19-1071; Rev 2; 10/01
KIT
ATION
EVALU
BLE
AVAILA
+2.7V, Low-Power, 4-Channel,
Serial 12-Bit ADCs in QSOP-16
Features
o
4-Channel Single-Ended or 2-Channel
Differential Inputs
o
Single-Supply Operation:
+2.7V to +3.6V (MAX1246)
+2.7V to +5.25V (MAX1247)
o
Internal 2.5V Reference (MAX1246)
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
16-Pin QSOP Package (same area as 8-pin SO)
General Description
The MAX1246/MAX1247 12-bit data-acquisition systems
combine a 4-channel multiplexer, high-bandwidth
track/hold, and serial interface with high conversion
speed and low power consumption. The MAX1246 oper-
ates from a single +2.7V to +3.6V supply; the MAX1247
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 MAX1246/
MAX1247 use either the internal clock or an external seri-
al-interface clock to perform successive-approximation
analog-to-digital conversions.
The MAX1246 has an internal 2.5V reference, while the
MAX1247 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 programmed to automatically shut down at the
end of a conversion. Accessing the serial interface auto-
matically powers up the MAX1246/MAX1247, and the
quick turn-on time allows them to be shut down between
all conversions. This technique can cut supply current to
under 60µA at reduced sampling rates. The MAX1246/
MAX1247 are available in a 16-pin DIP and a small QSOP
that occupies the same board area as an 8-pin SO.
For 8-channel versions of these devices, see the
MAX146/MAX147 data sheet.
MAX1246/MAX1247
Ordering Information
PART
MAX1246ACPE
MAX1246BCPE
MAX1246ACEE
MAX1246BCEE
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
16 Plastic DIP
16 Plastic DIP
16 QSOP
16 QSOP
INL
(LSB)
±1/2
±1
±1/2
±1
Ordering Information continued at end of data sheet.
________________________Applications
Portable Data Logging
Medical Instruments
Pen Digitizers
Data Acquisition
Battery-Powered Instruments
Process Control
0V TO
+2.5V
ANALOG
INPUTS
+3V
CH0
V
DD
DGND
V
DD
0.1µF
__________Typical Operating Circuit
MAX1246
AGND
CH3
VREF
COM
CS
SCLK
DIN
REFADJ
DOUT
SSTRB
SHDN
V
SS
I/O
SCK (SK)
MOSI (SO)
MISO (SI)
CPU
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, 4-Channel,
Serial 12-Bit ADCs in QSOP-16
MAX1246/MAX1247
ABSOLUTE MAXIMUM RATINGS
V
DD
to AGND, DGND................................................. -0.3V to 6V
AGND to DGND ...................................................... -0.3V to 0.3V
CH0–CH3, COM to AGND, DGND ............ -0.3V to (V
DD
+ 0.3V)
VREF 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 10.53mW/°C above +70°C) ......... 842mW
QSOP (derate 8.36mW/°C above +70°C) ................... 667mW
CERDIP (derate 10.00mW/°C above +70°C) .............. 800mW
Operating Temperature Ranges
MAX1246_C_E/MAX1247_C_E .......................... 0°C to +70°C
MAX1246_E_E/MAX1247_E_E........................ -40°C to +85°C
MAX1246_MJE/MAX1247_MJE .................... -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 (MAX1246); V
DD
= +2.7V to +5.25V (MAX1247); COM = 0V; f
SCLK
= 2.0MHz; external clock (50% duty cycle);
15 clocks/conversion cycle (133ksps); MAX1246—4.7µF capacitor at VREF pin; MAX1247—external reference, VREF = 2.5V applied
to VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
DC ACCURACY
(Note 1)
Resolution
MAX124_A
Relative Accuracy (Note 2)
No Missing Codes
Differential Nonlinearity
Offset Error
Gain Error (Note 3)
Gain Temperature Coefficient
Channel-to-Channel Offset
Matching
MAX124_A/MAX124_B
MAX1247C
Up to the 5th
harmonic
MAX1247C
65kHz, 2.500V
P-P
(Note 4)
-3dB rolloff
MAX124_A/MAX124_B
MAX1247C
80
70
INL
NMC
DNL
MAX124_A/MAX124_B
MAX124_C
MAX124_A
MAX124_B
±0.8
±0.5
±0.5
±0.5
±0.25
±0.25
±3
±4
±4
MAX124_B
MAX1247C
12
±1
12
±0.5
±1.0
±2.0
Bits
LSB
LSB
LSB
ppm/°C
LSB
LSB
Bits
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC SPECIFICATIONS
(10kHz sine-wave input, 0V to 2.500Vp-p, 133ksps, 2.0MHz external clock, bipolar input mode)
Signal-to-Noise + Distortion
Ratio
Total Harmonic Distortion
Spurious-Free Dynamic Range
