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LTC1746
Low Power,14-Bit, 25Msps ADC
FEATURES
s s s s s s s s s
DESCRIPTIO
Sample Rate: 25Msps 77.5dB SNR and 91dB SFDR (3.2V Range) 74dB SNR and 96dB SFDR (2V Range) No Missing Codes Single 5V Supply Low Power Dissipation: 390mW Selectable Input Ranges: ±1V or ±1.6V 240MHz Full Power Bandwidth S/H Pin Compatible Family 25 Msps: LTC1746 (14-Bit), LTC1745 (12-Bit) 50 Msps: LTC1744 (14-Bit), LTC1743 (12-Bit) 65 Msps: LTC1742 (14-Bit), LTC1741 (12-Bit) 80 Msps: LTC1748 (14-Bit), LTC1747 (12-Bit)
The LTC ®1746 is a 25Msps, sampling 14-bit A/D converter designed for digitizing high frequency, wide dynamic range signals. Pin selectable input ranges of ±1V and ±1.6V along with a resistor programmable mode allow the LTC1746’s input range to be optimized for a wide variety of applications. The LTC1746 is perfect for demanding communications applications with AC performance that includes 77.5dB SNR and 91dB spurious free dynamic range. Ultralow jitter of 0.3psRMS allows undersampling with excellent noise performance. DC specs include ±3LSB INL maximum and no missing codes over temperature. The digital interface is compatible with 5V, 3V and 2V logic systems. The ENC and ENC inputs may be driven differentially from PECL, GTL and other low swing logic families or from single-ended TTL or CMOS. The low noise, high gain ENC and ENC inputs may also be driven by a sinusoidal signal without degrading performance. A separate digital output power supply can be operated from 0.5V to 5V, making it easy to connect directly to low voltage DSPs or FIFOs. The TSSOP package with a flow-through pinout simplifies the board layout.
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Telecommunications Medical Imaging Receivers Base Stations Spectrum Analysis Imaging Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
BLOCK DIAGRA
AIN+ ±1V DIFFERENTIAL ANALOG INPUT
25Msps, 14-Bit ADC with a ± 1V Differential Input Range
OVDD OF D13 D0 CLKOUT 0.1µF 0.5V TO 5V 0.1µF
AIN–
S/H AMP
14-BIT PIPELINED ADC
14
SENSE BUFFER
RANGE SELECT
DIFF AMP GND CONTROL LOGIC
1746 BD
VCM 4.7µF
2.35VREF
REFLB 0.1µF 1µF
REFHA 4.7µF
REFLA
REFHB
ENC
ENC
MSBINV
0.1µF 1µF
DIFFERENTIAL ENCODE INPUT
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OUTPUT LATCHES • • • OGND VDD 1µF 1µF 5V 1µF OE
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1
LTC1746
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ABSOLUTE MAXIMUM RATINGS
OVDD = VDD (Notes 1, 2)
PACKAGE/ORDER INFORMATION
TOP VIEW SENSE VCM GND AIN+ AIN– GND VDD VDD GND REFLB REFHA GND GND REFLA REFHB GND VDD VDD GND VDD GND MSBINV ENC ENC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 FW PACKAGE 48-LEAD PLASTIC TSSOP 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 OF OGND D13 D12 D11 OVDD D10 D9 D8 D7 OGND GND GND D6 D5 D4 OVDD D3 D2 D1 D0 OGND CLKOUT OE
Supply Voltage (VDD) ............................................. 5.5V Analog Input Voltage (Note 3) .... – 0.3V to (VDD + 0.3V) Digital Input Voltage (Note 4) ..... – 0.3V to (VDD + 0.3V) Digital Output Voltage ................. – 0.3V to (VDD + 0.3V) OGND Voltage ..............................................– 0.3V to 1V Power Dissipation ............................................ 2000mW Operating Temperature Range LTC1746C ............................................... 0°C to 70°C LTC1746I ............................................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART NUMBER LTC1746CFW LTC1746IFW
TJMAX = 150°C, θJA = 35°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
CO VERTER CHARACTERISTICS
PARAMETER Resolution (No Missing Codes) Integral Linearity Error Differential Linearity Error Offset Error Gain Error Full-Scale Tempco
The q indicates specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)
CONDITIONS
q
MIN 14 –3 –1 – 30 – 2.5
q q
TYP ±1 ± 0.5 ±5 ±1 ± 40
MAX 3 1 30 2.5
UNITS Bits LSB LSB mV %FS ppm/°C
(Note 6) (Note 7) External Reference (SENSE = 1.6V) IOUT(REF) = 0
q q
A ALOG I PUT
SYMBOL VIN IIN CIN tACQ tAP tJITTER CMRR PARAMETER
The q indicates specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5)
CONDITIONS 4.75V ≤ VDD ≤ 5.25V Sample Mode ENC < ENC Hold Mode ENC > ENC
q q q
MIN –1
TYP ±1 to ±1.6
MAX 1
UNITS V µA pF pF
Analog Input Range (Note 8) Analog Input Leakage Current Analog Input Capacitance Sample-and-Hold Acquisition Time Sample-and-Hold Acquisition Delay Time Sample-and-Hold Acquisition Delay Time Jitter Analog Input Common Mode Rejection Ratio
8 4 15 0 0.3 18
psRMS dB
1746f
1.0V < (AIN = AIN
–
+) < 3.5V
80
2
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ns ns
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LTC1746
DY A IC ACCURACY
SYMBOL SNR PARAMETER Signal-to-Noise Ratio
The q indicates specifications which apply over the full operating temperature range, otherwise specifications are at.