__________________General Description
The MAX187/MAX189 serial 12-bit analog-to-digital
converters (ADCs) operate from a single +5V supply
and accept a 0V to 5V analog input. Both parts feature
an 8.5µs successive-approximation ADC, a fast
track/hold (1.5µs), an on-chip clock, and a high-speed
3-wire serial interface.
The MAX187/MAX189 digitize signals at a 75ksps
throughput rate. An external clock accesses data from
the interface, which communicates without external
hardware to most digital signal processors and micro-
controllers. The interface is compatible with SPITM,
QSPITM, and MicrowireTM.
The MAX187 has an on-chip buffered reference, and
the MAX189 requires an external reference. Both the
MAX187 and MAX189 save space with 8-pin DIP and
16-pin SO packages. Power consumption is 7.5mW
and reduces to only 10µW in shutdown.
Excellent AC characteristics and very low power con-
sumption combined with ease of use and small pack-
age size make these converters ideal for remote DSP
and sensor applications, or for circuits where power
consumption and space are crucial.
___________________________Applications
Portable Data Logging
Remote Digital Signal Processing
Isolated Data Acquisition
High-Accuracy Process Control
________________________________Features
o
12-Bit Resolution
o
±
1
/
2
LSB Integral Nonlinearity (MAX187A/MAX189A)
o
Internal Track/Hold, 75kHz Sampling Rate
o
Single +5V Operation
o
Low Power: 2µA Shutdown Current
1.5mA Operating Current
o
Internal 4.096V Buffered Reference (MAX187)
o
3-Wire Serial Interface, Compatible with SPI,
QSPI, and Microwire
o
Small-Footprint 8-Pin DIP and 16-Pin SO
_________________Ordering Information
MAX1
87/MAX189
+5V, Low-Power, 12-Bit Serial ADCs
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
19-0196; Rev 0; 10/93
PART
TEMP. RANGE PIN-PACKAGE ERROR
(LSB)
MAX187
ACPA
0°C to +70°C
8 Plastic DIP
±
1
/
2
MAX187BCPA
0°C to +70°C
8 Plastic DIP
±1
MAX187CCPA
0°C to +70°C
8 Plastic DIP
±2
MAX187ACWE
0°C to +70°C
16 Wide SO
±
1
/
2
MAX187BCWE
0°C to +70°C
16 Wide SO
±1
MAX187CCWE
0°C to +70°C
16 Wide SO
±2
MAX187BC/D
0°C to +70°C
Dice*
±1
TM SPI and QSPI are trademarks of Motorola. Microwire is a trademark of National Semiconductor.
Ordering Information continued on last page.
* Dice are specified at T
A
= +25°C, DC parameters only.
** Contact factory for availability and processing to MIL-STD-883.
________________Functional Diagram
GND
5
REF
4
AIN
2
VDD
1
T/H
BANDGAP
REFERENCE
+2.5V
(MAX187 ONLY)
10k
AV = 1.638
(4.096V)
REF-
REF+
DAC
OUTPUT
SHIFT
REGISTER
DOUT
6
SCLK
8
CS
7
SHDN
3
CONTROL
AND
TIMING
12-BIT
SAR
COMPARATOR
BUFFER ENABLE/DISABLE
NOTE: PIN NUMBERS SHOWN ARE FOR 8-PIN DIPs ONLY.
MAX187
MAX189
TOP VIEW
1
2
3
4
8
7
6
5
SCLK
CS
DOUT
GND
REF
SHDN
AIN
V
DD
DIP
MAX187
MAX189
Pin Configurations continued on last page.
