Maxim MAX1245BEPP, MAX1245BEAP, MAX1245BCPP, MAX1245AEPP, MAX1245AEAP Datasheet

...
19-1066; Rev 0; 6/96
+2.375V, Low-Power, 8-Channel,
Serial 12-Bit ADC
________________General Description
The MAX1245 12-bit data-acquisition system combines an 8-channel multiplexer, high-bandwidth track/hold, and serial interface with high conversion speed and ultra-low power consumption. It operates from a single +2.375V to +3.3V supply, and its analog inputs are software config­urable for unipolar/bipolar and single-ended/differential operation.
The 4-wire serial interface directly connects to SPI™, QSPI™, and Microwire™ devices without external logic. A serial strobe output allows direct connection to TMS320-family digital signal processors. The MAX1245 works with an external reference, and uses either the internal clock or an external serial-interface clock to perform successive-approximation analog-to-digital conversions.
This device provides 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 powers up the MAX1245, and the quick turn-on time allows it to be shut down between conversions. This technique can cut supply current to under 10µA at reduced sampling rates.
The MAX1245 is available in a 20-pin DIP package and an SSOP that occupies 30% less area than an 8-pin DIP. For supply voltages from +2.7V to +5.25V, use the pin­compatible MAX147.
________________________Applications
Portable Data Logging Medical Instruments Battery-Powered Instruments Data Acquisition
___________T ypical Operating Circuit
+2.5V
+2.048V
ANALOG
INPUTS
+2.048V
0V to
0.1µF
CH0
CH7
VREF
MAX1245
V
DGND AGND
COM
CS
SCLK
DIN
DOUT
SSTRB
SHDN
DD
0.1µF
V
DD
CPU
I/O SCK (SK)*
MOSI (SO) MISO (SI)
V
SS
____________________________Features
Single +2.375V to +3.3V Operation8-Channel Single-Ended or 4-Channel
Differential Analog Inputs
Low Power: 0.8mA (100ksps)
10µA (1ksps) 1µA (power-down mode)
Internal Track/Hold, 100kHz Sampling RateSPI/QSPI/Microwire/TMS320-Compatible
4-Wire Serial Interface
Software-Configurable Unipolar or Bipolar Inputs20-Pin DIP/SSOP Packages
________________Ordering Information
PART
MAX1245ACPP MAX1245BCPP MAX1245ACAP 0°C to +70°C MAX1245BCAP 0°C to +70°C 20 SSOP MAX1245BC/D 0°C to +70°C Dice*
Ordering Information continued at end of data sheet.
Contact factory for availability of alternate surface-mount
TEMP. RANGE PIN-PACKAGE
0°C to +70°C 0°C to +70°C
20 Plastic DIP 20 Plastic DIP 20 SSOP
packages.
*
Contact factory for availability.
INL
(LSB)
±1/2 ±1 ±1/2 ±1 ±1
___________________Pin Configuration
TOP VIEW
CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7
COM
1 2 3 4 5 6 7 8 9
10
MAX1245
DIP/SSOP
20
V
DD
19
SCLK
18
CS
17
DIN
16
SSTRB DOUT
15
DGND
14 13
AGND V
12
DD
11
VREFSHDN
MAX1245
SPI and QSPI are registered trademarks of Motorola, Inc. Microwire is a registered trademark of National Semiconductor Corp.
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
+2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC
ABSOLUTE MAXIMUM RATINGS
VDDto AGND, DGND.............................................. -0.3V to +6V
AGND to DGND.................................................... -0.3V to +0.3V
CH0–CH7, COM to AGND, DGND............ -0.3V to (V
VREF to AGND........................................... -0.3V to (V
Digital Inputs to DGND............................................ -0.3V to +6V
Digital Outputs to DGND........................... -0.3V to (V
Digital Output Sink Current.................................................25mA
Continuous Power Dissipation (T
MAX1245
Plastic DIP (derate 11.11mW/°C above +70°C) ......... 889mW
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.
