HT1621B
RAM Mapping 32x4 LCD Controller for I/O MCU
Features
Operating voltage: 2.4V ~ 5.2V
Built-in 256kHz RC oscillator
External 32.768kHz crystal or 256 kHz frequency source input
Selection of 1/2 or 1/3 bias, and selection of 1/2 or 1/3 or 1/4
duty LCD applications
Internal time base frequency sources
Two selectable buzzer frequencies (2kHz/4kHz)
Power down command reduces power consumption
Built-in time base generator and a WDT
Time base or WDT overflow output
8 kinds of time base/WDT clock sources
32x4 LCD driver
Built-in 32x4 bit display RAM
3-wire serial interface
Internal LCD driving frequency source
Software configuration feature
Data mode and command mode instructions
R/W address auto increment
Three data accessing modes
VLCD pin for adjusting LCD operating voltage
HT1621B: 48-pin SSOP/LQFP packages
HT1621D: 28-pin SKDIP package
HT1621G: Gold bumped chip
General Description
The HT1621 is a 128 pattern (32x4), memory mapping, and multi-function LCD driver. The S/W configuration feature of the HT1621
makes it suitable for multiple LCD applications including LCD modules and display sub-systems. Only three or four lines are required
for the interface between the host controller and the HT1621. The HT1621 contains a power down command to reduce power
consumption.
Selection Table
HT162X
HT1620
HT1621
HT1622
HT16220
HT1623
HT1625
HT1626
COM
4
4
8
8
8
8
16
SEG
32
32
32
32
48
64
48
Built-in Osc.
—
√
√
—
√
√
√
Crystal Osc.
√
√
—
√
√
√
√
Rev. 00
HT1621B
Block Diagram
Note:
:chip selection
BZ,
: Tone outputs
,
,DATA: Serial interface
COM0~COM3, SEG0 ~SEG31:LCD outputs
: Time base or WDT overflow output
Pin Assignment
HT1621B
HT1621D
-48 SSOP -A
-28 SKDIP -A
Rev. 00
HT1621B
Absolute Maximum Ratings
Supply Voltage…………………VSS –0.3V to VSS +5.5V
Storage Temperature…………………………-50℃ to 125℃
Input Voltage…………………VSS –0.3V to VDD +0.3V
Operating Temperature………………………-40℃ to 85℃
Note: These are stress ratings only. Stresses exceeding the range specified under “ Absolute Maximum Ratings” 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 exposure to extreme conditions may affect device reliability.
D.C.
Characteristics
Ta=25℃
Symbol
Parameter
VDD
IDD1
Operating Voltage
Operating Current
IDD2
Operating Current
IDD3
Operating Current
ISTB
Standby Current
VIL
Input Low Voltage
VIH
Input High Voltage
IOL1
DATA, BZ,
IOH1
DATA, BZ,
IOL2
LCD Common Sink Current
IOH2
LCD Common Source Current
IOL3
LCD Segment Sink Current
IOH3
LCD Segment Source Current
RPH
Pull-high Resistor
,
Test Conditions
Conditions
VDD
—
—
3V
No load/LCD ON
On-chip RC oscillator
5V
3V
No load/LCD ON
Crystal oscillator
5V
3V
No load/LCD ON
External clock source
5V
3V
No load, Power down mode
5V
3V
,
,
DATA,
5V
3V
,
,
DATA,
5V
3V
VOL=0.3V
5V
VOL=0.5V
3V
VOH=2.7V
5V
VOH=4.5V
3V
VOL=0.3V
5V
VOL=0.5V
3V
VOH=2.7V
5V
VOH=4.5V
3V
VOL=0.3V
5V
VOL=0.5V
3V
VOH=2.7V
5V
VOH=4.5V
3V
,
,
DATA,
5V
Min.
2.4
—
—
—
—
—
—
—
—
0
0
2.4
4.0
0.5
1.3
-0.4
-0.9
80
150
-80
-120
60
120
-40
-70
60
30
Typ.
—
150
300
60
120
100
200
0.1
0.3
—
—
—
—
1.2
2.6
-0.8
-1.8
150
250
-120
-200
120
200
-70
-100
120
60
Max.
