19-0465; Rev 2; 10/01
KIT
ATION
EVALU
E
BL
AVAILA
+2.7V, Low-Power, 8-Channel,
Serial 12-Bit ADCs
General Description
____________________________Features
o
8-Channel Single-Ended or 4-Channel
Differential Inputs
o
Single-Supply Operation
+2.7V to +3.6V (MAX146)
+2.7V to +5.25V (MAX147)
o
Internal 2.5V Reference (MAX146)
o
Low Power
1.2mA (133ksps, 3V supply)
54µA (1ksps, 3V supply)
1µA (power-down mode)
o
SPI/QSPI/MICROWIRE/TMS320-Compatible
4-Wire Serial Interface
o
Software-Configurable Unipolar or Bipolar Inputs
o
20-Pin DIP/SSOP Packages
MAX146/MAX147
The MAX146/MAX147 12-bit data-acquisition systems
combine an 8-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. The MAX146 oper-
ates from a single +2.7V to +3.6V supply; the MAX147
operates from a single +2.7V to +5.25V supply. Both
devices’ analog inputs are software configurable for
unipolar/bipolar and single-ended/differential operation.
The 4-wire serial interface connects directly to SPI™/
QSPI™ and MICROWIRE™ devices without external
logic. A serial strobe output allows direct connection to
TMS320-family digital signal processors. The
MAX146/MAX147 use either the internal clock or an exter-
nal serial-interface clock to perform successive-approxi-
mation analog-to-digital conversions.
The MAX146 has an internal 2.5V reference, while the
MAX147 requires an external reference. Both parts have
a reference-buffer amplifier with a ±1.5% voltage-
adjustment range.
These devices provide a hard-wired
SHDN
pin and a
software-selectable power-down, and can be pro-
grammed to automatically shut down at the end of a con-
version. Accessing the serial interface automatically
powers up the MAX146/MAX147, and the quick turn-on
time allows them to be shut down between all conver-
sions. This technique can cut supply current to under
60µA at reduced sampling rates.
The MAX146/MAX147 are available in 20-pin DIP and
SSOP packages.
For 4-channel versions of these devices, see the
MAX1246/MAX1247 data sheet.
Ordering Information
PART
MAX146ACPP
MAX146BCPP
MAX146ACAP
MAX146BCAP
MAX146BC/D
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
20 Plastic DIP
20 Plastic DIP
20 SSOP
20 SSOP
Dice*
INL
(LSB)
±1/2
±1
±1/2
±1
±1
Ordering Information continued at end of data sheet.
*Dice
are specified at T
A
= +25°C, DC parameters only.
Typical Operating Circuit
+3V
CH0
V
DD
DGND
V
DD
0.1µF
________________________Applications
Portable Data Logging
Medical Instruments
Pen Digitizers
Data Acquisition
Battery-Powered Instruments
Process Control
0V TO
+2.5V
ANALOG
INPUTS
MAX146
AGND
CPU
CH7
VREF
COM
CS
SCLK
DIN
REFADJ
DOUT
SSTRB
SHDN
V
SS
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
4.7µF
Pin Configuration appears at end of data sheet.
0.047µF
SPI and QSPI are registered trademarks of Motorola, Inc.
MICROWIRE is a registered trademark of National Semiconductor
Corp.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
+2.7V, Low-Power, 8-Channel,
Serial 12-Bit ADCs
MAX146/MAX147
ABSOLUTE MAXIMUM RATINGS
V
DD
to AGND, DGND................................................. -0.3V to 6V
AGND to DGND ...................................................... -0.3V to 0.3V
CH0–CH7, COM to AGND, DGND ............ -0.3V to (V
DD
+ 0.3V)
VREF, REFADJ to AGND ........................... -0.3V to (V
DD
+ 0.3V)
Digital Inputs to DGND .............................................. -0.3V to 6V
Digital Outputs to DGND ........................... -0.3V to (V
DD
+ 0.3V)
Digital Output Sink Current .................................................25mA
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 11.11mW/°C above +70°C) ......... 889mW
SSOP (derate 8.00mW/°C above +70°C) ................... 640mW
CERDIP (derate 11.11mW/°C above +70°C) .............. 889mW
Operating Temperature Ranges
MAX146_C_P/MAX147_C_P .............................. 0°C to +70°C
MAX146_E_P/MAX147_E_P............................ -40°C to +85°C
MAX146_MJP/MAX147_MJP ........................ -55°C to +125°C
Storage Temperature Range ............................ -60°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
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.
