Rainbow Electronics MAX6934 User Manual

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

________________________________________________________________ Maxim Integrated Products 1

For pricing delivery, and ordering information please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

General Description

The MAX6922/MAX6932/MAX6933/MAX6934 multi-out­put, 76V, vacuum-fluorescent display (VFD) tube drivers
that interface a VFD tube to a microcontroller or a VFD
controller, such as the MAX6850–MAX6853. The
MAX6922/MAX6934 have 32 outputs, while the MAX6932
has 27 outputs, and the MAX6933 has 28 outputs. All
devices are also suitable for driving telecom relays.

Data is input using standard 4-wire serial interface
(CLOCK, DATA, LOAD, BLANK) compatible with other
VFD drivers and controllers.

For easy display control, the active-high BLANK input
forces all driver outputs low, turning the display off, and
automatically puts the IC into shutdown mode. Display
intensity may also be controlled by directly pulse-width
modulating the BLANK input.

The MAX6922/MAX6932/MAX6934 have a serial inter­face data output, DOUT, allowing any number of
devices to be cascaded on the same serial interface.

The MAX6932/MAX6933/MAX6934 have a negative
supply voltage input, VSS, allowing the drivers’ output
swing to be made bipolar to simplify filament biasing in
many applications.

The MAX6922 is available in a 44-pin PLCC package,
the MAX6932 and MAX6933 are available in 36-pin
SSOP packages, and the MAX6934 is available in 44­pin PLCC and thin QFN packages.

Maxim also offers a 12-output VFD driver (MAX6920)
and 20-output VFD drivers (MAX6921/MAX6931).

Applications

White Goods Industrial Weighing
Gaming Machines Security
Automotive Telecom
Avionics VFD Modules
Instrumentation Industrial Control

Features

♦ 5MHz Industry-Standard 4-Wire Serial Interface
♦ 3V to 5.5V Logic Supply Range
♦ 8V to 76V Grid/Anode Supply Range
♦ -11V to 0V Filament Bias Supply

(MAX6932/MAX6933/MAX6934 Only)

♦ Push-Pull CMOS High-Voltage Outputs
♦ Outputs Can Source 40mA, Sink 4mA

Continuously

♦ Outputs Can Source 75mA Repetitive Pulses
♦ Outputs Can Be Paralleled for Higher Current Drive
♦ Any Output Can Be Used as a Grid or an Anode

Driver

♦ BLANK Input Simplifies PWM Intensity Control
♦ -40°C to +125°C Temperature Range as Standard

Ordering Information

19-3224; Rev 0; 1/04

PART TEMP RANGE PIN-PACKAGE

MAX6922AQH

44 PLCC

MAX6932AAX

36 SSOP

MAX6933AAX

36 SSOP

MAX6934AQH

44 PLCC

MAX6934ATH

44 Thin QFN

MAX6934

DIN

CLK

LOAD

BLANK

VFDOUT

VFCLK

VFLOAD

VFBLANK

VFD TUBE

12 16

THIN QFN

GND

-7V

37

17

µC

18

15

C1

100nF

C3

100nF

+5V

38

V

CC

V

SS

C2
100nF

+60V

39

V

BB

OUT0–OUT31

32

Typical Operating Circuit

Pin Configurations appear at end of data sheet.

Selector Guide

PART

NO. OF

BIPOLAR

OUTPUT

SWING

DOUT FOR

CASCADING

MAX6922 32 No Yes
MAX6932 27 Yes Yes
MAX6933 28 Yes No
MAX6934 32 Yes Yes

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

OUTPUTS

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Typical Operating Circuit, VBB= 8V to 76V, VCC= 3V to 5.5V, VSS= -11V to 0V, VBB- VSS≤ 76V, TA= T

MIN

to T

MAX

, unless other-

wise noted.) (Note 1)

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.

