mc145028 Freescale Semiconductor, Inc, mc145028 Datasheet - Page 12

• Manufacturer Part Number: mc145028
• Description: Mc145027 Encoder And Decoder Pair
• Manufacturer: Freescale Semiconductor, Inc

Pin Descriptions
12
external RC network; i.e.,
OSCILLATOR
This oscillator operates at a frequency determined by the
ENCODER
(PIN 15)
where: C
(PIN 12)
D
TE
out
DATA OUTPUTS
f ≈
for 1 kHz ≤ f ≤ 400 kHz
R
R
R
400 pF < C
TC
S
S
TC
′ = C
2.3 R
≈ 2 R
≥ 20 k
≥ 10 k
TC
(PIN 11)
TC
PW
TC
1
+ C
TC
C
min
VT
TC
layout
< 15 µF
′
11
(Hz)
+ 12 pF
MC145026, MC145027, MC145028 Technical Data, Rev. 4
HIGH
DIGIT
Figure 10. Encoder Oscillator Information
1ST
INTERNAL
ENABLE
R
1ST WORD
Figure 11. Timing Diagram
S
ENCODING SEQUENCE
OPEN
current through R
limit for R
R
minimum recommended oscillation frequency of this circuit is 1 kHz. Susceptibility
to externally induced noise signals may occur for frequencies below 1 kHz and/or
when resistors utilized are greater than 1 MΩ.
TC
The value for R
For frequencies outside the indicated range, the formula is less accurate. The
x C
DECODER
TC
S
.
ENCODER
DIGIT
must ensure that R
LOW
9TH
C
TC
S
S
should be chosen to be ≥ 2 times R
is insignificant compared to current through R
12
R
TC
S
x 5 pF (input capacitance) is small compared to
DIGIT
1ST
13
2ND WORD
TC
DIGIT
9TH
Freescale Semiconductor
. This range ensures that
CONTINUOUS
TRANSMISSION
2 WORD
TRANSMISSION
1.1 (R
TC
2
. The upper
C
2
)