MITSUBISHI IC’S
M35501FP
FLD (VFD) DIGIT EXPANDER
DESCRIPTION
The M35501FP generates digit signals for fluorescent display
when connected to the output port of a microcomputer. There are
up to 16 digit pins available, and more can be added by connect-
ing additional M35501FPs. The number of fluorescent displays
can be increased easily by connecting the M35501FP to the
CMOS FLD (VFD; Vacuum Fluorescent Display) output pins of an
8-bit microcomputer in MITSUBISHI’s 38B5 Group. The
M35501FP is suitable for fluorescent display control on household
electric appliances, audio products, etc.
FEATURES
qDigit
output ............................................................. 16 (maximum)
•Up to 16 pins can be selected
•More digits available by connecting additional M35501FPs
•Output structure: high-breakdown voltage, P-channel open-
drain; built-in pull-down resistor between digit output pins and
VEE pin
qPower-on
reset circuit ........................................................ Built-in
qPower
source voltage ................................................ 4.0 to 5.5 V
qPull-down
power source voltage ................................ Vcc – 43 V
qOperating
temperature range ................................... –20 to 85 °C
qPackage
............................................................................. 24P2E
qPower
dissipation ............... 250µW (at 100 kHz operation clock)
PIN CONFIGURATION (TOP VIEW)
24
23
22
21
20
19
18
17
16
15
14
13
M35501FP
1
2
3
4
5
6
7
8
9
10
11
12
SEL
RESET
OVF
IN
DIG
15
DIG
14
CLK
Outline: 24P2E-A
24-pin plastic-molded SSOP
Fig. 1 Pin configuration of M35501FP
OVF
OUT
DIG
13
DIG
12
DIG
11
V
SS
V
CC
DIG
10
←
→
DIG
0
DIG
6
DIG
5
DIG
7
DIG
2
DIG
8
←
→
DIG
1
DIG
3
DIG
4
DIG
9
←
→
V
EE
→
←
←
←
←
←
←
←
←
←
←
→
←
→
←
→
MITSUBISHI IC’S
M35501FP
FLD (VFD) DIGIT EXPANDER
FUNCTIONAL BLOCK
DIG
15
DIG
14
DIG
13
DIG
12
DIG
11
DIG
10
DIG
9
DIG
8
DIG
7
DIG
6
DIG
5
DIG
4
DIG
3
DIG
2
DIG
1
DIG
0
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24 V
EE
OVF
OUT
7
OVF
IN
6
V
CC
V
SS
3
1
Power-on
reset
Optional digit
counter
Shift register
RESET 4
5
2
CLK SEL
Fig. 2 Functional block diagram
PIN DESCRIPTION
Table 1 Pin description
Pin
V
CC
, V
SS
RESET
CLK
SEL
OVF
IN
Name
Power source input
Reset input
Clock input
Select input
Overflow signal input
Function
Apply 4.0–5.5 V to Vcc, and 0V to Vss.
Reset internal shift register (built-in power-on reset
circuit).
Digit output varies according to rising edge of clock
input.
Use when specifying the number of digits.
Input “H” when using one M35501FP. Connect to
OVF
OUT
pin of additional M35501FPs when using
multiple M35501FPs (to use 17 digits or more).
Leave open when using one M35501FP. Connect to
OVF
IN
pin of additional M35501FPs when using multiple
M35501FPs (to use 17 digits or more).
Output the digit output waveform of fluorescent
display. Leave open when not in use (V
EE
level
output).
Apply voltage to DIG
0
–DIG
15
pull-down resistors.
Output Structure
–
CMOS input level
Built-in pull-up resistor
CMOS input level
Built-in pull-down resistor
CMOS input level
Built-in pull-down resistor
CMOS input level
Fig. No.
–
3
2
2
4
OVF
OUT
Overflow signal output
CMOS output
5
DIG
15
–
DIG
0
V
EE
Digit output
Pull-down power source input
High-breakdown-voltage
P-channel open-drain output
Built-in pull-down resistor
–
1
–
2
MITSUBISHI IC’S
M35501FP
FLD (VFD) DIGIT EXPANDER
PORT BLOCK
(1) DIG
0
–DIG
15
(2) SEL, CLK
Shift register
Pull-down transistor
V
EE
(3) RESET
(4) OVF
IN
Pull-up transistor
(5) OVF
OUT
Shift register
Fig. 3 Port block diagram
3
MITSUBISHI IC’S
M35501FP
FLD (VFD) DIGIT EXPANDER
USAGE
Three usages of the M35501FP are described below.
(1) 16-Digit Mode:
16 digits selected
The number of digits is set to 16 by fixing the OVF
IN
pin to “H” and
the SEL pin to “L.” Figure 5 shows the output waveform.
(2) Optional Digit Mode:
1-16 digits selectable
When the number of CLK pin rising edges during an “H” period of
the SEL pin is n and the OVF
IN
pin is fixed to “H,” the number of
digits set is n. If n is 16 or more, all 16 digits are set. Figure 6
shows the output waveform.
SEL pin
n
CLK pin
Fig. 4 Digit setting
(3) Cascade Mode:
17 digits or more selectable
17 digits or more can be used by connecting two M35501FPs or
more. Figure 7 shows an example using three M35501FPs, offering
33 to 48 digit outputs.
Cascade mode will not operate if all M35501FPs are in 16-digit
mode (SEL = “L”). Use the most significant M35501FP in the optional
digit mode for DIG output. Figure 8 shows the output waveform.
4
MITSUBISHI IC’S
M35501FP
FLD (VFD) DIGIT EXPANDER
DIGIT OUTPUT WAVEFORM
SEL
CLK
DIG
0
DIG
1
DIG
2
“L”
DIG
13
DIG
14
DIG
15
OVF
OUT
Fig. 5 16-digit mode output waveform
RESET
SEL
CLK
DIG
0
DIG
1
DIG
2
DIG
3
DIG
4
DIG
15
“L”
“L”
OVF
OUT
Fig. 6 Optional digit mode output waveform
5
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