®
SP574B/674B/1674B/774B
12–Bit Sampling A/D Converters
s
Complete Monolithic 12–Bit A/D Converters
with Sample–Hold, Reference, Clock and Tri–
state Outputs
Full Nyquist Sampling at All Sample Rates
Choice of Sampling Rates — 40kHz, 66kHz,
100kHz or 125kHz
Low Power Dissipation — 110mW
12–Bit Linearity Over Temperature
Commercial, Industrial and Military Tempera-
ture Ranges
Next–Generation Replacement for 574A, 674A,
1674A, 774A Devices
s
s
s
s
s
s
DESCRIPTION…
The
SP574B/674B/1674B/774B (SPx74B) Series
are complete 12–bit successive–approxi-
mation A/D converters integrated on a single die with tri-state output latches, an internal
reference, clock and a sample–hold. The new “B–Series” features true Nyquist sampling while
maintaining compatibility with prior versions. They are drop–in replacements for the older 574A/
674A/1674A/774A type devices.
STS
28
DB11
27
DB10
26
DB9
25
DB8
24
DB7
23
DB6
22
DB5
21
DB4
20
DB3
19
DB2
18
DB1
17
DB0
16
DGND
15
NIBBLE A
NIBBLE B
THREE–STATE BUFFERS AND CONTROL
NIBBLE C
12–BIT SAR
OSC
COMP
12–BIT
CAPACITANCE
DAC
OFFSET/GAIN
TRIM
CONTROL LOGIC
REF
7.5K
15K
7.5K
7.5K
12
13
14
15K
N/C
1
2
3
4
5
6
7
8
9
10
11
VLOGIC
12/8
CS
A0
R/C
CE
VCC
REF
OUT
AGND
REF
IN
VEE
BIP
OFF
10V
IN
20V
IN
SP574B/674B/1674B/774B
12–Bit Sampling A/D Converters
© Copyright 2000 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
V
CC
to Digital Common .................................................. 0 to +16.5V
V
LOGIC
to Digital Common ................................................... 0 to +7V
Analog Common to Digital Common .........................................
±1V
Control Inputs to Digital Common ................. –0.5V to V
LOGIC
+0.5V
(CE, CS, A
0
, 12/8, R/C)
Analog Input Voltage Range ...........................................
±FS ±30%
Analog Inputs to Analog Common ......................................
±16.5V
(REF IN, BIP OFF, 10V
IN
)
20V
IN
to Analog Common ........................................................
±24V
REF OUT ............................................... Indefinite short to common
................................................................... Momentary short to V
CC
Power Dissipation ............................................................. 1000mW
Lead Temperature, Soldering .................................. 300˚C, 10Sec
J/C ..................................................................................... 45˚C/W
MTBF–25˚C Ground Base ................................ 2.915 million hours
MTBF–125˚C Missile Launch ...................... 10.16 thousand hours
•
CAUTION:
ESD (ElectroStatic Discharge) sensitive
device. Permanent damage may occur on
unconnected devices subject to high energy
electrostatic fields. Unused devices must be
stored in conductive foam or shunts.
Personnel should be properly grounded prior
to handling this device. The protective foam
should be discharged to the destination
socket before devices are removed.
Inputs exceeding +30% or –30% of FS will cause erratic performance.
SPECIFICATIONS
(Typical @ 25°C with V
CC
= +15V, V
EE
= 0V, V
LOGIC
= +5V unless otherwise noted.)
PARAMETER
MIN.
TYP.
MAX.
