LTC2368-16
16-Bit, 1Msps, Pseudo-
Differential Unipolar SAR
ADC with 94.7dB SNR
FEATURES
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DESCRIPTION
The LTC
®
2368-16 is a low noise, low power, high speed
16-bit successive approximation register (SAR) ADC.
Operating from a 2.5V supply, the LTC2368-16 has a 0V
to V
REF
pseudo-differential unipolar input range with V
REF
ranging from 2.5V to 5.1V. The LTC2368-16 consumes
only 13.5mW and achieves ±0.75LSB INL maximum, no
missing codes at 16 bits with 94.7dB SNR.
The LTC2368-16 has a high speed SPI-compatible serial
interface that supports 1.8V, 2.5V, 3.3V and 5V logic
while also featuring a daisy-chain mode. The fast 2Msps
throughput with no cycle latency makes the LTC2368-16
ideally suited for a wide variety of high speed applications.
An internal oscillator sets the conversion time, easing exter-
nal timing considerations. The LTC2368-16 automatically
powers down between conversions, leading to reduced
power dissipation that scales with the sampling rate.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
SoftSpan is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 7705765.
1Msps Throughput Rate
±0.75LSB INL (Max)
Guaranteed 16-Bit No Missing Codes
Low Power: 13.5mW at 1Msps, 13.5µW at 1ksps
94.7dB SNR (Typ) at f
IN
= 2kHz
–118dB
THD (Typ) at f
IN
= 2kHz
Guaranteed Operation to 125°C
2.5V Supply
Pseudo-Differential Unipolar Input Range: 0V to V
REF
V
REF
Input Range from 2.5V to 5.1V
No Pipeline Delay, No Cycle Latency
1.8V to 5V I/O Voltages
SPI-Compatible Serial I/O with Daisy-Chain Mode
Internal Conversion Clock
16-Lead MSOP and 4mm
×
3mm DFN Packages
APPLICATIONS
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Medical Imaging
High Speed Data Acquisition
Portable or Compact Instrumentation
Industrial Process Control
Low Power Battery-Operated Instrumentation
ATE
TYPICAL APPLICATION
32k Point FFT f
S
= 1Msps, f
IN
= 2kHz
2.5V
10µF
V
REF
0V
1.8V TO 5V
0.1µF
AMPLITUDE (dBFS)
OV
DD
0
–20
–40
–60
–80
–100
–120
–140
–160
–180
0
100
200
300
FREQUENCY (kHz)
400
500
SNR = 94.7dB
THD = –118dB
SINAD = 94.7dB
SFDR = 119dB
+
LT
®
6202
10
10nF
V
DD
IN
+
–
LTC2368-16
IN
–
REF
GND
CHAIN
RDL/SDI
SDO
SCK
BUSY
CNV
236816 TA01a
SAMPLE CLOCK
2.5V TO 5.1V
47µF
(X5R, 0805 SIZE)
236816 TA01b
236816f
1
LTC2368-16
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltage (V
DD
) ...............................................2.8V
Supply Voltage (OV
DD
) ................................................6V
Reference Input (REF).................................................6V
Analog Input Voltage (Note 3)
IN
+
, IN
–
.........................(GND – 0.3V) to (REF + 0.3V)
Digital Input Voltage
(Note 3) .......................... (GND – 0.3V) to (OV
DD
+ 0.3V)
Digital Output Voltage
(Note 3) .......................... (GND – 0.3V) to (OV
DD
+ 0.3V)
Power Dissipation .............................................. 500mW
Operating Temperature Range
LTC2368C ................................................ 0°C to 70°C
LTC2368I .............................................–40°C to 85°C
LTC2368H .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
CHAIN
V
DD
GND
IN
+
IN
–
GND
REF
REF
1
2
3
4
5
6
7
8
17
GND
16 GND
15 OV
DD
14 SDO
13 SCK
12 RDL/SDI
11 BUSY
10 GND
9 CNV
TOP VIEW
CHAIN
V
DD
GND
IN
+
IN
–
GND
REF
REF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
OV
DD
SDO
SCK
RDL/SDI
BUSY
GND
CNV
DE PACKAGE