ELECTRICAL CHARACTERISTICS
(V
DD
= +2.7V to +3.6V (MAX146); V
DD
= +2.7V to +5.25V (MAX147); COM = 0; f
SCLK
= 2.0MHz; external clock (50% duty cycle); 15
clocks/conversion cycle (133ksps); MAX146—4.7µF capacitor at VREF pin; MAX147—external reference, VREF = 2.500 V applied to
VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
DC ACCURACY
(Note 1)
Resolution
Relative Accuracy (Note 2)
No Missing Codes
Differential Nonlinearity
Offset Error
Gain Error (Note 3)
Gain Temperature Coefficient
Channel-to-Channel Offset
Matching
INL
NMC
DNL
MAX14_A/MAX14_B
MAX147C
MAX14_A
MAX14_B/MAX147C
±0.8
±0.5
±0.5
±0.5
±0.25
±0.25
±3
±4
±4
MAX14_A
MAX14_B
MAX147C
12
±1.0
SYMBOL
CONDITIONS
MIN
12
±0.5
±1.0
±2.0
Bits
LSB
LSB
LSB
ppm/°C
LSB
TYP
MAX
UNITS
Bits
LSB
DYNAMIC SPECIFICATIONS
(10kHz sine-wave input, 0V to 2.500Vp-p, 133ksps, 2.0MHz external clock, bipolar input mode)
MAX14_A/MAX14_B
70
73
Signal-to-Noise + Distortion Ratio
SINAD
dB
MAX147C
73
Total Harmonic Distortion
Spurious-Free Dynamic Range
Channel-to-Channel Crosstalk
Small-Signal Bandwidth
Full-Power Bandwidth
CONVERSION RATE
Internal clock,
SHDN
= FLOAT
Conversion Time (Note 5)
t
CONV
Internal clock,
SHDN
= V
DD
External clock = 2MHz, 12 clocks/conversion
5.5
35
6
7.5
65
µs
THD
SFDR
Up to the 5th
harmonic
MAX14_A/MAX14_B
MAX147C
65kHz, 2.500V
p-p
(Note 4)
-3dB rolloff
MAX14_A/MAX14_B
MAX147C
80
-88
-88
90
90
-85
2.25
1.0
-80
dB
dB
dB
MHz
MHz
2
_______________________________________________________________________________________
+2.7V, Low-Power, 8-Channel,
Serial 12-Bit ADCs
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX146); V
DD
= +2.7V to +5.25V (MAX147); COM = 0; f
SCLK
= 2.0MHz; external clock (50% duty cycle); 15
clocks/conversion cycle (133ksps); MAX146—4.7µF capacitor at VREF pin; MAX147—external reference, VREF = 2.500 V applied to
VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
Track/Hold Acquisition Time
Aperture Delay
Aperture Jitter
Internal Clock Frequency
External Clock Frequency
ANALOG/COM INPUTS
Input Voltage Range, Single-
Ended and Differential (Note 6)
Multiplexer Leakage Current
Input Capacitance
INTERNAL REFERENCE
(MAX146 only, reference buffer enabled)
VREF Output Voltage
T
A
= +25°C
VREF Short-Circuit Current
MAX146_C
VREF Temperature Coefficient
Load Regulation (Note 7)
Capacitive Bypass at VREF
Capacitive Bypass at REFADJ
REFADJ Adjustment Range
EXTERNAL REFERENCE AT VREF
(Buffer disabled)
VREF Input Voltage Range
(Note 8)
VREF Input Current
VREF Input Resistance
Shutdown VREF Input Current
REFADJ Buffer Disable Threshold
EXTERNAL REFERENCE AT REFADJ
Capacitive Bypass at VREF
