LTC2255/LTC2254
14-Bit, 125/105Msps
Low Power 3V ADCs
FEATURES
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DESCRIPTIO
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Sample Rate: 125Msps/105Msps
Single 3V Supply (2.85V to 3.4V)
Low Power: 395mW/320mW
72.4dB SNR
88dB 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: LTC2253 (12-Bit), LTC2255 (14-Bit)
105Msps: LTC2252 (12-Bit), LTC2254 (14-Bit)
80Msps: LTC2229 (12-Bit), LTC2249 (14-Bit)
65Msps: LTC2228 (12-Bit), LTC2248 (14-Bit)
40Msps: LTC2227 (12-Bit), LTC2247 (14-Bit)
25Msps: LTC2226 (12-Bit), LTC2246 (14-Bit)
10Msps: LTC2225 (12-Bit), LTC2245 (14-Bit)
32-Pin (5mm
×
5mm) QFN Package
The LTC
®
2255/LTC2254 are 14-bit 125Msps/105Msps,
low power 3V A/D converters designed for digitizing high
frequency, wide dynamic range signals. The LTC2255/
LTC2254 are perfect for demanding imaging and commu-
nications applications with AC performance that includes
72.3dB SNR and 85dB SFDR for signals at the Nyquist
frequency.
DC specs include
±1LSB
INL (typ),
±0.5LSB
DNL (typ) and
no missing codes over temperature. The transition noise
is a low 1.3 LSB
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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Wireless and Wired Broadband Communication
Imaging Systems
Ultrasound
Spectral Analysis
Portable Instrumentation
TYPICAL APPLICATIO
REFH
REFL
FLEXIBLE
REFERENCE
OV
DD
SNR (dBFS)
+
ANALOG
INPUT
INPUT
S/H
–
14-BIT
PIPELINED
ADC CORE
CORRECTION
LOGIC
OUTPUT
DRIVERS
D13
•
•
•
D0
OGND
CLOCK/DUTY
CYCLE
CONTROL
22554 TA01a
CLK
22554fa
U
LTC2255: SNR vs Input Frequency,
–1dB, 2V Range, 125Msps
75
74
73
72
71
70
69
68
67
66
65
0
50
100 150 200 250 300 350
33554 G09
INPUT FREQUENCY (MHz)
U
U
1
LTC2255/LTC2254
ABSOLUTE
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
SENSE
MODE
V
CM
D13
D12
D11
V
DD
OF
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
LTC2255C, LTC2254C ............................. 0°C to 70°C
LTC2255I, LTC2254I ...........................–40°C to 85°C
Storage Temperature Range ..................–65°C to 125°C
ORDER PART
NUMBER
24 D10
23 D9
22 D8
32 31 30 29 28 27 26 25
AIN
+
1
AIN
–
2
REFH 3
REFH 4
REFL 5
REFL 6
V
DD
7
GND 8
9 10 11 12 13 14 15 16
OE
D0
D1
D2
D3
CLK
SHDN
D4
33
21 OV
DD
20 OGND
19 D7
18 D6
17 D5
LTC2255CUH
LTC2255IUH
LTC2254CUH
LTC2254IUH
QFN PART*
MARKING
2255
2254
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 33) IS GND
MUST BE SOLDERED TO PCB
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/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
CO VERTER CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Differential Linearity Error
Offset Error
Gain Error
Offset Drift
Full-Scale Drift
Transition Noise
Internal Reference
External Reference
SENSE = 1V
CONDITIONS
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
LTC2255
MIN
TYP
MAX
●
LTC2254
MIN
TYP
MAX
14
–5.5
–1
–12
–2.5
±1
±0.5
±2
±0.5
±10
±30
±5
1.3
5.5
1
12
2.5
UNITS
Bits
LSB
LSB
mV
%FS
µV/°C
ppm/°C
ppm/°C
LSB
RMS
14
–5
–1
–12
–2.5
±1
±0.5
±2
±0.5
±10
±30
±5
1.3
5
1
12
2.5
Differential Analog Input (Note 5)
Differential Analog Input
(Note 6)
External Reference
●
●
●
●
22554fa
2
U
W
U
U
W W
W
U
LTC2255/LTC2254
A ALOG I PUT
SYMBOL
V
IN
V
IN,CM
I
IN
I
SENSE
I
MODE
t
AP
t
JITTER
CMRR
PARAMETER
The
●
denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25°C. (Note 4)
CONDITIONS
2.85V < V
DD
< 3.4V (Note 7)
Differential Input (Note 7)
0V < A
IN+
, A
IN–
< V
DD
0V < SENSE < 1V
●
●
●
●
●
Analog Input Range (A
IN+
–A
IN–
)
Analog Input Common Mode
Analog Input Leakage Current
SENSE Input Leakage
MODE Pin Leakage
Sample-and-Hold Acquisition Delay Time
Sample-and-Hold Acquisition Delay Time Jitter
Analog Input Common Mode Rejection Ratio
Full Power Bandwidth
DY A IC ACCURACY
SYMBOL
SNR
PARAMETER
Signal-to-Noise Ratio
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)
