1860_61 Layout
1
LTC1860/LTC1861
18601f
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
Power, 12-Bit, 250ksps
1- and 2-Channel ADCs in MSOP
Single 5V Supply, 250ksps, 12-Bit Sampling ADC
Supply Current vs Sampling Frequency
The LTC
1860/LTC1861 are 12-bit A/D converters that are
offered in MSOP and SO-8 packages and operate on a
single 5V supply. At 250ksps, the supply current is only
850
A. The supply current drops at lower speeds because
the LTC1860/LTC1861 automatically power down to a
typical supply current of 1nA between conversions. These
12-bit switched capacitor successive approximation ADCs
include sample-and-holds. The LTC1860 has a differential
analog input with an adjustable reference pin. The LTC1861
offers a software-selectable 2-channel MUX and an ad-
justable 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.
s
12-Bit 250ksps ADCs in MSOP Package
s
Single 5V Supply
s
Low Supply Current: 850
A (Typ)
s
Auto Shutdown Reduces Supply Current
to 2
A at 1ksps
s
True Differential Inputs
s
1-Channel (LTC1860) or 2-Channel (LTC1861)
Versions
s
SPI/MICROWIRE
TM
Compatible Serial I/O
s
High Speed Upgrade to LTC1286/LTC1298
s
Pin Compatible with 16-Bit LTC1864/LTC1865
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
High Speed Data Acquisition
s
Portable or Compact Instrumentation
s
Low Power Battery-Operated Instrumentation
s
Isolated and/or Remote Data Acquisition
MICROWIRE is a trademark of National Semiconductor Corporation.
1
2
3
4
8
7
6
5
V
REF
IN
+
IN
GND
V
CC
SCK
SDO
CONV
LTC1860
1860 TA01
ANALOG INPUT
0V TO 5V
5V
1
F
SERIAL DATA LINK TO
ASIC, PLD, MPU, DSP
OR SHIFT REGISTERS
SAMPLING FREQUENCY (kHz)
0.01
SUPPLY CURRENT (
A)
1000
100
10
1
0.1
0.01
100
1860 TA02
0.1
1
10
1000
2
LTC1860/LTC1861
18601f
Power Dissipation .............................................. 400mW
Operating Temperature Range
LTC1860C/LTC1861C ............................. 0
C to 70
C
LTC1860I/LTC1861I .......................... 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec)................. 300
C
Supply Voltage (V
CC
) ................................................. 7V
Ground Voltage Difference
AGND, DGND LTC1861 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)
(Notes 1, 2)
ORDER PART
NUMBER
MS8 PART MARKING
ORDER PART
NUMBER
LTC1860CMS8
LTC1860IMS8
LTWR
LTWS
MS PART MARKING
T
JMAX
= 150
C,
JA
= 210
C/W
T
JMAX
= 150
C,
JA
= 175
C/W
1
2
3
4
V
REF
IN
+
IN
GND
8
7
6
5
V
CC
SCK
SDO
CONV
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
LTC1861CMS
LTC1861IMS
LTWT
LTWU
Consult LTC Marketing for parts specified with wider operating temperature ranges.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution
q
12
Bits
No Missing Codes Resolution
q
12
Bits
INL
(Note 3)
q
1
LSB
Transition Noise
0.07
LSB
RMS
Gain Error
q
20
mV
Offset Error
LTC1860 SO-8 and MSOP, LTC1861 MSOP
q
2
5
mV
LTC1861 SO-8
q
3
7
mV
Input Differential Voltage Range
V
IN
= IN
+
IN
q
0
V
REF
V
Absolute Input Range
IN
+
Input
0.05
V
CC
+ 0.05
V
IN
Input
0.05
V
CC
/2
V
V
REF
Input Range
LTC1860 S0-8 and MSOP, LTC1861 MSOP
1
V
CC
V
Analog Input Leakage Current
(Note 4)
q
1
A
C
IN
Input Capacitance
In Sample Mode
12
pF
During Conversion
5
pF
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25
C.
V
CC
= 5V, V
REF
= 5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating Conditions, unless otherwise noted.