Channel-to-Channel Crosstalk
Small-Signal Bandwidth
Full-Power Bandwidth
SINAD
THD
SFDR
73
73
-88
-88
90
90
-85
2.25
1.0
-80
dB
dB
dB
dB
MHz
MHz
MAX124_A/MAX124_B
2
_______________________________________________________________________________________
+2.7V, Low-Power, 4-Channel,
Serial 12-Bit ADCs in QSOP-16
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX1246); V
DD
= +2.7V to +5.25V (MAX1247); COM = 0V; f
SCLK
= 2.0MHz; external clock (50% duty cycle);
15 clocks/conversion cycle (133ksps); MAX1246—4.7µF capacitor at VREF pin; MAX1247—external reference, VREF = 2.5V applied
to VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
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
1.5
30
<50
SHDN
= FLOAT
SHDN
= V
DD
0.1
Data transfer only
Unipolar, COM = 0V
Bipolar, COM = VREF / 2
On/off leakage current, V
CH
_ = 0V or V
DD
16
T
A
= +25°C
MAX1246_C
VREF Temperature Coefficient
Load Regulation (Note 8)
Capacitive Bypass at VREF
Capacitive Bypass at REFADJ
REFADJ Adjustment Range
VREF Input Voltage Range
(Note 9)
VREF Input Current
VREF Input Resistance
Shutdown VREF Input Current
REFADJ Buffer Disable
Threshold
VDD -
0.5
VREF = 2.5V
18
V
BST
= V
LX
= V
IN
= 28V, V
FB
= 1.5V
EXTERNAL REFERENCE AT VREF
(Buffer disabled)
1.0
100
25
0.01
100
VDD +
50mV
150
V
V
kΩ
µA
V
MAX1246_E
MAX1246_M
0mA to 0.2mA output load
Internal compensation mode
External compensation mode
0
4.7
0.047
±1.5
2.480
2.500
±30
±30
±30
±0.35
2.520
30
±50
±60
±80
mV
µF
µF
%
ppm/°C
0
1.8
0.225
2.0
2.0
0 to VREF
±VREF / 2
±0.01
±1
µs
ns
ps
MHz
MHz
7.5
65
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1246/MAX1247
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
t
ACQ
V
µA
pF
V
mA
INTERNAL REFERENCE
(MAX1246 only, reference buffer enabled)
VREF Output Voltage
VREF Short-Circuit Current
_______________________________________________________________________________________
3
+2.7V, Low-Power, 4-Channel,
Serial 12-Bit ADCs in QSOP-16
MAX1246/MAX1247
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX1246); V
DD
= +2.7V to +5.25V (MAX1247); COM = 0V; f
SCLK
= 2.0MHz; external clock (50% duty cycle);
15 clocks/conversion cycle (133ksps); MAX1246—4.7µF capacitor at VREF pin; MAX1247—external reference, VREF = 2.5V applied
to VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Internal compensation mode
External compensation mode
MAX1246
MAX1247
MAX1246
MAX1247
MIN
0
4.7
2.06
2.00
±50
±10
TYP
MAX
UNITS
EXTERNAL REFERENCE AT REFADJ
Capacitive Bypass at VREF
Reference Buffer Gain
REFADJ Input Current
µF
V/V
µA
4
_______________________________________________________________________________________
+2.7V, Low-Power, 4-Channel,
Serial 12-Bit ADCs in QSOP-16
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +3.6V (MAX1246); V
DD
= +2.7V to +5.25V (MAX1247); COM = 0V; f
SCLK
= 2.0MHz; external clock (50% duty cycle);
15 clocks/conversion cycle (133ksps); MAX1246—4.7µF capacitor at VREF pin; MAX1247—external reference, VREF = 2.5V applied
to VREF pin; T
A
= T
MIN
to T
MAX
; unless otherwise noted.)
PARAMETER
SYMBOL
V
DD
≤
3.6V
V
DD
> 3.6V, MAX1247 only
CONDITIONS
MIN
2.0
3.0
0.8
0.2
V
IN
= 0V or V
DD
(Note 7)
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
MAX1246/MAX1247
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
MAX1246
MAX1247
Operating mode, full-scale input
Positive Supply Current, MAX1246
I
DD
V
DD
= 3.6V Fast power-down
Full power-down
Operating mode,
full-scale input
Positive Supply Current, MAX1247
I
DD
Fast power-down
Full power-down
Supply Rejection (Note 10)
PSR
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
30
3.5
1.2
±0.3
3.60
5.25
2.0
70
10
2.5
1.5
70
15
10
mV
µA
V
mA
µA
mA
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 7)
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
V
DD
= 2.7V to V
DD(MAX)
, full-scale input,
external reference = 2.500V
_______________________________________________________________________________________
5
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