2251_50f.pm65
LTC2251/LTC2250
1
22510f
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
Sample Rate: 125Msps/105Msps
Single 3V Supply (2.85V to 3.4V)
Low Power: 395mW/320mW
61.6dB SNR
85dB SFDR
No Missing Codes
Flexible Input: 1V
P-P
to 2V
P-P
Range
640MHz Full Power Bandwidth S/H
Clock Duty Cycle Stabilizer
Shutdown and Nap Modes
Pin Compatible Family:
125Msps: LTC2251 (10-Bit), LTC2253 (12-Bit)
105Msps: LTC2250 (10-Bit), LTC2252 (12-Bit)
80Msps: LTC2239 (10-Bit), LTC2229 (12-Bit)
65Msps: LTC2238 (10-Bit), LTC2228 (12-Bit)
40Msps: LTC2237 (10-Bit), LTC2227 (12-Bit)
25Msps: LTC2236 (10-Bit), LTC2226 (12-Bit)
32-Pin (5mm
5mm) QFN Package
10-Bit, 125/105Msps
Low Noise 3V ADCs
The LTC
2251/LTC2250 are 10-bit 125Msps/105Msps,
low noise 3V A/D converters designed for digitizing high
frequency, wide dynamic range signals. The LTC2251/
LTC2250 are perfect for demanding imaging and commu-
nications applications with AC performance that includes
61.6dB SNR and 85dB SFDR for signals at the Nyquist
frequency.
DC specs include
0.1LSB INL (typ), 0.05LSB DNL (typ)
and
0.6LSB INL, 0.6LSB DNL over temperature. The
transition noise is a low 0.08LSB
RMS
.
A single 3V supply allows low power operation. A separate
output supply allows the outputs to drive 0.5V to 3.3V
logic.
A single-ended CLK input controls converter operation. An
optional clock duty cycle stabilizer allows high perfor-
mance at full speed for a wide range of clock duty cycles.
LTC2251: SNR vs Input Frequency,
1dB, 2V Range, 125Msps
Wireless and Wired Broadband Communication
Imaging Systems
Ultrasound
Spectral Analysis
Portable Instrumentation
+
INPUT
S/H
CORRECTION
LOGIC
OUTPUT
DRIVERS
10-BIT
PIPELINED
ADC CORE
CLOCK/DUTY
CYCLE
CONTROL
FLEXIBLE
REFERENCE
D9
D0
CLK
REFH
REFL
ANALOG
INPUT
22510 TA01
OV
DD
OGND
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
INPUT FREQUENCY (MHz)
0
55
SNR (dBFS)
56
58
59
60
65
62
100
200
250
22510 G09
57
63
64
61
50
150
300
350
LTC2251/LTC2250
2
22510f
LTC2251
LTC2250
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
10
10
Bits
Integral Linearity Error
Differential Analog Input
0.6
0.1
0.6
0.6
0.1
0.6
LSB
(Note 5)
Differential Linearity Error
Differential Analog Input
0.6
0.05
0.6
0.6
0.05
0.6
LSB
Offset Error
(Note 6)
12
2
12
12
2
12
mV
Gain Error
External Reference
2.5
0.5
2.5
2.5
0.5
2.5
%FS
Offset Drift
10
10
V/C
Full-Scale Drift
Internal Reference
30
30
ppm/
C
External Reference
5
5
ppm/
C
Transition Noise
SENSE = 1V
0.08
0.08
LSB
RMS
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
OV
DD
= V
DD
(Notes 1, 2)
Supply Voltage (V
DD
) ................................................. 4V
Digital Output Ground Voltage (OGND) ....... 0.3V to 1V
Analog Input Voltage (Note 3) ..... 0.3V to (V
DD
+ 0.3V)
Digital Input Voltage .................... 0.3V to (V
DD
+ 0.3V)
Digital Output Voltage ................ 0.3V to (OV
DD
+ 0.3V)
