LTC1857/LTC1858/LTC1859
8-Channel, 12-/14-/16-Bit,
100ksps SoftSpan A/D
Converters with Shutdown
FEATURES
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DESCRIPTION
The
LTC
®
1857/LTC1858/LTC1859
are 8-channel, low
power, 12-/14-/16-bit, 100ksps, analog-to-digital convert-
ers (ADCs). These SoftSpan™ ADCs can be software-
programmed for 0V to 5V, 0V to 10V, ±5V or ±10V input
spans and operate from a single 5V supply. The 8-channel
multiplexer can be programmed for single-ended inputs
or pairs of differential inputs or combinations of both. In
addition, all channels are fault protected to ±25V. A fault
condition on any channel will not affect the conversion
result of the selected channel.
An onboard high performance sample-and-hold and pre-
cision reference minimize external components. The low
40mW power dissipation is made even more attractive with
two user selectable power shutdown modes. DC specifica-
tions include ±3LSB INL for the LTC1859, ±1.5LSB INL
for the LTC1858 and ±1LSB for the LTC1857.
The internal clock is trimmed for 5µs maximum conversion
time and the sampling rate is guaranteed at 100ksps. A
separate convert start input and data ready signal (BUSY)
ease connections to FIFOs, DSPs and microprocessors.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation. SoftSpan is
a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
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Sample Rate: 100ksps
8-Channel Multiplexer with ±25V Protection
Single 5V Supply
Software-Programmable Input Ranges:
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0V to 5V, 0V to 10V, ±5V or ±10V
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Single-Ended or Differential
±3LSB INL for the LTC1859, ±1.5LSB INL for the
LTC1858, ±1LSB INL for the LTC1857
Power Dissipation: 40mW (Typ)
SPI/MICROWIRE™ Compatible Serial I/O
Power Shutdown: Nap and Sleep
Signal-to-Noise Ratio: 87dB (Typ) for the LTC1859
Operates with Internal or External Reference
Internal Synchronized Clock
28-Pin SSOP Package
APPLICATIONS
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Industrial Process Control
Multiplexed Data Acquisition Systems
High Speed Data Acquisition for PCs
Digital Signal Processing
TYPICAL APPLICATION
100kHz, 12-Bit/14-Bit/16-Bit Sampling ADC
COM
CONVST
CH0 LTC1857/
RD
CH1 LTC1858/ SCK
CH2 LTC1859 SDI
CH3
DGND
CH4
SDO
CH5
BUSY
CH6
OV
DD
DV
DD
CH7
AV
DD
MUXOUT
+
MUXOUT
–
AGND3
ADC
+
AGND2
ADC
–
REFCOMP
AGND1
V
REF
2.0
1.5
µP
CONTROL
LINES
INL (LSB)
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–32768
–16384
0
CODE
16384
32767
1859 TA02
LTC1859 Typical INL Curve
SOFTWARE-PROGRAMMABLE
SINGLE-ENDED OR
DIFFERENTIAL INPUTS
(0V TO 5V, 0V TO 10V,
±5V OR ±10V)
10µF
10µF
3V TO 5V
5V
5V
10µF
2.5V
1µF
10µF
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For more information
www.linear.com/LTC1857
1
LTC1857/LTC1858/LTC1859
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
COM
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
MUXOUT
+
ADC
+
Supply Voltage (OV
DD
= DV
DD
= AV
DD
= V
DD
) .............6V
Ground Voltage Difference
DGND, AGND1, AGND2, AGND3 ........................±0.3V