Voltage (with respect to GND)
V

BB

.........................................................................-0.3V to +80V

V

CC

...........................................................................-0.3V to +6V

V

SS

(MAX6932/MAX6933/MAX6934 only)..............-12V to +0.3V

V

BB

- VSS(MAX6932/MAX6933/MAX6934 only) ....-0.3V to +80V

OUT_ (MAX6922 only) ..................(GND - -0.3V) to (V

BB

+ 0.3V)

OUT_ (MAX6932/MAX6933/MAX6934 only)

........................................................(V

SS

- -0.3V) to (VBB+ 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 .........................-840mA

Total OUT_ Continuous Sink Current ...............................140mA

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)
36-Pin SSOP (derate 11.8mW/°C

over +70°C)..................................................................941mW

44-Pin Thin QFN (derate 27mW/°C

over +70°C)................................................................2165mW

44-Pin PLCC (derate 13.3mW/°C

over +70°C)................................................................1067mW

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

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Logic Supply Voltage V

CC

3 5.5 V

Tube Supply Voltage V

BB

876V

Bias Supply Voltage (MAX6932/

MAX6933/MAX6934 Only)

V

SS

-11 0 V

Total S up p l y V ol tag e ( M AX 6932/

M AX 6933/M AX 6934 O nl y)

76 V

TA = +25°C 81 170

CLK = idle

200

TA = +25°C

Logic Supply Operating Current

I

CC

CLK = idle

µA

TA = +25°C 2.4 5

6.9

TA = +25°C 1.3 2.1

Tube Supply Operating Current

I

BB

2.2

mA

TA = +25°C

-3

TA = +25°C

Bias Supply Operating Current

( M AX 6932/M AX 6933/M AX 6934
O nl y)

I

SS

mA

TA = +25°C VBB - 1.1
TA = -40°C to +85°C

VBB ≥ 15V,
I

OUT

= -25mA

TA = -40°C to +85°C

VBB ≥ 15V,
I

OUT

= -40mA

TA = +25°C VBB - 1.2
TA = -40°C to +85°C

High-Voltage OUT_ V

H

8V < VBB < 15V,
I

OUT

= -25mA

V

VBB - V

SS

All outputs OUT_ low,

All outputs OUT_ high,

All outputs OUT_ low

All outputs OUT_ high

All outputs OUT_ low

All outputs OUT_ high

TA = -40°C to +125°C

TA = -40°C to +125°C 1500

T

= -40°C to +125°C

A

T

= -40°C to +125°C

A

T

= -40°C to +125°C

A

T

= -40°C to +125°C -2.5

A

TA = -40°C to +125°C VBB - 2.5

TA = -40°C to +125°C VBB - 4.0

TA = -40°C to +125°C VBB - 3.0

-1.3 -0.65

-2.3 -1.5

VBB - 2

VBB - 3.5

VBB - 2.5

860 1400

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Typical Operating Circuit, VBB= 8V to 76V, VCC= 3V to 5.5V, VSS= -11V to 0V, VBB- VSS≤ 76V, TA= T

MIN

to T

MAX

, unless other-

wise noted.) (Note 1)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

TA = +25°C

1.2

TA = -40°C to +85°C 1.5

VBB ≥ 15V,
I

OUT

= 1mA

T

A

= -40°C to +125°C 2.1
TA = +25°C 0.8 1.3
TA = -40°C to +85°C 1.7

Low-Voltage OUT_
( M AX 6932 O nl y)

V

L

8V < VBB < 15V,
I

OUT

= 1mA

T

A

= -40°C to +125°C 2.2

V

TA = +25°C
TA = -40°C to +85°C

VBB ≥ 15V,
I

OUT

= 1mA

T

A

= -40°C to +125°C
TA = +25°C
TA = -40°C to +85°C

Low-Voltage OUT_
( M AX 6932/M AX 6933/M AX 6934
O nl y)