CO VERTER A D ULTIPLEXER CHARACTERISTICS
U
W
U
ORDER PART
NUMBER
S8 PART MARKING
LTC1860CS8
LTC1860IS8
1860
1860I
1
2
3
4
8
7
6
5
TOP VIEW
S8 PACKAGE
8-LEAD PLASTIC SO
V
REF
IN
+
IN
GND
V
CC
SCK
SDO
CONV
ORDER PART
NUMBER
S8 PART MARKING
LTC1861CS8
LTC1861IS8
1861
1861I
T
JMAX
= 150
C,
JA
= 210
C/W
T
JMAX
= 150
C,
JA
= 175
C/W
1
2
3
4
5
CONV
CH0
CH1
AGND
DGND
10
9
8
7
6
V
REF
V
CC
SCK
SDO
SDI
TOP VIEW
MS PACKAGE
10-LEAD PLASTIC MSOP
1
2
3
4
8
7
6
5
TOP VIEW
S8 PACKAGE
8-LEAD PLASTIC SO
CONV
CH0
CH1
GND
V
CC
SCK
SDO
SDI
3
LTC1860/LTC1861
18601f
The
q
denotes specifications which apply
over the full operating temperature range, otherwise specifications are T
A
= 25
C. V
CC
= 5V, V
REF
= 5V, unless otherwise noted.
T
A
= 25
C. V
CC
= 5V, f
SAMPLE
= 250kHz, unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SNR
Signal-to-Noise Ratio
72
dB
S/(N + D) Signal-to-Noise Plus Distortion Ratio
100kHz Input Signal
71
dB
THD
Total Hamonic Distortion Up to 5th Harmonic 100kHz Input Signal
77
dB
Full Power Bandwidth
20
MHz
Full Linear Bandwidth
S/(N + D)
68dB
125
kHz
DY
A
IC ACCURACY
U
W
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
U
The
q
denotes specifications which apply over the
full operating temperature range, otherwise specifications are T
A
= 25
C.
RECO
E
DED OPERATI
G CO DITIO
S
U
U
U
U
W
W
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
V
CC
= 5.25V
q
2.4
V
V
IL
Low Level Input Voltage
V
CC
= 4.75V
q
0.8
V
I
IH
High Level Input Current
V
IN
= V
CC
q
2.5
A
I
IL
Low Level Input Current
V
IN
= 0V
q
2.5
A
V
OH
High Level Output Voltage
V
CC
= 4.75V, I
O
= 10
A
q
4.5
4.74
V
V
CC
= 4.75V, I
O
= 360
A
q
2.4
4.72
V
V
OL
Low Level Output Voltage
V
CC
= 4.75V, I
O
= 1.6mA
q
0.4
V
I
OZ
Hi-Z Output Leakage
CONV = V
CC
q
3
A
I
SOURCE
Output Source Current
V
OUT
= 0V
25
mA
I
SINK
Output Sink Current
V
OUT
= V
CC
20
mA
I
REF
Reference Current (LTC1860 SO-8, MSOP and CONV = V
CC
q
0.001
3
A
LTC1861 MSOP)
f
SMPL
= f
SMPL(MAX)
q
0.05
0.1
mA
I
CC
Supply Current
CONV = V
CC
After Conversion
q
0.001
3
A
f
SMPL
= f
SMPL(MAX)
q
0.85
1.3
mA
P
D
Power Dissipation
f
SMPL
= f
SMPL(MAX)
4.25
mW
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Supply Voltage
4.75
5.25
V
f
SCK
Clock Frequency
q
DC
20
MHz
t
CYC
Total Cycle Time
12 SCK + t
CONV
s
t
SMPL
Analog Input Sampling Time
LTC1860
12
SCK
LTC1861
10
SCK
t
suCONV
Setup Time CONV
Before First SCK
,
30
ns
(See Figure 1)
t
hDI
Holdtime SDI After SCK
LTC1861
15
ns
t
suDI
Setup Time SDI Stable Before SCK
LTC1861
15
ns
t
WHCLK
SCK High Time
f
SCK
= f
SCK(MAX)
40%
1/f
SCK
t
WLCLK
SCK Low Time
f
SCK
= f
SCK(MAX)
40%
1/f
SCK
t
WHCONV
CONV High Time Between Data
t
CONV
s
Transfer Cycles
t
WLCONV
CONV Low Time During Data Transfer
12
SCK
t
hCONV
Hold Time CONV Low After Last SCK
13
ns
4
LTC1860/LTC1861
18601f
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.
