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The technical content of this austriamicrosystems datasheet is still valid.
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AS1538/AS1540
8 / 4 - C h a n n e l , 1 2 - B i t I ² C A n a l o g - t o - D i g i ta l C o n v e r t e r
Data Sheet
1 General Description
The AS1538/AS1540 are single-supply, low-power, 12-
bit data acquisition devices featuring a serial I²C inter-
face and an 8-channel (AS1538) or 4-channel (AS1540)
multiplexer.
The analog-to-digital (A/D) converters features a sam-
ple-and-hold amplifier an internal asynchronous clock
and an internal reference.
The combination of an I C serial, 2-wire interface and
micropower consumption makes the AS1538 and
AS1540 ideal for applications requiring the A/D con-
verter to be close to the input source in remote locations
and for applications requiring isolation.
2
2 Key Features
!
!
!
!
!
!
!
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!
Single Supply: 2.7 to 5.25V
4-Channel Multiplexer (AS1540)
Sampling Rate: 50kSPS
No Missing Codes
Internal Reference: 2.5V
2
The device is available in a TSSOP-16 or TQFN 4x4 16-
pin package.
Figure 1. Block Diagram
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AS1538 only
REF
IN/OUT
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High Speed I C Interface at 3.4MHz
<1.5µA Full Shutdown Current
TSSOP-16 or TQFN 4x4 16-pin Package
3 Applications
The device is ideal for voltage-supply monitoring, iso-
lated data acquisition, transducer interfaces, battery-
operated systems, remote data acquisition or any other
analog-to-digital conversion application.
CH0
Successive Approximation Register
CH1
CH2
CH3
CH4
CH5
CH6
CH7
AS1538/AS1540
8-Channel
MUX
Sample/
Hold
Amp
CDAC
Comparator
COM
Buffer
Internal
2.5V
Reference
Revision 1.03
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SDA
Serial
Interface
SCL
A0
A1
GND
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8-Channel Multiplexer (AS1538)
AS1538/AS1540
Data Sheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
+V
DD
SDA
CH0
N/C
CH1 2
CH2 3
CH3 4
CH4 5
CH5 6
CH6 7
CH7 8
15 SDA
14 SCL
CH1
CH2
CH3
N/C
1
2
16
15
14
13
12 SCL
11 A1
AS1538
13 A1
12 A0
11 COM
10 REF
IN/OUT
9 GND
AS1540
3
4
5
N/C
6
GND
7
REF
IN/OUT
Pin Descriptions
AS1538
-
1:8
9
10
11
12
13
14
15
16
-
Table 1. Pin Descriptions
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AS1540
1:3,16
-
6
7
8
10
11
12
13
15
4, 5, 9, 14
Pin Name
CH0:CH3
CH0:CH7
GND
REF
IN/OUT
COM
A0
A1
SCL
SDA
+V
DD
NC
Description
Analog Input Channels 0 to 3
Analog Input Channels 0 to 7
Analog Ground
Internal Reference/External Reference Input
Analog Input Channel Common
Slave Address Bit 0
Slave Address Bit 1
Serial Clock
Serial Data
Power Supply Input.
2.7 to 5.25V.
Not Connected
Revision 1.03
2 - 20
COM
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9
N/C
8
10 A0
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CH0 1
16 +V
DD
AS1538/AS1540
Data Sheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in
Table 2
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
Electrical Character-
istics on page 4
is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Table 2. Absolute Maximum Ratings
+V
DD
to GND
Digital Input Voltage to GND
Thermal Resistance
θ
JA
Operating Temperature Range
Storage Temperature Range
Junction Temperature (T
JMAX
)
ESD
-0.3
-0.3
+6
+V
DD
+
0.3
100
V
V
°C/W
ºC
ºC
ºC
kV
on PCB
-40
-65
1.5
+85
+150
150
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Package Body Temperature
+260
ºC
Revision 1.03
HBM MIL-Std. 883E 3015.7
methods
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/JEDEC J-STD-020C “Moisture/Reflow
Sensitivity Classification for Non-Hermetic
Solid State Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
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Parameter
Min
Max
Units
Comments
AS1538/AS1540
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
Electrical Characteristics
+V
DD
=
+2.7
to +5.25V, V
REF
=
+2.5V
external, SCL = 3.4MHz, T
AMB
= -40 to +85ºC (unless otherwise specified).
Table 3. Electrical Characteristics
Fullscale Input Span
Absolute Input Range
Positive input, negative input
Positive input
Negative Input
0
-0.3
-0.3
V
REF
+V
DD
+ 0.3
Capacitance
Leakage Current
Static Performance
I
LEAK
Track Mode
Hold Mode
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±0.1
±1
No Missing Codes
12
Integral Linearity Error
Offset Error
V
REF
= 2.5V, 1 LSB = 610µV
±0.75
±0.5
±0.5
±1.5
±1
±6
Differential Linearity Error
1
Offset Error Match
Gain Error
Gain Error Match
1
Power Supply Rejection
Dynamic Performance
Throughput Frequency
Conversion Time
AC Accuracy
THD
Total Harmonic Distortion
Signal-to-Noise Ratio
2
V
IN
= 2.5V
P-P
@ 10kHz
V
IN
= 2.5V
P-P
@ 10kHz
V
IN
= 2.5V
P-P
@ 10kHz
Signal-to-Noise (+ Distortion)
Ratio
Spurious-Free Dynamic Range
Voltage Reference Output
Range
Internal Reference Drift
Output Impedance
V
IN
= 2.5V
P-P
@ 10kHz
2.475
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Quiescent Current
Voltage Reference Input
Range
PD = 01 Internal Ref. OFF, ADC ON
@ 50kSPS
1
Input Resistance
Reference Input Current
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Revision 1.03
lv
15
8
pF
µA
Bits
LSB
LSB
LSB
LSB
LSB
LSB
mV
kHz
µs
dB
dB
dB
dB
V
ppm/ºC
Ω
µA
V
DD
1
4
V
GΩ
µA
±0.2
±1
±1
±6
±0.2
1
±1
50
6.67
-75
72
69.5
75
2.5
30
30
2.525
440
4 - 20
al
V
V
+V
DD
+ 0.3
id
V
Symbol
Analog Input
Parameter
Condition
Min
Typ
Max
Unit
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