Holtek Semiconductor Inc HT16512 Datasheet

1/4 to 1/11 Duty VFD Controller

Features

Logic voltage: 5V

·

High-voltage output: VDD-30V max.

·

Multiple display (11-segment & 11-digit to

·

16-segment & 4-digit)
6´4 matrix key scanning

·

8 steps dimmer circuit

·

4 LED output ports

·

Applications

Consumer products panel function control

·

Industrial measuring instrument panel func

·

tion control

General Description

HT16512 is a VFD (Vacuum Fluorescent Dis
play) controller/driver that is driven on a 1/4 to
1/11 duty factor. It consists of 11 segment out
put lines, 6 grid output lines, 5 segment/grid
output drive lines, 4 LED output ports, a con­trol circuit, a display memory, and a key scan
circuit.

HT16512

4-bit general purpose input port

·

No external resistors necessary for driver

·

output (provides PMOS open-drain and
pull-low resistor output)
Serial interface with MCU

·

(CLK, CS

Other similar application panel function

·

-

-

-

control

Serial data inputs to the HT16512 through a
three-line serial interface. This VFD control
ler/driver is ideal as a peripheral device for an
MCU.

, DI, DO)

-

1 December 24, 1999

Block Diagram

HT16512

DI

DO

CLK

CS

OSC

K0~K3

SW 0~SW 3

S e ria l I/F

OSC

4-B it

Latch

Pin Assignment

C om m and D ecoder

D isplay R A M

16-B it ´11 W ords

T im in g G e n e r a t o r

Key Scan

K e y D a ta R A M (4´6)

4 -B it L a tc h

LED0~LED 3

OSC

VSS

1

SW 0

2

SW 1

3

SW 2

4

SW 3

5

DO

6

DI

7

VSS

8

CLK

9

CS

10

K0

11

K1

12 13 14 15 16 17 18 19 20 21 22

K3

K2

LED 2

LED 1

LED 0

06$#

" " 3 . 2

VDD

S0/K0

S1/K1

16-B it

O utput Latch

11-B it

S h ift R e g is te r

VDD VSS VEE

LED 3

VDD

G1

G0

S2/K2

S3/K3

S4/K4

S5/K5

16 11

5

Selector

5

11 6

D im m ing C ircuit

G3

G2

3435363738394041424344

33
32
31
30
29
28
27

VEE

26
25
24
23

S6

S7

Data

G4
G5
S15/G 6
S14/G 7
S13/G 8
S12/G 9

S11/G 10
S10
S9
S8

5

Segm ent

Driver

M u lt ip le x e d

Driver

Grid

Driver

6

5

5

6

S0/K0~
S5/K5

S6~S10

S11/G 10~
S15/G 6

G0~G5

2 December 24, 1999

HT16512

Pin Description

Pin No. Pin Name I/O Description

1~4 SW0~SW3 I 4-bit general purpose input port

Output serial data at the falling edge of the shift clock,

5DO O

6DI I

7, 43 VSS

8 CLK I

9CS

10~13 K0~K3 I

14, 38 VDD

15~20 S0/K0~S5/K5 O

21~25 S6~S10 O

26, 28~31 S11/G10~S15/G6 O

27 VEE

37~32 G0~G5 O

42~39 LED0~LED3 O LED driver output ports. This is a CMOS output pin.

44 OSC I

starting from low order bit. This is an NMOS open-drain
output pin.

Input serial data at the rising edge of the shift clock, start
ing from the low order bit.

Power supply, ground

¾

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

Initializes serial interface at the rising or falling edge of the
HT16512. Then it waits to receive a command. Data input
after CS

I

mand data is processed, current processing is stopped, and
the serial interface is initialized. While CS
ignored.

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

Posistive power supply

¾

Segment or key source output pins (dual function). This is
PMOS open-drain and pull-low resistor output.

Segment driver output pins (segment only). This is PMOS
open-drain and pull-low resistor output.

Segment or Grid driver output pins. These pins are
selectable for segment or grid driving. This is PMOS
open-drain and pull-low resistor output.

VFD power supply

¾

Grid driver output pins (Grid only). This is PMOS
open-drain and pull-low resistor output.

