead DIP
3
TDC1044A
PRODUCT SPECIFICATION
Pin Descriptions
Pin Number
Pin Name
DIP
PLCC
Value
Description
VCC
10
13
+5.0V
Positive Supply Voltage
VEE
6
8
-5.2V
Negative Supply Voltage
DGND
11
14
0.0V
Digital Ground
AGND
1
1
0.0V
Analog Ground
RT
4
4
0.0V
Reference Resistor, Top
RM
8
11
-0.5V
Reference Resistor, Middle
RB
5
7
-1.0V
Reference Resistor, Bottom
NMINV
9
12
TTL
Not MSB Invert
NLINV
7
10
TTL
Not LSB Invert
16
20
TTL
Convert
2
2
0V to -1V
D1
12
15
TTL
D2
13
16
TTL
Power
Reference
Control
Convert
CONV
Analog Input
VIN
Analog Input Signal
Output
4
MSB Output
D3
14
17
TTL
D4
15
18
TTL
LSB Output
NC
3
3, 5, 6, 9, 19
AGND
No Connect
PRODUCT SPECIFICATION
TDC1044A
Absolute Maximum Ratings
(beyond which the device may be damaged)1
Type
Parameter
Min
Max
Unit
Supply Voltages
VCC (measured to DGND)
-0.5
7.0
V
VEE (measured to AGND)
+0.5
-7.0
V
Input Voltages
AGND (measured to DGND)
-0.5
+0.5
V
CONV, NMINV, NLINV (measured to DGND)
-0.5
+5.5
V
VIN, VRT, VRB (measured to AGND)
+0.5
VEE
V
-2.2
+2.2
V
Applied voltage (measured to DGND
-0.5
+5.5
V
forced3,4
-1.0
+6.0
mA
1
sec
+125
°C
Operating, junction
+150
°C
Lead, soldering (10 seconds)
+300
°C
+150
°C
VRT (measured to VRB)
Output
)2
Applied current, externally
Short circuit duration (single output in high state to ground)
Temperature
Operating, ambient
-55
Storage
-65
Notes:
1. Absolute maximum ratings are limiting values applied individually while all other parameters are within specified operating
conditions. Functional operation under any of these conditions is NOT implied.
2. Applied voltage must be current limited to specified range.
3. Forcing voltage must be limited to specified range.
4. Current is specified as positive when flowing into the device.
Operating Conditions
Parameter
Min.
Nom.
Max.
Units
VCC
Positive Supply Voltage (measured to DGND)
4.75
5.0
5.25
V
VEE
Negative Supply Voltage (measured to AGND)
-4.9
-5.2
-5.5
V
VAGND
Analog Ground Voltage (measured to DGND)
-0.1
0.0
0.1
V
tPWL
CONV Pulse Width, LOW
17
ns
tPWH
CONV Pulse Width, HIGH
17
ns
VIL
Input Voltage, Logic LOW
VIH
Input Voltage, Logic HIGH
IOL
Output Current, Logic LOW
0.8
2.0
V
V
4.0
mA
IOH
Output Current, Logic HIGH
-400
mA
VRT
Most Positive Reference
-1.9
0.0
0.1
V
VRB
Most Negative Reference
-2.1
-1.0
-0.1
V
VRT – VRB
Reference Differential
0.2
1.0
2.0
V
VIN
Input Voltage
VRB
VRT
V
TA
Ambient Temperature, Still Air
0
70
°C
5
TDC1044A
PRODUCT SPECIFICATION
Electrical Characteristics
Within specified operating conditions
Parameter
Test Conditions
Min.
static1
ICC
Positive Supply Current
VCC = Max,
IEE
Negative Supply Current
VEE = Max, static
Max.
