LM9831 is a single-chip USB image scanner system that provides all the functions (image sensor control, illumination control, analog front end, pixel processing function image data buffer/DRAM controller, microstepping motor controller, and USB interface) required to create a high-performance color scanner. The LM9831 scans images in 42-bit color/14-bit grayscale and has output data formats for 24-bit color/8-bit grayscale. The LM9831 supports sensors with pixel counts of up to 16384 pixels x 3 colors (1200 dpi x 13.6 inches). The LM9831's low operating and suspend mode supply currents allow design of USB bus-powered scanners. The only additional active components required are an external 4Mbit or 16Mbit DRAM for data buffering and power transistors for the stepper motor.
The LM9831 is a complete USB image scanner system‑on‑a‑chip that integrates sensor control, illumination, analog front‑end, pixel processing, DRAM interface, stepper‑motor driver and USB interface. It supports 42‑bit color (14‑bit gray) output and can handle sensors up to 16384 × 3 pixels (1200 dpi × 13.6 in). The device is designed for low power USB‑bus‑powered scanners with only external DRAM and motor driver components required.
The document provides a full description of the device’s features, key specifications, absolute maximum and operating ratings, electrical characteristics, pin assignments, mechanical dimensions, ordering information and connection diagrams. It also includes timing diagrams and details on the USB, DRAM, motor‑control and sensor‑control interfaces.
| Supply Voltage | +4.75 V to +5.25 V |
|---|---|
| External DRAM Support | 4 Mbit or 16 Mbit |
| ADC Resolution | 14 bit |
| Maximum Pixel Count | 16384 × 3 pixels (1200 dpi × 13.6 in) |
| Package Type | 100‑pin Thin Quad Flat‑Package (TQFP) |
The LM9831 operates from a supply voltage of +4.75 V to +5.25 V.
The LM9831 can be used with either a 4 Mbit or a 16 Mbit external DRAM.
It features a 14‑bit ADC capable of digitizing up to 6 Mpixel/s (2 M RGB pixels per second).
The device supports vertical resolutions from 50 dpi to 2400 dpi in 1 dpi increments.