= +70°C)
A
DD DD
DD
+ 0.3V) + 0.3V)
+ 0.3V)
ELECTRICAL CHARACTERISTICS
(VDD= +2.375V to +3.3V, COM = 0V, f VREF = 2.048V applied to VREF pin, T
DC ACCURACY (Note 1)
Differential Nonlinearity Offset Error
Channel-to-Channel Offset Matching
DYNAMIC SPECIFICATIONS (10kHz sine-wave input, 0Vp-p to 2.048Vp-p, 100ksps, 1.5MHz external clock, bipolar input mode)
CONVERSION RATE
Conversion Time (Note 5)
Track/Hold Acquisition Time External clock = 1.5MHz
Internal Clock Frequency
External Clock Frequency
= 1.5MHz, external clock (50% duty cycle), 15 clocks/conversion cycle (100ksps),
CLK
= T
to T
A
INLRelative Accuracy (Note 2)
t
CONV
ACQ
MIN
, unless otherwise noted.)
MAX
MAX1245A MAX1245B No missing codes over temperature
Up to the 5th harmonic
50kHz, 2V
-3dB rolloff
Internal clock, SHDN = FLOAT Internal clock, SHDN = V External clock = 1.5MHz, 12 clocks/conversion
SHDN = FLOAT SHDN = V
Data transfer only
p-p
DD
(Note 4)
SSOP (derate 8.00mW/°C above +70°C) ................... 640mW
CERDIP (derate 11.11mW/°C above +70°C).............. 889mW
Operating Temperature Ranges
MAX1245_C_P................................................... 0°C to +70°C
MAX1245_E_P ................................................ -40°C to +85°C
Storage Temperature Range............................ -60°C to +150°C
Lead Temperature (soldering, 10sec)............................ +300°C
CONDITIONS
±0.5 ±1.0
5.5 7.5
DD
35 65
8
1.5
0.225
0.1 1.5 0 1.5
UNITSMIN TYP MAXSYMBOLPARAMETER
ppm/°C±0.25Gain Temperature Coefficient
Bits12Resolution LSB LSB±1DNL
LSB±0.5 ±4 LSBGain Error (Note 3) ±0.5 ±4
LSB±0.2
dB68SINADSignal-to-Noise + Distortion Ratio dB-76THDTotal Harmonic Distortion dB76SFDRSpurious-Free Dynamic Range
dB-85Channel-to-Channel Crosstalk MHz2.25Small-Signal Bandwidth MHz1.0Full-Power Bandwidth
µs
µs2.0t ns40Aperture Delay
ps<50Aperture Jitter MHz
MHz
2 _______________________________________________________________________________________
+2.375V, Low-Power, 8-Channel,
Serial 12-Bit ADC
ELECTRICAL CHARACTERISTICS (continued)
(VDD= +2.375V to +3.3V, COM = 0V, f VREF = 2.048V applied to VREF pin, T
ANALOG/COM INPUTS
Input Voltage Range, Single­Ended and Differential (Note 6)
Multiplexer Leakage Current
EXTERNAL REFERENCE
VREF Input Voltage Range (Note 8)
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 Low Voltage SHDN Input Current
SHDN Input Mid Voltage 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 Positive Supply Current
= 1.5MHz, external clock (50% duty cycle), 15 clocks/conversion cycle (100ksps),
CLK
= T
to T
A
INH
INL
HYST
IN
IN
INH
INL IN
V
IM
FLT
V
OL
OH
L
OUT
DD
I
DD
MIN
, unless otherwise noted.)
