TP6312

1/4 TO 1/11-DUTY VFD CONTROLLER/DRIVER

General Description

The TP6312 is a VFD (Vacuum Fluorescent Display)
controller/driver that is driven on a 1/4 to 1/11-duty
factor. It consists of 11 segment output lines, 6 grid
output lines, 5 segment/grid output drivelines, a
display memory, a control circuit, and a Key scan
circuit. Serial data is input to TP6312 through a
three-line serial interface. This VFD controller/driver
is ideal as a peripheral device of a single-chip
microcomputer.

Features

Multiple display modes (11-segment & 11-digit to

16-segment & 4-digit)

Key scanning (6

4 matrices)

Dimming circuit (eight steps)

High-voltage output (V

35V max)

LED ports (4 chs, 20 mA max)

General-purpose input port (4 bits)

No external resistor necessary for driver outputs

(P-ch open-drain + pull-down resistor output)

Serial interface (CLK, STB, D

, D

OUT

)

Ordering Information

TP 6312

Package Type F: LQFP

Footprint

S: 2.0 mm
L: 3.2 mm

Footprint

Version

Package Type

Block Diagram

OUT

CLK

STB

Serial I/F

OSC

Command decoder

Display memory

16bit x 11 word

Timing generator key

scan

Key data memory

(4x6)

4 bit latch

4
bi

l
a
tch

Dimming circuit

1
6
-
bit o

u
tput

l
a
tch

1
6
-
b
i
t o

u
tput

tch

Segm

ent dri

v
e
r

gme

n
t/

gri

d
dri

v
er

Grid dr

i
v
er

Dat

a
s

e
l
e
c
t
o
r

(+5V)

(0V)

(-30V)

LED

Seg

/Gird

Seg

/Gird

Grid

Key1

Key4

SW1

SW4

LED

Version 1.1

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September 2003

TP6312

1/4 TO 1/11-DUTY VFD CONTROLLER/DRIVER

Pin Configuration (Top View)

KEY 3

KEY 4

S e g1 / KS 1

S e g2 / KS 2

S e g3 / KS 3

S e g4 / KS 4

S e g5 / KS 5

S e g6 / KS 6

S e g7

S e g8

Seg

r
i
d

3 /

r
i
d

14 /

r
i
d

15 /

r
i
d

16 /

r
i
d

i
d

G rid 4

G rid 3

G rid 2

G rid 1

LED 4

LED 3

LED 2

LED 1

VS S

OS C

Use all the power pins.

Pin Description

Pin No

Symbol

Pin Name

Description

6 D

Date

input

Inputs serial data at rising edge of shift clock,
starting from the lower bit.

5 D

OUT

Date

output

Outputs serial data at falling edge of shift clock,
starting from the lower bit. This is N-ch open-drain
output pin.

9 STB

Strobe

Initializes the serial interface at rising or falling edge
to make TP6312 waiting for reception of command.
Data input after STB has fallen is processed as
command. While command data is processed,
current processing is stopped and serial interface is
initialized. While STB is high, CLK is ignored.

8 CLK

Clock

input

Reads serial data at rising edge, and outputs data at
falling edge.

44 OSC Oscillator

Connects a resistor to this pin to determine the
oscillation frequency to this pin.

15 to 20

Seg

/KS

Seg

/KS

High-voltage output

Segment output pins (Dual function as Key source).

21 to 25

Seg

to Seg

High-voltage output

(Segment)

Segment output pins.

37 to 32

Grid

to Grid

High-voltage output

(Grid)

Grid output pins.

26, 28 to 31

Seg

/Grid

Seg

/Grid

High-voltage output

(Segment/grid)

These pins are selectable for segment or grid
driving.

42 to 39

LED

to LED

LED output

CMOS output. +20 mA max.

10 to 13

Key

to Key

Key data input

Data input to these pins is latched at the end of
display cycle.

