19-3020; Rev 1; 4/10
20-Output, 76V, Serial-Interfaced
VFD Tube Drivers
General Description
The MAX6921/MAX6931 are 20-output, 76V, vacuum-
fluorescent display (VFD) tube drivers that interface a
multiplexed VFD tube to a VFD controller, such as the
MAX6850–MAX6853, or to a microcontroller. The
MAX6921/MAX6931 are also ideal for driving static VFD
tubes or telecom relays.
Data is input using an industry standard 4-wire serial
interface (CLOCK, DATA, LOAD, BLANK), compatibile
with either Maxim’s or industry-standard VFD driver and
controller.
For easy display control, the active-high BLANK input
forces all driver outputs low, turning the display off, and
automatically puts the MAX6921/MAX6931 into shut-
down mode. Display intensity can also be controlled by
directly pulse-width modulating the BLANK input.
The MAX6921 has a serial interface data output, DOUT,
allowing any number of devices to be cascaded on the
same serial interface.
The MAX6931 has a negative supply voltage input, V
SS
,
allowing the drivers’ output swing to be made bipolar to
simplify filament biasing in many applications.
The MAX6921 is available in 28-pin TSSOP, SO, and
PLCC packages. The MAX6931 is available in a 28-pin
TSSOP package.
Maxim also offers 12-output VFD drivers (MAX6920) and
32-output VFD drivers (MAX6922/MAX6932).
Features
o
5MHz Industry-Standard 4-Wire Serial Interface
o
3V to 5.5V Logic Supply Range
o
8V to 76V Grid/Anode Supply Range
o
-11V to 0V Filament Bias Supply (MAX6931 Only)
o
Push-Pull CMOS High-Voltage Outputs
o
Outputs can Source 40mA, Sink 4mA
Continuously
o
Outputs can Source 75mA Repetitive Pulses
o
Outputs can be Paralleled for Higher Current Drive
o
Any Output can be Used as a Grid or an Anode
Driver
o
Blank Input Simplifies PWM Intensity Control
o
Small 28-Pin TSSOP Package
o
-40°C to +125°C Temperature Range
MAX6921/MAX6931
Ordering Information
PART
MAX6921AUI+
MAX6921AWI/V+
MAX6921AQI+
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
28 TSSOP
28 Wide SO
28 PLCC
MAX6931AUI+
-40°C to +125°C
28 TSSOP
+Denotes
a lead-free(Pb)/RoHS-compliant package.
/V denotes an automotive qualified part.
Applications
White Goods
Gaming Machines
Automotive
Avionics
Instrumentation
Industrial Weighing
Security
Telecom
VFD Modules
Industrial Control
µC
Typical Operating Circuit
+5V
C1
100nF
7
V
CC
8
V
BB
+60V
C2
100nF
VFDOUT
VFCLK
VFLOAD
VFBLANK
6
22
23
20
DIN
CLK
LOAD
BLANK
V
SS
9
20
OUT0–OUT19
-7V
C3
100nF
GND
21
Pin Configurations appear at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
VFD TUBE
MAX6931
20-Output, 76V, Serial-Interfaced
VFD Tube Drivers
MAX6921/MAX6931
ABSOLUTE MAXIMUM RATINGS
Voltage (with respect to GND)
V
BB
.........................................................................-0.3V to +80V
V
CC
...........................................................................-0.3V to +6V
V
SS
(MAX6931 only) ...............................................-12V to +0.3V
V
BB
- V
SS
(MAX6931 only) .....................................-0.3V to +80V
OUT_ (MAX6921 only) ..................(GND - -0.3V) to (V
BB
+ 0.3V)
OUT_ (MAX6931 only) ....................(V
SS
- -0.3V) to (V
BB
+ 0.3V)
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
OUT_ Continuous Source Current ....................................-45mA
OUT_ Pulsed (1ms max, 1/4 max duty) Source Current ...-80mA
Total OUT_ Continuous Source Current .........................-540mA
Total OUT_ Continuous Sink Current .................................90mA
Total OUT_ Pulsed (1ms max, 1/4 max duty)
Source Current ...........................................................-960mA
OUT_ Sink Current .............................................................15mA
CLK, DIN, LOAD, BLANK, DOUT Current .......................±10mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TSSOP (derate 12.8mW/°C
over +70°C)................................................................1025mW
28-Pin Wide SO (derate 12.5mW/°C
over +70°C)................................................................1000mW