V

L

8V < VBB < 15V,
I

OUT

= 1mA

T

A

= -40°C to +125°C

V

Rise Time OUT_ (20% to 80%) t

R

VBB = 60V, CL = 50pF, RL =2.3kΩ 0.9 2 µs

Fall Time OUT_ (80% to 20%) t

F

V

BB

= 60V, C

L

= 50pF, RL =2.3kΩ 0.6 1.5 µs

SERIAL INTERFACE TIMING CHARACTERISTICS

LOAD Rising to OUT_ Falling
Delay

(Notes 2, 3) 0.9 3 µs

LOAD Rising to OUT_ Rising
Delay

(Notes 2, 3) 1.2 5.5 µs

BLANK Rising to OUT_ Falling
Delay

(Notes 2, 3) 0.9 3 µs

BLANK Falling to OUT_ Rising
Delay

(Notes 2, 3) 0.5 1.3 5.5 µs

Input Leakage Current
CLK, DIN, LOAD, BLANK

I

IH

, I

IL

10 µA

Logic-High Input Voltage
CLK, DIN, LOAD, BLANK

V

IH

0.8 x
V

Logic-Low Input Voltage
CLK, DIN, LOAD, BLANK

V

IL

0.3 x
V

Hysteresis Voltage
DIN, CLK, LOAD, BLANK

∆V

I

0.6 V

High-Voltage DOUT V

OH

I

SOURCE

= -1.0mA

V

CC

-

0.5

V

Low-Voltage DOUT V

OL

I

SINK

= 1.0mA 0.5 V

VSS + 0.75 VSS + 1.2

VSS + 0.8 VSS + 1.3

V

CC

0.75

0.05

VSS + 1.5
VSS + 2.1

VSS + 1.7
VSS + 2.2

V

CC

Typical Operating Characteristics

(VCC= 5.0V, VBB= 76V, and TA= +25°C, unless otherwise noted.)

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Typical Operating Circuit, VBB= 8V to 76V, VCC= 3V to 5.5V, VSS= -11V to 0V, VBB- VSS≤ 76V, TA= T

MIN

to T

MAX

, unless other-

wise noted.) (Note 1)

PARAMETER

CONDITIONS

UNITS

3V to 4.5V 80 130

Rise and Fall Time DOUT

C

DOUT

= 10pF

(Note 2)

4.5V to 5.5V 50 80

ns

CLK Clock Period t

CP

ns

CLK Pulse-Width High t

CH

90 ns

CLK Pulse-Width Low t

CL

90 ns

CLK Rise to LOAD Rise Hold t

CSH

(Note 2)

ns

DIN Setup Time t

DS

5ns

3.0V to 4.5V 20

DIN Hold Time t

DH

4.5V to 5.5V 15

ns

3.0V to 4.5V 25

240

DOUT Propagation Delay t

DO

C

DOUT

= 10pF

4.5V to 5.5V 20 75 150

ns

LOAD Pulse High t

CSW

60 ns

Note 1: All parameters are tested at TA= +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.

TUBE SUPPLY CURRENT (IBB)

vs. TEMPERATURE (OUTPUTS LOW)

MAX6922 toc01

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

1008040 60020-20

0

1.2

0.8

0.4

1.6

2.0

2.4

2.8

-40 120

VBB = 8V

VBB = 40V

VBB = 76V

MAX6922 toc02

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

1008040 60020-20

0

0.8

0.6

0.4

0.2

1.0

1.2

1.4

1.6

2.0

1.8

-40 120

VBB = 8V

VBB = 40V

VBB = 76V

TUBE SUPPLY CURRENT (IBB)

vs. TEMPERATURE (OUTPUTS HIGH)

MAX6922 toc03

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

1008040 60020-20

0

0.4

0.3

0.2

0.1

0.5

0.6

0.7

0.8

1.0

0.9

-40 120

LOGIC SUPPLY CURRENT (ICC)

vs. TEMPERATURE (OUTPUTS LOW)

VCC = 5V, CLK = 5MHz

VCC = 3.3V, CLK = 5MHz

VCC = 5V, CLK = IDLE

VCC = 3.3V, CLK = IDLE

SYMBOL

MIN TYP MAX

200

100

120

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(VCC= 5.0V, VBB= 76V, and TA= +25°C, unless otherwise noted.)

