Keithley 708B Reference Manual page 159

Section 4: Theory of operations
12 x 12 LED matrix
The 12 x 12 matrix array of LEDs is driven by PWM signals that cause the intensity of the LED to be
bright or dim based on the appropriate setting from the instrument.
Each row and column is updated sequentially. The entire display has a refresh rate of approximately
60 Hz. The time domain details of display refreshing are shown below.
Slot indicators
The slot LEDs are treated the same as the matrix LEDs, as additional 13th and 14th columns.
4-8
Figure 77: Model 707B display refresh
All Rows
Refreshed
Period
. . .
Low brightness
1/20 of slice
High brightness
19/20 of slice
Models 707B and 708B Switching Matrix Reference Manual
Repeat . . .
Each row gets a time slice
of column data . . .
. . . then each row
gets divided into
20 time slots.
707B-901-01 Rev. A / August 2010