28-Pin PLCC (derate 10.5mW/°C
over +70°C)..................................................................842mW
Operating Temperature Range
(T
MIN
to T
MAX
) ...............................................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow)
Wide SO, TSSOP lead(Pb)-free ...................................+260°C
PLCC lead(Pb)-free......................................................+245°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Typical
Operating Circuit,
V
BB
= 8V to 76V, V
CC
= 3V to 5.5V, V
SS
= -11V to 0V, V
BB
- V
SS
≤
76V, T
A
= T
MIN
to T
MAX
, unless other-
wise noted.) (Note 1)
PARAMETER
Logic Supply Voltage
Tube Supply Voltage
Bias Supply Voltage
(MAX6931 Only)
Total Supply Voltage
(MAX6931 Only)
SYMBOL
V
CC
V
BB
V
SS
V
BB
- V
SS
All outputs OUT_ low, T
A
= +25°C
CLK = idle
T
A
= -40°C to +125°C
All outputs OUT_ high, T
A
= +25°C
CLK = idle
T
A
= -40°C to +125°C
All outputs OUT_ low
Tube Supply Operating Current
I
BB
All outputs OUT_ high
All outputs OUT_ low
Bias Supply Operating Current
(MAX6931 Only)
I
SS
All outputs OUT_ high
T
A
= +25°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +125°C
-0.8
-1.9
-1.4
-1.5
-0.87
-0.38
mA
0.85
78
540
1.65
CONDITIONS
MIN
3
8
-11
TYP
MAX
5.5
76
0
76
170
200
900
1000
3.0
6.9
1.3
1.4
mA
µA
UNITS
V
V
V
V
Logic Supply Operating Current
I
CC
2
_______________________________________________________________________________________
20-Output, 76V, Serial-Interfaced
VFD Tube Drivers
ELECTRICAL CHARACTERISTICS (continued)
(Typical
Operating Circuit,
V
BB
= 8V to 76V, V
CC
= 3V to 5.5V, V
SS
= -11V to 0V, V
BB
- V
SS
≤
76V, T
A
= T
MIN
to T
MAX
, unless other-
wise noted.) (Note 1)
PARAMETER
SYMBOL
V
BB
≥
15V
I
OUT
= -25mA
High-Voltage OUT_
V
BB
≥
15V
I
OUT
= -40mA
8V < V
BB
< 15V
I
OUT
= -25mA
V
BB
≥
15V
I
OUT
= 1mA
Low-Voltage OUT_
(MAX6921 Only)
V
L
8V < V
BB
< 15V
I
OUT
= 1mA
V
BB
≥
15V
I
OUT
= 1mA
Low-Voltage OUT_
(MAX6931 Only)
V
L
8V < V
BB
< 15V
I
OUT
= 1mA
Rise Time OUT_ (20% to 80%)
Fall Time OUT_ (80% to 20%)
LOAD Rising to OUT_ Falling Delay
LOAD Rising to OUT_ Rising Delay
BLANK Rising to OUT_ Falling Delay
BLANK Falling to OUT_ Rising Delay
Input Leakage Current
CLK, DIN, LOAD, BLANK
Logic-High Input Voltage
CLK, DIN, LOAD, BLANK
Logic-Low Input Voltage
CLK, DIN, LOAD, BLANK
Hysteresis Voltage
DIN, CLK, LOAD, BLANK
High-Voltage DOUT
Low-Voltage DOUT
I
IH
, I
IL
V
IH
V
IL
∆V
I
V
OH
V
OL
I
SOURCE
= -1.0mA
I
SINK
= 1.0mA
V
CC
-
0.5
0.5
0.6
0.8 x
V
CC
0.3 x
V
CC
t
R
t
F
CONDITIONS
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
0.9
0.6
0.9
1.2
0.9
0.5
1.3
0.05
0.8
V
BB
- 3.5
V
BB
- 4.0
V
BB
- 1.2
V
BB
- 2.5
V
BB
- 3.0
0.75
1
1.5
1.9
1.1
1.6
2.0
V
SS
+ 0.75 V
SS
+ 1
V
SS
+ 1.5
V
SS
+ 1.9
V
SS
+ 0.8 V
SS
+ 1.1
V
SS
+ 1.6
V
SS
+ 2.0
2
1.5
1.8
2.4
1.8
2.5
10
µs
µs
µs
µs
µs
µs
µA
V
V
V
V
V
V
V
V
MIN
V
BB
- 2
V
BB
- 2.5
TYP
MAX
UNITS
MAX6921/MAX6931
V
BB
= 60V, C
L
= 50pF, R
L
=2.3kΩ
V
BB
= 60V, C
L
= 50pF, R
L
=2.3kΩ
(Notes 2, 3)
(Notes 2, 3)
(Notes 2, 3)
(Notes 2, 3)
SERIAL INTERFACE TIMING CHARACTERISTICS
_______________________________________________________________________________________
3
20-Output, 76V, Serial-Interfaced
VFD Tube Drivers
MAX6921/MAX6931
ELECTRICAL CHARACTERISTICS (continued)
(Typical
Operating Circuit,
V
BB
= 8V to 76V, V
CC
= 3V to 5.5V, V
SS
= -11V to 0V, V
BB
- V
SS
≤
76V, T
A
= T
MIN
to T
MAX
, unless other-
wise noted.) (Note 1)
PARAMETER
Rise and Fall Time DOUT
CLK Clock Period
CLK Pulse-Width High
CLK Pulse-Width Low
CLK Rise to LOAD Rise Hold
DIN Setup Time
DIN Hold Time
DOUT Propagation Delay
LOAD Pulse High
t
CP
t
CH
t
CL
t
CSH
t
DS
t
DH
t
DO
t
CSW
3.0V to 4.5V
4.5V to 5.5V
C
DOUT
= 10pF
3.0V to 4.5V
4.5V to 5.5V
(Note 2)
SYMBOL
CONDITIONS
C
DOUT
= 10pF
(Note 2)
3V to 4.5V
4.5V to 5.5V
200
90
90
100
5
20
15
25
20
55
120
75
240
150
MIN
TYP
60
30
MAX
100
80
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
All parameters are tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
Note 2:
Guaranteed by design.
