pling 12-bit A/D converters designed for digitizing high
frequency, wide dynamic range signals. They are perfect
for demanding communications applications with AC
performance that includes 71.1dB SNR and 85dB spurious
free dynamic range (SFDR). Ultralow jitter of 0.17ps
RMS
allows undersampling of IF frequencies with excellent
noise performance.
DC specs include ±0.3LSB INL (typical), ±0.1LSB DNL
(typical) and no missing codes over temperature. The
transition noise is a low 0.3LSB
RMS
.
The digital outputs can be either full rate CMOS, double
data rate CMOS, or double data rate LVDS. A separate
output power supply allows the CMOS output swing to
range from 1.2V to 1.8V.
The ENC
+
and ENC
–
inputs may be driven differentially
or single-ended with a sine wave, PECL, LVDS, TTL or
CMOS inputs. An optional clock duty cycle stabilizer al-
lows high performance at full speed for a wide range of
clock duty cycles.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
71.1dB SNR
88dB SFDR
Low Power: 79mW/47mW/34mW
Single 1.8V Supply
CMOS, DDR CMOS or DDR LVDS Outputs
Selectable Input Ranges: 1V
P-P
to 2V
P-P
800MHz Full-Power Bandwidth S/H
Optional Data Output Randomizer
Optional Clock Duty Cycle Stabilizer
Shutdown and Nap Modes
Serial SPI Port for Configuration
Pin Compatible 14-Bit and 12-Bit Versions
40-Pin (6mm
×
6mm) QFN Package
APPLICATIONS
n
n
n
n
n
n
Communications
Cellular Base Stations
Software Defined Radios
Portable Medical Imaging
Multi-Channel Data Acquisition
Nondestructive Testing
TYPICAL APPLICATION
1.8V
V
DD
1.2V
TO 1.8V
OV
DD
2-Tone FFT, f
IN
= 68MHz and 69MHz
0
–10
–20
–30
AMPLITUDE (dBFS)
–40
–50
–60
–70
–80
+
ANALOG
INPUT
INPUT
S/H
–
12-BIT
PIPELINED
ADC CORE
CORRECTION
LOGIC
OUTPUT
DRIVERS
D11
CMOS
•
OR
•
LVDS
•
D0
OGND
CLOCK/DUTY
CYCLE
CONTROL
GND
225812 TA01a
–90
–100
–110
–120
0
20
10
FREQUENCY (MHz)
30
225812 TA01b
65MHz
CLOCK
225812p
1
LTC2258-12
LTC2257-12/LTC2256-12
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltages (V
DD
, OV
DD
) ....................... –0.3V to 2V
Analog Input Voltage (A
IN+
, A
IN–
,
PAR/SER, SENSE) (Note 3) ...........–0.3V to (V
DD
+ 0.2V)
Digital Input Voltage (ENC
+
, ENC
–
,
CS,
SDI, SCK) (Note 4) .................................... –0.3V to 3.9V
SDO (Note 4) ............................................ –0.3V to 3.9V
Digital Output Voltage ................ –0.3V to (OV
DD
+ 0.3V)
Operating Temperature Range:
LTC2258C, LTC2257C, LTC2256C............. 0°C to 70°C
LTC2258I, LTC2257I, LTC2256I ............ –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
PIN CONFIGURATIONS
D10_11
SENSE
FULL-RATE CMOS OUTPUT MODE
TOP VIEW
V
REF
DNC
V
CM
D11
D10
V
DD
D9
D8
OF
DOUBLE DATA RATE CMOS OUTPUT MODE
TOP VIEW
SENSE
D8_9
DNC
V
REF
DNC
DNC
DNC
30 D6_7
29 DNC
28 CLKOUT
+
27 CLKOUT
–
41
26 OV
DD
25 OGND
24 D4_5
23 DNC
22 D2_3
21 DNC
11 12 13 14 15 16 17 18 19 20
CS
DNC
DNC
SDO
SCK
SDI
D0_1
ENC
+
ENC
–
V
CM
V
DD
OF
40 39 38 37 36 35 34 33 32 31
A
IN+
1
A
IN–
2
