19-3720; Rev 1; 10/09
1.5V to 3.6V, 416ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 8-Bit, SAR ADCs
General Description
The MAX1391/MAX1394 micropower, serial-output,
8-bit, analog-to-digital converters (ADCs) operate with a
single power supply from +1.5V to +3.6V. These ADCs
feature automatic shutdown, fast wake-up, and a high-
speed 3-wire interface. Power consumption is only
0.743mW (V
DD
= +1.5V) at the maximum conversion
rate of 416ksps. AutoShutdown™ between conversions
reduces power consumption at slower throughput rates.
The MAX1391/MAX1394 require an external reference
V
REF
that has a wide range from 0.6V to V
DD
. The
MAX1391 provides one true-differential analog input
that accepts signals ranging from 0 to V
REF
(unipolar
mode) or ±V
REF
/2 (bipolar mode). The MAX1394 pro-
vides two single-ended inputs that accept signals rang-
ing from 0 to V
REF
. Analog conversion results are
available through a 5MHz 3-wire SPI™-/QSPI™-/
MICROWIRE™-/digital signal processor (DSP)-compati-
ble serial interface. Excellent dynamic performance,
low voltage, low power, ease of use, and small pack-
age sizes make these converters ideal for portable bat-
tery-powered data-acquisition applications, as well as
other applications that demand low-power consumption
and minimal space.
The MAX1391/MAX1394 are available in a space-sav-
ing (3mm x 3mm), 10-pin TDFN package. The parts
operate over the extended (-40°C to +85°C) tempera-
ture range.
Features
♦
416ksps, 8-Bit Successive-Approximation
Register (SAR) ADCs
♦
Single True-Differential Analog Input Channel
with Unipolar-/Bipolar-Selected Input (MAX1391)
♦
Dual Single-Ended Input Channel with Channel-
Selected Input (MAX1394)
♦
±0.2 LSB INL, ±0.2 LSB DNL, No Missing Codes
♦
±0.25 LSB Total Unadjusted Error (TUE)
♦
49dB SINAD at 100kHz Input Frequency
♦
Single-Supply Voltage (+1.5V to +3.6V)
♦
0.97mW at 416ksps, 1.8V
♦
0.230mW at 100ksps, 1.8V
♦
3.1µW at 1ksps, 1.8V
♦
< 1µA Shutdown Current
♦
External Reference (0.6V to V
DD
)
♦
AutoShutdown Between Conversions
♦
SPI-/QSPI-/MICROWIRE-/DSP-Compatible,
3- or 4-Wire Serial Interface
♦
Small (3mm x 3mm), 10-Pin TDFN
MAX1391/MAX1394
Applications
Portable Datalogging
Data Acquisition
Medical Instruments
Battery-Powered Instruments
Process Control
Typical Operating Circuit and Pin Configurations appear at
end of data sheet.
AutoShutdown is a trademark of Maxim Integrated Products, Inc.