16-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 150°C,
θ
JA
= 40°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
MS PACKAGE
16-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 110°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2368CMS-16#PBF
LTC2368IMS-16#PBF
LTC2368HMS-16#PBF
LTC2368CDE-16#PBF
LTC2368IDE-16#PBF
TAPE AND REEL
LTC2368CMS-16#TRPBF
LTC2368IMS-16#TRPBF
LTC2368CDE-16#TRPBF
LTC2368IDE-16#TRPBF
PART MARKING*
236816
236816
23686
23686
PACKAGE DESCRIPTION
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead Plastic MSOP
16-Lead (4mm
×
3mm) Plastic DFN
16-Lead (4mm
×
3mm) Plastic DFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
LTC2368HMS-16#TRPBF 236816
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping
container.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
236816f
2
LTC2368-16
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
SYMBOL
V
IN
+
V
IN
–
V
IN
+ – V
IN
–
I
IN
C
IN
CMRR
PARAMETER
Absolute Input Range (IN
+
)
Absolute Input Range (IN
–
)
Input Differential Voltage Range
Analog Input Leakage Current
Analog Input Capacitance
Input Common Mode Rejection Ratio
Sample Mode
Hold Mode
f
IN
= 500kHz
CONDITIONS
(Note 5)
(Note 5)
V
IN
= V
IN
+ – V
IN
–
l
l
l
l
ELECTRICAL CHARACTERISTICS
MIN
–0.1
–0.1
0
TYP
MAX
V
REF
+ 0.1
0.1
V
REF
±1
UNITS
V
V
V
µA
pF
pF
dB
45
5
80
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
SYMBOL PARAMETER
Resolution
No Missing Codes
Transition Noise
INL
DNL
ZSE
FSE
Integral Linearity Error
Differential Linearity Error
Zero-Scale Error
Zero-Scale Error Drift
Full-Scale Error
Full-Scale Error Drift
(Note 7)
l
CONVERTER CHARACTERISTICS
CONDITIONS
l
l
MIN
16
16
TYP
MAX
UNITS
Bits
Bits
0.5
(Note 6)
(Note 7)
l
l
l
LSB
RMS
0.75
0.5
4
20
LSB
LSB
LSB
mLSB/°C
LSB
ppm/°C
–0.75
–0.5
–4
–20
±0.1
±0.1
0
4
±2
±0.1
DYNAMIC ACCURACY
SYMBOL PARAMETER
SINAD
SNR
The
l
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C and A
IN
= –1dBFS. (Notes 4, 8)
CONDITIONS
f
IN
= 2kHz, V
REF
= 5V
f
IN
= 2kHz, V
REF
= 5V, (H-Grade)
Signal-to-Noise Ratio
f
IN
= 2kHz, V
REF
= 5V
f
IN
= 2kHz, V
REF
= 2.5V
f
IN
= 2kHz, V
REF
= 5V, (H-Grade)
f
IN
= 2kHz, V
REF
= 2.5V, (H-Grade)
THD
SFDR
Total Harmonic Distortion
Spurious Free Dynamic Range
–3dB Input Bandwidth
Aperture Delay
Aperture Jitter
Transient Response
Full-Scale Step
f
IN
= 2kHz, V
REF
= 5V
f
IN
= 2kHz, V
REF
= 2.5V
f
IN
= 2kHz, V
REF
= 5V
l
l
l
l
l
l
l
l
l
MIN
91.9
91.7
92.5
87.7
92.2
87.3
TYP
94.7
94.7
94.7
90.7
94.7
90.7
–118
–116
MAX
UNITS
dB
dB
dB
dB
dB
dB
Signal-to-(Noise + Distortion) Ratio
–101
–101
dB
dB
dB
MHz
ps
ps
ns
102
120
34
500
4
460
236816f
3
LTC2368-16
REFERENCE INPUT
SYMBOL
V
REF
I
REF
PARAMETER
Reference Voltage
Reference Input Current
The
l
denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25°C. (Note 4)
CONDITIONS
(Note 5)
(Note 9)
l
l
MIN
2.5
TYP
0.5
MAX
5.1
0.7
UNITS
V
mA
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
SYMBOL PARAMETER
V
IH
V
IL
I
IN
C
IN
V
OH
V
OL
I
OZ
I
SOURCE
I
SINK
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 Current
Output Source Current
Output Sink Current
I
O
= –500µA
I
O
= 500µA
V
OUT
= 0V to OV
DD
V
OUT
= 0V
V
OUT
= OV
DD
l
l
l
DIGITAL INPUTS AND DIGITAL OUTPUTS
CONDITIONS
MIN
l
l
TYP
MAX
0.2 • OV
DD
UNITS
V
V
µA
pF
V
0.8 • OV
DD
–10
5
OV
DD
– 0.2
0.2
–10
–10
10
10
10
V
IN
= 0V to OV
DD
l
V
µA
mA
mA
POWER REQUIREMENTS
SYMBOL
V
DD
OV
DD
I
VDD
I
OVDD
I
PD
I
PD
P
