ADC10461/ADC10462/ADC10464
10-Bit 600 ns A/D Converter with Input Multiplexer and
Sample/Hold
General Description
Using an innovative, patented multistep
*
conversion tech-
nique, the 10-bit ADC10461, ADC10462, and ADC10464
CMOS analog-to-digital converters offer sub-microsecond
conversion times yet dissipate a maximum of only 235 mW.
The ADC10461, ADC10462, and ADC10464 perform a
10-bit conversion in two lower-resolution "flashes", thus
yielding a fast A/D without the cost, power dissipation, and
other problems associated with true flash approaches. Dy-
namic
performance
(THD,
S/N)
is
guaranteed.
The
ADC10461 is pin-compatible with the ADC1061 but much
faster, thus providing a convenient upgrade path for the
ADC1061.
The analog input voltage to the ADC10461, ADC10462, and
ADC10464 is sampled and held by an internal sampling cir-
cuit. Input signals at frequencies from dc to over 200 kHz
can therefore be digitized accurately without the need for an
external sample-and-hold circuit.
The ADC10462 and ADC10464 include a "speed-up" pin.
Connecting an external resistor between this pin and ground
reduces the typical conversion time to as little as 350 ns with
only a small increase in linearity error.
For ease of interface to microprocessors, the ADC10461,
ADC10462, and ADC10464 have been designed to appear
as a memory location or I/O port without the need for exter-
nal interface logic.
Features
n
Built-in sample-and-hold
n
Single +5V supply
n
1, 2, or 4-input multiplexer options
n
No external clock required
n
Speed adjust pin for faster conversions (ADC10462 and
ADC10464)
Key Specifications
n
Conversion time to 10 bits
600 ns typical
n
Sampling Rate
800 kHz
n
Low power dissipation
235 mW (max)
n
Total harmonic distortion (50 kHz)
-60 dB (max)
n
No missing codes over temperature
Applications
n
Digital signal processor front ends
n
Instrumentation
n
Disk drives
n
Mobile telecommunications
Note:
*
U.S. Patent Number 4918449
Ordering Information
Industrial Temp Range
(-40C
T
A
+85C)
Package
ADC20461CIWM
M20B Small Outline
ADC20462CIWM
M24B Small Outline
ADC20464CIWM
M28B Small Outline
TRI-STATE
is a registered trademark of National Semiconductor Corporation.
June 1999
ADC10461/ADC10462/ADC10464
10-Bit
600
ns
A/D
Converter
with
Input
Multiplexer
and
Sample/Hold
1999 National Semiconductor Corporation
DS011108
www.national.com
Connection Diagrams
Pin Descriptions
DV
CC
, AV
CC
These are the digital and analog positive sup-
ply voltage inputs. They should always be con-
nected to the same voltage source, but are
brought out separately to allow for separate
bypass capacitors. Each supply pin should be
bypassed with a 0.1 F ceramic capacitor in
parallel with a 10 F tantalum capacitor to
ground.
INT
This is the active low interrupt output. INT
goes low at the end of each conversion, and
returns to a high state following the rising edge
of RD .
S /H
This is the Sample/Hold control input. When
this pin is forced low (and CS is low), it causes
the analog input signal to be sampled and ini-
tiates a new conversion.
RD
This is the active low Read control input.
When this RD and CS are low, any data
present in the output registers will be placed
on the data bus.
CS
This is the active low Chip Select control input.
When low, this pin enables the RD and S /H
pins.
S0, S1
On the multiple-input devices (ADC10462 and
ADC10464), these pins select the analog input
that will be connected to the A/D during the
conversion. The input is selected based on the
state of S0 and S1 when S /H makes its
High-to-Low transition (See the Timing Dia-
grams). The ADC10464 includes both S0 and
S1. The ADC10462 includes just S0, and the
ADC10461 includes neither.
V
REF-
,
V
REF+
These are the reference voltage inputs. They
may be placed at any voltage between GND
and V
CC
, but V
REF+
must be greater than
V
REF-
. An input voltage equal to V
REF-
pro-
duces an output code of 0, and an input volt-
age equal to (V
REF+
- 1 LSB) produces an out-
put code of 1023.
V
IN
, V
IN0
,
V
IN1
, V
IN2
,
V
IN3
These
are
the
analog
input
pins.
The
ADC10461 has one input (V
IN
), the ADC10462
has two inputs (V
IN0
and V
IN1
), and the
ADC10464 has four inputs (V
IN0
, V
IN1
, V
IN2
and V
IN3
). The impedance of the source
should be less than 500
for best accuracy
and conversion speed. For accurate conver-
sions, no input pin (even one that is not se-
lected) should be driven more than 50 mV
above V
CC
or 50 mV below ground.