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
Ordering Information
PART
MAX1391ETB+
MAX1394ETB+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 TDFN-EP*
10 TDFN-EP*
ANALOG INPUTS
1-CH DIFF
2-CH S/E
TOP MARK
AOX
APA
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1.5V to 3.6V, 416ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 8-Bit, SAR ADCs
MAX1391/MAX1394
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND ..............................................................-0.3V to +4V
SCLK,
CS, OE, CH1/CH2,
UNI/BIP,
DOUT to GND.........................................-0.3V to (V
DD
+ 0.3V)
AIN+, AIN-, AIN1, AIN2, REF to GND ........-0.3V to (V
DD
+ 0.3V)
Maximum Current into Any Pin .........................................±50mA
Continuous Power Dissipation (T
A
= +70°C)
10-Pin TDFN (derate 18.5mW/°C above +70°C) ....1481.5mW
Operating Temperature Ranges
MAX139_E_ _...................................................-40°C to +85°C
Junction Temperature ......................................................+150°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
= +1.5V to +3.6V, V
REF
= V
DD
, C
REF
= 0.1µF, f
SCLK
= 5MHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
DC ACCURACY (Note 2)
Resolution
Integral Nonlinearity
Differential Nonlinearity
Offset Error
Gain Error
Total Unadjusted Error
Offset-Error Temperature
Coefficient
Gain-Error Temperature
Coefficient
Channel-to-Channel Offset
Matching
Channel-to-Channel Gain
Matching
Input Common-Mode Rejection
DYNAMIC SPECIFICATIONS (Note 3)
Signal-to-Noise Plus Distortion
Signal-to-Noise Ratio
Total Harmonic Distortion
Spurious-Free Dynamic Range
Intermodulation Distortion
Channel-to-Channel Crosstalk
Full-Power Bandwidth
Full-Linear Bandwidth
CONVERSION RATE
Conversion Time
t
CONV
9 clock cycles per conversion
1.8
µs
SINAD
SNR
THD
SFDR
IMD
f
IN1
= 98kHz at -6.5dBFS,
f
IN2
= 102kHz at -6.5dBFS
MAX1394 only
-3dB point
SINAD > 48dB
MAX1391
MAX1394
-73
-70
4
200
150
49
49
-65
-66
dB
dB
dBc
dBc
dB
dB
MHz
kHz
CMR
MAX1394 only
MAX1394 only
V
CM
= 0 to V
DD
, MAX1391 only
TUE
±25
±0.06
±0.05
±0.05
±0.1
Offset nulled
INL
DNL
No missing code overtemperature
8
±0.2
±0.2
±0.15
±0.15
±0.25
Bits
LSB
LSB
LSB
LSB
LSB
mLSB/°C
mLSB/°C
LSB
LSB
mV/V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
1.5V to 3.6V, 416ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 8-Bit, SAR ADCs
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +1.5V to +3.6V, V
REF
= V
DD
, C
REF
= 0.1µF, f
SCLK
= 5MHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
Throughput Rate
Power-Up and Acquisition Time
Aperture Delay
Aperture Jitter
Serial-Clock Frequency
t
ACQ
t
AD
t
AJ
f
CLK
Unipolar
Bipolar, MAX1391 only, (AIN+ - AIN-)
Bipolar, MAX1391 only, [(AIN+) + (AIN-)] / 2
Channel not selected, or conversion
stopped, or in shutdown mode
16
V
DD
+
0.05
24
0.025
416ksps
20
±2.5
60
0.3 x
V
DD
0.7 x
V
DD
0.06 x
V
DD
I
IL
C
IN
Inputs at GND or V
DD
CS, OE
CH1/CH2,
UNI/BIP
1
12.5
0.1 x
V
DD
0.9 x
V
DD
±1
10
1.5
3.6
±1
0.1
0
-V
REF
/2
0
SYMBOL
CONDITIONS
12 clocks per conversion, includes power-
up acquisiton and conversion time
Three SCLK cycles
600
8
30
5.0
V
REF
+V
REF
/2
V
DD
±1.5
MIN
TYP
MAX
416
UNITS
ksps
ns
ns
ps
MHz
MAX1391/MAX1394
ANALOG INPUTS (AIN+, AIN-, AIN1, AIN2)
Input Voltage Range
Common-Mode Input Voltage
Range
Input Leakage Current
Input Capacitance
REFERENCE INPUT (REF)
