LTC1860L/LTC1861L
µPower,
3V, 12-Bit, 150ksps
1- and 2-Channel ADCs in MSOP
FEATURES
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
12-Bit 150ksps ADCs in MSOP Package
Single 3V Supply
Low Supply Current: 450µA (Typ)
Auto Shutdown Reduces Supply Current
to 10µA at 1ksps
True Differential Inputs
1-Channel (LTC1860L) or 2-Channel (LTC1861L)
Versions
SPI/MICROWIRE
TM
Compatible Serial I/O
High Speed Upgrade to LTC1285/LTC1288
Pin Compatible with 16-Bit LTC1864L/LTC1865L
No Minimum Data Transfer Rate
The LTC
®
1860L/LTC1861L are 12-bit A/D converters that
are offered in MSOP and SO-8 packages and operate on a
single 3V supply. At 150ksps, the supply current is only
450µA. The supply current drops at lower speeds because
the LTC1860L/LTC1861L automatically power down be-
tween conversions. These 12-bit switched capacitor suc-
cessive approximation ADCs include sample-and-holds.
The LTC1860L has a differential analog input with an
external reference pin. The LTC1861L offers a software-
selectable 2-channel MUX and an external reference pin on
the MSOP version.
The 3-wire, serial I/O, MSOP or SO-8 package and
extremely high sample rate-to-power ratio make these
ADCs ideal choices for compact, low power, high speed
systems.
These ADCs can be used in ratiometric applications or with
external references. The high impedance analog inputs
and the ability to operate with reduced spans down to 1V
full scale allow direct connection to signal sources in many
applications, eliminating the need for external 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
High Speed Data Acquisition
Portable or Compact Instrumentation
Low Power Battery-Operated Instrumentation
Isolated and/or Remote Data Acquisition
TYPICAL APPLICATIO
1µF
Supply Current vs Sampling Frequency
Single 3V Supply, 150ksps, 12-Bit Sampling ADC
1000
CONV LOW = 1.5µs
T
A
= 25°C
V
CC
= 2.7V
LTC1860L
1
2
ANALOG INPUT
0V TO 3V
3
4
V
REF
IN
+
IN
–
GND
V
CC
SCK
SDO
CONV
8
7
6
5
1860L TA01
SUPPLY CURRENT (µA)
3V
100
10
SERIAL DATA LINK TO
ASIC, PLD, MPU, DSP
OR SHIFT REGISTERS
1
0.1
0.01
1
10
0.1
100
SAMPLING FREQUENCY (kHz)
U
1000
1860L/61L TA02
U
U
18601Lf
1
LTC1860L/LTC1861L
ABSOLUTE
AXI U
RATI GS
Supply Voltage (V
CC
) ................................................. 7V
Ground Voltage Difference
AGND, DGND LTC1861L MSOP Package .........
±0.3V
Analog Input .................... (GND – 0.3V) to (V
CC
+ 0.3V)
Digital Input ..................................... (GND – 0.3V) to 7V
Digital Output .................. (GND – 0.3V) to (V
CC
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
REF
IN
+
IN¯
GND
1
2
3
4
8
7
6
5
V
CC
SCK
SDO
CONV
ORDER PART
NUMBER
LTC1860LCMS8
LTC1860LIMS8
MS8 PART MARKING
LTD2
LTD3
ORDER PART
NUMBER
LTC1860LCS8
LTC1860LIS8
S8 PART MARKING
1860L
1860LI
CONV
CH0
CH1
AGND
DGND
1
2
3
4
5
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 210°C/W
TOP VIEW
V
REF
1
IN
+
2
IN
–
8 V
CC
7 SCK
6 SDO
5 CONV
3
GND 4
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 175°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
CO VERTER A D
PARAMETER
Resolution
No Missing Codes Resolution
INL
Transition Noise
Gain Error
Offset Error
Input Differential Voltage Range
Absolute Input Range
V
REF
Input Range
Analog Input Leakage Current
C
IN
Input Capacitance
ULTIPLEXER CHARACTERISTICS
CONDITIONS
q
q
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
CC
= 2.7V, V
REF
= 2.5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating Conditions, unless otherwise noted.