5.2
300
600
120
240
200
400
5
10
0.6
1.0
3.0
5.0
—
—
—
—
—
—
—
—
—
—
—
—
200
100
Rev. 00
Unit
V
µA
µA
µA
µA
µA
µA
µA
µA
V
V
V
V
mA
mA
mA
mA
µA
µA
µA
µA
µA
µA
µA
µA
kΩ
kΩ
HT1621B
Ta=25℃
A.C. Characteristics
Symbol
Parameter
fSYS1
fSYS2
fSYS3
System clock
System clock
System clock
fLCD
LCD Clock
tCOM
fCLK1
LCD Common Period
Serial Data Clock (
Serial Data Clock (
fTONE
tCS
Tone Frequency
Serial Interface Reset Pulse
Width (Figure 3)
tCLK
,
Input Pulse Width
(Figure 1)
tau
Setup Time for DATA to
Max.
Unit
—
—
—
—
—
—
—
150
300
75
150
—
kHz
kHz
kHz
Hz
Hz
Hz
s
kHz
kHz
kHz
kHz
kHz
—
250
—
ns
Write mode
Read mode
Write mode
Read mode
3.34
6.67
1.67
3.34
—
—
—
—
125
—
125
—
—
—
—
120
—
ns
,
—
—
—
120
—
ns
,
—
—
—
120
—
ns
,
—
—
—
100
—
ns
,
—
—
—
100
—
ns
Duty cycle 50%
Duty cycle 50%
On-chip RC oscillator
—
3V
5V
Rise/Fall Time Serial Data
Clock Width (Figure 1)
Typ.
256
32.768
256
fSYS1/1024
fSYS2/128
fSYS3/1024
n/ fLCD
—
—
—
—
2.0 or 4.0
pin)
tr, tf
Min.
—
—
—
—
—
—
—
4
4
—
—
—
pin)
fCLK2
VDD
—
—
—
—
—
—
—
3V
5V
3V
5V
—
Test Conditions
Conditions
On-chip RC oscillator
Crystal oscillator
External clock source
On-chip RC oscillator
Crystal oscillator
External clock source
n: Number of COM
µs
µs
Clock Width (Figure 2)
th
Hold Time for DATA to
Clock Width (Figure 2)
tau1
Setup Time for
to
Clock Width (Figure 3)
th1
Hold Time for
to
Clock Width (Figure 2)
Figure 1
Figure 2
Figure 3
Rev. 00
HT1621B
Functional Description
Display Memory –RAM
The static display memory (RAM) is organized into 32x4 bits and
stores the displayed data. The contents of the RAM are directly
mapped to the contents of the LCD driver. Data in the RAM can be
accessed by the READ, WRITE, and READ-MODIFY- WRITE
commands. The following is a mapping from the RAM to the LCD
pattern:
command, using the SYS DIS command reduces power
consumption, serving as a system power down command. But if the
external clock source is chosen as the system clock, using the SYS
DIS command can neither turn the oscillator off nor carry out the
power down mode. The crystal oscillator option can be applied to
connect an external frequency source of 32kHz to the OSCI pin. In
this case, the system fails to enter the power down mode, similar to
the case in the external 256kHz clock source operation. At the initial
system power on, the HT1621 is at the SYS DIS state.
Time Base and Watchdog Timer (WDT)
The time base generator is comprised by an 8-stage count-up ripple
counter and is designed to generate an accurate time base. The
watch dog timer (WDT), on the other hand, is composed of an
8-stage time base generator along with a 2-stage count-up counter,
and is designed to break the host controller or other subsystems
from abnormal states such as unknown or unwanted jump,
execution errors, etc. The WDT time-out will result in the setting of
an internal WDT time-out flag. The outputs of the time base
generator and of the WDT time-out flag can be connected to
output by a command option. There are totally eight
the
frequency sources available for the time base generator and the
WDT clock. The frequency is calculated by the following equation.
RAM Mapping
System Oscillator
The HT1621 system clock is used to generate the time
base/Watchdog Timer (WDT) clock frequency, LCD driving clock,
and tone frequency. The source of the clock may be from an on-chip
RC oscillator (256kHz), a crystal oscillator (32.768kHZ), or an
external 256kHz clock by the S/W setting. The configuration of the
system oscillator is as shown. After the SYS DIS command is
executed, the system clock will stop and the LCD bias generator will
turn off. That command is ,however, available only for the on-chip
RC oscillator or for the crystal oscillator. Once the system clock
stops, the LCD display will become blank, and the time base/WDT
lose its function as well.
The LCD OFF command is used to turn the LCD bias generator off.
After the LCD bias generator switches off by issuing the LCD OFF
Where the value of n ranges from 0 to 7 by command options. The
32kHz in the above equation indicates that the source of the system
frequency is derived from a crystal oscillator of 32.768kHz, an
on-chip oscillator (256kHz), or an external frequency of 256KHz.