_________________Pin Configurations
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
MAX1
87/MAX189
+5V, Low-Power, 12-Bit Serial ADCs
2
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
DD
= +5V ±5%; GND = 0V; unipolar input mode; 75ksps, f
CLK
= 4.0MHz, external clock (50% duty cycle); MAX187--internal
reference: V
REF
= 4.096V, 4.7µF capacitor at REF pin, or MAX189--external reference: V
REF
= 4.096V applied to REF pin, 4.7µF
capacitor at REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC ACCURACY
(Note 1)
Resolution
12
Bits
MAX18_A
±
1
/
2
Relative Accuracy (Note 2)
MAX18_B
±1
LSB
MAX18_C
±2
Differential Nonlinearity
DNL
No missing codes over temperature
±1
LSB
Offset Error
MAX18_A
±1
1
/
2
LSB
MAX18_B/C
±3
Gain Error (Note 3)
MAX187
±3
LSB
MAX189A
±1
MAX189B/C
±3
Gain Temperature Coefficient
External reference, 4.096V
±0.8
ppm/°C
DYNAMIC SPECIFICATIONS
(10kHz sine wave input, 0V to 4.096V
p-p
, 75ksps)
Signal-to-Noise plus
Distortion Ratio
SINAD
70
dB
Total Harmonic Distortion
(up to the 5th harmonic)
THD
-80
dB
Spurious-Free Dynamic Range
SFDR
80
dB
Small-Signal Bandwidth
Rolloff -3dB
4.5
MHz
Full-Power Bandwidth
0.8
MHz
V
DD
to GND .............................................................-0.3V to +6V
AIN to GND................................................-0.3V to (V
DD
+ 0.3V)
REF to GND ...............................................-0.3V to (V
DD
+ 0.3V)
Digital Inputs to GND.................................-0.3V to (V
DD
+ 0.3V)
Digital Outputs to GND..............................-0.3V to (V
DD
+ 0.3V)
SHDN to GND.............................................-0.3V to (V
DD
+ 0.3V)
REF Load Current (MAX187) .........................4.0mA Continuous
REF Short-Circuit Duration (MAX187)................................20sec
DOUT Current ..................................................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ..500mW
16-Pin Wide SO (derate 8.70mW/°C above +70°C) ...478mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C) ......440mW
Operating Temperature Ranges:
MAX187_C_ _/MAX189_C_ _.............................0°C to +70°C
MAX187_E_ _/MAX189_E_ _ ..........................-40°C to +85°C
MAX187_MJA/MAX189_MJA .......................-55°C to +125°C
Storage Temperature Range............................-60°C to +150°C
Lead Temperature (soldering, 10sec) ............................+300°C
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CONVERSION RATE
Conversion Time
t
CONV
5.5
8.5
µs
Track/Hold Acquisition Time
t
ACQ
1.5
µs
Throughput Rate
External clock, 4MHz, 13 clocks
75
ksps
Aperture Delay
t
APR
10
ns
Aperture Jitter
<50
ps
ANALOG INPUT
Input Voltage Range
0 to V
REF
V
Input Capacitance (Note 4)
16
pF
INTERNAL REFERENCE
(MAX187 only, reference buffer enabled)
REF Output Voltage
V
REF
T
A
= +25°C
4.076
4.096
4.116
MAX187_C
4.060
4.132
T
A
= T
MIN
to T
MAX
MAX187_E
4.050
4.140
V
MAX187_M
4.040
4.150
REF Short-Circuit Current
30
mA
MAX187AC/BC
±30
±50
REF Tempco
MAX187AE/BE
±30
±60
ppm/°C
MAX187AM/BM
±30
±80
MAX187C
±30
Load Regulation (Note 5)
0mA to 0.6mA output load
1
mV
EXTERNAL REFERENCE AT REF
(Buffer disabled, V
REF
= 4.096V)
Input Voltage Range
2.50
V
DD
+ 50mV
V
Input Current
200
350
µA
Input Resistance
12
20
k
Shutdown REF Input Current