MIN
12
12
±1
0.13
q
q
(Note 3)
V
IN
= IN
+
– IN
–
IN
+
Input
IN
–
Input
LTC1860L S0-8 and MSOP, LTC1861L MSOP
(Note 4)
In Sample Mode
During Conversion
2
U
U
W
W W
U
W U
W
(Notes 1, 2)
Power Dissipation .............................................. 400mW
Operating Temperature Range
LTC1860LC/LTC1861LC ......................... 0°C to 70°C
LTC1860LI/LTC1861LI ...................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
10
9
8
7
6
V
REF
V
CC
SCK
SDO
SDI
ORDER PART
NUMBER
LTC1861LCMS
LTC1861LIMS
MS PART MARKING
LTD4
LTD5
ORDER PART
NUMBER
LTC1861LCS8
LTC1861LIS8
S8 PART MARKING
1861L
1861LI
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 210°C/W
TOP VIEW
CONV 1
CH0 2
CH1 3
GND 4
8 V
CC
7 SCK
6 SDO
5 SDI
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 175°C/W
U
TYP
MAX
UNITS
Bits
Bits
LSB
LSB
RMS
mV
mV
V
V
V
V
µA
pF
pF
18601Lf
q
±20
±2
0
– 0.05
– 0.05
1
±5
V
REF
V
CC
+ 0.05
V
CC
/2
V
CC
±1
12
5
q
q
LTC1860L/LTC1861L
DY A IC ACCURACY
T
A
= 25°C. V
CC
= 3V, V
REF
= 3V, f
SAMPLE
= 150kHz, unless otherwise specified.
SYMBOL PARAMETER
SNR
THD
Signal-to-Noise Ratio
1kHz Input Signal
Total Hamonic Distortion Up to 5th Harmonic 1kHz Input Signal
Full Power Bandwidth
Full Linear Bandwidth
S/(N + D)
≥
68dB
S/(N + D) Signal-to-Noise Plus Distortion Ratio
CONDITIONS
MIN
TYP
72
72
86
10
30
MAX
UNITS
dB
dB
dB
MHz
kHz
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
I
OZ
I
SOURCE
I
SINK
I
REF
I
CC
P
D
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 Current (LTC1860L SO-8, MSOP
and LTC1861L MSOP)
Supply Current
Power Dissipation
CONDITIONS
V
CC
= 3.3V
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
CONV = V
CC
V
OUT
= 0V
V
OUT
= V
CC
CONV = V
CC
f
SMPL
= f
SMPL(MAX)
CONV = V
CC
After Conversion
f
SMPL
= f
SMPL(MAX)
f
SMPL
= f
SMPL(MAX)
The
q
denotes specifications which apply
over the full operating temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 2.7V, V
REF
= 2.5V, unless otherwise noted.
MIN
q
q
q
q
q
q
q
q
RECO
V
CC
f
SCK
t
CYC
t
SMPL
t
suCONV
t
hDI
t
suDI
t
WHCLK
t
WLCLK
t
WHCONV
t
WLCONV
t
hCONV
full operating temperature range, otherwise specifications are T
A
= 25°C.
SYMBOL PARAMETER
Supply Voltage
Clock Frequency
Total Cycle Time
Analog Input Sampling Time (Note 5)
Setup Time CONV↓ Before First SCK↑,
(See Figure 1)
Holdtime SDI After SCK↑
Setup Time SDI Stable Before SCK↑
SCK High Time
SCK Low Time
CONV High Time Between Data
Transfer Cycles
CONV Low Time During Data Transfer
Hold Time CONV Low After Last SCK↑
LTC1861L
LTC1861L
f
SCK
= f
SCK(MAX)
f
SCK
= f
SCK(MAX)
LTC1860L
LTC1861L
CONDITIONS
E DED OPERATI G CO DITIO S
U
U
U
U WW
U
W U
TYP
MAX
0.45
2.5
– 2.5
UNITS
V
V
µA
µA
V
V
1.9
2.3
2.1
2.6
2.45
0.3
±3
– 6.5
6.5
V
µA
mA
mA
q
q
q
q
0.001
0.01
0.5
0.45
1.22
3
0.1
10
1.0
µA
mA
µA
mA
mW
The
q
denotes specifications which apply over the
MIN
2.7
q
TYP
MAX
3.6
8
UNITS
V
MHz
µs
SCK
SCK
ns
ns
ns
1/f
SCK
1/f
SCK
µs
SCK
ns
DC
12 • SCK + t
CONV
12
10
60
30
30
45%
45%
t
CONV
12
26
18601Lf
3
LTC1860L/LTC1861L
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. V
CC
= 2.7V, V
REF
= 2.5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating
Conditions, unless otherwise noted.
