Timing Generator Configuration for LM98714

Hi Jeffrey

For sensors with an external signal that controls an electronic shutter function, it is possible to shorten the integration time. The "Mode" timing generator can be used to generate an On/Off signal that controls the electronic shutter timing. (See Figure 29 on page 24, Figure 34 on page 28 and the the registers described at the bottom of page 68. (Register Page 4, Registers 0-3).

If sensors do not have an electronic shutter input there is really no way to decouple the integration time from the time required to clock the pixels out. Alternative, if the lamp source can be made dim enough, it is possible to make the integration time requirement always longer than the time for pixel conversion. Then the time can be extended as needed by lengthening the line timing beyond the minimum.

As far as synchronizing motor stepping to line conversion there are several approaches, with a lot of the detail depending on the necessary scan resolution. For low resolution scans it may be necessary to step multiple times per line to achieve the desired resolution. These steps must either be bunched together during a long SH interval as you say, or done smoothly as the image is integrated. You might want to look at the LM9833 datasheet on-line for some insight into the details of this.

http://www.ti.com/product/lm9833

While this device is much too slow (2 MHz pixel clock rate in 3 color mode) for modern applications it does have all of the stepper motor functions integrated, and therefore has a lot of that detail described in the datasheet.

I hope this is helpful.

Best regards,

Jim B