REF Input Voltage Range
REF Input Capacitance
REF DC Leakage Current
REF Input Dynamic Current
DIGITAL INPUTS (SCLK,
CS, OE, CH1/CH2,
UNI/BIP)
Input-Voltage Low
Input-Voltage High
Input Hysteresis
Input Leakage Current
Input Capacitance
DIGITAL OUTPUT (DOUT)
Output-Voltage Low
Output-Voltage High
Tri-State Leakage Current
Tri-State Output Capacitance
POWER SUPPLY
Positive Supply Voltage
V
DD
V
V
OL
V
OH
I
LT
C
OUT
I
SINK
= 2mA
I
SOURCE
= 2mA
OE
= V
DD
OE
= V
DD
V
V
µA
pF
V
IL
V
IH
V
V
V
µA
pF
V
REF
0.6
V
pF
µA
µA
V
IN
V
CM
V
V
µA
pF
_______________________________________________________________________________________
3
1.5V to 3.6V, 416ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 8-Bit, SAR ADCs
MAX1391/MAX1394
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +1.5V to +3.6V, V
REF
= V
DD
, C
REF
= 0.1µF, f
SCLK
= 5MHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
f
SAMPLE
= 100ksps
Positive Supply Current (Note 4)
I
DD
f
SAMPLE
= 416ksps
Power-down mode (Note 5)
Power-down mode (Note 6)
Power-Supply Rejection
PSR
V
DD
= 1.6V to 3.6V, full-scale input (Note 7)
V
DD
= 1.6V
V
DD
= 3V
V
DD
= 1.6V
V
DD
= 3V
MIN
TYP
125
150
520
710
5
0.2
±150
MAX
150
200
600
800
10
±2.5
±1000
µV/V
µA
UNITS
TIMING CHARACTERISTICS
(V
DD
= +1.5V to +3.6V, V
REF
= V
DD
, C
REF
= 0.1µF, f
SCLK
= 5MHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Figure 1)
PARAMETER
SCLK Clock Period
SCLK Pulse-Width High
SCLK Pulse-Width Low
CS
Fall to SCLK Rise Setup
SCLK Rise to
CS
Fall Ignore
SCLK Fall to DOUT Valid
OE
Rise to DOUT Disable
OE
Fall to DOUT Enable
CS
Pulse-Width High and Low
OE
Pulse-Width High and Low
CH1/CH2
Setup Time (to the First
SCLK)
CH1/CH2
Hold Time (to the First
SCLK)
UNI/BIP Setup Time (to the First
SCLK)
UNI/BIP Hold Time (to the First
SCLK)
SYMBOL
t
CP
t
CH
t
CL
t
CSS
t
CSO
t
DOV
t
DOD
t
DOE
t
CSW
t
OEW
t
CHS
t
CHH
t
UBS
t
UBH
MAX1394 only
MAX1394 only
MAX1391 only
MAX1391 only
80
80
10
0
10
0
C
LOAD
= 0 to 30pF
CONDITIONS
MIN
200
90
90
80
0
10
6
9
80
20
20
TYP
MAX
10,000
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Devices are production tested at room and +85°C. Specification to -40°C are guaranteed by design.
V
DD
= 1.6V, V
REF
= 1.6V, and V
AIN
= 1.6V.
V
DD
= 1.6V, V
REF
= 1.6V, V
AIN
= 1.6V
P-P
, f
SCLK
= 5MHz, f
SAMPLE
= 416ksps, and f
IN
(sine wave) = 100kHz.
All digital inputs swing between V
DD
and GND. V
REF
= V
DD
, f
IN
= 100kHz sine wave, V
AIN
= V
REFP-P,
C
LOAD
= 30pF on DOUT.
CS
= V
DD
,
OE
= UNI/BIP =
CH1/CH2
= V
DD
or GND, SCLK is active.
CS
= V
DD
,
OE
= UNI/BIP =
CH1/CH2
= V
DD
or GND, SCLK is inactive.
Change in V
AIN
at code boundary 254.5.
4
_______________________________________________________________________________________
1.5V to 3.6V, 416ksps, 1-Channel True-Differential/
2-Channel Single-Ended, 8-Bit, SAR ADCs
MAX1391/MAX1394
UNI/BIP OR
CH1/CH2
t
CHS
OE
t
UBS
t
CHH
t
UBH
t
OEW
CS
t
CSO
SCLK
t
DOE
t
CP
t
DOV
DOUT
HIGH-Z
t
DOD
HIGH-Z
t
CSS
t
CL
t
CH
t
CSW
Figure 1. Detailed Serial-Interface Timing Diagram
V
DD
6kΩ
DOUT
DOUT
6kΩ
50pF
GND
50pF
GND
b) HIGH IMPEDANCE TO V
OL
, V
OH
TO V
OL
,
AND V
OL
TO HIGH IMPEDANCE
a) HIGH IMPEDANCE TO V
OH
, V
OL
TO V
OH
,
AND V
OH
TO HIGH IMPEDANCE
Figure 2. Load Circuits for Enable/Disable Times
_______________________________________________________________________________________
5
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