Units
15
mA
TA = 0°C to 70°C
-50
mA
TA = 70°C
-40
mA
2
mA
IREF
Reference Current
VRT, VRB = Nom
RREF
Total Reference Resistance
RIN
Input Equivalent Resistance
CIN
Input Capacitance
ICB
Input Constant Bias Current
VEE = Max
IIL
Input Current, Logic LOW
VCC = Max, VI - 0.5V
VRT, VRB = Nom, VIN = VRB
500
Ohms
250
Kohms
25
pF
40
mA
CONV
-0.8
mA
NMINV, NLINV
-0.8
mA
IIH
Input Current, Logic HIGH
VCC = Max, VI = 2.4V
200
mA
II
Input Current, Max Input Voltage
VCC = Max, VI = 5.5V
1.0
mA
VOL
Output Voltage, Logic LOW
VCC = Min, IOL = Max
0.5
V
VOH
Output Voltage, Logic HIGH
VCC = Min, IOH = Max
IOS
Short Circuit Output Current
VCC = Max, One pin to ground, one
second duration, Output HIGH
CI
Digital Input Capacitance
TA = 25°C, F = 1 MHz
2.4
V
-300
mA
15
pF
Max.
Units
Note:
1. Worst case: all digital inputs and outputs LOW.
Switching Characteristics
Within specified operating conditions
6
Parameter
Test Conditions
FS
Maximum Conversion Rate
VCC = Min, VEE = Min
tSTO
Sampling Time Offset
VCC = Min, VEE = Min
tD
Digital Output Delay
VCC = Min, VEE = Min, Load 1
tHO
Digital Output Hold Time
VCC = Max, VEE = Max, Load 1
Min.
25
5
Msps
10
ns
30
ns
ns
PRODUCT SPECIFICATION
TDC1044A
System Performance Characteristics
Within specified operating conditions
Parameter
Test Conditions
ELI
Linearity Error Integral Independent
ELD
Linearity Error Differential
Min.
VRB = Nom
75
Max.
Units
1.6
%
1.6
%
CS
Code Size
VRT, VRB = Nom
125
% Nominal
EOT
Offset Error Top
VIN = VRT
+30
mV
EOB
Offset Error Bottom
VIN = VRB
+40
mV
TCO
Offset Error Temperature Coefficient
±20
mV/°C
BW
Bandwidth, Full Power Input
tTR
Transient Response, Full Scale
10
ns
EAP
Aperture Error
30
ps
12.5
MHz
Timing Diagram
1
FS
CONV
SAMPLE
N
tPWH
SAMPLE
N+1
tPWL
SAMPLE
N+2
ANALOG
INPUT
tSTO
DATA
N–1
DIGITAL
OUTPUT
tHO
DATA
N
DATA
N+1
65-1044A-04
tD
7
TDC1044A
PRODUCT SPECIFICATION
Equivalent Circuits
VIN
VIN
1-OF-15
COMPARATORS
CIN
RIN
ICB
VRB
VEE
REFERENCE
RESISTOR
CHAIN
VEEA
65-1044A-05
VEE
Figure 1. Simplified Analog Input Equivalent Circuit
+VCC
VCC
TO
OUTPUT
PIN
810½
VCC
20K
10K
OUTPUT
40pF
1N3062
INPUT
65-1044A-06
OUTPUT
EQUIVALENT
CIRCUIT
LOAD 1
TEST LOAD FOR DELAY
MEASUREMENTS
65-1044A-07
Figure 2. Digital Input Equivalent Circuit
8
Figure 3. Output Circuits
PRODUCT SPECIFICATION
Applications Discussion
Calibration
To calibrate the TDC1044A, adjust VRT and VRB to set the
1st and 15th thresholds to the desired voltages. Assuming a
0V to -1V desired range, continuously strobe the converter
with -0.0033V (1/2 LSB from 0.000V) on the analog input,
and adjust VRT for output toggling between codes 0000 and
0001. Then apply -0.976V (1/2 LSB from -1.000V) and
adjust VRB for toggling between codes 1110 and 1111.
Instead of adjusting VRT, RT can be connected to analog
ground and the 0V end of the range calibrated with an amplifier offset control. RB is a convenient point for gain adjustment that is not in the analog signal path.
