Page 1
1
Standard ICs
FL tube driver
BU2879AK
The BU2879AK is a driver IC for fluorescent displays. It is equipped with 26 high-voltage withstand outputs and can
display from 11 segments of 15 characters to 16 segments of 8 characters. This IC is equipped with a key scanning
function, and general-purpose input pins, and is ideal for front panels in VTRs and other equipment. A serial interface
allows functions to be controlled from a microcomputer.
•
Applications
VCRs
•
Absolute maximum ratings (Ta = 25°C, VSS = 0V)
Parameter
Applied voltage 1
Applied voltage 2
Input voltage
Power dissipation
V
DD
VEE
VIN
Pd
– 0.3 ~ + 7.0
V
DD + 0.3 ~ VDD – 40
– 0.3 ~ V
DD + 0.3
850
∗
V
Symbol Limits Unit
V
V
mW
Operating temperature Topr – 25 ~ + 75 °C
Storage temperature Tstg – 55 ~ + 125 °C
Note) Operation is not guaranteed at these values.
Note) Power dissipation is reduced by 8.5mW for each increase in Ta of 1°C over 25°C.
∗
When mounted on a 70 × 70 × 1.6mm glass epoxy board
•
Features
1) High withstanding voltage output.
2) Display modes: 11S × 15G ~ 16S × 8G.
3) Variable display luminance (7 steps).
4) 3-wire serial interface.
5) Key scanning function (6 × 4).
6) Internal pull-down resistance
(high voltage withstand output).
7) QFP 44 package.
•
Recommended operating conditions (Ta = 25°C, VSS = 0V)
Parameter
Operating power supply voltage 1 V
DD 4.5 5.0 5.5 V
Operating power supply voltage 2 VEE VDD – 37 VDD – 35 VDD – 0 V
Symbol Min. Typ. Max. Unit
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2
Standard ICs BU2879AK
•
Block diagram
CS SCK SI SO
S1
S11
S12
/ G15
S16
/ G11
VEE
SW4
SW1
K4
K1
OSC
G1
G10
VSS
8bit shift-REG.
16bit latch
SEGMENT Driver S / G Driver
KEY DATA
latch
(4 × 6)
V
DD
16bit × 15word
DISPLAY DATA RAM
OSC
CONTROL
LOGIC
4bit
data
GRID
Driver
Page 3
3
Standard ICs BU2879AK
•
Pins descriptions
Pin No. Pin Name I / O Function
14, 38
V
DD
Power supply pin 1
Oscillation pin
Ground pin
Input
Input
/
output
Input
Connected to system power supply.
OSC
Capacitor connection pin for oscillation
44
V
SS
Connected to system ground.
7, 43
Serial data input Input
SI
Serial data input starting from MSB
6
Serial clock input Input
SCK
Serial data read at rising edge.
8
Serial chip select Input
CS
Serial initialization when LOW, valid at HIGH.
9
High-voltage withstand
Output pin for segment; output is
output pin for segment
Output
Pch open drain + pull-down resistance.
S1
~
S1115
~
25
Power supply pin 2 Input
V
EE
Pull-down resistance connection for FLP driver output.
27
High-voltage withstand
Output pin for grid; output is Pch
output pin for grid
Output
open drain + pull-down resistance.
G1
~
G10
42
~
39,
37
~
32
High-voltage withstand
S12
/
G15
Used to switch output between segment and grid;
26,
output pin for segment / grid
Output
output is Pch open drain + pull-down resistance.
S16
/
G11
28
~
31
Key data input pin
Data input pin for key scanning.
Input
K1
~
K410
~
13
General-purpose input pin; input data can be
General-purpose input pin
Input
transmitted serially to microcomputer.
SW1
~
SW41
~
4
Serial data output Output
SO
Serial data output starting from MSB;
output is Nch open drain.
5
~
•
Electrical characteristics (unless otherwise noted, Ta = 25°C, VDD = 5V, VSS = 0V, VDD – VEE = 35V)
Parameter
Symbol Conditions
I
DD
Supply current 44-pin attachment, at 1000pF oscillation
V
IN
Input threshold voltage Pins 1 to 4, 6, 8, 9 to 13
I
IN
Input current Pins 1 to 4, 6, 8, 9 to 13
F
OSC
OSC oscillation frequency 44-pin attachment, at 1000pF oscillation
IOsegSegment output current Pins 15 to 26, 28 to 31, VO =
VDD –
2V
∗
IOgrdGrid output current Pins 26, 28 to 37, 39 to 42, VO =
VDD –
2V
∗
I
OFF
Leakage current when OFF Pins 15 to 26, 28 to 37, VO =
VDD –
V
EE
R
D
Output pull-down resistance Pins 15 to 26, 28 to 37
F
MAX
Maximum operating frequency Design guarantee value
〈
Serial transmission
〉
T
SH
Input data hold
T
SS
Input data setup
T
D
Output data delay
T
SCYC
Input clock cycle
T
SW
Input clock "H" width
Min.
—
1.5
—
130
6
18
—
35
—
0.16
0.16
—
0.5
40
Typ.
—
—
—
200
—
—
—
70
—
—
—
—
—
—
Max.
5
3.5
10
300
—
—
10
140
1
—
—
0.3
—
60
Unit
mA
V
µ
A
kHz
mA
mA
µ
A
k
Ω
MHz
µ
s
µ
s
µ
s
µ
s
%
At minimum input clock cycle
Measurement
circuit
Fig.1
Fig.4
Fig.2
Fig.3
Fig.2
Fig.2
Fig.2
Fig.2
Fig.3
—
—
—
—
—
—
—
—
—
∗
For the high voltage withstand output pins for the segment / grid of pins 26 and 28 to 31, when segment output is specified, segment output current is output, and
when grid output is specified, grid current is output.
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Standard ICs BU2879AK
•
Measurement circuits
1000p
OSC
V
EE VDD
VSS
A
Fig.1
n = Test pin
n
V
V
EE
VSS
VDD
A
Fig.2
1000p
OSC G1 Monitor
V
EE VDD
VSS
Fig.3
VEE VDD
VSS
Fig.4
•
Electrical characteristic curves
3.8
3.7
3.6
3.5
3.4
3.3
3.2
– 25 25 75
CIRCUIT CURRENT: IDD (mA)
TEMPERATURE: Ta (°C)
Fig. 5 Supply current
temperature characteristics
54
50
46
42
38
34
30
– 25 25 75
“H” GRID OUTPUT CURRENT: IOHgrd (mA)
TEMPERATURE: Ta (°C)
Fig. 6 “H” grid output current
temperature characteristics
16
15
14
13
12
11
10
– 25 25 75
OUTPUT CURRENT: IOHseg (mA)
“H” SEGMENT
TEMPERATURE: Ta (°C)
Fig.7 “H” segment output current
temperature characteristics
Page 5
5
Standard ICs BU2879AK
•
External dimensions (Units: mm)
0.15
33 23
22
12
1
34
44
10.0
± 0.2
14.0 ± 0.3
0.35
± 0.1
10.0
± 0.2
14.0 ± 0.3
1.2
0.05
2.15 ± 0.1
0.15
± 0.1
0.8
11
QFP44
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