If an on-chip oscillator (256kHz) or an external 256kHz frequency is
chosen as the source of the system frequency, the frequency source
is by default prescaled to 32kHz by a 3-stage prescaler. Employing
both the time base generator and the WDT related commands, one
should be careful since the time base generator and WDT share the
same 8-stage counter. For example, invoking the WDT DIS
command disables the time base generator whereas executing the
WDT EN command not only enables the time base generator but
activates
System Oscillator Configuration
Rev. 00
HT1621B
Timer and WDT Configurations
The WDT time-out flag output (connect the WDT time-out flag to the
pin). After the TIMER EN command is transferred, the WDT is
disconnected from the
pin, and the output of the time base
generator is connected to the
pin. The WDT can be cleared
by executing the CLR WDT command, and the contents of the time
base generator is cleared by executing the CLR WDT or the CLR
TIMER command. The CLR WDT or the CLR TIMER command
should be executed prior to the WDT EN or the TIMER EN
EN command
command respectively. Before executing the
the CLR WDT or CLR TIMER command should be executed first.
The CLR TIMER command has to be executed before switching
from the WDT mode to the time base mode. Once the WDT time-out
pin will stay at a logic low level until the CLR WDT
occurs, the
DIS command is issued. After the
output is
or the
disabled the
pin will remain at the floating state. The
output can be enabled or disabled by executing the
EN or the
DIS command, respectively. The
EN makes the output
of the time base generator or of the WDT time-out flag appear on
pin. The configuration of the time base generator along
the
with the WDT are as shown. In the case of on-chip RC oscillator or
crystal oscillator, the power down mode can reduce power
consumption since the oscillator can be turned on or off by the
corresponding system commands. At the power down mode the
time base/WDT loses all its functions.
On the other hand if an external clock is selected as the source of
system frequency the SYS DIS command turns out invalid and the
power down mode fails to be carried out. That is, after the external
clock source is selected, the HT1621 will continue working until
system power fails or the external clock source is removed. After the
will be disabled.
system power on, the
Name
Tone Output
A simple tone generator is implemented in the HT1621.The tone
generator can output a pair of differential driving signals on the BZ
, which are used to generate a single tone. By executing the
and
TONE4K and TONE2K commands there are two tone frequency
outputs selectable. The TONE4K and TONE2K commands set the
tone frequency to 4kHz and 2kHz, respectively. The tone output can
be turned on or off by invoking the TONE ON or the TONE OFF
command. The tone outputs , namely BZ and
, are a pair of
differential driving outputs used to drive a piezo buzzer. Once the
system is disabled or the tone output is inhibited, the BZ and the
outputs will remain at low level.
LCD Driver
The HT1621 is a 128 (32x4) pattern LCD driver. It can be configured
as 1/2 or 1/3 bias and 2 or 3 or 4 commons of LCD driver by the S/W
configuration. This feature makes the HT1621 suitable for multiply
LCD applications. The LCD driving clock is derived from the system
clock. The value of the driving clock is always 256Hz even when it is
at a 32.768kHz crystal oscillator frequency, an on-chip RC oscillator
frequency, or an external frequency. The LCD corresponding
commands are summarized in the table.
The bold form of 100, namely 100, indicates the command mode ID.
If successive commands have been issued, the command mode ID
except for the first command, will be omitted. The LCD OFF
command turns the LCD display off by disabling the LCD bias
generator. The LCD ON command, on the other hand, turns the
LCD display on by enabling the LCD bias generator. The BIAS and
COM are the LCD panel related commands. Using the LCD related
commands, the HT1621 can be compatible with most types of LCD
panels.
