ADC0816/ADC0817
8-Bit µP Compatible A/D Converters
with 16-Channel Multiplexer
ADC0816/ADC0817 8-Bit µP Compatible A/D Converters with 16-Channel Multiplexer
June 1999
General Description
The ADC0816, ADC0817 data acquisition component is a
monolithic CMOS device with an 8-bit analog-to-digital converter, 16-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses successive
approximation as the conversion technique. The converter
features a high impedance chopper stabilized comparator, a
256R voltage divider with analog switch tree and a successive approximation register. The 16-channel multiplexer can
directly access any one of 16-single-ended analog signals,
and provides the logic for additional channel expansion. Signal conditioning of any analog input signal is eased by direct
access to the multiplexer output, and to the input of the 8-bit
A/D converter.
The device eliminates the need for external zero and
full-scale adjustments. Easy interfacing to microprocessors
is provided by the latched and decoded multiplexer address
inputs and latched TTL TRI-STATE
The design of the ADC0816, ADC0817 has been optimized
by incorporating the most desirable aspects of several A/D
conversion techniques. The ADC0816, ADC0817 offers high
speed, high accuracy, minimal temperaturedependence,excellent long-term accuracy and repeatability, and consumes
minimal power. These features make this device ideally
suited to applications from process and machine control to
consumer and automotive applications. For similar performance in an 8-channel, 28-pin, 8-bit A/D converter, see the
ADC0808, ADC0809 data sheet. (See AN-258 for more information.)
®
outputs.
Block Diagram
Features
n Easy interface to all microprocessors
n Operates ratiometrically or with 5 V
adjusted voltage reference
n 16-channel multiplexer with latched control logic
n Outputs meet TTL voltage level specifications
n 0V to 5V analog input voltage range with single 5V
supply
n No zero or full-scale adjust required
n Standard hermetic or molded 40-pin DIP package
n Temperature range −40˚C to +85˚C or −55˚C to +125˚C
n Latched TRI-STATE output
n Direct access to “comparator in” and “multiplexer out” for
signal conditioning
n ADC0816 equivalent to MM74C948
n ADC0817 equivalent to MM74C948-1
or analog span
DC
Key Specifications
n Resolution8 Bits
n Total Unadjusted Error
n Single Supply5 V
n Low Power15 mW
n Conversion Time100 µs
1
±
⁄2LSB and±1 LSB
DC
DS005277-1
TRI-STATE®is a registered trademark of National Semiconductor Corporation.
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
Voltage at Any Pin−0.3V to (V
Except Control Inputs
Voltage at Control Inputs−0.3V to 15V
(START, OE, CLOCK, ALE, EXPANSION CONTROL,
ADD A, ADD B, ADD C, ADD D)
Storage Temperature Range−65˚C to + 150˚C
Package Dissipation at T
Note 1: AbsoluteMaximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its specified operating conditions.
Note 2: All voltages are measured with respect to GND, unless otherwise specified.
Note 3: Azener diode exists, internally, from V
Note 4: Two on-chip diodes are tied to each analog input which will forward conduct for analog input voltages one diode drop below ground or one diode drop greater
than the V
than 100 mV, the output code will be correct. To achieve an absolute 0 V
V
Note 5: Total unadjusted error includes offset, full-scale, and linearity errors. See
all zero code is desired for an analog input other than 0.0V, or if a narrow full-scale span exists (for example: 0.5V to 4.5V full-scale) the reference voltages can be
adjusted to achieve this. See
Note 6: Comparatorinput current is a bias current into or out of the chopper stabilized comparator.The bias current varies directly with clock frequency and has little
temperature dependence (
Note 7: Ifstart pulse is asynchronous with converter clock or if f
at f
Note 8: The outputs of the data register are updated one clock cycle before the rising edge of EOC.
Note 9: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
supply.The spec allows 100 mV forward bias of either diode. This means that as long as the analog VINdoes not exceed the supply voltage by more
CC
over temperature variations, initial tolerance and loading.
DC
Figure 13
Figure 6
). See paragraph 4.0.
≤ 640 kHz take start high within 100 ns of clock going low.
c
to GND and has a typical breakdown voltage of 7 VDC.
CC
.
=
=
REF(−)
GND, t
Figure 5
Figure 5
Figure 5
Figure 5
=
S
=
L
=
L
=
640 kHz, (
c
Figure 5
>
c
=
t
20 ns and T
r
f
) (Note 7)100200ns
)100200ns
)2550ns
)2550ns
Figure 5
OΩ (
50 pF, R
10 pF, R
)12.5µs
=
10k (
L
=
10k (
L
Figure 5
)08+2µsClock
to5VDCinput voltage range will therefore require a minimum supply voltage of 4.900
DC
Figure 3
640 kHz, the minimum start pulse width is 8 clock periods plus 2 µs. For synchronous operation
=
25˚C unless otherwise noted.
A
Figure 8
)125250ns
Figure 8
)125250ns
) (Note 8)90100116µs
. None of these A/Ds requires a zero or full-scale adjust. However, if an
Periods
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