ST STM86312 User Manual

1/4 to 1/11-duty VFD controller/driver

General features

■ Many display modes (11 segments & 11 digits

to 16 segments & 4 digits)

■ Key scanning (6 x 4 matrix)

■ Dimming circuit (eight steps)

■ High-voltage output (V

■ LED ports (4 chs, 20mA max)

■ General purpose input port (4 bits)

■ No external resistor necessary for driver output

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

■ Serial interface (CLK, STB, D

– 35V max)

DD

IN

, D

OUT

)

STM86312

PQFP44

Description

The STM86312 is a VFD (Vacuum Fluorescent
Display) controller/driver that is driven on a 1/4 to
1/11-duty factor . It consists of 1 1-segments output
lines, 6 grid output lines, 5 segments/grid output
drive lines, a display memory, a control circuit,
and a key scan circuit. Serial data are input to the
STM86312 through a three-line serial interface.
This VFD controller/driver is ideal as a peripheral
device for a single-chip microcomputer.

Order codes

Part number Temperature range Package Tube

STM86312 -40 to 85 °C PQFP44 Tray

March 2006 Rev 2 1/24

www.st.com

24

Contents STM86312

Contents

1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5 Display RAM address and display mode . . . . . . . . . . . . . . . . . . . . . . . 10

6 LED port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

7 SW data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8.1 Display mode setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8.2 Data setting comma nd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

8.3 Address setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

8.4 Display control com mand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

9 Serial communication format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

10 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

11 Mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2/24

STM86312 Block diagram

1 Block diagram

Figure 1. Block diagram

3/24

Pin settings STM86312

2 Pin settings

2.1 Pin connection

Figure 2. Pin connection

4/24

STM86312 Pin se tt i ngs

2.2 Pin description

Table 1. Pin description

Pin N° Symbol Name and function

1, 2, 3, 4

SW1, SW2,

SW3, SW4

General-purpose switch inputs.

5

6

D

OUT

D

IN

8CLK

9STB

10, 11, 12, 13

14, 38

15, 16, 17,

18, 19, 20

21, 22, 23,

24, 25

26, 28, 29,

30, 31

32, 33, 34,

35, 36, 37

KEY1, KEY2,

KEY3, KEY4

V

DD

SEG1/KS1 to

SEG6/KS6

SEG7 to SEG11 Segment output pins.

SEG12/GRID11 to

SEG16/GRID7

GRID1 to GRID 6 Grid output pins.

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

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

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

Initializes serial interface at risi ng or falling edge to make
STM86312 waiting f or reception of command. Data input after
STB has fall en are pr ocessed as a command. Whi le co mmand
data are processed, current processing is sto pped, and the
serial interfac e is initi alize d. While STB is high, CLK is ignored.

Input data to these pins are latched at end of the display cycle.

5V ± 10%.

Segment output pin s (Dual function as key source).

These pins are selectable for segment or grid driving.

39, 40, 41, 42 LED1 to LED4 CMOS outputs. +20 mA max.

7, 43

27

V

SS

V

EE

Connect this pin to system GND.
Pull-dow n le vel . V

- 35V max .

DD

44 OSC Connect to an external resistor.

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Maximum rating STM86312

3 Maximum rating

Stressing the device above the rating listed in the “Absolute Max imum Ratings” table may
cause permanent damage to the device. These are stress ratings only and operation of the
device at these or any other conditions above those indicated in the Operating sections of
this specification is not implied. Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability. Refer also to the STMicroelectronics SURE
Program and other relevant quality documents.