1 to 4

to SW

Switch

input

These pins constitute 4-bit general-purpose input
port.

14, 38

Logic

power

10%

7, 43

Logic ground

Connect this pin to system GND.

27 V

Pull-down

level

35 V max

Version 1.1

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September 2003

TP6312

1/4 TO 1/11-DUTY VFD CONTROLLER/DRIVER

Functional Description

Display RAM Address and Display Mode

The display RAM stores the data transmitted from an
external device to TP6312 through the serial interface,
and is assigned addresses as follows, in units of 8
bits:

Seg

00H

01H

DIG1

02H

03H

DIG2

04H

05H

DIG3

06H

07H

DIG4

08H

09H

DIG5

0AH

0BH

DIG6

0CH

0DH

DIG7

0EH

0FH

DIG8

10H

11H

DIG9

12H

13H

DIG10

14H

15H

DIG11

XX H

Lower 4 bits

Higher 4 bits.

Key Matrix and Key-Input Data Storage

RAM

The Key matrix is of 6

4 configuration, as shown

below.

KEY1

KEY2

KEY3

KEY4

Seg1/

KS1

Seg2/

KS2

Seg3/

KS3

Seg4/

KS4

Seg5/

KS5

Seg6/

KS6

The data of each Key is stored as illustrated below,
and is read by a read command, starting from the
least significant bit.

Key

Key

Seg

/ KS

Seg

/ KS

Seg

/ KS

Seg

/ KS

Seg

/ KS

Seg

/ KS

Reading sequence

b0 b3 b4 b7

LED Port

Data is written to the LED port by a write command,
starting from the least significant bit of the port.
When a bit of this port is 0, the corresponding LED
lights; when the bit is 1, the LED goes off. The data
of bits 5 through 8 is ignored.

----

Don't care

LED1
LED2
LED3
LED4

On power application, all LEDs are unlit.

SW Data

The SW data is read by a read command, starting
from the least significant bit. Bits 5 through 8 of the
SW data are 0.

SW1
SW2
SW3
SW4

MSB

LSB

Commands

A command sets the display mode and status of the
VFD driver.
The first 1 byte input to TP6312 through the D

after the STB pin has fallen is regarded as a
command.
If STB is high while a command/data is transmitted,
serial communication is initialized, and the
transmitting command/data is invalid; however, the

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TP6312

1/4 TO 1/11-DUTY VFD CONTROLLER/DRIVER

command/data already transmitted remains valid.

(1) Display mode setting command

This command initializes TP6312 and selects the
number of segments and number of grids (1/4 to 1/11-
duty, 11 segments to 16 segments).
On power application, the 11-digit, 11-segment mode
is selected.

----

MSB

LSB

Display mode settings

Irrelevant

000 : 4 digits, 16 segments
001 : 5 digits, 16 segments
010 : 6 digits, 16 segments
011 : 7 digits, 15 segments
100 : 8 digits, 14 segments
101 : 9 digits, 13 segments
110 : 10 digits, 12 segments
111 : 11 digits, 11 segments

(2) Data setting commands

This command sets data write and read modes.

----

MSB

LSB

Irrelevant

Address increment mode (display memory).
0:Increments address after data has been written.

1:Fixes address.

Test mode settings.
0:Normal operation.

1:Test mode.

Data write and read mode settings

00:Writes data to display memory
01:Writes data to LED port
10:Reads key data.
11:Reads SW data.

On power application, the normal operation mode and
address increment mode set.

(3) Address setting command

This command sets an address of the display
memory.

----

Address (00H-15H)

MSB

LSB

If address 16H or higher is set, the data is ignored
and unit a correct address is set.
On power application, the address is set to 00H.

(4) Display control command

----

Dimming quantity settings.

000 : Sets pulse width to 1/16.
001 : Sets pulse width to 2/16.

010 : Sets pulse width to 4/16.
011 : Sets pulse width to 10/16.