Connected to an external resistor or an RC oscillator cir
cuit.

has fallen is processed as a command. While com

is high, CLK is

-

-

-

3 December 24, 1999

Approximate internal connections

HT16512

NMOS OUT

PM O S OUT CMOS OUT

V

V

DD

V

EE

DD

Absolute Maximum Ratings

Supply Voltage..............................-0.3V to 5.5V

Input Voltage .................V

-0.3V to VDD+0.3V

SS

Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maxi

mum Ratings² may cause substantial damage to the device. Functional operation of this device
at other conditions beyond those listed in the specification is not implied and prolonged expo
sure to extreme conditions may affect device reliability.

D.C. Characteristics

Symbol Parameter

V

DD

V

EE

f

OSC

R

PL

I

DD

I

OL

I

OL1

I

OH1

I

OH21

Logic Supply Voltage

VFD Supply Voltage

Oscillation Frequency 5V

Output Pull-low Resistor 5V Driver output 50 100 150

Operating Current 5V

Driver Leakage Current 5V

LED Sink Current 5V

LED Source Current 5V

Segment/Key Source Current 5V

V

DD

¾¾

¾¾

Operating Temperature ..............-25°Cto75°C

Storage Temperature.................-50°Cto125°C

Test Conditions

Min. Typ. Max. Unit

Conditions

4.5 5 5.5 V

=51kW

R

OSC

No load,
VFD display off

O=VDD

-30V

V
VFD driver off

=1V

V

OL

LED0~LED3

=0.9V

V

OH

DD

LED0~LED3

V

OH=VDD

-2V

S0/K0~S5/K5,

0

350 500 650 kHz

¾¾

¾¾-10 mA

20

-1 ¾¾

-3 ¾¾

¾ V

¾¾

S6~S10

Ta=25°C

V

-30

DD

kW

5mA

mA

mA

mA

-

-

4 December 24, 1999

HT16512

Symbol Parameter

I

OH22

I

OL3

V

IH

V

IL

V

OH1

V

OL1

V

OL2

Segment/Grid Source Current 5V

DO Sink Current 5V

²H² Input Voltage ¾¾

²L² Input Voltage ¾¾

High-level Output Voltage 5V

Low-level Output Voltage 5V

Low-level Output Voltage 5V

A.C. Characteristics

Symbol Parameter

t

t

t

t

t

t

C

t

t

t

t

t

t

PHL

PLH

r1

r2

f

max

i

CW

SW

SU

h

CS

W

Propagation Delay Time

Rise Time

Fall Time 5V

Maximum Clock Frequency 5V Duty=50% 1

Input Capacitance 5V

Clock Pulse Width 5V

Strobe Pulse Width 5V

Data Setup Time 5V

Data Hold Time 5V

Clock-Strobe Time 5V

Wait Time 5V

Test Conditions

V

DD

V

OH=VDD

G0~G5,
S11/G10~S15/G6

V

OL

LED0~LED3,
I

OH1

LED0~LED3,
I

OL1

DO, I

Test Conditions

V

DD

5V

CLK®DO

=15pF, RL=10kW

C

L

5V

C

=300pF,

L

5V

S0~S10

=300pF,

C

L

G0~G5,

5V

S11/G10~S15/G6

C

=300pF, Sn, Gn

L

CLK rising edge to
CS rising edge

CLK rising edge to
CLK falling edge

Conditions

Min. Typ. Max. Unit

-2V

-15 ¾¾

=0.4V

=-1mA

=20mA

=4mA

OL2

0.7V

0.9V

4

0

0

0

¾¾

¾

DD

¾

¾

DD

¾

¾

Min. Typ. Max. Unit

Conditions

¾¾

¾¾

¾¾

¾¾

¾¾

¾¾

¾¾¾

¾

¾

¾

¾

400

1

100

100

1

1

¾¾

¾¾

¾¾

¾¾

¾¾ms

¾¾ms

mA

mA

V

DD

0.3V

DD

V

DD

1V

0.4 V

Ta=25°C

300 ns

100 ns

2

ms

0.5

120

ms

ms

MHz

15 pF

ns

us

ns

ns

V

V

V

5 December 24, 1999

Functional Description

Display RAM and display mode

The static display RAM is organized into 22´8
bits and stores the data transmitted from an ex
ternal device to the HT16512 through a serial
interface. The contents of the RAM are directly
mapped to the contents of the VFD driver. Data
in the RAM can be accessed through the data
setting, address setting and display control
commands. It is assigned addresses in 8-bit
unit as follows:

S0

S3 S4~

Address: 00H

02H
04H
06H
08H
0AH
0C H
0EH
10H
12H
14H

b0 b1 b2 b3 b4 b5 b6 b7

~

S7~S8 S11S12

01H
03H
05H
07H
09H
0BH
0D H
0FH
11H
13H
15H

b0 b1 b2 b3 b4 b5 b6 b7

~

S15

Digit0
Digit1
Digit2
Digit3

Digit4
Digit5
Digit6
Digit7
Digit8
Digit9
Digit10

K0~K3 are sampled by strobe signal
S0/K0~S5/K5 and latched into the register.

