Page 1
7872
14-Bit A/D Converter
FEATURES:
• 14-bit resolution and accuracy
• Total dose hardness:
- > 100 krad (Si), depending upon space mission
• Single event effects:
- SEL > 104 MeV/mg/cm
- SEUTH = 1.4 MeV/mg/cm
- SEU
= 1E-3 cm2/Device
Sat
• Package:
- 16 pin R
- 16 pin R
AD-PAK® flat package
AD-PAK® dual-in-line package
• Fast Conversion Times: 10 µs
• Low 50 mW typical power consumption
• High speed LC
2
MOS technology
- Analog input range of ±3V
- 83 KSPS throughput rate
- Operates with +5V/-5V power supplies
- 80 dB SNR at 10 kHz input frequency
- 2 s complement coding
- Serial output
2
2
CLK
CONTROL
CONVST
AGND C
12 11 13 14 9 16
3
1
2
REF
3V
REFERENCE
CLOCK
CONTROL
LOGIC
REF OUT V
IN
R
R
14-BIT DAC
SERIAL
INTERFACE
4 5 6
SSTRB SCLK SDATA DGND V
TRACK/HOLD
SAR + COUNTER
Logic Diagram
DESCRIPTION:
Maxwell Technologies’ 7872 high-speed 14-bit ADC microcircuit features a greater than 100 krad (Si) total dose tolerance;
depending upon orbit. The 7872 consists of a track/hold amplifier, successive-approximation ADC, 3V buried Zener reference and versatile interface logic. It features a self-contained,
laser- trimmed internal clock, so no external clock timing components are required. For minimum noise possible, the onchip clock may be overridden to synchronize the device operation to the digital system. The 7872 is a serial output device.
It is capable of interfacing to all modern microprocessors and
digital signal processors. The 7872 operates from ±5V power
supplies, accepts bipolar input signals of ±3V and is able to
convert full power signals up to 41.5 kHz. It is also fully specified for dynamic performance parameters including distortion
and signal-to-noise ratio.
Maxwell Technologies' patented R
ogy incorporates radiation shielding in the microcircuit package. It eliminates the need for box shielding while providing
the required radiation shielding for a lifetime in orbit or space
mission. In a GEO orbit, R
krad (Si) radiation dose tolerance. This product is available
with screening up to Class S.
AD-PAK® packaging technol-
AD-PAK provides greater than 100
V
DD
8 15
V
DD
COMP
SS
Memory
(858) 503-3300 - Fax: (858) 503-3301 - www.maxwell.com
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
1
Page 2
14-Bit A/D Converter
PIN SIGNAL DESCRIPTION
TABLE 1. 7872 PIN DESCRIPTION
1 CONTROL Control Function
2 CONVST
3 CLK Clock Input
4SSTRB
5 SCLK Serial Clock
6 SDATA Serial Data
7 NC Non Connect
8 DGND Digital Ground
Convert Start
Serial Strobe
7872
9V
DD
Positive Supply
10 NC No Connect
11 C
REF
Reference Capacitor
12 AGND Analog Ground
13 REF
14 V
15 V
16 V
OUT
IN
SS
DD
Voltage Reference Output
Analog Input
Negative Supply
Positive Supply
TABLE 2. 7872 ABSOLUTE MAXIMUM RATINGS
PARAMETER SYMBOL MIN MAX UNIT
Positive Supply Voltage; Relative to GND V
Negative Supply Voltage; Relative to GND V
DD
SS
AGND to DGND; Relative to GND -- -0.3 V
REF
, C
OUT
V
to AGND -- VSS -0.3 VDD +0.3 V
IN
Digital Input Voltage V
Digital Output Voltage V
Thermal Impedance
Storage Temperature Range T
Operating Temperature Range T
to AGND -- 0 V
REF
IN
OUT
Θ
JC
S
A
-0.3 7.0 V
0.3 7.0 V
+0.3 V
DD
DD
-0.3 VDD +0.3 V
-0.3 VDD +0.3 V
-- 2.44 °C/W
-65 150 °C
-55 125 °C
V
Memory
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
2
Page 3
14-Bit A/D Converter
7872
TABLE 3. 7872 DC ELECTRICAL CHARACTERISTICS FOR DYNAMIC PERFORMANCE
(VDD = 5 V ± 5%, VSS = -5 V ± 5%, AGND = DGND = 0 V, f
P
ARAMETER SYMBOL MIN TYP MAX UNIT
Signal to Noise Ratio VIN = 10kHz Sine Wave , T
T
;
MAX
SNR is typically 82dB for V
Total Harmonic Distortion V
< 41.5kHz
IN
= 10kHz Sine Wave THD -- -86 -- dB
IN
2
MIN
to
= 2 MHZ EXTERNAL, f
CLK
SPECIFIED)
= 83 KHZ, -55 TO 125 °C UNLESS OTHERWISE
SAMPLE
SNR 79 -- -- dB
1
Peak Harmonic or Spurious Noise -- -- -86 -- dB
Intermodulation Distortion
Second Order T erms: f
= 9 kHz, fb = 9.5 kHz, f
a
= 50 kHz
Third Order Terms: f
= 9 kHz, fb = 9.5 kHz, f
a
SAMPLE
SAMPLE
IMD
--
--
-86
-86
--
--
=
50 kHz
Track/Hold Acquisition Time -- -- -- 2 µs
1. V
= ± 3 V. Guaranteed by design.