SYMBOL
t
CONV
t
dDO
t
dis
t
en
t
hDO
t
r
t
f
PARAMETER
Conversion Time (See Figure 1)
Delay Time, SCK↓ to SDO Data Valid
Delay Time, CONV↑ to SDO Hi-Z
Delay Time, CONV↓ to SDO Enabled
Time Output Data Remains
Valid After SCK↓
SDO Rise Time
SDO Fall Time
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
q
q
q
q
TI I G CHARACTERISTICS
f
SMPL(MAX)
Maximum Sampling Frequency
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:
Integral nonlinearity is defined as deviation of a code from a
straight line passing through the actual endpoints of the transfer curve.
The deviation is measured from the center of the quantization band.
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Sampling
Frequency
1000
CONV LOW = 1.5µs
T
A
= 25°C
V
CC
= 2.7V
600
500
f
S
= 150kHz
V
CC
= 2.7V
V
REF
= 2.5V
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
100
SHUTDOWN CURRENT (µA)
10
1
0.1
0.01
1
10
0.1
100
SAMPLING FREQUENCY (kHz)
4
U W
UW
CONDITIONS
q
q
MIN
150
TYP
3.7
45
55
35
MAX
4.66
55
60
120
120
UNITS
µs
kHz
ns
ns
ns
ns
ns
ns
ns
5
15
25
12
Note 4:
Channel leakage current is measured while the part is in sample
mode.
Note 5:
Assumes f
SCK
= f
SCK(MAX)
. In the case of the LTC1860L SCK does
not have to be clocked during this time if the SDO data word is not
desired. In the case of the LTC1861L a minimum of 2 clocks are required
on the SCK input after CONV falls to configure the MUX during this time.
Supply Current vs Temperature
20
Sleep Current vs Temperature
f
S
= 150kHz
V
CC
= 2.7V
V
REF
= 2.5V
15
400
300
200
100
0
–50 –25
10
5
1000
50
25
75
0
TEMPERATURE (°C)
100
125
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1860L/61L G01
1860L/61L G02
1860L/61L G03
18601Lf
LTC1860L/LTC1861L
TYPICAL PERFOR A CE CHARACTERISTICS
Reference Current vs
Sampling Rate
10
9
REFERENCE CURRENT (µA)
REFERENCE CURRENT (µA)
7
6
5
4
3
2
1
0
0
25
75
100
125
50
SAMPLING FREQUENCY (kHz)
150
REFERENCE CURRENT (µA)
8
CONV LOW = 1.5µs
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
Typical INL Curve
1.0
f
S
= 150kHz
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
DNL ERROR (LSBs)
ANALOG INPUT LEAKAGE (nA)
0.5
INL ERROR (LSBs)
0
–0.5
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1860L/61L G07
Change in Offset vs
Reference Voltage
2
f
S
= 150kHz
T
A
= 25°C
V
CC
= 3.6V
CHANGE IN OFFSET (LSB)
1
CHANGE IN OFFSET (LSB)
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
GHANGE IN GAIN ERROR (LSB)
0
–1
–2
0
2
3
1
REFERENCE VOLTAGE (V)
U W
1860L/61L G04
1860L/61L G10
Reference Current vs
Temperature
25
f
S
= 150kHz
V
CC
= 2.7V
V
REF
= 2.5V
25
Reference Current vs
Reference Voltage
f
S
= 150kHz
T
A
= 25°C
V
CC
= 3.6V
20
20
15
15
10
10
5
5
0
–50 –25
0
50
25
75
0
TEMPERATURE (°C)
100
125
0
0.5
1.0 1.5 2.0 2.5 3.0
REFERENCE VOLTAGE (V)
3.5
4.0
1860L/61L G05
1860L/61L G06
Typical DNL Curve
1.0
f
S
= 150kHz
T
A
= 25°C
V
CC
= 2.7V
V
REF
= 2.5V
100
Analog Input Leakage vs
Temperature
CONV = 0V
V
CC
= 2.7V
V
REF
= 2.5V
0.5
75
0
50
–0.5
25
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1860L/61L G08
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1860L/61L G09
Change in Offset vs Temperature
1.0
0.8
f
S
= 150kHz
V
CC
= 2.7V
V
REF
= 2.5V
2
Change in Gain Error vs
Reference Voltage
f
S
= 150kHz
T
A
= 25°C
V
CC
= 3.6V
1
0
–1
–1.0
4
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
–2
0
2
3
1
REFERENCE VOLTAGE (V)
4
1860L/61L G12
1860L/61L G11
18601Lf
5
PCB Design
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