CMOS Video Speed, 8-Bit, 50 MSPS, R2R
D/A Converters
The CA3338 family are CMOS/SOS high speed R2R voltage
output digital-to-analog converters. They can operate from a
single +5V supply, at video speeds, and can produce
“rail-to-rail” output swings. Internal level shifters and a pin for
an optional second supply provide for an output range below
digital ground. The data complement control allows the
inversion of input data while the latch enable control provides
either feedthrough or latched operation. Both ends of the
R2R ladder network are available externally and may be
modulated for gain or offset adjustments. In addition, “glitch”
energy has been kept very low by segmenting and
thermometer encoding of the upper 3 bits.
The CA3338 is manufactured on a sapphire substrate to give
low dynamic power dissipation, low output capacitance, and
inherent latch-up resistance.
Intersil Pb-free products employ special Pb-free material sets;
molding compounds/die attach materials and 100% matte tin plate
termination finish, which is compatible with both SnPb and Pb-free
soldering operations. Intersil Pb-free products are MSL classified at
Pb-free peak reflow temperatures that meet or exceed the Pb-free
requirements of IPC/JEDEC J Std-020B.
±0.75 LSB-40 to 8516 Ld PDIP
(Pb-free)
±1.0 LSB-40 to 8516 Ld SOIC
(Pb-free)
±0.75 LSB-40 to 8516 Ld SOIC
(Pb-free)
E16.3
M16.3
M16.3
V
1
D7
2
D6
3
D5
4
D4
5
D3
D2
6
7
D1
8
V
SS
16
15
14
13
12
11
10
9
DD
LE
COMP
V
REF
V
OUT
V
REF
V
EE
D0
+
-
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
Copyright Harris Corporation 1997. Copyright Intersil Americas Inc. 2003, 2004. All Rights Reserved
| Intersil (and design) is a registered trademark of Intersil Americas Inc.
All other trademarks mentioned are the property of their respective owners.
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
is measured with the component mounted on an evaluation PC board in free air.
1. θ
JA
o
C to 85oC
(oC/W) θJC (oC/W)
JA
. . . . -65oC to 150oC
STG
o
o
C
C
Electrical SpecificationsT
= 25oC, VDD = 5V, V
A
Unless Otherwise Specified
REF
+ = 4.608V, VSS = VEE = V
- = GND, LE Clocked at 20MHz, RL ≥ 1 MΩ,
REF
PARAMETERTEST CONDITIONSMINTYPMAXUNITS
ACCURACY
Resolution8--Bits
Integral Linearity ErrorSee Figure 4
CA3338--±1LSB
CA3338A--±0.75LSB
Differential Linearity ErrorSee Figure 4
CA3338--±0.75LSB
CA3338A--±0.5LSB
Gain ErrorInput Code = FF
, See Figure 3
HEX
CA3338--±0.75LSB
CA3338A--±0.5LSB
Offset ErrorInput Code = 00
; See Figure 3--±0.25LSB
HEX
DIGITAL INPUT TIMING
Update RateTo Maintain
Update RateV
Set Up Time t
Set Up Time t
Hold Time t
Latch Pulse Width t
Latch Pulse Width t
SU1
SU2
H
W
W
OUTPUT PARAMETERS R
Output Delay t
Output Delay t
Rise Time t
Settling Time t
D1
D2
r
S
Output ImpedanceV
REF
For Low Glitch--2-ns
For Data Store-8-ns
For Data Store-5-ns
For Data Store-5-ns
V
REF
Adjusted for 1V
L
From LE Edge-25-ns
From Data Changing-22-ns
10% to 90% of Output-4-ns
10% to Settling to 1/2 LSB-20-ns
14COMPData Complement Control input. Active High
15LE Latch Enable Input. Active Low
16V
Digital Ground
SS
Analog Ground
EE
Reference Voltage Negative Input
-
REF
Analog Output
OUT
Reference Voltage Positive Input
+
REF
Digital Power Supply, +5V
DD
Digital Signal Path
The digital inputs (LE, COMP, and D0 - D7) are of TTL
compatible HCT High Speed CMOS design: the loading is
essentially capacitive and the logic threshold is typically
1.5V.
The 8 data bits, D0 (weighted 2
are applied to Exclusive OR gates (see Functional Diagram).
The COMP (data complement) control provides the second
input to the gates: if COMP is high, the data bits will be
inverted as they pass through.
