HT16566
1/2 Duty VFD Digital Clock
Features
·
VFD display 24 hour clock function
·
Directly drive VFD panels at 1/2 Duty cycle
·
4.194304MHz crystal oscillation
·
Zero adjust function
·
Integrated voltage regulator permits wide 4V to 18V
operating voltage range
·
Four levels of illumination control function
·
30-pin SSOP package
General Description
The HT16566 provides direct drive to VFD panels to im-
plement a 24 hour clock function. Obtaining its time
base from a 4.194304MHz crystal oscillation source
and in having a wide operating voltage due to its internal
voltage regulator, the device also contains a host of
other features. These include a choice of adjustment
modes, including single push increment or 2Hz fast for-
ward functions. Additional features are provided in the
form of Blank control, Zero adjustment and four levels of
illumination control.
Block Diagram
V C C
V S S
V
D D
V
D D
V o lta g e R e g u la to r C ir c u it
V D D
V
D D
H o u r C o u n te r
A /C
V
T im e A d ju s tm e n t
D D
1 a , 3 a
1 b , 3 b
1 c , 3 c
1 d , 3 d
1 e , 3 e
1 f, 3 f
1 g , 3 g
2 a , 2 d , 4 a
2 b , 4 b
2 c , c o l*
2 c , c o l'*
2 e , 4 e
2 f, 4 c
Z A
V
M in u te C o u n te r
D D
S e g m e n t
D e c o d e r
S e g m e n t O u tp u t D r iv e r
H S
V
D D
S e c o n d C o u n te r
M S
B L A N K
T E S T
C o lo n
F re q u e n c y
2 g , 4 g , 4 d
6 4 H z
X T
O s c illa to r
X T
D IM 1
B r ig h tn e s s A d ju s tm e n t
D IM 2
G r id
D e c o d e r
F r e q u e n c y D r iv e r C ir c u it
G r id O u tp u t D r iv e r
G R 1
G R 2
Note:
²*²
col indicates a blink colon and col¢ indicates a continuous light colon.
Rev. 1.00
1
March 28, 2007
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