The key matrix is made up of a 6´4 matrix, as

­shown below.

S3/K3S0/K0 S1/K1 S2/K2

K0

K1

K2

K3

Detail

Key matrix

S5/K5S4/K4

The data of each key is stored as illustrated be
low, and is read with the read command, start
ing from the least significant bit.

K0~K3K0~K3

S0/K0

S2/K2

S4/K4

S1/K1

S3/K3

S5/K5

R eading first

R eading last

HT16512

-

-

Dimming control

HT16512 porvides 8-step dimmer function on
display by controlling the 3-bit binary com­mand code. The full pulse width of grid signal is
divides into 16 uniform sections by PWM (pulse
width modulation) technology.

The 16 uniform sections available form 8 steps
dimmer via 3-bit binary code. The 8-step dim­mer includes 1/16, 2/16, 4/16, 10/16, 11/16,
12/16, 13/16 and 14/16. The 1/16 pulse width in
dicates minimum lightness. The 14/16 pulse
width represents maximum lightness. (Refer to
the display control command).

Key matrix and key-input data storage RAM

The key matrix scans the series key states at
each level of the key strobe signal
(S0/K0~S5/K5) output of the HT16512. The key
strobe signal outputs are time-multiplexed sig
nals from S0/K0~S5/K5. The states of inputs

b0 b1 b2 b3 b4 b5 b6 b7

LED port

The LED port belongs to the CMOS output con­figuration.

Data is written to the LED port with the write
command, starting from the least port¢s least
significant bit. In our application (see applica
tion circuits), the user adopts an internal

­NMOS device to a driver LED component by

connecting VDD. When a bit of this port is 0,
the corresponding LED lights; when the bit is 1,
the LED turns off. The data of bits 5 through 8
are ignored.

MSB LSB

b0b1b2b3

-

D on't care

6 December 24, 1999

LED 0
LED 1
LED 2
LED 3

-

HT16512

SW data

HT16512 provides an extra 4-bit general input port. The SW data is provided with available binary
code. The SW data is read with the read command, starting from the least significant bit. Bits 5
through 8 of the SW data are 0.

MSB LSB

0000

Commands

Commands set the display mode and status of the VFD driver.

The first 1 byte input to the HT16512 through the DI pin after the CS
command. If CS

is set high while commands/data are transmitted, serial communication is initial
ized, and the commands/data being transmitted are not valid (however, the commands/data previ
ously transmitted remains valid).

·

Display mode setting commands
These commands initialize the HT16512 and select the number of segments and the number of

grids (1/4~1/11 duty, 11 segments to 16 segments).

When these commands are executed, the display is forcibly turned off, and key scanning is also
stopped. To resume display, the display command ²ON² must be executed. If the same mode is se
lected, nothing happens.

b0b1b2b3

SW 0
SW 1
SW 2
SW 3

pin has fallen, is regarded as a

-

-

-

MSB LSB

00

D on't care

b0b1b2

D isplay m ode settings
000: 4 digits, 16 segm ents
001: 5 digits, 16 segm ents
010: 6 digits, 16 segm ents
011: 7 digits, 15 segm ents
100: 8 digits, 14 segm ents
101: 9 digits, 13 segm ents
110: 10 digits, 12 segm ents
111: 11 digits, 11 segm ents

7 December 24, 1999

·

Data setting commands

These commands set the data write and data read modes.

MSB LSB

01

b0b1b2b3

HT16512

D on't care

·

Address setting commands

D ata w rite and read m ode settings
00: W rite data to display m em ory
01: W rite data to LED port
10: R ead key data
11: R ead SW data

Address increm ent m ode settings (display m em ory)
0: Increm ents address after data has been w ritten
1: Fixes address

T e s t m o d e s e ttin g s
0: Norm al m ode
1: Test m ode, user don't use

These commands set the address of the display memory.

MSB LSB

11

D on't care

b3b4

b0b1b2

Address (00H ~15H)

If address 16H or higher is set, data is ignored until a valid address is set.

