LTC1594L/LTC1598L
4- and 8-Channel,
3V Micropower Sampling
12-Bit Serial I/O A/D Converters
FEATURES
s
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
12-Bit Resolution on 3V Supply
Low Supply Current: 160µA Typ
Auto Shutdown to 1nA
Guaranteed
±3/4LSB
Max DNL
Guaranteed 2.7V Operation
(5V Versions Available: LTC1594/LTC1598)
Multiplexer: 4-Channel MUX (LTC1594L)
8-Channel MUX (LTC1598L)
Separate MUX Output and ADC Input Pins
MUX and ADC May Be Controlled Separately
Sampling Rate: 10.5ksps
I/O Compatible with QSPI, SPI and MICROWIRE
TM
, etc.
Small Package: 16-Pin Narrow SO (LTC1594L)
24-Pin SSOP (LTC1598L)
The LTC
®
1594L/LTC1598L are 3V micropower, 12-bit
sampling A/D converters that feature 4- and 8-channel
multiplexers, respectively. They typically draw only 160µA
of supply current when converting and automatically
power down to a typical supply current of 1nA between
conversions. The LTC1594L is available in a 16-pin SO
package and the LTC1598L is packaged in a 24-pin
SSOP. Both operate on a 3V 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
APPLICATIO S
s
s
s
s
s
s
Pen Screen Digitizing
Battery-Operated Systems
Remote Data Acquisition
Isolated Data Acquisition
Battery Monitoring
Temperature Measurement
TYPICAL APPLICATION
12µW, 8-Channel, 12-Bit ADC Samples at 200Hz and Runs Off a 3V Supply
OPTIONAL
ADC FILTER
1k
1µF
18
MUXOUT
20
21
22
ANALOG
INPUTS
0V TO 3V
RANGE
23
24
1
2
3
8
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
8-CHANNEL
MUX
12-BIT
SAMPLING
ADC
CSADC
CSMUX
10
6
5, 14
7
11
12
13
1
0.1
1594L/98L TA01
3V
17
ADCIN
16
15, 19
V
REF
V
CC
1µF
SERIAL DATA LINK
MICROWIRE AND
SPI COMPATABLE
SUPPLY CURRENT (µA)
+
CLK
D
IN
D
OUT
MPU
–
LTC1598L
GND
4, 9
NC
NC
U
Supply Current vs Sample Rate
1000
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
f
CLK
= 200kHz
100
10
1
10
SAMPLE FREQUENCY (kHz)
100
1594L/98L TA02
U
U
15948lfb
1
LTC1594L/LTC1598L
ABSOLUTE
MAXIMUM
RATINGS
(Notes 1, 2)
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 INFORMATION
ORDER PART
NUMBER
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
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
LTC1594LCS
LTC1594LIS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 120°C/ W
Consult factory for Military grade parts.
the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
SYMBOL
V
CC
f
CLK
t
CYC
t
hDI
t
suCS
t
suDI
t
WHCLK
t
WLCLK
t
WHCS
t
WLCS
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
CONDITIONS
V
CC
= 2.7V
f
CLK
= 200kHz
V
CC
= 2.7V
V
CC
= 2.7V
V
CC
= 2.7V
V
CC
= 2.7V
V
CC
= 2.7V
f
CLK
= 200kHz
f
CLK
= 200kHz
RECOM ENDED OPERATING CONDITIONS
The
q
denotes the specifications which apply over
MIN
2.7
(Note 4)
95
450
2
600
1.5
1.5
25
70
TYP
MAX
3.6
200
UNITS
V
kHz
µs
ns
µs
ns
µs
µs
µs
µs
2
U
U
U
U
U
W
W W
U
W
Power Dissipation .............................................. 500mW
Operating Temperature Range
LTC1594LCS/LTC1598LCG ..................... 0°C to 70°C
LTC1594LIS/LTC1598LIG ................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1598LCG
LTC1598LIG
CSADC 10
D
OUT
11
NC 12
G PACKAGE
24-LEAD PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 110°C/ W
U WW
15948lfb
LTC1594L/LTC1598L
CONVERTER AND
MULTIPLEXER
CHARACTERISTICS
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
q
The
q
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
LTC1594LCS/LTC1598LCG
LTC1594LIS/LTC1598LIG
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
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
= 3.6V
V
CC
= 2.7V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 2.7V, I
O
= 10µA
V
CC
= 2.7V, I
O
= 360µA
V
CC
= 2.7V, I
O
= 400µA
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
≤
200kHz
CS = V
CC
, CLK = V
CC
, D
IN
= V
CC
t
CYC
≥
760µs, f
CLK
≤
25kHz
t
CYC
≥
60µs, f
CLK
≤
200kHz
The
q
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
q
q
q
q
q
q
q
q
I
CC
Supply Current
W U
U
W U
U
(Note 6)
q
q
q
q
(Notes 7, 8)
(Notes 7, 8)
Off Channel
Off Channel
(Note 9)
q
q
q
T
A
= 25°C, f
SMPL
= 10.5kHz. (Note 5)
CONDITIONS
1kHz Input Signal
1kHz Input Signal
1kHz Input Signal
1kHz Input Signal
MIN
TYP
68
– 78
80
– 80
MAX
UNITS
dB
dB
dB
dB
MIN
2.0
TYP
MAX
0.8
2.5
– 2.5
2.4
2.1
2.64
2.30
0.4
±3
– 10
15
2700
60
0.001
50
50
0.001
160
160
q
q
q
q
2.5
70
±5
400
UNITS
V
V
µA
µA
V
V
V
µA
mA
mA
MΩ
kΩ
µA
µA
µA
µA
µA
µA
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3
LTC1594L/LTC1598L
AC CHARACTERISTICS
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
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
The
q
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C.(Note 5)
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
10.5
TYP
MAX
UNITS
CLK Cycles
kHz
CLK Cycles
ns
ns
ns
ns
ns
ns
ns
ns
ns
pF
pF
pF
q
q
q
q
q
q
q
q
q
125
12
600
220
180
520
60
80
540
190
350
20
5
5
1500
600
500
180
180
1200
500
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All voltage values are with respect to GND.