Note 4: Channel leakage current is measured while the part is in sample
mode.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
t
CONV
Conversion Time (See Figure 1)
q
2.75
3.2
s
f
SMPL(MAX)
Maximum Sampling Frequency
q
250
kHz
t
dDO
Delay Time, SCK
to SDO Data Valid
C
LOAD
= 20pF
15
20
ns
q
25
ns
t
dis
Delay Time, CONV
to SDO Hi-Z
q
30
60
ns
t
en
Delay Time, CONV
to SDO Enabled
C
LOAD
= 20pF
q
30
60
ns
t
hDO
Time Output Data Remains
C
LOAD
= 20pF
q
5
10
ns
Valid After SCK
t
r
SDO Rise Time
C
LOAD
= 20pF
8
ns
t
f
SDO Fall Time
C
LOAD
= 20pF
4
ns
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are T
A
= 25
C. V
CC
= 5V, V
REF
= 5V, f
SCK
= f
SCK(MAX)
as defined in Recommended Operating
Conditions, unless otherwise noted.
TI I G CHARACTERISTICS
U
W
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Supply Current vs Sampling
Frequency
Supply Current vs Temperature
Sleep Current vs Temperature
SAMPLING FREQUENCY (kHz)
0.01
SUPPLY CURRENT (
A)
1000
100
10
1
0.1
0.01
100
1860/61 G01
0.1
1.0
10
1000
CONV LOW = 800ns
T
A
= 25
C
V
CC
= 5V
TEMPERATURE (
C)
50
SUPPLY CURRENT (
A)
1000
800
600
400
200
0
0
50
75
1860/61 G02
25
25
100
125
CONV HIGH = 3.2
S
f
SMPL
= 250kHz
V
CC
= 5V
V
REF
= 5V
TEMPERATURE (
C)
50
SLEEP CURRENT (nA)
1000
900
800
700
600
500
400
300
200
100
0
0
50
75
1860/61 G03
25
25
100
125
CONV = V
CC
= 5V
5
LTC1860/LTC1861
18601f
Reference Current vs
Sample Rate
Reference Current vs
Temperature
Reference Current vs
Reference Voltage
Typical INL Curve
Typical DNL Curve
Analog Input Leakage vs
Temperature
SAMPLE RATE (kHz)
0
REFERENCE CURRENT (
A)
60
50
40
30
20
10
0
50
100
150
200
1860/61 G04
250
CONV IS LOW FOR 800ns
T
A
= 25
C
V
CC
= 5V
V
REF
= 5V
TEMPERATURE (
C)
50
REFERENCE CURRENT (
A)
55
54
53
52
51
50
49
48
47
46
45
0
50
75
1860/61 G05
25
25
100
125
f
S
= 250kHz
V
CC
= 5V
V
REF
= 5V
V
REF
(V)
0
I
REF
(
A)
60
50
40
30
20
10
0
1
2
3
4
1860/61 G06
5
f
S
= 250kHz
T
A
= 25
C
V
CC
= 5V
CODE
0
INL COC ERROR (LSBs)
4096
1860/61 G07
1024
2048
3072
1.0
0.5
0
0.5
1.0
512
1536
2560
3584
T
A
= 25
C
V
CC
= 5V
V
REF
= 5V
CODE
0
DNL EOC ERROR (LSBs)
4096
1860/61 G07
1024
2048
3072
1.0
0.5
0
0.5
1.0
512
1536
2560
3584
T
A
= 25
C
V
CC
= 5V
V
REF
= 5V
TEMPERATURE (
C)
50
ANALOG INPUT LEAKAGE (nA)
100
1860/61 G09
0
50
100
75
50
25
0
25
25
75
125
V
CC
= 5V
V
REF
= 5V
CONV = 0V
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Change in Offset Error vs
Reference Voltage
Change in Offset vs Temperature
Change in Gain Error vs
Reference Voltage
REFERENCE VOLTAGE (V)
0
CHANGE IN OFFSET ERROR (LSB)
5
4
3
2
1
0
1
2
3
4
5
4
1860/61 G10
1
2
3
5
T
A
= 25
C
V
CC
= 5V
TEMPERATURE (
C)
50
CHANGE IN OFFSET (LSB)
1.0
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
0.8
1.0
0
50
75
1860/61 G11
25
25
100
125
V
CC
= 5V
REFERENCE VOLTAGE(V)
0
CHANGE IN GAIN ERROR (LSB)
5
4
3
2
1
0
1
2
3
4
5
2
4
5
1860/61 G12
1
3
V
CC
= 5V
T
A
= 25
C
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