UPD75216ACW

Manufacturer Part NumberUPD75216ACW
Description4-BIT SINGLE-CHIP MICROCOMPUTER
ManufacturerNEC
UPD75216ACW datasheet
 


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Page 47/72:

Calculation of total loss

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* 1. Calculation of total loss
Design so that the sum of the following three power consumption values for the PD75216ACW/GF will be
less than the total loss P
(It is recommended to use the system with 80 % or less of the rating).
T
CPU loss
: Given as V
Output pin loss
: There are normal output pin loss and display output pin loss. It is necessary
to add a loss derived from the flow of maximum current to each output pin.
Pull-down register loss : Power loss due to a pull-down resistor incorporated in the display output pin
by mask option.
Example
Suppose 4-LED output with 9
3 mA, 15 mA and up to 10 mA flow to the segment pin, timing pin and LED output pin, respectively.
Further, let the voltage of fluorescent display tube (V
CPU loss : 5.5 V
9.0 mA = 49.5 mW
Pin loss : Segment pin ..... 2V
Timing pin ......... 2V
LED output ........
Pull-down resistor loss ........
PT =
+
+
= 690.6 mW
In this example, since the allowable total loss is 600 mW for the shrink DIP package, it is necessary to
decrease power consumption by decreasing the number of on-chip pull-down resistors. In this example,
power consumption can be adjusted to 577.8 mW by incorporating pull-down resistors in only 11 digit
outputs and 7 segment outputs and externally mounting pull-down resistors to the 2 remaining segment
outputs.
2. Except the system clock oscillator, display controller and timer/pulse generator.
3. The operating voltage range varies depending on the cycle time. Refer to the section describing AC
characteristics.
(MAX.)
I
(MAX.)
DD
DD1
11
, V
= 5 V + 10 % and 4.19 MHz oscillation and let a current of
SEG
DIGIT
DD
voltage) be –30 V and normal voltage be small.
LOAD
3 mA
9 = 54 mW
15 mA = 30 mW
10
2 V
10 mA
4 = 53 mW
15
2
(30 + 5.5V)
10 = 504.1 mW
25 k
PD75216A
47