GND, AGND,
DGND
These are the power supply ground pins. The
ADC10461 has a single ground pin (GND),
and the ADC10462 and ADC10464 have
separate analog and digital ground pins
(AGND and DGND) for separate bypassing of
the analog and digital supplies. The ground
pins
should
be
connected
to
a
stable,
noise-free system ground. For the devices
with two ground pins, both pins should be re-
turned to the same potential.
DB0DB9
These are the TRI-STATE output pins.
SPEED ADJ (ADC10462 and ADC10464 only). This pin is
normally left unconnected, but by connecting a
resistor between this pin and ground, the con-
version time can be reduced. See the Typical
Performance Curves and the table of Electri-
cal Characteristics.
DS011108-10
Top View
DS011108-11
Top View
DS011108-12
Top View
www.national.com
2
Absolute Maximum Ratings
(Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
+
= AV
CC
= DV
CC
)
-0.3V to +6V
Voltage at Any Input or Output
-0.3V to V
+
+ 0.3V
Input Current at Any Pin (Note 3)
5 mA
Package Input Current (Note 3)
20 mA
Power Dissipation (Note 4)
875 mW
ESD Susceptability (Note 5)
2000V
Soldering Information (Note 6)
N Package (10 Sec)
260C
SO Package:
Vapor Phase (60 Sec)
215C
Infrared (15 Sec)
220C
Storage Temperature Range
-65C to +150C
Junction Temperature
150C
Operating Ratings
(Notes 1, 2)
Temperature Range
T
MIN
T
A
T
MAX
ADC10461CIWM,
ADC10462CIWM,
ADC10464CIWM
-40C
T
A
+85C
Supply Voltage Range
4.5V to 5.5V
Converter Characteristics
The following specifications apply for V
+
= +5V, V
REF(+)
= +5V, V
REF(-)
= GND, and Speed Adjust pin unconnected unless
otherwise specified. Boldface limits apply for T
A
= T
J
= T
Min
to T
Max
; all other limits T
A
= T
J
= +25C.
Symbol
Parameter
Conditions
Typical
Limit
Units
(Note 7)
(Note 8)
(Limit)
Resolution
10
Bits
Integral Linearity Error
R
SA
18 k
0.5
LSB
Offset Error
1
LSB (max)
Full-Scale Error
1
LSB (max)
Total Unadjusted Error
R
SA
18 k
0.5
LSB
Missing Codes
0
(max)
Power Supply Sensitivity
V
+
= 5V
5%, V
REF
= 4.5V
1/16
LSB
V
+
= 5V
10%, V
REF
= 4.5V
1
/
8
LSB
THD
Total Harmonic Distortion
f
IN
= 1 kHz, 4.85 V
P-P
-68
dB
f
IN
= 50 kHz, 4.85 V
P-P
-66
-60
dB (max)
f
IN
= 100 kHz, 4.85 V
P-P
-62
dB
f
IN
= 240 kHz, 4.85 V
P-P
-58
dB
SNR
Signal-to-Noise Ratio
f
IN
= 1 kHz, 4.85 V
P-P
61
dB
f
IN
= 50 kHz, 4.85 V
P-P
60
58
dB (min)
f
IN
= 100 kHz, 4.85 V
P-P
60
dB
ENOB
Effective Number of Bits
f
IN
= 1 kHz, 4.85 V
P-P
9.6
Bits
f
IN
= 50 kHz, 4.85 V
P-P
9.5
9
Bits (min)
R
REF
Reference Resistance
650
400
(min)
R
REF
Reference Resistance
650
900
(max)
V
REF(+)
V
REF(+)
Input Voltage
V
+
+ 0.05
V (max)
V
REF(-)
V
REF(-)
Input Voltage
GND - 0.05
V (min)
V
REF(+)
V
REF(+)
Input Voltage
V
REF(-)
V (min)
V
REF(-)
V
REF(-)
Input Voltage
V
REF(+)
V (max)
V
IN
Input Voltage
V
+
+ 0.05
V (max)
V
IN
Input Voltage
GND - 0.05
V (min)
OFF Channel Input Leakage Current
CS = V
+
, V
IN
= V
+
0.01
3
A (max)
ON Channel Input Leakage Current
CS = V
+
, V
IN
= V
+
1
-3
A (max)
DC Electrical Characteristics
The following specifications apply for V
+
= +5V, V
REF(+)
= 5V V
REF(-)
= GND, and Speed Adjust pin unconnected unless oth-
erwise specified. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C.
Symbol
Parameter
Conditions
Typical
Limit
Units
(Note 7)
(Note 8)
(Limits)
V
IN(1)
Logical "1" Input Voltage
V
+
= 5.5V
2.0
V (min)
www.national.com
3
DC Electrical Characteristics
(Continued)
The following specifications apply for V
+
= +5V, V
REF(+)
= 5V V
REF(-)
= GND, and Speed Adjust pin unconnected unless oth-
erwise specified. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C.