D
PARAMETER
Supply Voltage
Supply Voltage
Supply Current
Supply Current
Power Down Mode
Power Down Mode
Power Dissipation
Power Down Mode
Power Down Mode
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 4)
CONDITIONS
l
l
MIN
2.375
1.71
TYP
2.5
5.4
0.9
0.9
0.9
13.5
2.25
2.25
MAX
2.625
5.25
6.3
90
140
15.8
225
315
UNITS
V
V
mA
mA
µA
µA
mW
µW
µW
1Msps Sample Rate
1Msps Sample Rate (C
L
= 20pF)
Conversion Done (I
VDD
+ I
OVDD
+ I
REF
, V
REF
> 2V)
Conversion Done (I
VDD
+ I
OVDD
+ I
REF
, V
REF
> 2V, H-Grade)
1Msps Sample Rate
Conversion Done (I
VDD
+ I
OVDD
+ I
REF
, V
REF
> 2V)
Conversion Done (I
VDD
+ I
OVDD
+ I
REF
, V
REF
> 2V, H-Grade)
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l
l
ADC TIMING CHARACTERISTICS
SYMBOL
f
SMPL
t
CONV
t
ACQ
t
CYC
t
CNVH
t
BUSYLH
t
CNVL
t
QUIET
t
SCK
t
SCKH
PARAMETER
Maximum Sampling Frequency
Conversion Time
Acquisition Time
Time Between Conversions
CNV High Time
CNV↑ to BUSY Delay
Minimum Low Time for CNV
SCK Quiet Time from CNV↑
SCK Period
SCK High Time
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
CONDITIONS
l
l
MIN
460
460
1
20
TYP
MAX
1
527
UNITS
Msps
ns
ns
µs
ns
t
ACQ
= t
CYC
– t
CONV
– t
BUSYLH
(Note 10)
l
l
l
C
L
= 20pF
(Note 11)
(Note 10)
(Notes 11, 12)
l
l
l
l
l
13
20
20
10
4
ns
ns
ns
ns
ns
236816f
4
LTC2368-16
ADC TIMING CHARACTERISTICS
SYMBOL
t
SCKL
t
SSDISCK
t
HSDISCK
t
SCKCH
t
DSDO
t
HSDO
t
DSDOBUSYL
t
EN
t
DIS
PARAMETER
SCK Low Time
SDI Setup Time From SCK↑
SDI Hold Time From SCK↑
SCK Period in Chain Mode
SDO Data Valid Delay from SCK↑
SDO Data Remains Valid Delay from SCK↑
SDO Data Valid Delay from BUSY↓
Bus Enable Time After RDL↓
Bus Relinquish Time After RDL↑
(Note 11)
(Note 11)
t
SCKCH
= t
SSDISCK
+ t
DSDO
(Note 11)
C
L
= 20pF (Note 11)
C
L
= 20pF (Note 10)
C
L
= 20pF (Note 10)
(Note 11)
(Note 11)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
CONDITIONS
l
l
l
l
l
l
l
l
l
MIN
4
4
1
13.5
TYP
MAX
UNITS
ns
ns
ns
ns
9.5
1
5
16
13
ns
ns
ns
ns
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 effect device
reliability and lifetime.
Note 2:
All voltage values are with respect to ground.
Note 3:
When these pin voltages are taken below ground or above REF or
OV
DD
, they will be clamped by internal diodes. This product can handle
input currents up to 100mA below ground or above REF or OV
DD
without
latch-up.
Note 4:
V
DD
= 2.5V, OV
DD
= 2.5V, REF = 5V, f
SMPL
= 1MHz.
Note 5:
Recommended operating conditions.
Note 6:
Integral nonlinearity is defined as the 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 7:
Zero-scale error is the offset voltage measured from 0.5LSB
when the output code flickers between 0000 0000 0000 0000 and
0000 0000 0000 0001. Full-scale error is the deviation of the last code
transition from ideal and includes the effect of offset error.
Note 8:
All specifications in dB are referred to a full-scale 5V input with a
5V reference voltage.
Note 9:
f
SMPL
= 1MHz, I
REF
varies proportionately with sample rate.
Note 10:
Guaranteed by design, not subject to test.
Note 11:
Parameter tested and guaranteed at OV
DD
= 1.71V, OV
DD
= 2.5V
and OV
DD
= 5.25V.
Note 12:
t
SCK
of 10ns maximum allows a shift clock frequency up to
100MHz for rising capture.
0.8*OV
DD
0.2*OV
DD
t
DELAY
0.8*OV
DD
0.2*OV
DD
t
DELAY
0.8*OV
DD
0.2*OV
DD
50%
t
WIDTH
50%
236816 F01
Figure 1. Voltage Levels for Timing Specifications
236816f
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