Note 3:
Delay measured from control edge to when output OUT_ changes by 1V.
Typical Operating Characteristics
(V
CC
= 5.0V, V
BB
= 76V, and T
A
= +25°C, unless otherwise noted.)
TUBE SUPPLY CURRENT (I
BB
)
vs. TEMPERATURE (OUTPUTS LOW)
MAX6921/31 toc01
TUBE SUPPLY CURRENT (I
BB
)
vs. TEMPERATURE (OUTPUTS HIGH)
MAX6921/31 toc02
LOGIC SUPPLY CURRENT (I
CC
)
vs. TEMPERATURE (OUTPUTS LOW)
350
SUPPLY CURRENT (µA)
300
250
200
150
100
50
0
V
CC
= 5V, CLK = IDLE
V
CC
= 3.3V, CLK = IDLE
-40 -20
0
20
40
60
80
100 120
V
CC
= 3.3V, CLK = 5MHz
V
CC
= 5V, CLK = 5MHz
MAX6921/31 toc03
2.0
1.8
1.6
SUPPLY CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
-40 -20
0
20
40
V
BB
= 40V
V
BB
= 76V
2.0
1.8
1.6
SUPPLY CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
BB
= 40V
V
BB
= 8V
V
BB
= 76V
400
V
BB
= 8V
60
80
100 120
-40 -20
0
20
40
60
80
100 120
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
20-Output, 76V, Serial-Interfaced
VFD Tube Drivers
Typical Operating Characteristics (continued)
(V
CC
= 5.0V, V
BB
= 76V, and T
A
= +25°C, unless otherwise noted.)
LOGIC SUPPLY CURRENT (I
CC
)
vs. TEMPERATURE (OUTPUTS HIGH)
MAX6921/31 toc04
MAX6921/MAX6931
OUTPUT VOLTAGE (V
BB
- V
H
)
vs. TEMPERATURE (OUTPUT HIGH)
I
OUT
= -40mA
3.0
V
BB
= 8V
OUTPUT VOLTAGE (V)
2.5
2.0
V
BB
= 40V
1.5
1.0
0.5
0
V
BB
= 76V
MAX6921/31 toc05
800
750
SUPPLY CURRENT (µA)
700
650
600
550
500
450
400
-40 -20
0
20
40
60
80
V
CC
= 3.3V, CLK = 5MHz
V
CC
= 5V, CLK = IDLE
V
CC
= 3.3V, CLK = IDLE
V
CC
= 5V, CLK = 5MHz
3.5
100 120
-40 -20
0
20
40
60
80
100 120
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT VOLTAGE
vs. TEMPERATURE (OUTPUT LOW)
I
OUT
= 4mA
12
OUTPUT VOLTAGE (V)
10
8
6
4
2
0
-40 -20
0
20
40
60
80
100 120
V
BB
= 8V
V
BB
= 76V
V
BB
= 40V
MAX6921/31 toc06
OUTPUT RISE AND FALL WAVEFORM
MAX6921/31 toc07
14
BLANK
2V/div
OUT_
20V/div
1µs/div
TEMPERATURE (°C)
Pin Description
PIN
TSSOP
MAX6921
1–5
6
7
8
9
MAX6931
1–5
6
7
8
—
WIDE
SO/PLCC
MAX6921
—
27
28
1
2
OUT4 to
OUT0
DIN
V
CC
V
BB
DOUT
VFD Anode and Grid Drivers. OUT4 to OUT0 are push-pull outputs swinging from
V
BB
to GND (MAX6921 only), and from V
BB
to V
SS
(MAX6931 only).
Serial-Data Input. Data is loaded into the internal shift register on CLK’s rising edge.
Logic Supply Voltage. Bypass to GND with 100nF capacitor.
VFD Tube Supply Voltage. Bypass to GND with 100nF capacitor.
Serial-Clock Output. Data is clocked out of the internal shift register to DOUT on
CLK’s rising edge.
NAME
FUNCTION
_______________________________________________________________________________________
5
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