IN
2. SNR calculation includes distortion and noise components.
TABLE 4. 7872 DC ELECTRICAL CHARACTERISTICS FOR ACCURACY
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
dB
Memory
P
ARAMETER SYMBOL MIN TYP MAX UNIT
Resolution -- 14 -- -- Bits
Resolution for Which No Missing Codes are Guaran-
-- 14 -- -- Bits
teed
°
Integral Nonlinearity @ 25
Integral Nonlinearity T
C----±1--LSB
MIN
to T
MAX
-- -- -- ±2 LSB
Bipolar Zero Error -- -- -- ±12 LSB
Positive Gain Error
Negative Gain Error
1
1
-- -- -- ±12 LSB
-- -- -- ±12 LSB
1. Measured with respect to internal reference.
TABLE 5. 7872 DC ELECTRICAL CHARACTERISTICS FOR ANALOG INPUT
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
P
ARAMETER SYMBOL MIN MAX UNITS
Input Voltage Range -- -3 3 V
Input Current -- -500 500 µA
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
3
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14-Bit A/D Converter
TABLE 6. 7872 DC ELECTRICAL CHARACTERISTICS FOR REFERENCE OUTPUT
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
P
ARAMETER SYMBOL MIN MAX UNIT
REF
@ +25 °C -- 2.99 3.01 V
OUT
REF
REF
Reference Load Sensitivity (DREF
Change (0-300 µA); Reference Load Should Not Be Changed During Conversion
P
ARAMETER SYMBOL MIN MAX UNIT
to T
OUT TMIN
Tempco: Typically 35ppm -- -- ±40 ppm/oC
OUT
MAX
/DI) Reference Load Current
OUT
-- 2.98 3.02 V
-- -- 1.2 mV
TABLE 7. 7872 DC ELECTRICAL CHARACTERISTICS FOR LOGIC INPUTS
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
7872
Input High Voltage: VDD 5 V ± 5% V
Input Low Voltage: V
Input Current: V
5 V ± 5% V
DD
= 0 V to V
IN
DD
INH
I
INL
IN
2.4 -- V
-- 0.8 V
-10 10 µA
Input Current: (14/8/CLK input only) VIN = VSS to VDD -- -10 10 µA
Input Capacitance
1
C
IN
-- 10 pF
1. Not tested.
TABLE 8. 7872 DC ELECTRICAL CHARACTERISTICS FOR LOGIC OUTPUTS
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
P
ARAMETER SYMBOL MIN MAX UNIT
Output High Voltage I
Output Low Voltage I
Floating-State Leakage Current -- -- 10 µA
Floating-State Output Capacitance
1. Not tested.
= 40 µA V
SOURCE
= 1.6 mA V
SINK
1
OH
OL
4.0 -- V
-- 0.4 V
-- -- 15 pF
Memory
TABLE 9. 7872 DC ELECTRICAL CHARACTERISTICS FOR CONVERSION TIME
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
P
ARAMETER SYMBOL MIN MAX UNIT
External Clock -- -- 10 µs
Internal Clock: Nominal Value = 2 MHz -- -- 11 µs
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
4
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14-Bit A/D Converter
7872
TABLE 10. 7872 DC ELECTRICAL CHARACTERISTICS FOR POWER REQUIREMENTS
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
P
ARAMETER SYMBOL CONDITIONS REQUIREMENTS UNITS
Positive Supply Voltage V
Negative Supply Voltage V
Positive Supply Current I
Negative Supply Current I
Power Dissipation P
TABLE 11. 7872 TIMING CHARACTERISTICS
DD
SS
DD
SS
5% for Specified Performance 5 V
5% for Specified Performance -5 V
Typically 6mA 13 mA max
Typically 4mA 6 mA max
Typically 50mW 95 mW max
D
1,2
(VDD = 5V ±5%, VSS = -5 V ± 5%, TA = -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)
ARAMETER/CONDITION SYMBOL MIN MAX UNITS
P
CONVST Pulse Width t
SSTRB
to SCLK Falling Edge Setup Time t
SCLK Cycle Time
SCLK to Valid Data Delay: C
3
= 35 pF
L
4
SCLD Rising Edge to SSTRB
Bus Relinquish Time After SCLK t
1
10
t
11
t
12
t
13
14
50 -- ns
100 -- ns
440 -- ns
-- 155 ns
20 150 ns
4 100 ns
1. All input signals are specified with tr = tr = 5 ns (10% to 90% of 5 V) and timed from a voltage level of 1.6 V.
2. Serial timing is measured with a 4.7 k
Ω pull-up resistor on SDATA and SSTRB and a 2 kΩ pull-up resistor on SCLK. The
capacitance on all three outputs is 35 pF.