UNIT
RESOLUTION
All models
12
Bits
ANALOG INPUTS
Input Ranges
Bipolar
±5, ±10
V
Unipolar
0 to +10, 0 to +20
V
Input Impedance
SP574B/SP674B
10 Volt Input
3.75
6.25
kΩ
20 Volt Input
15
25
kΩ
SP1674B/SP774B
10 Volt Input
1.875
3.125
kΩ
20 Volt Input
7.45
12.42
kΩ
Nyquist Frequency
SP574B
20
kHz
SP674B
33
kHz
SP1674B
50
kHz
SP774B
62.5
kHz
DIGITAL INPUTS
Logic Inputs CE, CS R/C, A
O
, 12/8
Logic 1
+2.4
+5.5
V
Logic 0
–0.3
+0.8
V
Current
±0.1
±50
µA
±5
µA
Capacitance
5
pF
12/8 Control Input
Hardwire to V
LOGIC
or DIGITAL COMMON
DIGITAL OUTPUTS
Logic Outputs DB
11
–DB
0
, STS
Logic 1
+2.4
V
Logic 0
+0.4
V
Leakage (High Z State)
±40
µA
Capacitance
5
pF
Parallel Data Output Codes
Unipolar
Positive true binary
Bipolar
Positive true offset binary
INTERNAL REFERENCE
Output Voltage
10.00
±0.1
V
Output Current
2
mA
CONDITIONS
–0.3V to +5.5V Input
0V to +5.5V Input
I
SOURCE
≤
500µA
I
SINK
≤
1.6mA
Data bits only
Note 1
SP574B/674B/1674B/774B
12–Bit Sampling A/D Converters
© Copyright 2000 Sipex Corporation
2
PIN ASSIGNMENTS…
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
FUNCTION
V
LOGIC
12/8
CS
A
0
R/C
CE
V
CC
REF OUT
ANA GND(AC)
REF IN
N/C*
BIP OFF
10V
IN
PIN
28
27
26
25
24
23
22
21
20
19
18
17
16
FUNCTION
STS
DB
11
(MSB)
DB
10
DB
9
DB
8
DB
7
DB
6
DB
5
DB
4
DB
3
DB
2
DB
1
DB
0
(LSB)
CIRCUIT OPERATION…
The
SPx74B
are complete monolithic capacitor
DAC–based 12–bit analog-to-digital convert-
ers with integral voltage reference, comparator,
successive–approximation register (SAR),
sample–and–hold, clock, output buffers and
control circuitry. The high level of integration
of the
SPx74B Series
means they require few
external components.
When the control section of the
SPx74B
initiates
a conversion command, the clock is enabled and
the successive–approximation register is reset to
all zeros. Once the conversion cycle begins, it can
not be stopped or restarted and data is not available
from the output buffers. The SAR, timed by the
clock, sequences through the conversion cycle and
returns an end–of–convert flag to the control sec-
tion of the ADC. The clock is then disabled by the
control section, the output status goes low, and the
control section is enabled to allow the data to be
read by external command.
The internal
SPx74B
12–bit CDAC is sequenced
by the SAR starting from the MSB to the LSB at
the beginning of the conversion cycle to provide
an output voltage from the CDAC that is equal
to the input signal voltage (which is divided by
the input voltage divider network). The com-
parator determines whether the addition of each
successively–weighted bit voltage causes the
CDAC output voltage summation to be greater
or less than the input voltage; if the sum is less,
the bit is left on; if more, the bit is turned off.
After testing all the bits, the SAR contains a 12–
bit binary code which accurately represents the
input signal to within
±
1
⁄
2
LSB.
The internal reference provides the voltage refer-
ence to the CDAC with excellent stability over
temperature and time. The reference is trimmed
to 10.00 Volts
±1%
and can supply up to 2mA to
an external load in addition to that required to
drive the reference input resistor (1mA) and
offset resistor (1mA) when operating with
±15V
supplies. If the
SPx74B
is used with
±12V
supplies, or if external current must be supplied
over the full temperature range, an external
buffer amplifier is recommended. Any external
load on the
SPx74B
reference must remain
constant during conversion.
14
20V
IN
15
DIG. GND
*This pin is not connected inside the device so it can
be tied to –15V, ground, or left floating.
FEATURES…
The
SPx74B Series
feature standard bipolar
and unipolar input ranges of 10V and 20V. Input
ranges are controlled by a bipolar offset pin and
laser-trimmed for specified linearity, gain and
offset accuracy. Power requirements are +5V
and +12V to +15V with a maximum dissipation
of 150mW at the specified voltages. Conversion
times of 8µs, 10µs, 15µs and 25µs are available,
as are units with 10, 25 or 50ppm/°C tempera-
ture coefficients for flexible matching to spe-
cific application requirements.
The
SPx74B Series
are available in nine prod-
uct grades for each conversion time. The –J
and –K models are specified over 0˚C to +
70˚C commercial temperature range; the –A
and –B models are specified over the –40˚C
to +85˚C industrial temperature range; the –S
and –T models are specified over the –55˚C to
+125˚C military temperature range. Package
options include 28–pin CDIP, 28–pin plastic
DIP (both narrow and wide), 28-pin PLCC
and 28–pin SOIC.
SP574B/674B/1674B/774B
12–Bit Sampling A/D Converters
© Copyright 2000 Sipex Corporation
5
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