MAX6922 toc04

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

1008040 60020-20

0.6

0.8

0.7

0.9

1.0

1.2

1.1

-40 120

LOGIC SUPPLY CURRENT (ICC)

vs. TEMPERATURE (OUTPUTS HIGH)

VCC = 5V, CLK = 5MHz

VCC = 3.3V, CLK = 5MHz

VCC = 5V, CLK = IDLE

VCC = 3.3V, CLK = IDLE

MAX6922 toc05

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

1008040 60020-20

0

16

14

12

10

8

6

4

2

-40 120

VBB = 8V

VBB = 40V

VBB = 76V

OUTPUT VOLTAGE

vs. TEMPERATURE (OUTPUTS LOW)

I

OUT

= 4mA

MAX6922 toc06

TEMPERATURE (°C)

OUTPUT VOLTAGE (V)

1008040 60020-20

0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

-40 120

VBB = 8V

VBB = 76V

VBB = 40V

I

OUT

= -40mA

OUTPUT VOLTAGE (VBB - VT)

vs. TEMPERATURE (OUTPUTS HIGH)

OUTPUT FALL AND RISE TIME

MAX6922 toc07

1µs/div

BLANK
2V/div

OUT
20V/div

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

6 _______________________________________________________________________________________

PIN

MAX6934

PLCC

SSOP

NAME FUNCTION

1139V

BB

VFD Supply Voltage

2240

DOUT

Serial-Data Output. Data is clocked out of the internal shift register to DOUT
on CLK’s falling edge. For the MAX6933 only—VFD anode and grid driver.

2

(OUT27)

(OUT27 is a push-pull output swinging from V

BB

to VSS.)

3, 4, 5, 7–
17, 19, 20,
25, 26, 27,

30–42

—

1–11, 13,
14, 19, 20,
21, 24–36,

OUT0 to

OUT31

VFD Anode and Grid Drivers. OUT_ are push-pull outputs swinging from
GND to V

SS

for the MAX6922 and from VBB to VSS for the MAX6934.

—

3 –13, 15,

—

OUT0 to

OUT26

VFD Anode and Grid Drivers. OUT_ are push-pull outputs swinging from
V

BB

to VSS.

6, 28, 29 —

N.C. No Connection. Not internally connected.

18 — —

For the MAX6922—No Connection. Not internally connected. For the
MAX6934—bias supply voltage.

—1412VSSBias Supply Voltage

21 17 15 BLANK

Blanking Input. High forces outputs OUT_ low without altering the contents
of the output latches. Low enables outputs OUT_ to follow the state of the
output latches.

22 18 16 GND Ground

23 19 17 CLK

Serial-Clock Input. Data is loaded into the internal shift register on CLK’s
rising edge. On CLK’s falling edge, data is clocked out of DOUT.

24 20 18 LOAD

Load Input. Data is loaded transparently from the internal shift register to the
output latch while LOAD is high. Data is latched into the output latch on
LOAD's rising edge, and retained while LOAD is low.

43 35 37 DIN

Serial-Data Input. Data is loaded into the internal shift register on CLK’s
rising edge.

44 36 38 V

CC

Logic Supply Voltage

Pin Description

MAX6922/

MAX6932/

MAX6933

16, 21–34

MAX6934

THIN QFN

41, 42, 43

22, 23, 44

(MAX6932)

(MAX6933)

N.C. (VSS)

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

_______________________________________________________________________________________ 7

Detailed Description

The MAX6922/MAX6932/MAX6933/MAX6934 are VFD
tube drivers comprising a 4-wire serial interface driving
high-voltage Rail-to-Railoutput ports. The driver is suit­able for both static and multiplexed displays.

The output ports feature high current-sourcing capabili­ty to drive current into grids and anodes of static or
multiplex VFDs. The ports also have active current sink­ing for fast discharge of capacitive display electrodes
in multiplexing applications.