Power Dissipation ............................................ 1500mW
Operating Temperature Range
LTC2251C, LTC2250C ............................. 0
C to 70C
LTC2251I, LTC2250I ...........................40
C to 85C
Storage Temperature Range ..................65
C to 125C
ORDER PART
NUMBER
QFN PART*
MARKING
T
JMAX
= 125
C,
JA
= 34
C/W
EXPOSED PAD (PIN 33) IS GND
MUST BE SOLDERED TO PCB
2251
2250
LTC2251CUH
LTC2251IUH
LTC2250CUH
LTC2250IUH
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
The
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 4)
CO VERTER CHARACTERISTICS
U
32 31 30 29 28 27 26 25
9
10 11 12
TOP VIEW
UH PACKAGE
32-LEAD (5mm
5mm) PLASTIC QFN
13 14 15 16
17
18
19
20
21
22
23
24
8
7
6
5
4
3
2
1
AIN
+
AIN
REFH
REFH
REFL
REFL
V
DD
GND
D6
D5
D4
OV
DD
OGND
D3
D2
D1
V
DD
V
CM
SENSE
MODE
OF
D9
D8
D7
CLK
SHDN
OE
NC
NC
NC
NC
D0
33
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
LTC2251/LTC2250
3
22510f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Analog Input Range (A
IN
+
A
IN
)
2.85V < V
DD
< 3.4V (Note 7)
0.5V to 1V
V
V
IN,CM
Analog Input Common Mode
Differential Input (Note 7)
1
1.5
1.9
V
I
IN
Analog Input Leakage Current
0V < A
IN
+
, A
IN
< V
DD
1
1
A
I
SENSE
SENSE Input Leakage
0V < SENSE < 1V
3
3
A
I
MODE
MODE Pin Leakage
3
3
A
t
AP
Sample-and-Hold Acquisition Delay Time
0
ns
t
JITTER
Sample-and-Hold Acquisition Delay Time Jitter
0.2
ps
RMS
CMRR
Analog Input Common Mode Rejection Ratio
80
dB
Full Power Bandwidth
Figure 8 Test Circuit
640
MHz
The
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25
C. A
IN
= 1dBFS. (Note 4)
LTC2251
LTC2250
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
SNR
Signal-to-Noise Ratio
5MHz Input
61.6
61.6
dB
30MHz Input
61.6
61.6
dB
70MHz Input
60
61.5
60
61.5
dB
140MHz Input
61.4
61.4
dB
SFDR
5MHz Input
85
85
dB
30MHz Input
85
85
dB
70MHz Input
69
82
69
83
dB
140MHz Input
77
77
dB
SFDR
5MHz Input
85
85
dB
30MHz Input
85
85
dB
70MHz Input
75
85
75
85
dB
140MHz Input
85
85
dB
S/(N+D)
5MHz Input
61.5
61.6
dB
30MHz Input
61.5
61.6
dB
70MHz Input
60
61.4
60
61.5
dB
140MHz Input
61.2
61.3
dB
IMD
f
IN1
= 28.2MHz,
80
80
dB
f
IN2
= 26.8MHz
A ALOG I PUT
U
U
DY
A
IC ACCURACY
U
W
The
denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25
C. (Note 4)
Signal-to-Noise
Plus Distortion
Ratio
Intermodulation
Distortion
Spurious Free
Dynamic Range
2nd or 3rd
Harmonic
Spurious Free
Dynamic Range
4th Harmonic
or Higher
LTC2251/LTC2250
4
22510f
I TER AL REFERE CE CHARACTERISTICS
U
U
U
(Note 4)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CM
Output Voltage
I
OUT
= 0
1.475
1.500
1.525
V
V
CM
Output Tempco
25
ppm/
C
V
CM
Line Regulation
2.85V < V
DD
< 3.4V
3
mV/V
V
CM
Output Resistance
1mA < I
OUT
< 1mA
4
DIGITAL I PUTS A D DIGITAL OUTPUTS
U
U
The
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25
C. (Note 4)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS (CLK, OE, SHDN)