Analog Input Voltage
ADC
+
, ADC
–
(Note 3) ................. (AGND1 – 0.3V) to (AV
DD
+ 0.3V)
CH0-CH7, COM ..................................................±25V
Digital Input Voltage (Note 4).......(DGND – 0.3V) to 10V
Digital Output Voltage ..(DGND – 0.3V) to (DV
DD
+ 0.3V)
Power Dissipation ...............................................500mW
Operating Temperature Range
LTC1857C/LTC1858C/LTC1859C .............. 0°C to 70°C
LTC1857I/LTC1858I/LTC1859I.............. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
1
2
3
4
5
6
7
8
9
10
12
28 CONVST
27
RD
26 SCK
25 SDI
24 DGND
23 SDO
22
BUSY
21 OV
DD
20 DV
DD
19 AV
DD
18 AGND3
17 AGND2
16 REFCOMP
15 V
REF
MUXOUT
–
11
ADC
–
13
AGND1 14
G PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 110°C,
θ
JA
= 95°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1857CG#PBF
LTC1857IG#PBF
LTC1858CG#PBF
LTC1858IG#PBF
LTC1859CG#PBF
LTC1859IG#PBF
TAPE AND REEL
LTC1857CG#TRPBF
LTC1857IG#TRPBF
LTC1858CG#TRPBF
LTC1858IG#TRPBF
LTC1859CG#TRPBF
LTC1859IG#TRPBF
PART MARKING
LTC1857CG
LTC1857IG
LTC1858CG
LTC1858IG
LTC1859CG
LTC1859IG
PACKAGE DESCRIPTION
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
28-Lead Plastic SSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
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2
For more information
www.linear.com/LTC1857
LTC1857/LTC1858/LTC1859
CONVERTER AND MULTPLEXER CHARACTERISTICS
LTC1857
PARAMETER
Resolution
No Missing Codes
Transition Noise
Integral Linearity Error
Differential Linearity Error
Bipolar Zero Error
Bipolar Zero Error Drift
Bipolar Zero Error Match
Unipolar Zero Error
Unipolar Zero Error Drift
Unipolar Zero Error Match
Bipolar Full-Scale Error
Bipolar Full-Scale Error Drift
Bipolar Full-Scale Error Match
Unipolar Full-Scale Error
Unipolar Full-Scale Error Drift
Unipolar Full-Scale Error Match
Input Common Mode Range
Input Common Mode Rejection Ratio
Unipolar Mode
Bipolar Mode
l
l
The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. MUXOUT connected to ADC inputs. (Notes 5, 6)
LTC1858
MAX
MIN
14
14
0.06
(Notes 7, 15)
(Note 15)
(Note 8)
l
l
l
LTC1859
MAX
MIN
16
15
TYP
MAX
UNITS
Bits
Bits
1
±1.5
±3
–2
±0.1
±6
±15
±10
±25
±1
±2
±0.15
±0.4
±8
±0.1
±0.4
±2.5
±7
±10
±0.25
±0.85
±15
±0.2
±0.75
±2.5
±7
±12
±15
0 to 10
±10
96
4
±28
1.5
±17
LSB
RMS
LSB
LSB
LSB
ppm/°C
LSB
LSB
ppm/°C
LSB
%
%
ppm/°C
ppm/°C
LSB
%
%
ppm/°C
ppm/°C
LSB
V
V
dB
CONDITIONS
l
l
MIN
12
12
TYP
TYP
0.26
±1
1
±9
–1
±0.1
±4
±6
–1
±0.1
(Note 8)
l
±1
±1.2
External Reference (Note 11)
l
Internal Reference (Note 11)
External Reference
Internal Reference
External Reference (Note 11)
l
Internal Reference (Note 11)
External Reference
Internal Reference
±2.5
±7
±5
0 to 10
±10
96
±2.5
±7
±5
±0.45
±0.75
±0.35
±0.45
±1
±2.5
±7
±2.5
±7
0 to 10
±10
96
The
l
denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25°C. (Note 5)
PARAMETER
Analog Input Range
CONDITIONS
CH0 to CH7, COM
ADC
+
, ADC
–
(Note 3)
MIN
TYP
0 to 5, 0 to 10
±5, ±10
0 to 2.048
0 to 4.096
ADC
–
±1.024
ADC
–
±2.048
42
31
10
5
Hi-Z
5
24
12
4
l
ANALOG INPUT
MAX
UNITS
V
V
V
V
V
V
kΩ
kΩ
kΩ
kΩ
kΩ
pF
pF
pF
pF
Impedance
CH0 to CH7, COM
Unipolar
Bipolar
MUXOUT
+
, MUXOUT