The 4-wire serial interface comprises a shift register
and transparent latch with 32 bits for the MAX6922/
MAX6934, 28 bits for the MAX6933, and 27 bits for the
MAX6932. The shift register is written through a clock
input CLK and a data input DIN. For the MAX6922/
MAX6932/MAX6934, the data propagates to a data out­put DOUT. The data output allows multiple drivers to be
cascaded and operated together. The output latch is
transparent to the shift register outputs when LOAD is
high, and latches the current state on the falling edge
of LOAD.

Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.

SERIAL-TO-PARALLEL SHIFT REGISTER

LATCHES

CLK

DIN

LOAD

BLANK

OUT0 OUT1 OUT2

OUTn

WHERE n =
27 FOR MAX6932
28 FOR MAX6933
32 FOR MAX6922/MAX6934

DOUT

MAX6922/MAX6932/

MAX6934 ONLY

MAX6922
MAX6932
MAX6933
MAX6934

Figure 1. MAX6922/MAX6932/MAX6933/MAX6934 Functional Diagram

SLEW-RATE

CONTROL

V

BB

OUT_

40Ω
TYPICAL

750Ω
TYPICAL

Figure 2. MAX6922 CMOS Output Driver Structure Figure 3. MAX6932/MAX6933/MAX6934 CMOS Output Driver

Structure

V

BB

40Ω

SLEW-RATE

CONTROL

TYPICAL

750Ω
TYPICAL

V

SS

OUT_

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

8 _______________________________________________________________________________________

Each driver output is a slew-rate controlled CMOS
push-pull switch driving between VBBand GND
(MAX6922) or VBBand VSS(MAX6932/MAX6933/
MAX6934). The output rise time is always slower than
the output fall time to avoid shoot-through currents dur­ing output transitions. The output slew rates are slow
enough to minimize EMI, yet are fast enough so as not
to impact the typical 100µs digit multiplex period and
affect the display intensity.

Initial Power-Up and Operation

An internal reset circuit clears the internal registers on
power-up. All outputs and the interface output DOUT
(MAX6922/MAX6932/MAX6934 only) initialize low
regardless of the initial logic levels of the CLK, DIN,
BLANK, and LOAD inputs.

4-Wire Serial Interface

These driver ICs use a 4-wire serial interface with three
inputs (DIN, CLK, LOAD) and a data output (DOUT,
MAX6922/MAX6932/MAX6934 only). This interface is
used to write data to the ICs (Figure 4) (Table 1). The
serial interface data word length is 32 bits for the
MAX6922/MAX6934, 27 bits for the MAX6932, and 28
bits for the MAX6933.

The functions of the four serial interface pins are:

• CLK input is the interface clock, which shifts data
into the shift register on its rising edge.

• LOAD input passes data from the shift register to the
output latch when LOAD is high (transparent latch),
and latches the data on LOAD’s falling edge.

• DIN is the interface data input, and must be stable
when it is sampled on the rising edge of CLK.

• DOUT is the interface data output, which shifts data
out from the shift register on the rising edge of CLK.
Data at DIN is propagated through the shift register
and appears at DOUT (n CLK cycles + tDO) later,
where n is the number of drivers in the IC.

A fifth input, BLANK, can be taken high to force the out­puts low, without altering the contents of the output latch­es. When the BLANK input is low, the outputs follow the
state of the output latches. A common use of the BLANK
input is PWM intensity control.

The BLANK input’s function is independent of the oper­ation of the serial interface. Data can be shifted into the
serial interface shift register and latched regardless of
the state of BLANK.

Writing Device Registers Using

the 4-Wire Serial Interface

The MAX6922/MAX6932/MAX6933/MAX6934 are nor­mally written using the following sequence:

1) Take CLK low.

2) Clock n bits of data in order D

n-1

first to D0 last into

DIN, observing the data setup and hold times.

3) Load the n output latches with a falling edge on LOAD,

where n is 27 for the MAX6932, 28 for the MAX6933,
and 32 for the MAX6922 and MAX6934.