3. SCLK mark/space ration (measured from a voltage level of 1.6 V) is 40/60 to 60/40.
4. SDATA will drive higher capacitive loads, but this will add to t12 since it increases the external RC time constant (4.7kΩ/CL)
and hence, the time to reach 2.4 V.
Memory
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
5
Page 6
14-Bit A/D Converter
FIGURE 1. MODE 1 TIMING DIAGRAM SERIAL
t
1
7872
CONVST
1
SSTRB
t
10
2
SCLK
SDATA
1. External 4.7 kΩ pull-up resistor.
2. External 2 k
Ω pull-up resistor continuos SCLK (DASHED LINE) when 14/8/CLK (CONTROL) = -5 V; noncontinuous when 14/
8/CLK (CONTROL) = 0 V.
FIGURE 2. MODE 2 TIMING DIAGRAM, SERIAL READ
TRACK HOLD
GOES INTO HOLD
t
11
LEADING
DB13 DB12 DB11 DB10 DB0
ZEROS
t
13
t
t
12
14
Memory
1
HBEN
2
SSTRB
t
11
12
t
13
t
14
3
SCLK
SDATA
t
10
t
2
1. Times t15, t18, t19 and t20 are the same for a high byte read as for a low byte read.
2. External 4.7 k
Ω pull-up resistor.
3. Continuos SCLK (DASHED LINE) when 14/8/CLK (CONTROL) = -5 V; noncontinuous when 14/8/CLK (CONTROL) = 0 V.
External 2 k
Ω pull-up resistor.
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
6
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14-Bit A/D Converter
FIGURE 3. LOAD CIRCUIT FOR ACCESS TIME
1.6mA
I
OL
7872
TO OUTPUT
PIN
FIGURE 4. LOAD CIRCUIT FOR OUTPUT FLOAT DELAY
TO OUTPUT
PIN
C
50pF
C
50pF
+2.1V
L
I
OH
200uA
Memory
I
OL
1.6mA
+2.1V
L
I
OH
200uA
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
7
Page 8
14-Bit A/D Converter
7872
Memory
16 PIN RAD-PAK® FLAT PACKAGE
SYMBOL
MIN NOM MAX
A 0.116 0.130 0.143
b 0.015 0.017 0.022
c 0.004 0.005 0.009
D -- 0.415 0.440
E 0.245 0.280 0.285
E1 -- -- 0.315
E2 0.130 0.156 -E3 0.030 0.062 --
e 0.050 BSC
L 0.325 0.335 0.345
Q 0.020 0.033 0.045
S1 0.005 0.024 --
N16
F16-01
Note: All dimensions in inches
DIMENSION
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
8
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14-Bit A/D Converter
7872
E
N/2
D
S2
A
c
Q
L
S1
e
b2
b
eA/2
eA
16 PIN RAD-PAK® DUAL IN LINE PACKAGE
SYMBOL
MIN NOM MAX
A -- 0.157 0.200
b 0.014 0.018 0.026
b2 0.045 0.047 0.065
c 0.008 0.010 0.018
D -- 0.800 0.840
E 0.220 0.295 0.310
eA 0.300 BSC
eA/2 0.150 BSC
e 0.100 BSC
L 0.135 0.145 0.155
Q 0.000 0.002 0.060
S1 0.005 0.027 -S2 0.005 -- --
N16
DIMENSION
Memory
D16-01
Note: All dimensions in inches
12.19.01 Rev 4
All data sheets are subject to change without notice
9
©2001 Maxwell Technologies
All rights reserved.
Page 10
14-Bit A/D Converter
Important Notice:
These data sheets are created using the chip manufacturer’s published specifications. Maxwell Technologies verifies
functionality by testing key parameters either by 100% testing, sample testing or characterization.
The specifications presented within these data sheets represent the latest and most accurate information available to
date. However, these specifications are subject to change without notice and Maxwell Technologies assumes no
responsibility for the use of this information.
Maxwell Technologies’ products are not authorized for use as critical components in life support devices or systems
without express written approval from Maxwell Technologies.
Any claim against Maxwell Technologies must be made within 90 days from the date of shipment from Maxwell Technologies. Maxwell Technologies’ liability shall be limited to replacement of defective parts.
7872
Memory
12.19.01 Rev 4
All data sheets are subject to change without notice
©2001 Maxwell Technologies
All rights reserved.
10
Page 11
14-Bit A/D Converter
)
Product Ordering Options
Model Number
7872
7872
RP
X X
Feature
Screening Flow
Package
Option Details
Monolithic
S = Maxwell Class S
B = Maxwell Class B
E = Engineering (testing @ +25°C
I = Industrial (testing @ -55°C,
+25°C, +125°C)
Memory
D = Dual In-line Package (DIP)
F = Flat Pack
Radiation Feature
Base Product
Nomenclature
12.19.01 Rev 4
RP = R
AD-PAK® package
14-Bit A/D Converter
All data sheets are subject to change without notice
11
©2001 Maxwell Technologies
All rights reserved.
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