MAX
CONDITIONS
Unipolar, COM = 0V Bipolar, COM = VREF/2 On/off leakage current, VIN= 0V or V (Note 7)
VREF = 2.048V
VIN= 0V or V (Note 7)
SHDN = 0V or V
SHDN = open SHDN = open
I
SINK
I
SINK
I
SOURCE
CS = V CS = VDD(Note 7)
Operating mode, full-scale input
VDD= 2.375V to 3.3V, full-scale input, external reference = 2.048V
DD
DD
= 5mA = 16mA
=0.5mA
DD
DD
0 to VREF
±VREF/2
V
0.5
1.2 10Power-down
DD
50mV
0.4
1.0
VDD/2 VDD/2
- 0.3 + 0.3
MAX1245
UNITSMIN TYP MAXSYMBOLPARAMETER
V
µA±0.01 ±1
pF16Input Capacitance
+
V
µA82 120VREF Input Current k18 25VREF Input Resistance µA0.01 10Shutdown VREF Input Current
V2.0V V0.8V V0.2V
µA±0.01 ±1I
pF15C
VVDD- 0.4V V0.4V
µA±4.0I
V VVDD/2V
nA±80
V VVDD - 0.375V
µA±0.01 ±10I
pF15C
V2.375 3.3V
mA0.8 1.3
µA mV±0.3PSRSupply Rejection (Note 9)
_______________________________________________________________________________________ 3
+2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC
TIMING CHARACTERISTICS
(VDD= +2.375V to +3.3V, COM = 0V, TA= T
PARAMETER
Acquisition Time DIN to SCLK Setup DIN to SCLK Hold SCLK Fall to Output Data Valid
MAX1245
CS Fall to Output Enable CS Rise to Output Disable CS to SCLK Rise Setup CS to SCLK Rise Hold
SCLK Pulse Width Low SCLK Fall to SSTRB ns
CS Fall to SSTRB Output Enable CS Rise to SSTRB Output Disable
SSTRB Rise to SCLK Rise
Note 1: Tested at V Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the full-scale range has
= +2.375V; COM = 0V; unipolar single-ended input mode.
DD
been calibrated.
Note 3: External reference (VREF = +2.048V), 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 Note 7: Guaranteed by design. Not subject to production testing. Note 8: ADC performance is limited by the converter’s noise floor, typically 300µVp-p. Note 9: Measured as
VFS(2.375V) - VFS(3.3V)|.
|
to T
MIN
, unless otherwise noted.)
MAX
CONDITIONS
ACQ
DS DH
t
Figure 1 ns20 260
DO
Figure 1
DV
Figure 2
TR
CSS
t
CSH
t
CH CL
Figure 1
SSTRB
External clock mode only, Figure 1
SDV
External clock mode only, Figure 2
STR
Internal clock mode only (Note 7)
SCK
DD
.
300t
0t
260t
UNITSMIN TYP MAXSYMBOL
µs2.0t ns200t ns0t
ns240t ns400t ns200t ns0 ns300SCLK Pulse Width High ns
ns240t ns400t ns
__________________________________________Typical Operating Characteristics
(VDD= 2.5V, VREF = 2.048V, f
SUPPLY CURRENT
1.25
1.00
(mA)
DD
I
0.75
0.50
vs. SUPPLY VOLTAGE
RL =  CODE = 101010100000
C
= 50pF
LOAD
2.625
2.375
C
= 20pF
LOAD
2.875 (V)
V
DD
4 _______________________________________________________________________________________
= 1.5MHz, C
CLK
3.125
3.375
LOAD
0.90
MAX1245-01
0.85
0.80
(mA)
DD
I
0.75
0.70
0.65
-55 -30 70
= 20pF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT 
vs. TEMPERATURE
RL =  CODE = 101010100000
20 145120-5 45 95
TEMPERATURE (°C)
MAX1245-02
0.50
0.45
0.40
0.35
0.30
0.25
INL (LSB)
0.20
0.15
0.10
0.05
0.00
2.375
INTEGRAL NONLINEARITY
vs. SUPPLY VOLTAGE
2.875
V
(V)
DD
3.3753.1252.625
MAX1245-03
+2.375V, Low-Power, 8-Channel,
Serial 12-Bit ADC
____________________________Typical Operating Characteristics (continued)
(VDD= 2.5V, VREF = 2.048V, f
INTEGRAL NONLINEARITY
0.50
0.45
0.40
0.35
0.30
0.25
INL (LSB)
0.20
0.15
0.10
0.05 0
-55 -30 45
vs. TEMPERATURE
VDD = 2.375V
20-5 70 95 145120
TEMPERATURE (˚C)
CHANNEL-TO-CHANNEL OFFSET MATCHING 
0
2.375
vs. SUPPLY VOLTAGE
2.875
V
(V)
DD
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
OFFSET MATCHING (LSB)
0.10
0.05
GAIN ERROR 
0.50
0.45
0.40
0.35
0.30
0.25
0.20
GAIN ERROR (LSB)
0.15
0.10
0.05 0
vs. TEMPERATURE
-55
-5 45 120
-30 20 TEMPERATURE (˚C)
CLK
3.1252.625
70
= 1.5MHz, C
95
MAX1245-04
MAX1245-07
3.375
MAX1245-10
145
= 20pF, TA = +25°C, unless otherwise noted.)