Note 3:
These devices are specified at 3V. Consult factory for 5V
specified devices (LTC1594/LTC1598).
Note 4:
Increased leakage currents at elevated temperatures cause the S/H
to droop, therefore it is recommended that f
CLK
≥
200kHz at 85°C,
f
CLK
≥
75kHz at 70°C and f
CLK
≥
1kHz at 25°C.
Note 5:
V
CC
= 2.7V, V
REF
= 2.5V and CLK = 200kHz 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 2.7V
≤
V
CC
≤
3.6V. 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 3V
input voltage range, it will therefore require a minimum supply voltage of
2.950V over initial tolerance, temperature variations and loading.
Note 8:
Recommended operating condition.
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
= 2.7V
V
REF
= 2.5V
f
CLK
= 200kHz
100
260
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
REFERENCE CURRENT (µA)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
10
1
0.1
1
10
SAMPLE FREQUENCY (kHz)
100
1594L/98L G01
4
U W
Supply Current vs Temperature
53
52
51
50
49
48
47
46
45
44
Reference Current vs Temperature
V
CC
= 2.7V
V
REF
= 2.5V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
220
180
140
100
60
– 55 – 35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1594L/98L G02
43
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1594L/98L G03
15948lfb
LTC1594L/LTC1598L
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
CHANGE IN OFFSET (LSB)
T
A
= 25°C
V
CC
= 2.7V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
0.5
1.0
1.5
2.0
2.5
REFERENCE VOLTAGE (V)
Change in Gain
vs Reference Voltage
–9
–8
CHANGE IN GAIN (LSB)
EFFECTIVE NUMBER OF BITS (ENOBs)
T
A
= 25°C
V
CC
= 2.7V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
DIFFERENTIAL NONLINEARITY ERROR (LSB)
–10
–7
–6
–5
–4
–3
–2
–1
0
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
REFERENCE VOLTAGE (V)
1594L/98L G07
Spurious Free Dynamic Range
vs Input Frequency
100
SIGNAL-TO-NOISE PLUS DISTORTION (dB)
SPURIOUS-FREE DYNAMIC RANGE (dB)
90
80
70
60
50
40
30
20
10
0
1
10
INPUT FREQUENCY (kHz)
100
1594L/98L G10
50
40
30
20
10
0
– 45 – 40 – 35 – 30 – 25 – 20 – 15 – 10 – 5
INPUT LEVEL (dB)
0
ATTENUATION (%)
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
f
SMPL
= f
SMPL(MAX)
U W
1594L/98L G04
Change in Offset vs Temperature
0.20
V
CC
= 2.7V
V
REF
= 2.5V
0.15
f
CLK
= 200kHz
0.10 f
SMPL
= f
SMPL(MAX)
0.05
0
– 0.05
– 0.10
– 0.15
– 0.20
3.0
0
10
20
50
40
30
TEMPERATURE (°C)
60
70
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
Change in Linearity
vs Reference Voltage
T
A
= 25°C
V
CC
= 2.7V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
REFERENCE VOLTAGE (V)
1594L/98L G06
1594L/98L G05
Differential Nonlinearity vs Code
1
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
f
CLK
= 200kHz
12
11
10
9
8
7
6
5
4
3
2
1
0
Effective Bits and S/(N + D)
vs Input Frequency
74
68
62
56
50
S/(N + D) (dB)
0.5
0
– 0.5
T
A
= 25°C
V
CC
= 2.7V
f
CLK
= 200kHz
f
SMPL
= 10.5kHz
1
10
INPUT FREQUENCY (kHz)
100
1594L/98L G09
–1
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1594L/98L G08
S/(N + D) vs Input Level
T
A
= 25°C
V
CC
= 2.7V
70
V
REF
= 2.5V
f
IN
= 1kHz
60
f
SMPL
= f
SMPL(MAX)
80
0
10
20
30
40
50
60
70
80
90
100
Frequency Response
(MUX + A
DC
)
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
f
SMPL
= f
SMPL(MAX)
1k
100k
1M
10k
INPUT FREQUENCY (Hz)
10M
1594L/98L G12
1594L/98/ G11
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