Typical Interface Circuit
The TDC1044A does not require a special input buffer
amplifier to drive the analog input because of its low input
capacitance. A terminated low-impedance transmission line
(<100 Ohms) connected to the VIN terminal of the device is
sufficient if the input voltage levels match those of the A/D
converter.
However, many driver circuits lack sufficient offset control,
drive current, or gain stability. The typical interface circuit in
Figure 4 shows a simple amplifier and voltage reference circuit that may be used with the device. U2 is a wide-band
operational amplifier with a gain factor of -1. As the video
TDC1044A
input increases from zero to one volt, VIN of the TDC1044A
decreases from zero to -1 volt. With true binary selected
(NMINV = 1 and NLINV = 1), output codes increase from
0000 to 1111.
A small value resistor, R12, serves to isolate the small input
capacitance of the A/D converter from the amplifier output
and insure frequency stability. Pulse and frequency response
of the amplifier are optimized by variable capacitor C12. The
reference voltage for the TDC1044A is generated by amplifier U3. System gain is adjusted by varying R9, which controls the reference voltage level to the A/D converter.
Input voltage range and input impedance for the circuit are
determined by resistors R1 and R2. Formulas for calculating
values for these input resistors are:
1
R1 = ----------------------------------2VR
1
æ ------------ ö – ----------è Z IN ø 1000
and
1000 R1
R2 = Z IN – æ -------------------------ö
è 1000 + R1 ø
where VR is the input voltage range of the circuit, ZIN is the
input impedance of the circuit, and the constant 1000 comes
from the value of R3. As shown, the circuit is set up for
1Vp-p 75 Ohm video input.
9
TDC1044A
PRODUCT SPECIFICATION
+5V
L1
FERRITE BEAD
INDUCTOR
R5
220
C1
10
25V
+
10
C12 1–6pF
VIDEO INPUT
1Vp-p
R1
37.4
R3
1K
R2
39.2
R6
2K
1
+
3
C3 +
10
24V
U4
LM313
C7
0.1
50V
R9
2K
10-TURN
"GAIN"
C8
0.1
50V
R8
2K
10-TURN
"OFFSET"
2
3
3
8
R12
27
2
C10
0.1
50V
1
4
–
C5
0.1
50V
8
+
4
5
C11
0.1
50V
VIN
D2
C6
0.1
50V
CLK
AGND
R16
2.2K
RT
15
RM
RB
DGND
NLINV
DGND
NMINV
16
7
9
CONV
VEE
4
–5.2V
14
U1
TDC1044A
11
6
U3
LM741C
13
R15
2.2K
D3 (LSB)
R11
10K
7
R14
2.2K
AGND
L2
FERRITE BEAD
INDUCTOR
C4
10
25V
12
NC
D1
C9
10 0.1
14
–
50V
R7
1K
D0 (MSB)
R4 2K
U2
HA-2539
R13
2.2K
VCC
+
C2
10
25V
65-1044A-08
Figure 4. Typical Interface Circuit
10
PRODUCT SPECIFICATION
TDC1044A
Notes:
11
TDC1044A
Notes:
12
PRODUCT SPECIFICATION
PRODUCT SPECIFICATION
TDC1044A
Mechanical Dimensions
16-Lead Ceramic DIP Package
Inches
Symbol
Min.
A
b1
b2
c1
D
E
e
eA
L
Q
s1
a
Notes:
Millimeters
Max.
Min.
—
.200
.014
.023
.050
.065
.008
.015
.745
.840
.220
.310
.100 BSC
.300 BSC
.115
.160
.015
.060
.005
—
90¡
105¡
Notes
Max.
—
5.08
.36
.58
1.27
1.65
.20
.38
18.92
21.33
5.59
7.87
2.54 BSC
7.62 BSC
2.92
4.06
.38
1.52
.13
—
90¡
105¡
1. Index area: a notch or a pin one identification mark shall be located
adjacent to pin one. The manufacturer's identification shall not be
used as pin one identification mark.
