UPD75218 NEC, UPD75218 Datasheet - Page 43

• Manufacturer Part Number: UPD75218
• Description: 4-BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

Notes 1. Calculation of total loss
Example
CAPACITANCE (Ta = 25 C, V
Input capacitance
Output capacitance
Input /output capacitance
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 AC characteristics.
Design so that the sum of the following three power consumption values for the PD75218CW/GF will be
less than the total loss P
Suppose 4-LED output with 9 segments and 11 digits, V
Further, let the voltage of fluorescent display tube (V
P
In this example, the power consumption of 690.6 mW is higher than the allowable total loss for the shrink
a maximum of 3 mA, 15 mA and, 10 mA flow to a segment pin, timing pin and LED output pin, respectively.
DIP package (600 mW). 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.
T
=
Pull-down register loss: Power loss due to a pull-down resistor incorporated in the display output
CPU loss
Output pin loss
CPU loss : 5.5 V
Pin loss : Segment pin ..... 2 V
Pull-down resistor loss ........
+
Parameter
+
Except display output
Display output
= 690.6 mW
Timing pin ......... 2 V
LED output ........
DD
= 0 V)
9.0 mA = 49.5 mW
T
(It is recommended to use the system with 80 % or less of the rating).
: Given as V
: 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.
pin by mask option.
(30 + 5.5 V)
10
15
25 k
Symbol
3 mA
15 mA = 30 mW
DD
C
C
C
2 V
OUT
IN
IO
(Max.)
2
9 = 54 mW
10 = 504.1 mW
f = 1 MHz
0 V for pins other than pins
to be measured
10 mA
I
DD1
LOAD
(Max.)
DD
Conditions
voltage) be –30 V and normal voltage be small.
4 = 53 mW
= 5 V + 10 % and 4.19 MHz oscillation and let
Min.
Typ.
Max.
15
15
35
15
PD75218
Unit
pF
pF
pF
pF
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