LTC1594/LTC1598
4- and 8-Channel,
Micropower Sampling
12-Bit Serial I/O A/D Converters
FEATURES
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DESCRIPTIO
12-Bit Resolution
Auto Shutdown to 1nA
Low Supply Current: 320μA Typ
Guaranteed
±3/4LSB
Max DNL
Single Supply 5V Operation
(3V Versions Available: LTC1594L/LTC1598L)
Multiplexer: 4-Channel MUX (LTC1594)
8-Channel MUX (LTC1598)
Separate MUX Output and ADC Input Pins
MUX and ADC May Be Controlled Separately
Sampling Rate: 16.8ksps
I/O Compatible with QSPI, SPI and MICROWIRE
TM
, etc.
Small Package: 16-Pin Narrow SO (LTC1594)
24-Pin SSOP (LTC1598)
The LTC
®
1594/LTC1598 are micropower, 12-bit sampling
A/D converters that feature 4- and 8-channel multiplexers,
respectively. They typically draw only 320μA of supply
current when converting and automatically power down to
a typical supply current of 1nA between conversions. The
LTC1594 is available in a 16-pin SO package and the
LTC1598 is packaged in a 24-pin SSOP. Both operate on
a 5V supply. The 12-bit, switched-capacitor, successive
approximation ADCs include a sample-and-hold.
On-chip serial ports allow efficient data transfer to a wide
range of microprocessors and microcontrollers over three
or four wires. This, coupled with micropower consump-
tion, makes remote location possible and facilitates trans-
mitting data through isolation barriers.
The circuit can be used in ratiometric applications or with
an external reference. The high impedance analog inputs
and the ability to operate with reduced spans (to 1.5V full
scale) allow direct connection to sensors and transducers
in many applications, eliminating the need for gain stages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Pen Screen Digitizing
Battery-Operated Systems
Remote Data Acquisition
Isolated Data Acquisition
Battery Monitoring
Temperature Measurement
TYPICAL APPLICATIO
OPTIONAL
ADC FILTER
1k
1μF
18
MUXOUT
20 CH0
21 CH1
22 CH2
ANALOG
INPUTS
0V TO 5V
RANGE
23 CH3
24 CH4
1 CH5
2 CH6
3 CH7
8 COM
8-CHANNEL
MUX
24μW, 4-Channel, 12-Bit ADC Samples at 200Hz and Runs Off a 5V Supply
Supply Current vs Sample Rate
5V
17
ADCIN
16
15, 19
V
REF
V
CC
10
6
5, 14
7
11
12
13
1
0.1
1
10
SAMPLE FREQUENCY (kHz)
100
1594/98 TA02
1000
1μF
SERIAL DATA LINK
MICROWIRE AND
SPI COMPATABLE
SUPPLY CURRENT (μA)
100
CSADC
CSMUX
+
12-BIT
SAMPLING
ADC
CLK
D
IN
D
OUT
NC
MPU
–
GND
4, 9
NC
1594/98 TA01
U
T
A
= 25°C
V
CC
= 5V
V
REF
= 5V
f
CLK
= 320kHz
10
15948fb
U
U
1
LTC1594/LTC1598
ABSOLUTE
(Notes 1, 2)
AXI U RATI GS
Power Dissipation .............................................. 500mW
Operating Temperature Range
LTC1594CS/LTC1598CG ......................... 0°C to 70°C
LTC1594IS/LTC1598IG ..................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Supply Voltage (V
CC
) to GND ................................... 12V
Voltage
Analog Reference .................... – 0.3V to (V
CC
+ 0.3V)
Analog Inputs .......................... – 0.3V to (V