8
2
2. The minimum limit for dimension "b2" may be .023 (.58mm) for leads
number 1, 8, 9 and 16 only.
8
4
3. Dimension "Q" shall be measured from the seating plane to the base
plane.
4
5, 9
7
4. This dimension allows for off-center lid, meniscus and glass overrun.
3
6
5. The basic pin spacing is .100 (2.54mm) between centerlines. Each
pin centerline shall be located within ±.010 (.25mm) of its exact
longitudinal position relative to pins 1 and 16.
6. Applies to all four corners (leads number 1, 8, 9, and 16).
7. "eA" shall be measured at the center of the lead bends or at the
centerline of the leads when "a" is 90¡.
8. All leads – Increase maximum limit by .003 (.08mm) measured at the
center of the flat, when lead finish applied.
9. Fourteen spaces.
D
8
1
9
16
NOTE 1
E
s1
eA
e
A
Q
L
a
c1
b1
13
TDC1044A
PRODUCT SPECIFICATION
Mechanical Dimensions (continued)
16-Lead Plastic DIP Package
Inches
Symbol
Min.
Max.
Min.
Max.
A
A1
A2
—
.015
.115
.210
—
.195
—
.38
2.93
5.33
—
4.95
B
B1
C
D
D1
E
E1
e
eB
.014
.022
.045
.070
.008
.015
.745
.840
.005
—
.300
.325
.240
.280
.100 BSC
—
.430
.115
.160
16
L
N
Notes:
Millimeters
Notes
1. Dimensioning and tolerancing per ANSI Y14.5M-1982.
2. "D" and "E1" do not include mold flashing. Mold flash or protrusions
shall not exceed .010 inch (0.25mm).
3. Terminal numbers are shown for reference only.
4. "C" dimension does not include solder finish thickness.
.36
.56
1.14
1.78
.20
.38
18.92
21.33
.13
—
7.62
8.26
6.10
7.11
2.54 BSC
—
10.92
2.92
4.06
16
5. Symbol "N" is the maximum number of terminals.
4
2
2
5
D
8
1
9
16
E1
D1
E
e
A2
A
A1
C
L
B1
14
B
eB
PRODUCT SPECIFICATION
TDC1044A
Mechanical Dimensions (continued)
20-Lead PLCC Package
Inches
Symbol
Min.
A
A1
A2
B
B1
D/E
D1/E1
D3/E3
e
J
ND/NE
N
ccc
Max.
.165
.180
.090
.120
.020
—
.013
.021
.026
.032
.385
.395
.350
.356
.200 BSC
.050 BSC
.042
.048
5
20
—
.004
Millimeters
Min.
Notes:
Notes
1. All dimensions and tolerances conform to ANSI Y14.5M-1982
Max.
4.19
4.57
2.29
3.05
.51
—
.33
.53
.66
.81
9.78
10.03
8.89
9.04
5.08 BSC
1.27 BSC
1.07
1.22
5
20
—
0.10
2. Corner and edge chamfer (J) = 45¡
3. Dimension D1 and E1 do not include mold protrusion. Allowable
protrusion is .245" (.101mm)
3
2
E
E1
D
J
D1
D3/E3
e
B1
J
A
A1
A2
B
–C–
LEAD COPLANARITY
ccc C
15
TDC1044A
PRODUCT SPECIFICATION
Ordering Information
Product Number
Temperature Range
Screening
Package
Package Marking
TDC1044AB9C
0°C to 70°C
Commercial
16-Lead Ceramic DIP
1044AB9C
TDC1044AN9C
0°C to 70°C
Commercial
16-Lead Plastic DIP
1044AN9C
TDC1044AR4C
0°C to 70°C
Commercial
20-Lead PLCC
1044AR4C
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
5/20/98 0.0m 001
Stock#DS7001044A
Ó 1998 Fairchild Semiconductor Corporation