Reference Buffer Gain
REFADJ Input Current
Internal compensation mode
External compensation mode
MAX146
MAX147
MAX146
MAX147
0
4.7
2.06
2.00
±50
±10
µF
V/V
µA
V
DD
-
0.5
VREF = 2.5V
18
1.0
100
25
0.01
10
V
DD
+
50mV
150
V
µA
kΩ
µA
V
MAX146_E
MAX146_M
0 to 0.2mA output load
Internal compensation mode
External compensation mode
0
4.7
0.047
±1.5
±30
±30
±30
0.35
2.480
Unipolar, COM = 0V
Bipolar, COM = VREF / 2
On/off leakage current, V
CH_
= 0V or V
DD
±0.01
16
2.500
2.520
30
±50
±60
±80
mV
µF
µF
%
ppm/°C
0 to VREF
V
±VREF / 2
±1
µA
pF
V
mA
SHDN
= FLOAT
SHDN
= V
DD
0.1
Data transfer only
0
SYMBOL
t
ACQ
30
<50
1.8
0.225
2.0
2.0
CONDITIONS
MIN
TYP
MAX
1.5
UNITS
µs
ns
ps
MHz
MHz
MAX146/MAX147
_______________________________________________________________________________________
3
+2.7V, Low-Power, 8-Channel,
Serial 12-Bit ADCs
MAX146/MAX147
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX146); V
DD
= +2.7V to +5.25V (MAX147); COM = 0; f
SCLK
= 2.0MHz; external clock (50% duty cycle); 15
clocks/conversion cycle (133ksps); MAX146—4.7µF capacitor at VREF pin; MAX147—external reference, VREF = 2.500 V applied to
VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
SYMBOL
V
DD
≤
3.6V
V
DD
> 3.6V, MAX147 only
CONDITIONS
MIN
2.0
3.0
0.8
0.2
V
IN
= 0V or V
DD
(Note 9)
V
DD
- 0.4
1.1
SHDN = 0V or V
DD
SHDN = FLOAT
SHDN = FLOAT
V
DD
/ 2
±100
V
DD
- 1.1
0.4
±4.0
±0.01
±1
15
TYP
MAX
UNITS
DIGITAL INPUTS
(DIN, SCLK, CS, SHDN)
DIN, SCLK,
CS
Input High Voltage
DIN, SCLK,
CS
Input Low Voltage
DIN, SCLK,
CS
Input Hysteresis
DIN, SCLK,
CS
Input Leakage
DIN, SCLK,
CS
Input Capacitance
SHDN
Input High Voltage
SHDN
Input Mid Voltage
SHDN
Input Low Voltage
SHDN
Input Current
SHDN
Voltage, Floating
SHDN
Maximum Allowed
Leakage, Mid Input
DIGITAL OUTPUTS
(DOUT, SSTRB)
Output Voltage Low
Output Voltage High
Three-State Leakage Current
Three-State Output Capacitance
POWER REQUIREMENTS
Positive Supply Voltage
V
DD
MAX146
MAX147
Operating mode, full-scale input
Positive Supply Current, MAX146
I
DD
V
DD
= 3.6V Fast power-down
Full power-down
Positive Supply Current, MAX147
Positive Supply Current, MAX147
Supply Rejection (Note 10)
I
DD
I
DD
PSR
Operating mode,
full-scale input
Full power-down
V
DD
= 5.25V
V
DD
= 3.6V
V
DD
= 5.25V
V
DD
= 3.6V
2.70
2.70
1.2
30
1.2
1.8
0.9
2.1
1.2
±0.3
3.60
5.25
2.0
70
10
2.5
1.5
15
10
V
mA
µA
mA
µA
µA
mV
V
OL
V
OH
I
L
C
OUT
I
SINK
= 5mA
I
SINK
= 16mA
I
SOURCE
= 0.5mA
CS
= V
DD
CS
= V
DD
(Note 9)
V
DD
- 0.5
±0.01
±10
15
0.4
0.8
V
V
µA
pF
V
IH
V
IL
V
HYST
I
IN
C
IN
V
SH
V
SM
V
SL
I
S
V
FLT
V
V
V
µA
pF
V
V
V
µA
V
nA
Full-scale input, external reference = 2.5V,
V
DD