0
) through D7 (weighted 27),
INPUT
DAT A
LATCH
ENABLE
t
D1
t
D2
OUTPUT
VOLTAGE
FIGURE 2. DATA AND LATCH ENABLE TO OUTPUT TIMING
90%
t
r
10%
t
S
1
/2 LSB
1
/2 LSB
Latch Operation
Data is fed from input to output while LE is low: LE should be
tied low for non-clocked operation.
Non-clocked operation or changing data while LE is low is
not recommended for applications requiring low output
“glitch” energy: there is no guarantee of the simultaneous
changing of input data or the equal propagation delay of all
bits through the converter. Several parameters are given if
the converter is to be used in either of these modes: t
gives the delay from the input changing to the output
changing (10%), while t
and tH give the set up and hold
SU2
times (referred to LE rising edge) needed to latch data. See
Figures 1 and 2.
Clocked operation is needed for low “glitch” energy use. Data
must meet the given t
set up time to the LE falling edge,
SU1
and the tH hold time from the LE rising edge. The delay to
the output changing, t
, is now referred to the LE falling
D1
edge.
D2
The input data and the LE (latch enable) signals are next
applied to a level shifter. The inputs, operating between the
levels of V
and VSS, are shifted to operate between V
DD
DD
and VEE. VEE optionally at ground or at a negative voltage,
will be discussed under bipolar operation. All further logic
elements except the output drivers operate from the V
and V
supplies.
EE
DD
The upper 3 bits of data, D5 through D7, are input to a 3-to-7
line bar graph encoder. The encoder outputs and D0 through
D4 are applied to a feedthrough latch, which is controlled by
LE (latch enable).
INPUT DATA
t
SU1
LATCHEDLATCHED
LATCH
ENABLE
FIGURE 1. DATA TO LATCH ENABLE TIMING
t
W
DAT A
FEEDTHROUGH
t
t
H
SU2
5
There is no need for a square wave LE clock; LE must only
meet the minimum t
pulse width for successful latch
W
operation. Generally, output timing (desired accuracy of
settling) sets the upper limit of usable clock frequency.
Output Structure
The latches feed data to a row of high current CMOS drivers,
which in turn feed a modified R2R ladder network.
The “N” channel (pull down) transistor of each driver plus the
bottom “2R” resistor are returned to V
scale reference. The “P” channel (pull up) transistor of each
driver is returned to V
In unipolar operation, V
+, the (+) full-scale reference.
REF
- would typically be returned to
REF
analog ground, but may be raised above ground (see
specifications). There is substantial code dependent current
that flows from V
specifications), so V
REF
+ to V
REF
- (see V
REF
- should have a low impedance path
to ground.
- this is the (-) full-
REF
+ input current in
REF
CA3338, CA3338A
In bipolar operation, V
voltage (the maximum voltage rating to V
observed). V
, which supplies the gate potential for the
EE
- would be returned to a negative
REF
must be
DD
output drivers, must be returned to a point at least as
negative as V
-. Note that the maximum clocking speed
REF
decreases when the bipolar mode is used.
Static Characteristics
The ideal 8-bit D/A would hav e an output eq ual to V
an input code of 00
equal to 255/256 of V
code of FF
HEX
(zero scale output), and an output
HEX
+ (referred to V
REF
-) with an input
REF
(full scale output). The difference between the
ideal and actual values of these two par ameters are the
OFFSET and GAIN errors, respectively; see Figure 3.
If the code into an 8-bit D/A is changed by 1 count, the output
should change by 1/255 (full scale output - zero scale output). A
deviation from this step size is a diff erential linearity error, see
Figure 4. Note that the error is expressed in fractions of the
ideal step size (usually called an LSB). Also note that if the (-)
differential linearity error is less (in absolute numbers) than 1
LSB, the device is monotonic. (The output will always increase
for increasing code or decrease for decreasing code).
If the code into an 8-bit D/A is at any value, say “N”, the output
voltage should be N/255 of the full scale output (referred to the
zero scale output). Any deviation from that output is an integral
linearity error, usually expressed in LSBs. See Figure 4.
Note that OFFSET and GAIN errors do not affect integral
linearity, as the linearity is referenced to actual zero and full
scale outputs, not ideal. Absolute accuracy would have to
also take these errors into account.