LOAD
OFFSET vs. SUPPLY VOLTAGE
0.50
0.45
0.40
0.35
0.30
0.25
0.20
OFFSET (LSB)
0.15
0.10
0.05 0
2.375
CHANNEL-TO-CHANNEL OFFSET MATCHING 
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
OFFSET MATCHING (LSB)
0.10
0.05 0
-55
-30 45
CHANNEL-TO-CHANNEL GAIN MATCHING 
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
GAIN MATCHING (LSB)
0.10
0.05 0
2.375
2.875
V
(V)
DD
vs. TEMPERATURE
20
-5 TEMPERATURE (˚C)
70
vs. SUPPLY VOLTAGE
2.875
2.625 V
(V)
DD
3.1252.625
95
MAX1245-05
3.375
MAX1245-08
145120
MAX1245-11
3.3753.125
OFFSET vs. TEMPERATURE
0.50
0.45
0.40
0.35
0.30
0.25
0.20
OFFSET (LSB)
0.15
0.10
0.05 0
-55 -30
20-5 70 14512095
45
TEMPERATURE (˚C)
GAIN ERROR 
0
2.375 2.875 3.3753.1252.625
vs. SUPPLY VOLTAGE
V
(V)
DD
0.50
0.45
0.40
0.35
0.30
0.25
0.20
GAIN ERROR (LSB)
0.15
0.10
0.05
CHANNEL-TO-CHANNEL GAIN MATCHING 
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
GAIN MATCHING (LSB)
0.10
0.05 0
-55
vs. TEMPERATURE
-30
-5 45 TEMPERATURE (˚C)
20
MAX1245
MAX1245-06
MAX1245-09
MAX1245-12
1451209570
_______________________________________________________________________________________
5
+2.375V, Low-Power, 8-Channel, Serial 12-Bit ADC
____________________________Typical Operating Characteristics (continued)
(VDD= 2.5V, VREF = 2.048V, f
= 1.5MHz, C
CLK
= 20pF, TA = +25°C, unless otherwise noted.)
LOAD
1000
MAX1245
0.25
0.20
0.15
0.10
0.05 0
INL (BITS)
-0.05
-0.10
-0.15
-0.20
-0.25
100
(µA)
10
DD
I
1
0.1
0

AVERAGE SUPPLY CURRENT 
vs. CONVERSION RATE
V
VREF = 2.5V
DD =
CODE = 101010100000
=
R
L
8 CHANNELS
1 CHANNEL
0.1
CONVERSIONS PER CHANNEL PER SECOND (Hz)
101 1k 10k100 100k
MAX1245-13
INTEGRAL NONLINEARITY
  
2048
DIGITAL CODE
4096
12.0
11.5
11.0
10.5
EFFECTIVE NUMBER OF BITS
10.0 1 10 100
20
0
-20
-40
-60
AMPLITUDE (dB)
-80
-100
-120 0

EFFECTIVE NUMBER OF BITS
vs. INPUT FREQUENCY
MAX1245-14
INPUT FREQUENCY (kHz)
FFT PLOT
f
= 10ksps
TONE
= 100ksps
f
SAMPLE
  
10 20 30 40 50
FREQUENCY (kHz)
6 _______________________________________________________________________________________
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