CC
+ 0.3V)
Digital Inputs .........................................– 0.3V to 12V
Digital Output .......................... – 0.3V to (V
CC
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CH0 1
CH1 2
CH2 3
CH3 4
ADCIN 5
V
REF
6
COM 7
GND 8
16 V
CC
15 MUXOUT
14 D
IN
13 CSMUX
12 CLK
11 V
CC
10 D
OUT
9
CSADC
ORDER PART
NUMBER
LTC1594CS
LTC1594IS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 120°C/ W
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
RECO
SYMBOL
V
CC
f
CLK
t
CYC
t
hDI
t
suCS
t
suDI
t
WHCLK
t
WLCLK
t
WHCS
t
WLCS
E DED OPERATI G CO DITIO S
CONDITIONS
V
CC
= 5V
f
CLK
= 320kHz
V
CC
= 5V
V
CC
= 5V
V
CC
= 5V
V
CC
= 5V
V
CC
= 5V
f
CLK
= 320kHz
f
CLK
= 320kHz
PARAMETER
Supply Voltage (Note 3)
Clock Frequency
Total Cycle Time
Hold Time, D
IN
After CLK↑
Setup Time CS↓ Before First CLK↑ (See Operating Sequence)
Setup Time, D
IN
Stable Before CLK↑
CLK High Time
CLK Low Time
CS High Time Between Data Transfer Cycles
CS Low Time During Data Transfer
2
U
U
U
U
U
W
W W
U
W
TOP VIEW
CH5
CH6
CH7
GND
CLK
CSMUX
D
IN
COM
GND
1
2
3
4
5
6
7
8
9
24 CH4
23 CH3
22 CH2
21 CH1
20 CH0
19 V
CC
18 MUXOUT
17 ADCIN
16 V
REF
15 V
CC
14 CLK
13 NC
ORDER PART
NUMBER
LTC1598CG
LTC1598IG
CSADC 10
D
OUT
11
NC 12
G PACKAGE
24-LEAD PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 110°C/ W
U WW
(Note 5)
MIN
4.5
(Note 4)
60
150
1
400
1
1
16
44
TYP
MAX
5.5
320
UNITS
V
kHz
μs
ns
μs
ns
μs
μs
μs
μs
15948fb
LTC1594/LTC1598
CONVERTER AND
MULTIPLEXER
CHARACTERISTICS
The
●
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Differential Linearity Error
Offset Error
Gain Error
REF Input Range
Analog Input Range
MUX Channel Input Leakage Current
MUXOUT Leakage Current
ADCIN Input Leakage Current
CONDITIONS
●
DYNAMIC ACCURACY
SYMBOL
S/(N + D)
THD
SFDR
PARAMETER
Signal-to-Noise Plus Distortion Ratio
Total Harmonic Distortion (Up to 5th Harmonic)
Spurious-Free Dynamic Range
Peak Harmonic or Spurious Noise
DIGITAL AND DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
I
OZ
I
SOURCE
I
SINK
R
REF
I
REF
PARAMETER
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
High Level Output Voltage
Low Level Output Voltage
Hi-Z Output Leakage
Output Source Current
Output Sink Current
Reference Input Resistance
Reference Current
CONDITIONS
V
CC
= 5.25V
V
CC
= 4.75V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 4.75V, I
O
= – 10μA
V
CC
= 4.75V, I
O
= –360A
V
CC
= 4.75V, I
O
= 1.6mA
CS = High
V
OUT
= 0V
V
OUT
= V
CC
CS = V
IH
CS = V
IL
CS = V
CC
t
CYC
≥
760μs, f
CLK
≤
25kHz
t
CYC
≥
60μs, f
CLK
≤
320kHz
CS = V
CC
, CLK = V
CC
, D
IN
= V
CC
t
CYC
≥
760μs, f
CLK
≤
25kHz
t
CYC
≥
60μs, f
CLK
≤
320kHz
The
●
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
●
●
●
●
●
●
●
●
I
CC
Supply Current
W U
U
W U
U
(Note 6)
●
●
●
●
(Notes 7, 8)
(Notes 7, 8)
Off Channel
Off Channel
(Note 9)
●
●
●
LTC1594CS/LTC1598CG
LTC1594IS/LTC1598IG
MIN
TYP
MAX
MIN
TYP
MAX
12
12
±3
±3
±
3/4
±1
±3
±3