255/256
REF
+ - V
254/256
REF
253/256
3/256
2/256
1/256
0
OUTPUT VOLTAGE AS A FRACTION OF V
00010203FDFEFF
FIGURE 3. D/A OFFSET AND GAIN ERROR
= IDEAL TRANSFER CURVE
= ACTUAL TRANSFER CURVE
OFFSET
ERROR
(SHOWN +)
INPUT CODE IN HEXADECIMAL (COMP = LOW)
GAIN ERROR
(SHOWN -)
REF
- with
STRAIGHT LINE
FROM “0” SCALE
TO FULL SCALE
= IDEAL TRANSFER CURVE
= ACTUAL TRANSFER CURVE
OUTPUT VOLTAGE
0
00
FIGURE 4. D/A INTEGRAL AND DIFFERENTIAL LINEARITY
A
C
ERROR
VOLTAGE
INTEGRAL LINEARITY
ERROR (SHOWN -)
B
A = IDEAL STEP SIZE (1/255 OF FULL
SCALE -“0” SCALE VOLTAGE)
B - A = +DIFFERENTIAL LINEARITY ERROR
C - A = -DIFFERENTIAL LINEARITY ERROR
INPUT CODE
Dynamic Characteristics
Keeping the full-scale range (V
possible gives the best linearity and lowest “glitch” energy
(referred to 1V). This provides the best “P” and “N” channel
gate drives (hence saturation resistance) and propagation
delays. The V
REF
+ (and V
REF
well bypassed as near the chip as possible.
“Glitch” energy is defined as a spu rious voltage that occu rs as
the output is changed from one voltage to another. In a binary
input converter, it is usually highe st at the most significa nt bit
transition (7F
HEX
to 80
for an 8 bit device), and can be
HEX
measured by displaying the output as the input co de
alternates around that point. The “glitch” energy is the area
between the actual output display and an ideal one L SB step
voltage (subtracting negative area from positi ve), at either the
positive or negative-going step. It is usually expressed in pV/s .
The CA3338 uses a modified R2R ladder, whe re the 3 mo st
significant bits drive a bar graph decoder and 7 equally
weighted resistors. This makes the “glitch” energy at each
scale transition (1F
HEX
to 20
essentially equal, and far less than the MSB transition would
otherwise display.
For the purpose of comparison to other converters, the output
should be resistively divided to 1V full scale. Figure 5 shows a
typical hook-up for checking “glitch” energy or settling time .
The settling time of the A/D is mainly a function of the output
resistance (approxi ma tely 160 Ω i n par allel w ith the load
resistance) and the load plus internal chip capacitance. Both
“glitch” energy and settling time measurements require v e ry
good circuit and probe grounding: a probe tip connector such
as Tektronix part number 131-0258-00 is recommended.
REF
+ - V
-) as high as
REF
- if bipolar) terminal should be
HEX
, 3F
HEX
to 40
HEX
, etc.)
1
/8
6
CLOCK
8 DATA BITS
+5V
1-7, 9
CA3338, CA3338A
CA3338
R1
+5V
+2.5V
-2.5V
R2
PROBE TIP
OR BNC
CONNECTOR
R3
REMOTE
V
OUT
15
LE
D0 - D7
16
V
DD
+
14
COMP
8
V
SS
12
V
OUT
13
V
+
REF
11
-
V
REF
10
V
EE
+
+
DIGITAL
GROUND
FUNCTIONCONNECTORR1R2R3V
ANALOG
GROUND
OUT (P-P)
Oscilloscope DisplayProbe Tip82Ω62ΩN/C1V
Match 93Ω CableBNC75160931V
Match 75Ω CableBNC18130751V
Match 50Ω CableBNCShort75500 79V
NOTES:
3. V
OUT(P-P)
4. All drawn capacitors are 0.1µF multilayer ceramic/4.7µF tantalum.
is approximate, and will vary as R
of D/A varies.
OUT
5. Dashed connections are for unipolar operation. Solid connection are for bipolar operation.
FIGURE 5. CA3338 DYNAMIC TEST CIRCUIT
+6V
4.7µF TAN
+
5pF
11
6
0.1µF CER.
+
0.1µF
CER.
4.7µF
TAN
UP TO 5 OUTPUT LINES
FOR R = 75Ω, 3 LINES
FOR R = 50Ω
R
= ±1.5V
V
OUT
R
V
R
PEAK
V
R
CA3338
15
16
14
8
LE
D0 - D7
V
DD
COMP
V
SS
V
12
OUT
13
V
+
REF
11
-
V
REF
10
V
EE
CLOCK
8 DATA
BITS
+5V
1-7, 9
4.7µF
+
TAN
0.1µF
CER.
NOTES:
1. Both V
bypassed within
+ pin and 392Ω resistor should be
REF
1
/4 inch.
2. Keep nodal capacitance at CA3450 pin 3 as
+3.00V AT 25mA
1kΩ
+
4.7µF TAN
0.1µF CER.
392Ω
1%
10kΩ
ADJUST
OFFSET
7, 8
14
3
392Ω
1%
9
+
CA3450
4, 5, 12, 13
-6V
low as possible.