GND 3
REFH 4
REFH 5
REFL 6
REFL 7
PAR/SER 8
V
DD
9
V
DD
10
11 12 13 14 15 16 17 18 19 20
CS
SDO
DNC
DNC
SCK
D0
ENC
+
ENC
–
SDI
D1
41
30 D7
29 D6
28 CLKOUT
+
27
CLKOUT
–
A
IN+
1
A
IN–
2
GND 3
REFH 4
REFH 5
REFL 6
REFL 7
PAR/SER 8
V
DD
9
V
DD
10
40 39 38 37 36 35 34 33 32 31
26 OV
DD
25 OGND
24 D5
23 D4
22 D3
21 D2
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 32°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
T
JMAX
= 150°C,
θ
JA
= 32°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
DOUBLE DATA RATE LVDS OUTPUT MODE
TOP VIEW
D10_11
+
D10_11
–
SENSE
D8_9
+
D0_1
–
D8_9
–
30 D6_7
+
29 D6_7
–
28 CLKOUT
+
27 CLKOUT
–
41
26 OV
DD
25 OGND
24 D4_5
+
23 D4_5
–
22 D2_3
+
21 D2_3
–
11 12 13 14 15 16 17 18 19 20
CS
SDO
DNC
ENC
+
ENC
–
DNC
SCK
SDI
D0_1
+
V
REF
V
CM
V
DD
OF
+
OF
–
40 39 38 37 36 35 34 33 32 31
A
IN+
1
A
IN–
2
GND 3
REFH 4
REFH 5
REFL 6
REFL 7
PAR/SER 8
V
DD
9
V
DD
10
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 32°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
225812p
2
LTC2258-12
LTC2257-12/LTC2256-12
ORDER INFORMATION
LEAD FREE FINISH
LTC2258CUJ-12#PBF
LTC2258IUJ-12#PBF
LTC2257CUJ-12#PBF
LTC2257IUJ-12#PBF
LTC2256CUJ-12#PBF
LTC2256IUJ-12#PBF
TAPE AND REEL
LTC2258CUJ-12#TRPBF
LTC2258IUJ-12#TRPBF
LTC2257CUJ-12#TRPBF
LTC2257IUJ-12#TRPBF
LTC2256CUJ-12#TRPBF
LTC2256IUJ-12#TRPBF
PART MARKING*
LTC2258UJ-12
LTC2258UJ-12
LTC2257UJ-12
LTC2257UJ-12
LTC2256UJ-12
LTC2256UJ-12
PACKAGE DESCRIPTION
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
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. *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/
CONVERTER CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
LTC2261-12
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
External Reference
Differential Analog Input
(Note 7)
Internal Reference
External Reference
CONDITIONS
l
LTC2260-12
MIN
12
–1
–0.4
–9
–1.5
TYP
±0.3
±0.1
±1.5
±1.5
±0.4
±20
±30
±10
0.3
MAX
1
0.4
9
1.5
12
–1
LTC2259-12
MIN
TYP
±0.3
±0.1
±1.5
±1.5
±0.4
±20
±30
±10
0.3
MAX
1
0.4
9
1.5
UNITS
Bits
LSB
LSB
mV
%FS
%FS
μV/°C
ppm/°C
ppm/°C
LSB
RMS
MIN
12
–1
–0.4
–9
–1.5
TYP
±0.3
±0.1
±1.5
±1.5
±0.4
±20
±30
±10
0.3
MAX
1
0.4
9
1.5
Differential Analog Input (Note 6)
l
l
l
l
–0.4
–9
–1.5
225812p
3
LTC2258-12
LTC2257-12/LTC2256-12
ANALOG INPUT
SYMBOL PARAMETER
V
IN
V
IN(CM)
V
SENSE
I
INCM
Analog Input Range (A
IN+
– A
IN–
)
Analog Input Common Mode (A
IN+
+ A
IN–
)/2
Analog Input Common Mode Current
The
l
denotes the specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25°C. (Note 5)
CONDITIONS
1.7V < V
DD
< 1.9V
Differential Analog Input (Note 8)
Per Pin, 125Msps
Per Pin, 105Msps
Per Pin, 80Msps
0 < A
IN+
, A
IN–
< V
DD
, No Encode
0 < PAR/SER < V
DD
0.625V < SENSE < 1.3V
l
l
l
l
l
l
MIN
V
CM
– 100mV
0.625
TYP
1 to 2
V
CM
1.250
155
130
100
MAX
V
CM
+ 100mV
1.300
UNITS
V
P-P
V
V
μA
μA
μA
External Voltage Reference Applied to SENSE External Reference Mode
I
IN1
I
IN2
I
IN3
t
AP
t
JITTER
CMRR
BW-3B
