LM98714 datasheet(49/115 Pages) TI1

49 / 115 page

LM98714

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SNAS254A – OCTOBER 2006 – REVISED JANUARY 2014

PIX SIGNAL GENERATOR OR/NOR MODES

As shown in Figure 32, the PIX signal generators outputs can be used in their normal form and sent to the

LM98714 output pins, or, they can be sent through an additional layer of OR and NOR logic to provide a number

of clocking variations. The OR and NOR combinations of multiple PIX signals can be useful for such modes as

pixel lumping, or other modes where more complicated phi clocks are required.

The OR and NOR functions are chosen through the PIX OR/NOR Control 1 and PIX OR/NOR Control 2 registers

on Page 4 of the serial interface register map. When all of the OR/NOR control bits are 0 (default) the PIX

signals are sent directly from the pix signal generators to the output pins configured by the Output Mapping

Control registers (register Page 3). When an OR/NOR control bit is set to 1, the OR or NOR product of multiple

pix signal generators is routed to the output pin described in the register details.

SH2 AND SH3 GENERATION

In some sensors, there is a requirement for up to three “SH” type signals. The LM98714 CCD Timing Generator

can be configured to produce optional SH signals as shown in Figure 46, these SH signals (SH2 and SH3) toggle

every other line and are coincident with the original SH pulse.

Figure 46. SH2 and SH3 Generation

The “Start Scan (BOS)” request bit is used to begin the proper sequence of CCD Timing outputs at the beginning

of a scan. The first line of pixels are being processed by the CCD during the first integration period (after the first

SH). The BOS signal (internal to the LM98714) occurs at the second SH to signal when the first line of pixels are

actually shifting out of the CCD and in to the AFE. The SH2 pulse is synchronized with the BOS signal and

continues to toggle on an every other line basis. The SH3 signal occurs on opposite lines from SH2.

The SH2 and SH3 signals are available in place of the Lamp IR1 and Lamp IR2 outputs respectively. The routing

of SH2 and SH3 is depicted in Figure 32. The use of SH2 and SH3 is selected by the SH2/SH3 Control register

(0x0F) on Page 4 of the register map.

Figure 47. Sensor Control Outputs

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