HCMS-2819 Datasheet, PDF (10/12 Pages) AVAGO TECHNOLOGIES LIMITED – High Performance CMOS 5x7 AlphaNumeric InGaN Blue Display

CE
RS
BL
RESET
CLK
D_OUT
SEL
OSC
CE
RS
BL
RESET
CLK
IC1
BITS 0-159
CHARACTERS 0-3
DOUT
D_IN
SEL
OSC
CE
RS
BL
RESET
CLK
DOUT
OSC
SEL
IC2
BITS 160-319
CHARACTERS 4-7
D_IN
D_IN
Figure 5. Cascaded ICs.
Appendix A. Thermal Considerations
The display IC has a maximum junction temperature of
150°C. The IC junction temperature can be calculated with
Equation 1 below.
A typical value for RT_JA is 100°C/W. This value is typical for
a display mounted in a socket and covered with a plastic
filter. The socket is soldered to a .062 in. thick PCB with .020
inch wide, one ounce copper traces. PD can be calculated
as Equation 2 below.
Figure 6 shows how to derate the power of one IC versus
ambient temperature. Operation at high ambient tem-
peratures may require the power per IC to be reduced.
The power consumption can be reduced by changing
either the N, I_PIXEL, Osc cyc or V_LED. Changing V_LOGIC has
very little impact on the power consumption.
1.3
1.2
1.1
Rθ_J-A = 100 °C/W
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
25 30 35 40 45 50 55 60 65 70 75 80 85 90
TA - AMBIENT TEMPERATURE - C
Figure 6. Maximum power dissipation per IC versus ambient temperature.
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