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PDF HT16565 Data sheet ( Hoja de datos )
| Número de pieza | HT16565 | |
| Descripción | 24 Hour System VFD Digital Clock | |
| Fabricantes | Holtek Semiconductor | |
| Logotipo |  |
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DataSheet.in
HT16565
24 Hour System VFD Digital Clock
Features
· VFD display 24 hour clock function
· 4.194304MHz crystal oscillation
· Zero adjust function
· Integrated voltage regulator permits wide 4V to 16V
operating voltage range
· Four level contrast control function
· 44-pin QFP package
General Description
The HT16565 provides direct drive to VFD panels to im-
plement a 24 hour clock function. In addition to obtaining
its time base from a 4.194304MHz crystal oscillation
source and in having a wide operating voltage, the de-
vice also contains a host of other features. These in-
clude a choice of adjustment modes, including single
push increment or 2Hz fast forward functions. Additional
features are provided in the form of Zero adjustment and
four levels of contrast control.
Block Diagram
O SCO
O SCI
TEST3
TEST2
TEST1
A /C
SE
ZA
MS
HS
O s c illa to r
V DD
T est
A d ju s tm e n t
V DD V DD
F r e q u e n c y D iv id e r s 1 H z
S e c o n d C o u n te r
M in u te C o u n te r
H o u r C o u n te r
CM OS
D ecoder
S egm ent
D ecoder
S egm ent
64H z
1H z
a1
b1
c1
C O N T2
C O N T1
D IM
V DD
C o n tra s t
A d ju s tm e n t
g3
b4
c4
a4,d4
e4,g4
TEST4
S 1224
V DD
V DD
Rev. 1.00
1 February 7, 2007
1 page  
DataSheet.in
HT16565
Functional Description
VFD Display Driving
The device can directly drive VFD clock panels dynami-
cally. The clock will be displayed in a 24-hour format with
the hours ranging from 0 to 23 and and minutes from 00
to 59. If the most significant numeral is zero then the dis-
play will be extinguished.
· Segment connections
A 7-segment display is shown below showing the illu-
mination pattern for each numeral.
A
FG
B
ED C
7 -S e g m e n ts
As the device is designed for clock applications, four
7-segment displays are required to display the correct
time output. The connections for the segments are
shown below, however it should be noted that the
fourth segment only requires two of its segments to be
driven.
a4
g4 b4
e4 d4 c4
d ig it4
a3
f3 g 3 b 3
e3 d3 c3
d ig it3
1H z
1H z
a2 a1
f2 g 2 b 2 f1 g 1 b 1
e2 d2 c2 e1 d1 c1
d ig it2
d ig it1
Other Pin Functions
The external reset pin A/C is used to reset the internal
circuit of the device. When this pin is pulled low the de-
vice will be reset, when the pin is allowed to go high, via
its internal pull-high resistor, then the display will indi-
cate a ²0:00² output.
In the open status, the SE pin is held to ²high² level by a
pull-high resistor, enabling the inputs from MS, HS and
ZA pins. These inputs become invalid by setting this pin
to a ²low² level externally.
The 64Hz pin allows monitoring of the system frequency
to allow frequency adjustments to be executed. As the
name suggests, this output pin will continuously output
a frequency of 64Hz.
In the open status, the TEST1 and TEST2 pins are kept
at a ²0² level by pull-down resistors.
In the open status, the TEST3 and TEST4 pins are kept
at a ²1² level by pull-up resistors.
The Test pin function is as shown in the following table.
TEST select function 1
Switch Pin Name
TEST1
TEST2
TEST3
0
(or Open)
0
(or Open)
1
(or Open)
F(Pulse)
1
1
(or Open)
1
F(Pulse)
1
(or Open)
1 F(Pulse) 0
F(Pulse)
1
0
F(Pulse)
0
(or Open)
0
Operating mode
Normal function.
Input pulses to the 16.384kHz system of the circuit.
Input pulses to the 16.384kHz system of the circuit.
Input pulses to the 64Hz system of the circuit.
Input pulses to the 64Hz system of the circuit.
Input pulses for the minute and hour counters, which advances 1 count
with 1 pulse. No carry functions for hour and minute counters.
TEST select function 2
TEST3
Switch Pin Name
DIM CONT1
CONT2
Operating mode
0 F(Pulse) *
00 *
*
The pulse widths of the all segment outputs are controlled
by the pulse width of the DIM signal
* Sets all segment outputs to high impedance
Note: ²*² Indicates that the input level can be ²0² and ²1²
Rev. 1.00
5 February 7, 2007
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet HT16565.PDF ] | |
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