Standard ICs
Segment-type LCD driver
BU9729K
The BU9729K is a driver for segmented liquid crystal displays, which enables connection with a microcomputer
through a serial interface. 4-bit common output and an internal power supply circuit for LCD drive make it possible to
configure a low-cost display system.
•
Applications car audio equipment, telephones
Movie projectors,
•
Features (8-bit length).
1) Serial interface
2) Display RAM: 72bits, internal (up to 72 segments
can be displayed).
3) Internal power supply circuit for liquid crystal drive.
4) Display duty: 1 / 4.
5) Low-voltage and low-current operation supported.
•
Block diagram
V
LCD
V
C
LCD Driver
Bias Circuit
V
DD
V
SS
SEG1
SD
SCK
C/D
CS
Serial
Interface
Address
Counter
Display Data RAM
(DD RAM)
LCD
Segment
Driver
18bits
SEG18
SEG2
Command / Data
Register
LCD
Common
Driver
4bits
COM1
COM2
COM3
COM4
Command
Decoder
Timing
Generator
Common
Counter
OSC1
OSC2
1
Standard ICs
BU9729K
•
Pin descriptions
Pin name
OSC1
OSC2
V
SS
V
C
V
LCD
V
DD
SCK
Pin No.
1
2
3
4
5
6
7
—
I
I/O
I
O
—
—
Function
These are the I / O pins for the internal oscillator.
Resistance should be connected between the pins when the internal clock is operating.
When an external clock is operating, input should be done from OSC1, and OSC2 should be left open.
This is the V
SS
pin.
This is the power supply pin for LCD drive.
The condition V
LCD
This is the V
DD
pin.
This is the shift lock input pin for serial data.
The contents of the SD pin are read one bit at a time at the rising edge of this pin.
This is the serial data input pin.
SD
8
I
Display data and commands are input here.
When this is
“
0
”
, display data is not displayed, and when
“
1
”
, the data is displayed.
This is the chip select signal input pin.
CS
9
I
When this is LOW, SD input can be received.
The SCK counter is incremented at the timing at which CS goes from HIGH to LOW.
This is the signal input which recognizes whether the SD input consists of commands or display data.
C/D
10
I
When the SCK of the eighth clock rises, this pin judges the input to be display data if the
level is LOW, and a command if the level is HIGH.
COM1
~
COM4
SEG1
~
SEG18
15 ~ 32
O
These are the segment output pins for LCD drive.
They are connected to the segments of the LCD panel.
11 ~ 14
O
These are the common output pins for LCD drive.
They are connected to the commons of the LCD panel.
V
C
V
SS
must be satisfied.
•
Absolute maximum ratings (Ta = 25°C, V
Parameter
Power supply voltage 1
Power supply voltage 2
Power dissipation
Operating temperature
Storage temperature
Input voltage
Output voltage
Symbol
V
DD
V
LCD
Pd
Topr
SS
= 0V)
Limits
Unit
V
V
mW
°C
°C
V
V
– 0.3 ~ + 7.0
– 0.3 ~ + 7.0
∗
1
400
∗
2
– 20 ~ + 75
– 55 ~ + 125
– 0.3 ~ V
DD
+ 0.3
– 0.3 ~ V
DD
+ 0.3
Tstg
V
IN
V
OUT
∗
1 The condition V
LCD
V
C
V
SS
must be satisfied.
∗
2 Reduced by – 4.0mW for each increase in Ta of 1°C over 25°C.
3
Standard ICs
BU9729K
SS
•
Recommended operating conditions (Ta = 25°C, V
Parameter
Power supply voltage 1
Power supply voltage 2
Oscillation frequency
Symbol
V
DD
V
LCD
f
OSC
Min.
2.5
2.5
—
—
—
= 0V)
Max.
5.5
5.5
—
Unit
V
V
kHz
Conditions
—
Typ.
The condition V
LCD
R
f
=
470k
Ω
V
C
V
SS
must be satisfied.
36
•
Electrical characteristics otherwise noted, V
DC characteristics (unless
Parameter
Input high level voltage
Symbol
V
IH1
Min.
DD
= 2.5V to 5.5V, V
SS
= 0V, Ta = 25°C)
Max.
V
DD
0.2
×
V
DD
Unit
V
Conditions
—
Applicable pin
OSC1, SD, SCK, C / D, CS
Typ.
—
0.8
×
V
DD
Input low level voltage
LCD driver on-resistance
∗
1
Input high level current 2
Input low level current
Input capacitance
V
IL1
0
—
V
kΩ
µA
µA
pF
µA
µA
µA
µA
While
—
∆V
ON
= 0.1V
V
IN
= 0
V
IN
= V
DD
—
quiescent
∗
2
V
DD
—
SEG1 ~ 32, COM1 ~ 4
OSC1, SD, SCK, C / D, CS
OSC1, SD, SCK, C / D ,CS
SD,SCK, C / D, CS
R
ON
I
IL2
I
IH
C
I
—
—
–2
—
—
—
—
—
5
0.05
8
40
100
30
2
—
—
1
25
80
250
Current consumption
I
DD
—
—
—
When
“
ALL OFF
”
is displayed
For display operations
∗
3
For access operations
∗
4
∗
1 The internal power supply impedance is not included in the LCD driver on-resistance.
∗
2 All input is fixed at either V
DD
or V
SS
.
∗
3 Except for R
f
= 470kΩ and OSC1, all input is fixed at V
DD
or V
SS
.
∗
4 R
f
= 470kΩ, fSCK = 200kHz.
AC characteristics (unless otherwise noted, V
DD
= 2.5V to 5.5V, V
SS
= 0V, Ta = 25°C)
Parameter
SCK rise time
SCK fall time
SCK cycle time
Command wait time
SCK pulse width HIGH
SCK pulse width LOW
Data setup time
Data hold time
CS pulse width HIGH
CS pulse width LOW
CS setup time
CS hold time
C / D setup time
C / D hold time
C / D-CS time
∗
5
C / D-SCK time
∗
5
Symbol
t
TLH
t
THL
t
CYC
t
WAIT
t
WH1
t
WL1
t
SU1
t
H1
t
WH2
t
WL2
t
SU2
t
H2
t
SU3
t
H3
t
CCH
t
SCH
Min.
—
—
Typ.
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Max.
100
100
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Conditions
—
—
—
—
—
—
—
—
—
—
—
—
—
800
800
300
300
100
100
300
6400
100
100
100
100
100
100
8th rise of SCK used as reference
CS rise used as reference
8th fall of SCK used as reference
∗
5
Should satisfy either one of these conditions.
4
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