±8
±8
1.5V to V
CC
+ 0.05V
– 0.05V to V
CC
+ 0.05V
±200
±200
±200
±200
±1
±1
UNITS
Bits
LSB
LSB
LSB
LSB
V
V
nA
nA
μA
(Note 5) f
SMPL
= 16.8kHz
CONDITIONS
1kHz Input Signal
1kHz Input Signal
1kHz Input Signal
1kHz Input Signal
MIN
TYP
71
– 78
80
– 80
MAX
UNITS
dB
dB
dB
dB
MIN
2.6
TYP
MAX
0.8
2.5
– 2.5
4.0
2.4
4.64
4.62
0.4
±3
– 25
45
5000
55
0.001
90
90
0.001
320
320
●
●
●
●
2.5
140
±7
690
UNITS
V
V
μA
μA
V
V
V
μA
mA
mA
MΩ
kΩ
μA
μA
μA
μA
μA
μA
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3
LTC1594/LTC1598
AC CHARACTERISTICS
The
●
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. (Note 5)
PARAMETER
Analog Input Sample Time
Maximum Sampling Frequency
Conversion Time
Delay Time, CLK↓ to D
OUT
Data Valid
Delay Time, CS↑ to D
OUT
Hi-Z
Delay Time, CLK↓ to D
OUT
Enabled
Time Output Data Remains Valid After CLK↓
D
OUT
Fall Time
D
OUT
Rise Time
Enable Turn-On Time
Enable Turn-Off Time
Break-Before-Make Interval
Input Capacitance
SYMBOL
t
SMPL
f
SMPL(MAX)
t
CONV
t
dDO
t
dis
t
en
t
hDO
t
f
t
r
t
ON
t
OFF
t
OPEN
C
IN
CONDITIONS
See Figure 1 in Applications Information
See Figure 1 in Applications Information
See Figure 1 in Applications Information
See Test Circuits
See Test Circuits
See Test Circuits
C
LOAD
= 100pF
See Test Circuits
See Test Circuits
See Figure 1 in Applications Information
See Figure 2 in Applications Information
Analog Inputs On-Channel
Off-Channel
Digital Input
●
●
●
●
●
●
●
●
●
MIN
1.5
16.8
TYP
MAX
UNITS
CLK Cycles
kHz
CLK Cycles
ns
ns
ns
ns
ns
ns
ns
ns
ns
pF
pF
pF
35
12
250
135
75
230
50
50
260
100
160
20
5
5
600
300
200
150
150
700
300
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All voltage values are with respect to GND.
Note 3:
These devices are specified at 5V. Consult factory for 3V
specified devices (LTC1594L/LTC1598L).
Note 4:
Increased leakage currents at elevated temperatures cause the S/H
to droop, therefore it is recommended that f
CLK
≥
160kHz at 85°C,
f
CLK
≥
75kHz at 70°C and f
CLK
≥
1kHz at 25°C.
Note 5:
V
CC
= 5V, V
REF
= 5V and CLK = 320kHz unless otherwise specified.
CSADC and CSMUX pins are tied together during the test.
Note 6:
Linearity error is specified between the actual end points of the
A/D transfer curve.
Note 7:
Two on-chip diodes are tied to each reference and analog input
which will conduct for reference or analog input voltages one diode drop
below GND or one diode drop above V
CC
. This spec allows 50mV forward
bias of either diode for 4.5V
≤
V
CC
≤
5.5V. This means that as long as the
reference or analog input does not exceed the supply voltage by more than
50mV, the output code will be correct. To achieve an absolute 0V to 5V
input voltage range, it will therefore require a minimum supply voltage of
4.950V over initial tolerance, temperature variations and loading.
Note 8:
Recommended operating condition. Not 100% production tested.
Note 9:
Channel leakage current is measured after the channel selection.
