PCA2117DUGSSLASHDA datasheet(41/107 Pages) NXP

41 / 107 page

PCA2117

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 4 — 8 April 2015

41 of 107

NXP Semiconductors

PCA2117

Automotive LCD driver for character displays

8.4.5 Temperature measurement and temperature compensation of VLCD

8.4.5.1

Temperature readout

The PCA2117 has a built-in temperature sensor which provides an 8-bit digital value

(TD[7:0]) of the ambient temperature. This value can be read by command (see

Section 8.1.1.6 on page 11). The actual temperature is determined from TD[7:0] using

Equation 4.

(4)

TD[7:0] = FFh means that no temperature readout is available or was performed. FFh is

the default value after initialization. The measurement needs about 8 ms to complete. It is

repeated periodically every second as long as bit TME is set logic 1 (see Table 32 on

page 26).

Due to the nature of a temperature sensor, oscillations may occur. To avoid it, a filter has

been implemented in PCA2117. A control bit, TMF, is implemented to enable or disable

the digital temperature filter (see Table 32 on page 26). The system is exemplified in

Figure 23.

Conditions: VDD2 =5V; VLCD =16V; Tamb =25 C; RITO(VSS2), RITO(VDD2), RITO(VLCDOUT) =50 .

(1) VLCD =2  VDD2.

(2) VLCD =3  VDD2.

(3) VLCD =4  VDD2.

Iload is the overall current sink of the column and row outputs depending on the display, plus the

on-chip VLCD current consumption.

Fig 22. VLCD with respect to Iload at VDD2 =5V

C



0.6275

–



PCA2117DUGS/DA Datasheet(PDF) 41 Page - NXP Semiconductors