參數資料
型號: HCMS-2915
英文描述: High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
中文描述: 高性能CMOS 5 × 7字母數字顯示器(高性能的CMOS 5 × 7文字數字顯示器)
文件頁數: 14/16頁
文件大?。?/td> 304K
代理商: HCMS-2915
14
P
D
can be calculated as Equation
2 below.
Figure 4 shows how to derate the
power of one IC versus ambient
temperature. Operation at high
ambient temperatures 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.
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 R
θ
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.
Equation 1:
T
J
MAX = T
A
+ P
D
* R
θ
JA
Where:
T
J
MAX = maximum IC junction temperature
T
A
= ambient temperature surrounding the display
R
θ
JA
= thermal resistance from the IC junction to ambient
P
D
= power dissipated by the IC
Equation 2:
P
D
= (N * I
PIXEL
* Duty Factor * V
LED
) + I
LOGIC
* V
LOGIC
Where:
P
D
= total power dissipation
N = number of pixels on (maximum 4 char * 5 * 7 = 140)
I
PIXEL
= peak pixel current.
Duty Factor = 1/8 * Osccyc/64
Osc cyc = number of ON oscillator cycles per row
I
LOGIC
= IC logic current
V
LOGIC
= logic supply voltage
Equation 3:
I
PEAK
= M * 20 * I
PIXEL
Where:
I
PEAK
= maximum instantaneous peak current for the display
M = number of ICs in the system
20 = maximum number of LEDs on per IC
I
PIXEL
= peak current for one LED
Equation 4:
I
LED
(AVG) = N * I
PIXEL
* 1/8 * (oscillator cycles)/64
(see Variable Definitions above)
Appendix B. Electrical
Considerations
Current Calculations
The peak and average display
current requirements have a
significant impact on power
supply selection. The maximum
peak current is calculated with
Equation 3 below.
The average current required by
the display can be calculated with
Equation 4 below.
The power supply has to be able
to supply I
PEAK
transients and
supply I
LED
(AVG) continuously.
The range on V
LED
allows noise on
this supply without significantly
changing the display brightness.
V
LOGIC
and V
LED
Considerations
The display uses two independent
electrical systems. One system is
used to power the display’s logic
and the other to power the
display’s LEDs. These two
systems keep the logic supply
clean.
Separate electrical systems allow
the voltage applied to V
LED
and
V
LOGIC
to be varied independently.
Thus, V
LED
can vary from 0 to 5.5
V without affecting either the Dot
or the Control Registers. V
LED
can
P
D
D
0
25
T – AMBIENT TEMPERATURE – °C
0.7
0.6
0.5
0.4
0.3
0.2
0.1
60
55
50
45
40
35
30
0.8
0.9
1.0
1.1
1.2
85
80
75
70
65
R J-A
90
1.3
Figure 4.
相關PDF資料
PDF描述
HCMS-2921 High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
HCMS-2922 High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
HCMS-2901 High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
HCMS-2902 High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
HCMS-2903 High Performance CMOS 5 x 7 Alphanumeric Displays(高性能CMOS 5 x 7 文字數字顯示器)
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