1.5
10
µA
MAX1
87/MAX189
+5V, Low-Power, 12-Bit Serial ADCs
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%; GND = 0V; unipolar input mode; 75ksps, f
CLK
= 4.0MHz, external clock (50% duty cycle); MAX187--internal
reference: V
REF
= 4.096V, 4.7µF capacitor at REF pin, or MAX189--external reference: V
REF
= 4.096V applied to REF pin, 4.7µF
capacitor at REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
MAX1
87/MAX189
+5V, Low-Power, 12-Bit Serial ADCs
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V ±5%; GND = 0V; unipolar input mode; 75ksps, f
CLK
= 4.0MHz, external clock (50% duty cycle); MAX187--internal
reference: V
REF
= 4.096V, 4.7µF capacitor at REF pin, or MAX189--external reference: V
REF
= 4.096V applied to REF pin, 4.7µF
capacitor at REF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL INPUTS (SCLK,
CS
,
SHDN
)
SCLK,
CS Input High Voltage
V
INH
2.4
V
SCLK,
CS Input Low Voltage
V
INL
0.8
V
SCLK,
CS Input Hysteresis
V
HYST
0.15
V
SCLK,
CS Input Leakage
I
IN
V
IN
= 0V or V
DD
±1
µA
SCLK,
CS Input Capacitance
C
IN
(Note 4)
15
pF
SHDN Input High Voltage
V
INSH
V
DD
- 0.5
V
SHDN Input Low Voltage
V
INSL
0.5
V
SHDN Input Current
I
INS
SHDN = V
DD
or 0V
±4.0
µA
SHDN Input Mid Voltage
V
IM
1.5
V
DD
-1.5
V
SHDN Voltage, Floating
V
FLT
SHDN = open
2.75
V
SHDN Maximum Allowed
SHDN = open
-100
100
nA
Leakage, Mid Input
DIGITAL OUTPUT (DOUT)
Output Voltage Low
V
OL
I
SINK
= 5mA
0.4
V
I
SINK
= 16mA
0.3
Output Voltage High
V
OH
I
SOURCE
= 1mA
4
V
Three-State Leakage Current
I
L
CS = 5V
±10
µA
Three-State Output
C
OUT
CS = 5V (Note 4)
15
pF
Capacitance
POWER REQUIREMENTS
Supply Voltage
V
DD
4.75
5.25
V
Supply Current
Operating mode
MAX187
1.5
2.5
mA
I
DD
MAX189
1.0
2.0
Power-down mode
2
10
µA
V
DD
= +5V, ±5%; external reference, 4.096V;
Power-Supply Rejection
PSR
full-scale input (Note 6)
±0.06
±0.5
mV
MAX1
87/MAX189
+5V, Low-Power, 12-Bit Serial ADCs
_______________________________________________________________________________________
5
TIMING CHARACTERISTICS
(V
DD
= +5.0V ±5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Track/Hold Acquisition Time
t
ACQ
CS = high (Note 7)
1.5
µs
SCLK Fall to Output Data Valid
t
DO
C
LOAD
= 100pF
MAX18_ _C/E
20
150
ns
MAX18_ _M
20
200
CS Fall to Output Enable
t
DV
C
LOAD
= 100pF
100
ns
CS Rise to Output Disable
t
TR
C
LOAD
= 100pF
100
ns
SCLK Clock Frequency
f
SCLK
5
MHz
SCLK Pulse Width High
t
CH
100
ns
SCLK Pulse Width Low
t
CL
100
ns
SCLK Low to
CS Fall
t
CSO
50
ns
Setup Time
CS Pulse Width
t
CS
500
ns
Note 1:
Tested at V
DD
= +5V.
Note 2:
Relative accuracy is the deviation of the analog value at any code from its theoretical value after the full-scale range has
been calibrated.
Note 3:
MAX187--internal reference, offset nulled; MAX189external +4.096V reference, offset nulled. Excludes reference errors.
Note 4:
Guaranteed by design. Not subject to production testing.
Note 5:
External load should not change during conversion for specified ADC accuracy.
Note 6:
DC test, measured at 4.75V and 5.25V only.
Note 7:
To guarantee acquisition time, t
ACQ
is the maximum time the device takes to acquire the signal, and is also the minimum
time needed for the signal to be acquired.
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