Symbol
Parameter
Conditions
Typical
Limit
Units
(Note 7)
(Note 8)
(Limits)
V
IN(0)
Logical "0" Input Voltage
V
+
= 4.5V
0.8
V (max)
I
IN(1)
Logical "1" Input Current
V
IN(1)
= 5V
0.005
3.0
A (max)
I
IN(0)
Logical "0" Input Current
V
IN(0)
0V
-0.005
-3.0
A (max)
V
OUT(1)
Logical "1" Output Voltage
V
+
= 4.5V, I
OUT
= -360 A
2.4
V (min)
V
+
= 4.5V, I
OUT
= -10 A
4.25
V (min)
V
OUT(0)
Logical "0" Output Voltage
V
+
= 4.5V, I
OUT
= 1.6 mA
0.4
V (max)
I
OUT
TRI-STATE
Output Current
V
OUT
= 5V
0.1
50
A (max)
V
OUT
= 0V
-0.1
-50
A (max)
DI
CC
DV
CC
Supply Current
CS = S /H = RD = 0, R
SA
=
1.0
2
mA (max)
CS = S /H = RD = 0, R
SA
= 18 k
1.0
mA (max)
AI
CC
AV
CC
Supply Current
CS = S /H = RD = 0, R
SA
=
30
45
mA (max)
CS = S /H = RD = 0, R
SA
= 18 k
30
mA (max)
AC Electrical Characteristics
The following specifications apply for V
+
= +5V, t
r
= t
f
= 20 ns, V
REF(+)
= 5V, V
REF(-)
= GND, and Speed Adjust pin uncon-
nected unless otherwise specified. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C.
Symbol
Parameter
Conditions
Typical
Limit
Units
(Note 7)
(Note 8)
(Limits)
t
CONV
Mode 1 Conversion Time
CIN,
from Rising Edge of S /H
CIWM Suffixes
600
750/900
ns (max)
to Falling Edge of INT
R
SA
= 18k
375
ns
t
CRD
Mode 2 Conversion Time
CIN,
CIWM Suffixes
850
1400
ns (max)
Mode 2, R
SA
= 18k
530
ns
t
ACC1
Access Time (Delay from Falling
Mode 1; C
L
= 100 pF
30
60
ns (max)
Edge of RD to Output Valid)
t
ACC2
Access Time (Delay from Falling
Mode 2; C
L
= 100 pF
900
t
CRD
+ 50
ns (max)
Edge of RD to Output Valid)
t
SH
Minimum Sample Time
(
Figure 1) ; (Note 9)
250
ns (max)
t
1H
, t
0H
TRI-STATE Control (Delay
R
L
= 1k, C
L
= 10 pF
from Rising Edge of RD
30
60
ns (max)
to High-Z State)
t
INTH
Delay from Rising Edge of RD
C
L
= 100 pF
to Rising Edge of INT
25
50
ns (max)
t
P
Delay from End of Conversion
50
ns (max)
to Next Conversion
t
MS
Multiplexer Control Setup Time
10
75
ns (max)
t
MH
Multiplexer Hold Time
10
40
ns (max)
C
VIN
Analog Input Capacitance
35
pF (max)
C
OUT
Logic Output Capacitance
5
pF (max)
C
IN
Logic Input Capacitance
5
pF (max)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-
tional. These ratings do not guarantee specific performance limits, however. For guaranteed specifications and test conditions, see the Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed
test conditons.
Note 2: All voltages are measured with respect to GND, unless otherwise specified.
Note 3: When the input voltage (V
IN
) at any pin exceeds the power supply rails (V
IN
<
GND or V
IN
>
V
+
) the absolute value of current at that pin should be limited
to 5 mA or less. The 20 mA package input current limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.
www.national.com
4
AC Electrical Characteristics
(Continued)
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
JMAX
,
JA
and the ambient temperature, T
A
. The maximum
allowable power dissipation at any temperature is P
D
= (T
JMAX
- T
A
)/
JA
or the number given in the Absolute Maximum Ratings, whichever is lower. In most cases,
the maximum derated power dissipation will be reached only during fault conditions. For these devices, T
JMAX
for a board-mounted device can be found from the
tables below:
Device
JA
(C/W)
ADC20461CIWM
85
ADC20462CIWM
82
ADC20464CIWM
78
Note 5: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 6: See AN-450 "Surface Mounting Methods and Their Effect on Product Reliability" or the section titled "Surface Mount" found in a current National Semicon-
ductor Linear Data Book for other methods of soldering surface mount devices.
Note 7: Typicals represent most likely parametric norm.
Note 8: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 9: Accuracy may degrade if t
SH
is shorter than the value specified. See curves of Accuracy vs t
SH
.
www.national.com
5
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