= 2.7V to V
DD(MAX)
4
_______________________________________________________________________________________
+2.7V, Low-Power, 8-Channel,
Serial 12-Bit ADCs
TIMING CHARACTERISTICS
(V
DD
= +2.7V to +3.6V (MAX146); V
DD
= +2.7V to +5.25V (MAX147); T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
Acquisition Time
DIN to SCLK Setup
DIN to SCLK Hold
SCLK Fall to Output Data Valid
CS
Fall to Output Enable
CS
Rise to Output Disable
CS
to SCLK Rise Setup
CS
to SCLK Rise Hold
SCLK Pulse Width High
SCLK Pulse Width Low
SCLK Fall to SSTRB
CS
Fall to SSTRB Output Enable
CS
Rise to SSTRB Output Disable
SSTRB Rise to SCLK Rise
SYMBOL
t
ACQ
t
DS
t
DH
t
DO
t
DV
t
TR
t
CSS
t
CSH
t
CH
t
CL
t
SSTRB
t
SDV
t
STR
t
SCK
Figure 1
External clock mode only, Figure 1
External clock mode only, Figure 2
Internal clock mode only (Note 9)
0
Figure 1
Figure 1
Figure 2
100
0
200
200
240
240
240
MAX14_ _C/E
MAX14_
Figure 1 _M
CONDITIONS
MIN
1.5
100
0
20
20
200
240
240
240
TYP
MAX
UNITS
µs
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
MAX146/MAX147
Note 1:
Tested at V
DD
= 2.7V; COM = 0; unipolar single-ended input mode.
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:
MAX146—internal reference, offset nulled; MAX147—external reference (VREF = +2.5V), offset nulled.
Note 4:
Ground “on” channel; sine wave applied to all “off” channels.
Note 5:
Conversion time defined as the number of clock cycles multiplied by the clock period; clock has 50% duty cycle.
Note 6:
The common-mode range for the analog inputs is from AGND to V
DD
.
Note 7:
External load should not change during conversion for specified accuracy.
Note 8:
ADC performance is limited by the converter’s noise floor, typically 300µVp-p.
Note 9:
Guaranteed by design. Not subject to production testing.
Note 10:
Measured as
|
V
FS
(2.7V) - V
FS
(V
DD, MAX
)
|
.
Typical Operating Characteristics
(V
DD
= 3.0V, VREF = 2.5V, f
SCLK
= 2.0MHz, C
LOAD
= 20pF, T
A
= +25°C, unless otherwise noted.)
INTEGRAL NONLINEARITY
vs. CODE
0.5
0.4
0.3
0.2
INL (LSB)
INL (LSB)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
1024
2048
CODE
3072
4096
MAX146/47-01
INTEGRAL NONLINEARITY
vs. SUPPLY VOLTAGE
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
2.25
2.75
3.25
4.25
3.75
V
DD
(V)
4.75
5.25
MAX147
MAX146
INL (LSB)
MAX146/47-02
INTEGRAL NONLINEARITY
vs. TEMPERATURE
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
-60
-20
20
60
100
140
TEMPERATURE (°C)
MAX147
MAX146
V
DD
= 2.7V
MAX146/47-03
0.50
_______________________________________________________________________________________
5
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