Command Code
Function
LCD OFF
10000000010X
Turn off LCD outputs
LCD ON
10000000011X
Turn on LCD outputs
BIAS & COM
1000010abxcx
C=0:1/2 bias option
C=1: 1/3 bias option
ab=00:2 commons option
ab=01:3 commons option
ab=10:4 commons option
Rev. 00
HT1621B
Command Format
The HT1621 can be configured by the S/W setting . There are two
mode commands to configure the HT1621 resources and to transfer
the LCD display data. The configuration mode of the HT1621 is
called command mode, and its command mode ID is 100. The
command mode consists of a system configuration command, a
system frequency selection command, a LCD configuration
command, a tone frequency selection command, a timer/WDT
setting command, and an operating command. The data mode, on
the
other
hand,
includes
READ,
WRITE,
and
READ-MODIFY-WRITE operations. The following are the data
mode IDS and the command mode ID;
Operation
Mode
ID
Read
Data
110
Write
Data
101
Read-Modify-write
Data
101
Command
Command
100
The mode command should be issued before the data or command
is transferred. If successive commands have been issued. The
command mode ID, namely 100, can be omitted. While the system
Before issuing a mode command or mode switching, a high level
pulse is required to initialize the serial interface of the HT1621. The
DATA line is the serial data input/output line. Data to be read or
written or commands to be written have to be passed through the
DATA line. The
line is the READ clock input Data in the RAM
signal, and the clocked
are clocked out on the falling edge of the
out data will then appear on the DATA line. It is recommended that
the host controller read in correct data during the interval between
the rising edge and the next falling edge of the
signal. The
line is the WRITE clock input. The data, address, and
command on the DATA line are all clocked into the HT1621 on the
rising edge of the
signal. There is an optional
line to be
used as an interface between the host controller and the HT1621.
The
pin can be selected as a timer output or a WDT overflow
flag output by the S/W setting. The host controller can perform the
time base or the WDT function by being connected with the
pin of the HT1621.
Crystal Selection
A 32768Hz crystal can be directly connected to the HT1621 via
OSCI and OSCO. In order to obtain the correct frequency, two
additional load capacities (C1, C2) are needed. The value of the
capacity depends on how accurate the crystal is. We suggest that
you can follow the table. Which suggests the value of capacities.
The table illustrations the suggestion value of capacities (C1, C2)
is operating in the non-successive command or the non-successive
address data mode, the
pin should be set to “1” and the previous
operation mode will be reset also. Once the
pin returns to “0” a
new operation mode ID should be issued first.
Interfacing
Only four lines are required to interface with the HT1621, the
line is used to initialize the serial interface circuit and to terminate
the communication between the host controller and the HT1621. If
pin is set to 1, the data and command issued between the
the
host controller and the HT1621 are first disabled and then initialized.
Crystal Error
Capacity Value
±10ppm
0~10p
10~20ppm
10~20p
Timing Diagrams
READ Mode (Command Code:110)
Rev. 00
HT1621B
READ Mode (Successive Address Reading)
WRITE Mode (Command Code: 101)
Write Mode (Successive Address Writing)
Read-Modify-Write Mode (Command Code: 101)
Rev. 00
HT1621B
Read-Modify-Write Mode (Successive Address Accessing)
Command Mode (Command Code : 100)
Mode (Data and Command Mode)
Note: It is recommended that the host controller should read in the data from the DATA line between the rising edge of the
line and the falling edge of the next
line.
9
Rev. 00
HT1621B
Application Circuits
Host Controller with an HT1621 Display System
Note: The connection of
and
pin can be selected depending on the requirement of the MCU.
The voltage applied to VLCD pin must be lower than VDD.
Adjust VR to fit LCD display, at VDD = 5V, VLCD = 4V, VR=15kΩ ± 20%.
Adjust R (external pull-high resistance) to fit user’s time base clock.
In order to obtain the correct frequency, two additional load capacities (C1,C2) are needed. The value of the capacity depends
on how accurate the crystal is. We suggest that you can follow the table, which suggests the value of capacities.
The table illustrations the suggestion value of capacities (C1,C2)
Crystal Error
Capacity Value
±10ppm
0~10p
10~20ppm
10~20p
Command Summary
Name
READ
WRITE
READ-MODIFYWRITE
SYS DIS
ID
110
101
101
Command Code
A5A4A3A2A1A0D0D1D2D3
A5A4A3A2A1A0D0D1D2D3
A5A4A3A2A1A0D0D1D2D3
D/C
D
D
D
Function
Read data from the RAM
Write data to the RAM
READ and WRITE to the RAM
Def.
100
0000-0000-X
C
SYS EN
LCD OFF
LCD ON
TIMER DIS
WDT DIS
TIMER EN
WDT EN
100
100
100
100
100
100
100
0000-0001-X
0000-0010-X
0000-0011-X
0000-0100-X
0000-0101-X
0000-0110-X
0000-0111-X
C
C
C
C
C
C
C
Turn off both system oscillator and LCD
Bias generator
Turn on system oscillator
Turn off LCD bias generator
Turn on LCD bias generator
Disable time base output
Disable WDT time-out flag output
Enable time base output
Enable WDT time-out flag output
Yes
Yes
Rev. 00
HT1621B
Name
ID
Command Code
D/C
Function
Def.
