LC80101M Datasheet, PDF (4/9 Pages) Sanyo Semicon Device – VICS LSI

Pin Assignment
LC80101M
Notes on the pull-up resistor used between the LC72700E pin 32 (DO) and this LSI’s pin 5 (DI1)
The value of the pull-up resistor Rp1 must be determined based on the printed circuit board’s floating capacitance and the
LC80101M’s clock. The time t_CL for the LC80101M clock is 1.1 µs (corresponding to 450 kHz). This clock is used as
the readout clock output to the LC72700E during the period discussed in note 1 for the basic timing of the external
interface as discussed on page 7. If the t_CL of the CL2 clock from the microprocessor is longer than the t_CL of the
LC80101M clock, a t_CL of 1.1 µs must be used in the formulas below. If the t_CL of that clock is shorter than that of the
LC80101M clock, then the t_CL of CL2 must be substituted in the formulas below.
For example, in the configuration shown in the figure above, assuming the t_CL of CL2 is 1.0 µs (i.e. CL2 = 500 kHz),
then: T = t_CL – 555 ns (the LC72700E data output time)
Since T ≈ 2.2 (C1 + C2) R
Rp1 ≈
445 ns
2.2 (C1 + C2)
Assuming that C1 = 10 pF and C2 = 10 pF, then Rp1 will be ≤ 10.1 kΩ. These considerations must be used as guidelines
when determining the value of the pull-up resistor Rp1.
No. 5438-4/9