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Sample Rate
1000
T
A
= 25°C
V
CC
= 5V
V
REF
= 5V
f
CLK
= 320kHz
100
450
T
A
= 25°C
V
CC
= V
REF
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
REFERENCE CURRENT (μA)
SUPPLY CURRENT (μA)
SUPPLY CURRENT (μA)
10
1
0.1
1
10
SAMPLE FREQUENCY (kHz)
100
1594/98 G01
4
U W
Supply Current vs Temperature
95.0
94.5
94.0
93.5
93.0
92.5
Reference Current vs Temperature
V
CC
= V
REF
= 5V
f
SMPL
= 16.8kHz
f
CLK
= 320kHz
400
350
300
250
200
– 55 – 35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1594/98 G02
92.0
– 55 – 35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1594/98 G03
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LTC1594/LTC1598
TYPICAL PERFORMANCE CHARACTERISTICS
Change in Offset
vs Reference Voltage
3.0
CHANGE IN OFFSET (LSB = 1/4096 V
REF
)
CHANGE IN LINEARITY (LSB)
2.5
2.0
1.5
1.0
0.5
0
1.0
CHANGE IN OFFSET (LSB)
T
A
= 25°C
V
CC
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
1.5
2.0 2.5 3.0 3.5 4.0
REFERENCE VOLTAGE (V)
Change in Gain
vs Reference Voltage
–10
–9
–8
CHANGE IN GAIN (LSB)
T
A
= 25°C
V
CC
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
ADC NOISE IN LBSs
T
A
= 25°C
V
CC
= 5V
f
CLK
= 320kHz
DIFFERENTIAL NONLINEARITY ERROR (LBS)
–7
–6
–5
–4
–3
–2
–1
0
1.0
1.5
2.0 2.5 3.0 3.5 4.0
REFERENCE VOLTAGE (V)
4.5
5.0
Effective Bits and S/(N + D)
vs Input Frequency
SPURIOUS FREE DYNAMIC RANGE (dB)
EFFECTIVE NUMBER OF BITS (ENOBs)
90
80
70
60
50
40
30
20 T = 25°C
A
10 V
CC
= V
REF
= 5V
f
SMPL
= 16.8kHz
0
1
10
100
INPUT FREQUENCY (kHz)
SIGNAL-TO-NOISE PLUS DISTORTION (dB)
12
11
10
9
8
7
6
5
4
3
2
1
0
1
10
100
INPUT FREQUENCY (kHz)
T
A
= 25°C
V
CC
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
U W
4.5
1594/98 G04
Change in Offset vs Temperature
0
– 0.5
–1.0
–1.5
– 2.0
– 2.5
V
CC
= V
REF
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
65
85
Change in Linearity
vs Reference Voltage
–0.50
–0.45
–0.40
–0.35
–0.30
–0.25
–0.20
–0.15
–0.10
–0.05
0
1.0
1.5
2.0 2.5 3.0 3.5 4.0
REFERENCE VOLTAGE (V)
4.5
5.0
T
A
= 25°C
V
CC
= 5V
f
CLK
= 320kHz
f
SMPL
= 16.8kHz
5.0
– 3.0
45
– 55 – 35 – 15
5
25
TEMPERATURE (°C)
1594/98 G05
1594/98 G06
Peak-to-Peak ADC Noise
vs Reference Voltage
2.0
1.0
0.8
0.6
0.4
0.2
0.0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
Differential Nonlinearity vs Code
1.5
1.0
0.5
0
1
3
4
2
REFERENCE VOLTAGE (V)
5
1594/98 G08
0
2048
CODE
4096
1594/98 G09
1594/98 G07
Spurious Free Dynamic Range
vs Frequency
74
68
62
56
50
44
38
S/(N + D) vs Input Level
80
70
60
50
40
30
20
10
0
– 40
T
A
= 25°C
V
CC
= V
REF
= 5V
f
IN
= 1kHz
f
SMPL
= 16.8kHz
100
1000
1594/98 G10
1000
1594/98 G11
– 30
–20
–10
INPUT LEVEL (dB)
0
1594/98 G12
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5
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