V
IH
High Level Input Voltage
V
DD
= 3V
2
V
V
IL
Low Level Input Voltage
V
DD
= 3V
0.8
V
I
IN
Input Current
V
IN
= 0V to V
DD
10
10
A
C
IN
Input Capacitance
(Note 7)
3
pF
LOGIC OUTPUTS
OV
DD
= 3V
C
OZ
Hi-Z Output Capacitance
OE = High (Note 7)
3
pF
I
SOURCE
Output Source Current
V
OUT
= 0V
50
mA
I
SINK
Output Sink Current
V
OUT
= 3V
50
mA
V
OH
High Level Output Voltage
I
O
= 10
A
2.995
V
I
O
= 200
A
2.7
2.99
V
V
OL
Low Level Output Voltage
I
O
= 10
A
0.005
V
I
O
= 1.6mA
0.09
0.4
V
OV
DD
= 2.5V
V
OH
High Level Output Voltage
I
O
= 200
A
2.49
V
V
OL
Low Level Output Voltage
I
O
= 1.6mA
0.09
V
OV
DD
= 1.8V
V
OH
High Level Output Voltage
I
O
= 200
A
1.79
V
V
OL
Low Level Output Voltage
I
O
= 1.6mA
0.09
V
LTC2251/LTC2250
5
22510f
TI I G CHARACTERISTICS
U
W
The
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 4)
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 ground with GND and OGND
wired together (unless otherwise noted).
Note 3: When these pin voltages are taken below GND or above V
DD
, they
will be clamped by internal diodes. This product can handle input currents
of greater than 100mA below GND or above V
DD
without latchup.
Note 4: V
DD
= 3V, f
SAMPLE
= 125MHz (LTC2251) or 105MHz (LTC2250),
input range = 2V
P-P
with differential drive, clock duty cycle stabilizer on,
unless otherwise noted.
Note 5: 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 6: Offset error is the offset voltage measured from 0.5 LSB when
the output code flickers between 00 0000 0000 and 11 1111 1111.
Note 7: Guaranteed by design, not subject to test.
Note 8: V
DD
= 3V, f
SAMPLE
= 125MHz (LTC2251) or 105MHz (LTC2250),
input range = 1V
P-P
with differential drive.
Note 9: Recommended operating conditions.
LTC2251
LTC2250
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
f
s
Sampling Frequency
(Note 9)
1
125
1
105
MHz
t
L
CLK Low Time
Duty Cycle Stabilizer Off
3.8
4
500
4.5
4.76
500
ns
Duty Cycle Stabilizer On
3
4
500
3
4.76
500
ns
(Note 7)
t
H
CLK High Time
Duty Cycle Stabilizer Off
3.8
4
500
4.5
4.76
500
ns
Duty Cycle Stabilizer On
3
4
500
3
4.76
500
ns
(Note 7)
t
AP
Sample-and-Hold
0
0
ns
Aperture Delay
t
D
CLK to DATA Delay
C
L
= 5pF (Note 7)
1.4
2.7
5.4
1.4
2.7
5.4
ns
Data Access Time
C
L
= 5pF (Note 7)
4.3
10
4.3
10
ns
After OE
BUS Relinquish Time
(Note 7)
3.3
8.5
3.3
8.5
ns
Pipeline
6
6
Cycles
Latency
POWER REQUIRE E TS
W
U
The
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 8)
LTC2251
LTC2250
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
V
DD
Analog Supply
(Note 9)
2.85
3
3.4
2.85
3
3.4
V
Voltage
OV
DD
Output Supply
(Note 9)
0.5
3
3.6
0.5
3
3.6
V
Voltage
I
VDD
Supply Current
132
156
107
126
mA
P
DISS
Power Dissipation
395
468
320
378
mW
P
SHDN
Shutdown Power
SHDN = H,
2
2
mW
OE = H, No CLK
P
NAP
Nap Mode Power
SHDN = H,
15
15
mW
OE = L, No CLK
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