–
Unipolar
Bipolar
ADC
+
, ADC
–
Capacitance
CH0 to CH7, COM
Sample Mode ADC
+
, ADC
–
0V to 2.048V, ±1.024V
0V to 4.096V, ±2.048V
Hold Mode ADC
+
, ADC
–
Input Leakage Current
ADC
+
, ADC
–
, CONVST = Low
±1
µA
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3
LTC1857/LTC1858/LTC1859
DYNAMIC ACCURACY
SYMBOL PARAMETER
THD
Total Harmonic Distortion
Peak Harmonic or Spurious Noise
Channel-to-Channel Isolation
–3dB Input Bandwidth
Aperture Delay
Aperture Jitter
Transient Response
Overvoltage Recovery
Full-Scale Step
(Note 9)
(Note 13)
150
The
l
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. MUXOUT connected to ADC inputs. (Notes 5, 12)
LTC1857
CONDITIONS
1kHz Input Signal,
First Five Harmonics
1kHz Input Signal
1kHz Input Signal
MIN
TYP
74
–101
–103
–120
1
–70
60
4
150
MAX
MIN
LTC1858
TYP
83
–101
–103
–120
1
–70
60
4
150
MAX
MIN
LTC1859
TYP
87
–101
–103
–120
1
–70
60
4
MAX
UNITS
dB
dB
dB
dB
MHz
ns
ps
µs
ns
S/(N + D) Signal-to-(Noise + Distortion) Ratio 1kHz Input Signal
INTERNAL REFERENCE CHARACTERISTICS
PARAMETER
V
REF
Output Voltage
V
REF
Output Temperature Coefficient
V
REF
Output Impedance
V
REFCOMP
Output Voltage
CONDITIONS
I
OUT
= 0
I
OUT
= 0
–0.1mA ≤ I
OUT
≤ 0.1mA
I
OUT
= 0
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
MIN
l
TYP
2.5
±10
8
4.096
MAX
2.525
UNITS
V
ppm/°C
kΩ
V
2.475
DIGITAL INPUTS AND DIGITAL OUTPUTS
SYMBOL
V
IH
V
IL
I
IN
C
IN
V
OH
V
OL
I
OZ
C
OZ
I
SOURCE
I
SINK
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
Low Level Output Voltage
Hi-Z Output Leakage
Hi-Z Output Capacitance
Output Source Current
Output Sink Current
CONDITIONS
V
DD
= 5.25V
V
DD
= 4.75V
V
IN
= 0V to V
DD
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
MIN
l
l
l
TYP
MAX
0.8
±10
UNITS
V
V
µA
pF
V
V
2.4
5
V
DD
= 4.75V, I
O
= –10µA, OV
DD
= V
DD
V
DD
= 4.75V, I
O
= –200µA, OV
DD
= V
DD
V
DD
= 4.75V, I
O
= 160µA, OV
DD
= V
DD
V
DD
= 4.75V, I
O
= 1.6mA, OV
DD
= V
DD
V
OUT
= 0V to V
DD
,
RD
= High
RD
= High
V
OUT
= 0V
V
OUT
= V
DD
l
l
l
4
4.74
0.05
0.10
15
–10
10
0.4
±10
V
V
µA
pF
mA
mA
POWER REQUIREMENTS
PARAMETER
Positive Supply Voltage
Positive Supply Current
Nap Mode
Sleep Mode
Power Dissipation
Nap Mode
Sleep Mode
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 5)
CONDITIONS
(Notes 9 and 10)
l
MIN
4.75
TYP
5
8
5.5
8
40
27.5
40
MAX
5.25
13
8
15
UNITS
V
mA
mA
µA
mW
mW
µW
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CONVST = 0V or 5V
CONVST = 0V or 5V
4
For more information
www.linear.com/LTC1857
LTC1857/LTC1858/LTC1859
TIMING CHARACTERISTICS
SYMBOL
f
SAMPLE(MAX)
t
CONV
t
ACQ
f
SCK
t
r
t
f
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
10
t
11
t
12
t
13
PARAMETER
Maximum Sampling Frequency
Conversion Time
Acquisition Time
SCK Frequency
SDO Rise Time
SDO Fall Time
CONVST High Time
CONVST to
BUSY
Delay
SCK Period
SCK High
SCK Low
Delay Time, SCK↓ to SDO Valid
Time from Previous SDO Data Remains
Valid After SCK↓
SDO Valid After
RD↓
RD↓
to SCK Setup Time
SDI Setup Time Before SCK↑
SDI Hold Time After SCK↑
SDO Valid Before
BUSY↑
Bus Relinquish Time
,
RD
= Low, C
L
= 25pF See Test Circuits
See Test Circuits
,
C
L
= 25pF See Test Circuits
C
L
= 25pF See Test Circuits
