Relation between Segment and Digit Outputs

Figure 4

Descriptions

1. Consider the examples shown in Figure 4, where data is set up so that the segment outputs S1 to S37 output a low

level on the G1 digit output timing and a high level on the G2 digit output timing. (Here, the G2 side being lighted)

2. The digit output G1 and G2 waveforms in Example 1 are output when the 10 bits of dimmer data (DM0 to DM9) are

t1 = 2/1.6 [MHz] = 1.25 [µs].

Note that t1 and t2 are the same period in Example 1.

3. The digit output G1 and G2 waveforms in Example 2 are those when the dimmer data (DM0 to DM9) are set to a

smaller value. Although the time t1, which is from the point where digit output falls to segment output changes, does

not change, the time t2, which is from the point where segment output changes to the time the digit output rises,

= 391 [Hz],

and,

t3 = 1.28 [ms].

Therefore,

t2 =

= 0.96 [ms].

4. When the dimmer data (DM0 to DM9) are set to an even smaller value, the time t2, which is from the point where

segment output changes to the time the digit output rises, becomes even longer, as in Example 3. Note that t1 does

not change here, either.

(1.28 [ms] – 1.25 [µs]

× 2) × (3FF

1023

No. 3586-8/10

LC7574NE, 7574NW