·

Display control commands

MSB LSB

10

D on't care

b0b1b2b3

D im m ing quantity settings
000: Set pulse w idth to 1/16
001: Set pulse w idth to 2/16
010: Set pulse w idth to 4/16
011: Set pulse w idth to 10/16
100: Set pulse w idth to 11/16
101: Set pulse w idth to 12/16
110: Set pulse w idth to 13/16
111: Set pulse w idth to 14/16

Turns on/off display
0 : D is p la y o ff (k e y s c a n c o n tinues)
1: D isplay on

8 December 24, 1999

Timing Diagrams

Sn/G n

CS

CLK

HT16512

t

f

90%

10%

t

CW

t

CW

(tr2)

t

r1

t

SW

t

CS

t

SU

DI

DO

Key scanning and display timing

G 0 output

G 1 output

G 2 output

G n output

t t

t

h

t

PHL

t

PLH

Key scan data

1 2 3 4 5 6 D ig it 0D ig it 0 D ig it 1 D ig it 2 D ig it nSn/K n output

T @ 500 ms

1 fram e=T ´ (n + 1 )

N o te : n = 0 ~ 5
t= 1 /1 6 T
T : p u ls e w id th o f s e g m e n t s ignal is decided by oscillator frequency
O n e c y c le o f k e y s c anning consists of one fram e.

9 December 24, 1999

Serial communication format

·

Reception (command/data write)

CS

HT16512

CLK

·

Transmission (data read)

CS

CLK

DO b0

123 7 8

b0 b1 b2 b6 b7DI

12

b0DI

345678 123456

b2 b3 b4 b5 b6 b7b1

t

W

D O m ust be sure to connect an external pull-high resistor to this pin (1kW to 1 0 kW).
N ote: W hen data is read, a w ait tim e "t

·

Updating display memory by incrementing address

CS

" o f 1ms is necessary.

W

b1

b2 b3 b4 b5

D ata is readA data read com m and is set

CLK

D I C om m and 1 C om m and 2 C om m and 3 Data 1 Data n C om m and 4

C om m and 1: sets display m ode
C om m and 2: sets data
C om m and 3: sets address
D a ta 1 to n : tra n s fe rs d is p la y d a ta (2 2 b y te s m a x .)
C om m and 4: controls diplay

10 December 24, 1999

·

Updating specific addresses

CS

CLK

D I C om m and 1 C om m and 2 Data C om m and 2 Data

C om m and 1: sets data
C om m and 2: sets address
D ata: display data

Application Circuits

R6

R7

R8

R9

HT16512

V

DD

VDD

K0 S0/K0

K1 K2 K3 S 1 /K 1 S 2 /K 2 S 3 /K 3 S 4 /K 4 S 5 /K 5

R

Note:

OSC

MCU

R

=51kW for oscillator resistor

OSC

R1

OSC

CS
CLK

DI

V

DD

DO

R2 R3 R4 R5

V

DD

LED2 LE D 3

R1=1~10kW for external pull-high resistor
R2~R5=750W~1.2kW
R6~R9=10kW for external pull-low resistor
D1~D6=1N4001
Ef=Filament voltage for VFD

D1 D2 D3 D4 D5 D6

S6~S10

0 6$#

SW 0 SW 1 SW 2 SW 3

S11/G 10~S 15/G 6

G0~G5

VEE

VSSLED0 LE D 1

S0
S1
S2
S3
S4
S5

5 S egm ents

5 G rids/S egm ents

6 G rids

-25V

VFD

Ef

11 December 24, 1999

HT16512

Holtek Semiconductor Inc. (Headquarters)

No.3 Creation Rd. II, Science-based Industrial Park, Hsinchu, Taiwan, R.O.C.
Tel: [phone]
Fax: [phone]

Holtek Semiconductor Inc. (Taipei Office)

5F, No.576, Sec.7 Chung Hsiao E. Rd., Taipei, Taiwan, R.O.C.
Tel: [phone]
Fax: [phone]
Fax: [phone] (International sales hotline)

Holtek Semiconductor (Hong Kong) Ltd.

RM.711, Tower 2, Cheung Sha Wan Plaza, 833 Cheung Sha Wan Rd., Kowloon, Hong Kong
Tel: [phone]
Fax: [phone]

Copyright ã 1999 by HOLTEK SEMICONDUCTOR INC.

The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek
assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are
used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications
will be suitable without further modification, nor recommends the use of its products for application that may pres
ent a risk to human life due to malfunction or otherwise. Holtek reserves the right to alter its products without prior
notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.tw.

12 December 24, 1999

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