,
,
C
L
= 25pF See Test Circuits
C
L
= 25pF See Test Circuits
,
Through CH0 to CH7 Inputs
Through ADC
+
, ADC
–
Only
(Note 14)
See Test Circuits
See Test Circuits
l
l
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 5)
CONDITIONS
Through CH0 to CH7 Inputs
Through ADC
+
, ADC
–
Only
l
l
l
MIN
100
TYP
166
4
1
MAX
UNITS
kHz
kHz
5
4
20
µs
µs
µs
MHz
ns
ns
ns
l
0
6
6
40
15
50
10
10
25
5
20
11
20
0
7
5
20
10
30
ns
ns
ns
ns
45
ns
ns
30
ns
ns
ns
ns
ns
30
ns
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 ground with DGND, AGND1,
AGND2 and AGND3 wired together unless otherwise noted.
Note 3:
When these pin voltages are taken below ground or above AV
DD
=
DV
DD
= OV
DD
= V
DD
, they will be clamped by internal diodes. This product
can handle currents of greater than 100mA below ground or above V
DD
without latchup.
Note 4:
When these pin voltages are taken below ground they will be
clamped by internal diodes. This product can handle currents of greater
than 100mA below ground without latchup. These pins are not clamped
to V
DD
.
Note 5:
V
DD
= 5V, f
SAMPLE
= 100kHz, t
r
= t
f
= 5ns unless otherwise
specified.
Note 6:
Linearity, offset and full-scale specifications apply for a single-
ended analog MUX input with respect to ground or ADC
+
with respect to
ADC
–
tied to ground.
Note 7:
Integral nonlinearity is defined as the deviation of a code from a
straight line passing through the actual end points of the transfer curve.
The deviation is measured from the center of the quantization band.
Note 8:
Bipolar zero error is the offset voltage measured from – 0.5LSB
when the output code flickers between 0000 0000 0000 0000 and 1111
1111 1111 1111 for the LTC1859, between 00 0000 0000 0000 and 11
1111 1111 1111 for the LTC1858 and between 0000 0000 0000 and
1111 1111 1111 for the LTC1857. Unipolar zero error is the offset voltage
measured from 0.5LSB when the output codes flicker between 0000 0000
0000 0000 and 0000 0000 0000 0001 for the LTC1859, between 00 0000
0000 0000 and 00 0000 0000 0001 for the LTC1858 and between 0000
0000 0000 and 0000 0000 0001 for the LTC1857.
Note 9:
Guaranteed by design, not subject to test.
Note 10:
Recommended operating conditions.
Note 11:
Full-scale bipolar error is the worst case of –FS or +FS
untrimmed deviation from ideal first and last code transitions, divided by
the full-scale range, and includes the effect of offset error. For unipolar
full-scale error, the deviation of the last code transition from ideal, divided
by the full-scale range, and includes the effect of offset error.
Note 12:
All Specifications in dB are referred to a full-scale ±10V input.
Note 13:
Recovers to specified performance after (2 • FS) input
overvoltage.
Note 14:
t
6
of 45ns maximum allows f
SCK
up to 10MHz for rising capture
with 50% duty cycle and f
SCK
up to 20MHz for falling capture (with 5ns
setup time for the receiving logic).
Note 15:
The specification is referred to the ±10V input range.
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For more information
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5
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