100 : Sets pulse width to 11/16.

101 : Sets pulse width to 12/16.
110 : Sets pulse width to 13/16.

111 : Sets pulse width to 14/16.

MSB

LSB

Irrelevant

Turns on/off display

0:Display off (key scan continues)

1:Display on.

On power application, the 14/16-pulse width is set and
the display is turned off.

Key Scanning and Display Timing

DIG1

DIG2

DIG3

..............

DIGn

1 2

...

SEG Output

DIG1

1 frame=T

DISP

x (n+1)

TDISP 500

µs

Key scan data

1/16

DISP

One cycle of Key scanning consists of two frames,
and data of 6

4 matrices is stored in RAM.

Serial Communication Format

Reception (command/data write)

......

STB

DIN

CLK

If data is cintiguous

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TP6312

1/4 TO 1/11-DUTY VFD CONTROLLER/DRIVER

Transmission (data read)

STB

DIN

CLK

DOUT

WAIT

Data reading command is set.

Data reading starts.

Because the D

OUT

pin is an N-ch open-drain output

pin, be sure to connect an external pull-up resistor to
this pin (1k

to 10 k

*: When data is read, a wait time (t

WAIT)

of 1

s is

necessary from the rising of the eighth clock that has
set the command till the falling of the first clock that
has read the data.

Absolute Maximum Ratings (Ta = 25°C, Vss = 0V)

Parameter

Symbol

Ratings

Unit

Logic Supply Voltage

-0.5 to + 7.0

Driver Supply Voltage

+0.5 to V

-40

Logic Input Voltage

-0.5 to V

+0.5

VFD Driver Output Voltage

0.5 to V

+0.5

LED Driver Output Current

+25

VFD Driver Output Current

-40 (grid)

-15 (segment)

Power Dissipation

800

Operating Ambient Temperature

opt

-40 to +70

Storage Temperature

stg

-65 to +150

* Derate at 6.4 mW/

at Ta = 25

or higher.

Recommended Operating Conditions (Ta = -20°C to +70°C, Vss = 0V)

Parameter

Symbol

Min.

Typ.

Max.

Unit

Test Condition

Logic Supply Voltage

4.5 5

5.5

High-Level input Voltage

0.7V

Low-Level input Voltage

0.3V

Driver Supply Voltage

-35

Maximum power consumption P

MAX

= VFD driver dissipation + R

dissipation + LED driver dissipation + dynamic power

consumption.
Where segment current = 3 mA, grid current = 15mA, and LED current = 20 mA,
VFD driver dissipation = number of segments x 6 + number of grids/(number of grids + 1) x 30(mW)
R

dissipation

-V

)

/50 x (segment+1) (mW)

LED driver dissipation = number of LEDs x 20(mW)
Dynamic power consumption = V

x 5(mW)

Electrical Characteristics (Ta = -20°C to +70°C, V

= 4.5V to 5.5V, V

= 0V, V

= V

- 35V)

Parameter

Symbol

Min

Typ.

Max.

Unit

Test Conditions

High-Level Output Voltage

OH1

0.9

V LED

LED

, I

OH1

= -1 mA

Low-Level Output Voltage

OL1

1 V LED

LED

, I

OL1

= 20 mA

Low-Level Output Voltage

OL2

0.4 V

OUT

, I

OL2

= 4 mA

High-Level Output Current

OH21

-3

mA V

= V

2V, Seg

to Seg

High-Level Output Current

OH22

-15

= V

2V,Grid

to Grid

Seg

/Seg

to Seg

/Seg

Driver Leakage Current

OLEAK

-10

= V

- 35V, Drive off

Output Pull-Down Resistor

100

150

Drive output

Input Current

= V

or V

High-Level Input Voltage

0.6

Low-Level Input Voltage

0.3

Hysteresis Voltage

0.35

CLK,

, STB

Dynamic Current Consumption

DDdyn

Under no load, display off

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