Table 2. Absolute maximum rati ngs

Symbol Parameter Value Unit

V
V

V

I

I

Logic Supply Voltage -0.5 to 7 V

DD

Driver Supply Voltage

EE

V

Logic Input Voltage

I

VFD Driver Output Voltage

O2

LED Driver Output Current 25 mA

O1

VFD Driver Output Current

O2

T

Operating Ambient Temperature -40 to 85 °C

A

3.1 Thermal data

Table 3. Therma l data

Symbol Parameter Value Unit

R

thJC

Thermal Resistance Junction-case 56 °C/W

3.2 Recommended operating conditions

V

+0.5 to VDD-40

DD

-0.5 to V

-0.5 to VDD+0.5

V

EE

-40 (Grid)

-15 (Segment)

DD

+0.5

V
V
V

mA

Table 4. Recommended operating conditions

Symbol Parameter Min Typ Max Unit

V

DD

V

IH

V

IL

V

EE

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Logic Supply Voltage 4.5 5 5.5 V
High Level Input Voltage 0.7xV
Low Level Input Voltage 0 0.3xV
Driver Supply Voltage 0 VDD-35 V

DD

V

DD

DD

V
V

STM86312 Maximum rating

Maximum power consumption P

= VFD driver dissipation + RL dissipation + LED driver

MAX

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

30 (mW)

dissipation = (VDD - VEE)2/50 x (segment + 1) (mW)

R

L

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

x 5 (mW)

DD

Example

Where V

= -25 V, V

EE

= 5 V, and in 16-segment and 6-digit modes,

DD

VFD driver dissipation = 16 x 6 + 6/7 x 30 = 122

dissipation = 302/50 x 17 = 306

R

L

LED driver dissipation = 4 x 20 = 80
Dynamic power consumption = 5 x 5 = 25
Total 553 mW.

7/24

Electrical characteristics STM86312

4 Electrical characteristics

Table 5. Electrical characteristics (V

to 70°C, unless otherwise noted. Typical values are at T

Symbol Parameter Test Conditions

V
V
V

I

OH21

High Level Output Voltage LED1-LED4, I

OH1

Low Level Output Voltage LED1-LED4, I

OL1

Low Level Output Voltage D

OL2

High Level Output Current VO = V

= 4.5 to 5.5V, V

DD

, I

OUT

OL2

DD

Seg11

= 0V, V

SS

= 25°C)

A

EE

= V

DD

- 35V, TA = -20

Value

Min. Typ. Max.

=-1mA 0.9V

OH1

=20mA 1 V

OL1

DD

= 4mA 0.4 V

- 2V, Seg1 to

-3 mA

Unit

V

I

OH22

High Level Output Current VO = V

- 2V, Grid1 to

DD

Grid6,
Seg12/Grid11 to
Seg16/Grid7

I

OLEAK

Driver Leakage Current VO = V

R

Output Pull-Down

L

- 35V, driver off -10 µA

DD

Driver Output 50 1 00 150 kΩ

Resistor

I
V
V

V

HYS

I

DDdyn

Input Current VI = V

I

High Level Input Voltage 0.7V

IH

Low Level Input Voltage 0.3V

IL

Hysteresis Voltage CLK, DIN, STB 0.35 V
Dynamic Current

Under no load, display off 5 mA

DD

or V

SS

Consumption

Table 6. Switching characteristics (V

= 4.5 to 5.5V, VSS = 0V, V

DD

to 70°C, unless otherwise noted. Typical values are at T

Symbol Parameter Test Conditions

t
t

t

TZH1

t

TZH2

Propagation Delay CLK → D

PLZ

OUT

RL = 10 kΩ, CL = 15 pF

PZL

Rise Time CL = 300 pFSeg1 to Seg11 2 µs

Grid1 to Grid6,
Seg12/Grid11 to
Seg16/Grid7

= 25°C)

A

-15 mA

±1 µA

DD

V
V

DD

EE

= V

DD

- 35V, TA = -20

Value

Unit

Min. Typ. Max.

300 ns
100

0.5

t

THZ

f

MAX

Fall Time CL = 300 pF , Segn, Gridn 120 µs
Maximum Clock

Duty = 50% 1 MHz

Frequency

C

Inpu t C a pacita nce 15 pF

I

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