Analog Input Leakage Current
PAR/SER Input Leakage Current
SENSE Input Leakage Current
Sample-and-Hold Acquisition Delay Time
Sample-and-Hold Acquisition Delay Jitter
Analog Input Common Mode Rejection Ratio
Full-Power Bandwidth
–1
–3
–6
0
0.17
80
1
3
6
μA
μA
μA
ns
ps
RMS
dB
MHz
Figure 6 Test Circuit
800
The
l
denotes the specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. A
IN
= –1dBFS. (Note 5)
LTC2258-12
SYMBOL
SNR
PARAMETER
Signal-to-Noise Ratio
CONDITIONS
5MHz Input
70MHz Input
140MHz Input
l
DYNAMIC ACCURACY
LTC2257-12
MIN
69.4
TYP
70.8
70.6
70.4
91.7
91.3
85.7
97.8
97.4
95.6
70.7
70.6
70.2
MAX
LTC2256-12
MIN
69.1
TYP
70.5
70
69.7
91.9
95.4
89.8
98.3
98.4
88.1
70.4
69.8
69.5
MAX
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
MIN
69.4
TYP
71.1
71
70.8
91.7
91.5
81.1
98.5
99.1
98.3
71
70.9
70.3
MAX
SFDR
Spurious Free Dynamic Range 5MHz Input
2nd or 3rd Harmonic
70MHz Input
140MHz Input
Spurious Free Dynamic Range 5MHz Input
4th Harmonic or Higher
70MHz Input
140MHz Input
l
76
76
79
l
83
82
85
S/(N+D)
Signal-to-Noise Plus
Distortion Ratio
5MHz Input
70MHz Input
140MHz Input
l
68.6
68.6
68.8
INTERNAL REFERENCE CHARACTERISTICS
PARAMETER
V
CM
Output Voltage
V
CM
Output Temperature Drift
V
CM
Output Resistance
V
REF
Output Voltage
V
REF
Output Temperature Drift
V
REF
Output Resistance
V
REF
Line Regulation
–400μA < I
OUT
< 1mA
1.7V < V
DD
< 1.9V
–600μA < I
OUT
< 1mA
I
OUT
= 0
CONDITIONS
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
0.5 • V
DD
– 25mV
TYP
0.5 • V
DD
±25
4
1.225
1.250
±25
7
0.6
1.275
MAX
0.5 • V
DD
+ 25mV
UNITS
V
ppm/°C
Ω
V
ppm/°C
Ω
mV/V
225812p
4
LTC2258-12
LTC2257-12/LTC2256-12
DIGITAL INPUTS AND OUTPUTS
SYMBOL PARAMETER
ENCODE INPUTS (ENC
+
, ENC
–
)
Differential Encode Mode (ENC
–
Not Tied to GND)
V
ID
V
ICM
V
IN
R
IN
C
IN
V
IH
V
IL
V
IN
R
IN
C
IN
V
IH
V
IL
I
IN
C
IN
R
OL
I
OH
C
OUT
Differential Input Voltage
Common Mode Input Voltage
Input Voltage Range
Input Resistance
Input Capacitance
High Level Input Voltage
Low Level Input Voltage
Input Voltage Range
Input Resistance
Input Capacitance
High Level Input Voltage
Low Level Input Voltage
Input Current
Input Capacitance
Logic Low Output Resistance to GND
Logic High Output Leakage Current
Output Capacitance
(Note 8)
Internally Set
Externally Set (Note 8)
ENC
+
, ENC
–
to GND
(See Figure 10)
(Note 8)
V
DD
= 1.8V
V
DD
= 1.8V
ENC
+
to GND
(See Figure 11)
(Note 8)
V
DD
= 1.8V
V
DD
= 1.8V
V
IN
= 0V to 3.6V
(Note 8)
V
DD
= 1.8V, SDO = 0V
SDO = 0V to 3.6V
(Note 8)
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
MIN
TYP
MAX
UNITS
0.2
1.2
1.1
0.2
10
3.5
1.2
0.6
0
30
3.5
1.3
0.6
–10
3
200
–10
4
10
10
3.6
1.6
3.6
V
V
V
V
kΩ
pF
V
V
V
kΩ
pF
V
V
μA
pF
Ω
μA
pF
Single-Ended Encode Mode (ENC
–
Tied to GND)
DIGITAL INPUTS (CS, SDI, SCK)
SDO OUTPUT (Open-Drain Output. Requires 2k Pull-Up Resistor if SDO is Used)
DIGITAL DATA OUTPUTS (CMOS MODES: FULL DATA RATE AND DOUBLE DATA RATE)
嵌入式系统
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