CONDITIONS
5MHz Input
30MHz Input
70MHz Input
140MHz Input
SFDR
Spurious Free Dynamic Range
2nd or 3rd Harmonic
5MHz Input
30MHz Input
70MHz Input
140MHz Input
SFDR
Spurious Free Dynamic Range
4th Harmonic or Higher
5MHz Input
30MHz Input
70MHz Input
140MHz Input
S/(N+D)
Signal-to-Noise Plus
Distortion Ratio
5MHz Input
30MHz Input
70MHz Input
140MHz Input
IMD
Intermodulation
Distortion
f
IN1
= 28.2MHz
f
IN2
= 26.8MHz
●
●
●
●
U
W U
U
MIN
1
–1
–3
–3
TYP
1.5
MAX
1.9
1
3
3
UNITS
V
V
µA
µA
µA
ns
ps
RMS
dB
MHz
±0.5V
to
±1V
0
0.2
80
Figure 8 Test Circuit
640
MIN
LTC2255
TYP
MAX
72.4
72.3
LTC2254
MIN
TYP
MAX
72.5
72.4
69.4
72.3
71.7
88
88
71
84
80
90
90
79
90
90
72.4
72.2
68.5
72
70.6
85
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
68.9
72.1
71.7
88
85
73
82
78
90
90
77
90
90
72.2
72
68
71.9
70.2
85
22554fa
3
LTC2255/LTC2254
I TER AL REFERE CE CHARACTERISTICS
PARAMETER
V
CM
Output Voltage
V
CM
Output Tempco
V
CM
Line Regulation
V
CM
Output Resistance
CONDITIONS
I
OUT
= 0
DIGITAL I PUTS A D DIGITAL OUTPUTS
SYMBOL
V
IH
V
IL
I
IN
C
IN
LOGIC OUTPUTS
OV
DD
= 3V
C
OZ
I
SOURCE
I
SINK
V
OH
V
OL
OV
DD
= 2.5V
V
OH
V
OL
OV
DD
= 1.8V
V
OH
V
OL
High Level Output Voltage
Low Level Output Voltage
I
O
= –200µA
I
O
= 1.6mA
High Level Output Voltage
Low Level Output Voltage
I
O
= –200µA
I
O
= 1.6mA
Hi-Z Output Capacitance
Output Source Current
Output Sink Current
High Level Output Voltage
Low Level Output Voltage
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Input Current
Input Capacitance
CONDITIONS
V
DD
= 3V
V
DD
= 3V
LOGIC INPUTS (CLK, OE, SHDN)
The
●
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 4)
MIN
●
●
●
POWER REQUIRE E TS
SYMBOL
V
DD
OV
DD
IV
DD
P
DISS
P
SHDN
P
NAP
PARAMETER
Analog Supply Voltage
Output Supply Voltage
Supply Current
Power Dissipation
Shutdown Power
Nap Mode Power
The
●
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 8)
CONDITIONS
(Note 9)
(Note 9)
●
●
●
●
4
U W
U
U
U
U
U
(Note 4)
MIN
1.475
TYP
1.500
±25
3
4
MAX
1.525
UNITS
V
ppm/°C
mV/V
Ω
2.85V < V
DD
< 3.4V
–1mA < I
OUT
< 1mA
TYP
MAX
UNITS
V
2
0.8
–10
3
10
V
µA
pF
V
IN
= 0V to V
DD
(Note 7)
OE = High (Note 7)
V
OUT
= 0V
V
OUT
= 3V
I
O
= –10µA
I
O
= –200µA
I
O
= 10µA
I
O
= 1.6mA
●
●
3
50
50
2.7
2.995
2.99
0.005
0.09
2.49
0.09
1.79
0.09
0.4
pF
mA
mA
V
V
V
V
V
V
V
V
LTC2255
MIN
TYP
MAX
2.85
0.5
3
3
132
395
2
15
3.4
3.6
156
468
LTC2254
MIN
TYP
MAX
2.85
0.5
3
3
107
320
2
15
3.4
3.6
126
378
UNITS
V
V
mA
mW
mW
mW
SHDN = H,
OE = H, No CLK
SHDN = H,
OE = L, No CLK
22554fa
LTC2255/LTC2254
The
●
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 4)
SYMBOL
f
s
t
L
PARAMETER
Sampling Frequency
CLK Low Time
CONDITIONS
(Note 9)
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
(Note 7)
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
(Note 7)
●
●
●
●
●
TI I G CHARACTERISTICS
t
H
t
AP
t
D
Pipeline Latency
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 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 (LTC2255) or 105MHz (LTC2254),
input range = 2V
P-P
with differential drive, clock duty cycle stabilizer on,
unless otherwise noted.
UW
LTC2255
MIN
TYP
MAX
1
3.8
3
3.8
3
4
4
4
4
0
125
500
500
500
500
LTC2254
MIN
TYP
MAX
1
4.5
3
4.5
3
4.76
4.76
4.76
4.76
0
105
500
500
500
500
UNITS
MHz
ns
ns
ns
ns
ns
CLK High Time
Sample-and-Hold
Aperture Delay
CLK to DATA delay
Data Access Time
After OE↓
BUS Relinquish Time
C
L
= 5pF (Note 7)
C
L
= 5pF (Note 7)
(Note 7)
●
●
●
1.4
2.7
4.3
3.3
5
5.4
10
8.5
1.4
2.7
4.3
3.3
5
5.4
10
8.5
ns
ns
ns
Cycles
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 0000 and
11 1111 1111 1111.
Note 7:
Guaranteed by design, not subject to test.
Note 8:
V
DD
= 3V, f
SAMPLE
= 125MHz (LTC2255) or 105MHz (LTC2254),
input range = 1V
P-P
with differential drive.
Note 9:
Recommended operating conditions.
22554fa
5
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