3. V
Range = ±3V at CA3450.
OUT
FIGURE 6. CA3338 AND CA3450 FOR DRIVING MULTIPLE COAXIAL LINES
OUT
OUT
1
N
7
CA3338, CA3338A
TABLE 1. OUTPUT VOLTAGE vs INPUT CODE AND V
V
+
REF
V
-
REF
STEP SIZE
Input Code
11111111
111111102=FE
10000001
100000002=80
011111112=7F
00000001
000000002=00
•
•
•
•
•
•
2
2
2
=FF
=81
=01
HEX
HEX
HEX
HEX
HEX
HEX
HEX
5.12V
0
0.0200V
5.1000V
5.0800
2.5800
2.5600
2.5400
0.0200
0.0000
5.00V
0.0195V
4.9805V
4.9610
2.5195
2.5000
2.4805
0.0195
0.0000
0
4.608V
0
0.0180V
4.5900V
4.5720
2.3220
2.3040
2.2860
0.0180
0.0000
-2.56V
0.0200V
2.5400V
2.5200
0.0200
0.0000
- 0.0200
-2.5400
-2.5600
2.56V
REF
2.50V
-2.50V
0.0195V
2.4805V
2.4610
0.0195
0.0000
-0.0195
-2.4805
-2.5000
Applications
The output of the CA3338 can be resistively divided to match a
doubly terminated 50Ω or 75Ω line, although peak-to-peak
swings of less than 1V may result. The output magnitude will
also vary with the converter’s output impedance. Figure 5
shows such an application. Note that because of the HCT input
structure, the CA3338 could be operated up to +7.5V V
V
+ supplies and still accept 0V to 5V CMOS input voltages.
REF
If larger voltage swings or better accuracy is desired, a high
speed output buffer, such as the HA-5033, HA-2542, or
CA3450, can be employed. Figure 6 shows a typical
application, with the output capable of driving ±2V into
multiple 50Ω terminated lines.
DD
and
Operating and Handling Considerations
HANDLING
All inputs and outputs of CMOS devices have a network for
electrostatic protection during handling. Recommended
handling practices for CMOS devices are described in
AN6525. “Guide to Better Handling and Operation of CMOS
Integrated Circuits.”
OPERATING
OPERATING VOLTAGE
During operation near the maximum supply voltage limit,
care should be taken to avoid or suppress power supply
turn-on and turn-off transients, power supply ripple, or
ground noise; any of these conditions must not cause the
absolute maximum ratings to be exceeded.
INPUT SIGNALS
To prevent damage to the input protection circuit, input
signals should never be greater than V
Input currents must not exceed 20mA even when the power
supply is off.
UNUSED INPUTS
A connection must be provided at every input terminal. All
unused input terminals must be connected to either V
GND, whichever is appropriate.
nor less than VSS.
DD
CC
or
8
Dual-In-Line Plastic Packages (PDIP)
CA3338, CA3338A
N
D1
-C-
E1
-B-
A1
A2
E
A
L
e
C
C
L
e
A
C
e
B
INDEX
AREA
BASE
PLANE
SEATING
PLANE
D1
B1
12 3N/2
-AD
e
B
0.010 (0.25)C AMBS
NOTES:
1. Controlling Dimensions: INCH. In case of conflict between English and
Metric dimensions, the inch dimensions control.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of
Publication No. 95.
4. Dimensions A, A1 and L are measured with the package seated in JEDEC seating plane gauge GS-3.
5. D, D1, and E1 dimensions do not include mold flash or protrusions.
Mold flash or protrusions shall not exceed 0.010 inch (0.25mm).
6. E andare measured with the leads constrained to be perpendic-
7. e
e
A
ular to datum .
and eC are measured at the lead tips with the leads unconstrained.
B
e
must be zero or greater.
C
-C-
8. B1 maximum dimensions do not include dambar protrusions. Dambar
protrusions shall not exceed 0.010 inch (0.25mm).
9. N is the maximum number of terminal positions.
10. Corner leads (1, N, N/2 and N/2 + 1) for E8.3, E16.3, E18.3, E28.3,
E42.6 will have a B1 dimension of 0.030 - 0.045 inch (0.76 - 1.14mm).
1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of
Publication Number 95.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
4. Dimension “E” does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater above
the seating plane, shall not exceed a maximum value of 0.61mm (0.024
inch)
10. Controlling dimension: MILLIMETER. Converted inch dimensions are
not necessarily exact.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or pat ent rights of In tersi l or its subs idiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
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