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LM98725 -
Three Channel, 16-Bit, 81 MSPS Analog Front End with LVDS/CMOS Output and Integrated CCD/CIS Sensor Timing Generator
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Features
| • | LVDS/CMOS Outputs |
| • | LVDS/CMOS/Crystal Clock Source with PLL Multiplication |
| • | Integrated Flexible Spread Spectrum Clock Generation |
| • | CDS or S/H Processing for CCD or CIS sensors |
| • | Independent Gain/Offset Correction for Each Channel |
| • | Automatic per-Channel Gain and Offset Calibration |
| • | Programmable Input Clamp Voltage |
| • | Flexible CCD/CIS Sensor Timing Generator |
Key Specification
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Maximum Input Level
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1.2 or 2.4 Volt Modes
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(both with + or - polarity option)
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ADC Resolution
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16-Bit
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ADC Sampling Rate
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81 MSPS
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INL
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+17/- 28 LSB (typ)
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Channel Sampling Rate
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30/30/27 MSPS
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PGA Gain Steps
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256 Steps
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PGA Gain Range
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0.62 to 8.3x
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Analog DAC Resolution
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+/-9 Bits
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Analog DAC Range
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+/-307mV or +/-614mV
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Digital DAC Resolution
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+/-6 Bits
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Digital DAC Range
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-2048 LSB to + 2016 LSB
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SNR
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-74dB (@0dB PGA Gain)
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Power Dissipation
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755mW (LVDS)
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Operating Temp
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0 to 70°C
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Supply Voltage
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3.3V Nominal (3.0V to 3.6V range)
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General Description
The LM98725 is a fully integrated, high performance 16-Bit, 81 MSPS signal processing solution for digital color copiers,
scanners, and other image processing applications. More...
Applications
| • | Multi-Function Peripherals |
| • | High-speed Currency/Check Scanners |
| • | Flatbed or Handheld Color Scanners |
| • | High-speed Document Scanners |
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Typical Application
click for larger image
Typical Application
| Parameters | Values |
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| Input Channels |
3 |
| ADC Sampling Rate |
81 MSPS |
| Channel Sampling Rate (MSPS) |
3 to 30 |
| ADC Resolution |
16 bits |
| Input Signal Polarity |
Both Pos, Neg |
| Input Sampler Type |
Both SH, CDS |
| Integrated Timing Generator |
Yes |
| Output Type |
Both LVDS, CMOS |
| Input Voltage Swing (Max) |
2.3 Volt |
| INL (+/-) |
23 LSB |
| Noise Floor |
-76 dB |
| PGA Gain Resolution |
8 bits |
| PGA Gain (Min) |
-4.2 dB |
| PGA Gain (Max) |
18.4 dB |
| DAC Offset Resolution (+/-) |
9 bits |
| DAC Offset Range (+/-) |
307 mV |
| Supply Voltage |
3.3 Volt |
| Power Dissipation |
0.755 Watt |
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Also Recommended
| LM98519▲ | For A 6-channel AFE, With CMOS Outputs |
| LM98620▲ | For A 6-channel AFE, With LVDS Outputs |
| LM98714▲ | For A Lower-Speed Part With Fewer Features |
Block Diagram
click for larger image
System Block Diagram
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Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
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| LM98725 3 Channel, 16-Bit, 81 MSPS Analog Front End with LVDS/CMOS Output, Integrated CCD/CIS Sensor Timing Generator and Spread Spectrum Clock Generation |
464
Kbytes |
24-Sep-09 |
Download |
Package Availability, Models, Samples & Pricing
General Description
The LM98725 is a fully integrated, high performance 16-Bit, 81 MSPS signal processing solution for digital color copiers,
scanners, and other image processing applications. High-speed signal throughput is achieved with an innovative architecture
utilizing Correlated Double Sampling (CDS), typically employed with CCD arrays, or Sample and Hold (S/H) inputs (for higher
speed CCD or CMOS image sensors). The signal paths utilize 8 bit Programmable Gain Amplifiers (PGA), a +/-9-Bit offset correction
DAC and independently controlled Digital Black Level correction loops for each input. The PGA and offset DAC are programmed
independently allowing unique values of gain and offset for each of the three analog inputs. The signals are then routed to
a 81MHz high performance analog-to-digital converter (ADC). The fully differential processing channel shows exceptional noise
immunity, having a very low noise floor of -74dB. The 16-bit ADC has excellent dynamic performance making the LM98725 transparent
in the image reproduction chain.
A very flexible integrated Spread Spectrum Clock Generation (SSCG) modulator is included to assist with EM compliance and
reduce system costs.
[Information as of 7-Nov-2009]
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