TONE OFF
100
0000-1000-X
C
Turn off tone outputs
Yes
TONE ON
100
0000-1001-X
C
Turn on tone outputs
CLR TIMER
100
0000-11XX-X
C
Clear the contents of time base generator
CLR WDT
100
0000-111X-X
C
Clear the contents of WDT stage
XTAL 32K
100
0001-01XX-X
C
System clock source, crystal oscillator
RC 256K
100
0001-10XX-X
C
System clock source, on-chip RC oscillator
EXT 256K
100
0001-11XX-X
C
System clock source, external clock source
C
BIAS 1/2
100
0010-abX0-X
BIAS 1/3
100
0010-abX1-X
C
TONE 4K
100
010X-XXXX-X
C
LCD 1/2 bias option
ab=00:2 commons option
ab=01:3 commons option
ab=10:4 commons option
LCD 1/3 bias option
ab=00:2 commons option
ab=01:3 commons option
ab=10:4 commons option
Tone frequency, 4kHz
TONE 2K
100
011X-XXXX-X
C
Tone frequency, 2kHz
DIS
100
100X-0XXX-X
C
Disable
output
EN
100
010X-1XXX-X
C
Enable
output
F1
100
101X-X000-X
C
F2
100
101X-X001-X
C
F4
100
101X-X010-X
C
F8
100
101X-X011-X
C
F16
100
101X-X100-X
C
F32
100
101X-X101-X
C
F64
100
101X-X110-X
C
F128
100
101X-X111-X
C
TEST
100
1110-0000-X
C
Time base/WDT clock output: 1Hz
The WDT time-out flag after: 4s
Time base/WDT clock output: 2Hz
The WDT time-out flag after: 2s
Time base/WDT clock output: 4Hz
The WDT time-out flag after: 1s
Time base/WDT clock output: 8Hz
The WDT time-out flag after: 1/2s
Time base/WDT clock output: 16Hz
The WDT time-out flag after: 1/4s
Time base/WDT clock output: 32Hz
The WDT time-out flag after: 1/8s
Time base/WDT clock output: 64Hz
The WDT time-out flag after: 1/16s
Time base/WDT clock output: 128Hz
The WDT time-out flag after: 1/32s
Test mode, user don’t use.
NORMAL
100
1110-0011-X
C
Normal mode
Yes
Yes
Yes
Yes
Note: x: Don’t care
A5~A0:RAM addresses
D3~D0: RAM data
D/C: Data/command mode
Def.: Power on reset default
All the bold forms, namely 110,101, and 100, are mode commands, of these, 100 indicates the command mode ID. If successive
commands have been issued, the command mode ID except for the first command will be omitted. The source of the tone frequency
and of the time base/WDT clock frequency can be derived from an on-chip 256kHz RC oscillator, a 32.768kHz crystal oscillator, or an
external 256kHz clock. Calculation of the frequency is based on the system frequency sources as stated above. It is recommended
that the host controller should initialize the HT1621 after power on reset, for power on reset may fail, which in turn leads to the
malfunctioning of the HT1621.
Rev. 00
HT1621B
Package Information
48-pin SSOP (300mil) Outline Dimensions
Dimensions in mil
Symbol
Min.
Nom.
Max.
A
395
—
420
B
291
—
299
C
8
—
12
C’
613
—
637
D
85
—
99
E
—
25
—
F
4
—
10
G
25
—
35
H
4
—
12
α
0˚
—
8˚
Rev. 00
HT1621B
48-pin LQFP (7x7) Outline Dimensions
Dimensions in mil
Symbol
Min.
Nom.
Max.
A
8.90
—
9.10
B
6.90
—
7.10
C
8.90
—
9.10
D
6.90
—
7.10
E
—
0.50
—
F
—
0.20
—
G
1.35
—
1.45
H
—
—
1.60
I
—
0.10
—
J
0.45
—
0.75
K
0.10
—
0.20
α
0˚
—
7˚
Rev. 00
HT1621B
28-pin SKDIP (300mil) Outline Dimensions
Dimensions in mil
Symbol
Min.
Nom.
Max.
A
1375
—
1395
B
278
—
298
C
125
—
135
D
125
—
145
E
16
—
20
F
50
—
70
G
—
100
—
H
295
—
315
I
330
—
375
α
0˚
—
15˚
Rev. 00