LOAD may be high or low during a transmission. If
LOAD is high, then the data shifted into the shift regis­ter at DIN appears at the OUT0 to OUT

n-1

outputs.

CLK and DIN may be used to transmit data to other
peripherals. Activity on CLK always shifts data into the
shift register. However, the output latches only update
on the rising edge of LOAD, and the last n bits of data

LOAD

t

CSW

t

CP

t

CSH

t

CH

t

DH

t

DO

t

DS

Dn-1 Dn-2 D1 D0

Dn-1

t

CL

CLK

DIN

DOUT

Figure 4. 4-Wire Serial Interface Timing Diagram

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

_______________________________________________________________________________________ 9

clocked in are loaded. Therefore, multiple devices can
share CLK and DIN, as long as they have unique LOAD
controls.

Determining Driver Output Voltage Drop

The outputs are CMOS drivers, and have a resistive
characteristic. The typical and maximum sink and
source output resistances can be calculated from the
VHand VLelectrical characteristics. Use this calculated
resistance to determine the output voltage drop at dif­ferent output currents.

Output Current Ratings

The continuous current-source capability is 40mA per
output. Outputs may drive up to 75mA as a repetitive
peak current, subject to the on-time (output high) being
no longer than 1ms, and the duty cycle being such that
the output power dissipation is no more than the dissipa­tion for the continuous case. The repetitive peak rating
allows outputs to drive a higher current in multiplex grid
driver applications, where only one grid is on at a time,
and the multiplex time per grid is no more than 1ms.

Since dissipation is proportional to current squared, the
maximum current that can be delivered for a given mul­tiplex ratio is given by:

I

PEAK

= (grids x 1600)

1/2

mA

where grids is the number of grids in a multiplexed
display.

This means that a duplex application (two grids) can use
a repetitive peak current of 56.5mA, a triplex (three grids)
application can use a repetitive peak current of 69.2mA,
and higher multiplex ratios are limited to 75mA.

Paralleling Outputs

Any number of outputs within the same package may
be paralleled in order to raise the current drive or
reduce the output resistance. Only parallel outputs
directly (by shorting outputs together) if the interface
control can be guaranteed to set the outputs to the
same level. Although the sink output is relatively weak
(typically 750Ω), that resistance is low enough to dissi­pate 530mW when shorted to an opposite level output
at a VBBvoltage of only 20V. A safe way to parallel out­puts is to use diodes to prevent the outputs from sink­ing current (Figure 5). Because the diodes also stop
the outputs from sinking current from the VFD tube, an
external discharge resistor, R, is required. For static
tubes, R can be a large value such as 100kΩ. For multi­plexed tubes, the value of the resistor can be deter­mined by the load capacitance and timing

MAX6922
MAX6932
MAX6933
MAX6934

OUT0

OUT1

D1

D2

R

OUTPUT

Figure 5. Paralleling Outputs

L = Low logic level.
H = High logic level.
X = Don’t care.
P = Present state (shift register).
R = Previous state (latched).

CLOCK

SHIFT REGISTER CONTENTS

LOAD

LATCH CONTENTS

BLANKING

INPUT

OUTPUT CONTENTS

SERIAL

DATA

INPUT

DIN

H
L
X

XL

H

L
H

Table 1. 4-Wire Serial Interface Truth Table

INPUT

CLK D0 D1 D2 … Dn-2 Dn-1 LOAD D0 D1 D2 … Dn-2 Dn-1 BLANK D0 D1 D2 … Dn-2 Dn-1

INPUT

HR0R1…Rn-2 Rn-1

LR0R1…Rn-2 Rn-1

R0 R1 R2 … Rn-1 Rn

XXX…X

P0 P1 P2 … Pn-1 Pn

R0 R1 R2 … Rn-1 Rn

P0 P1 P2 … Pn-1 Pn

XXX…X X

P0 P1 P2 … Pn-1 Pn

LLL…L L

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

10 ______________________________________________________________________________________

characteristics required. Resistor R discharges tube
capacitance C to 10% of the initial voltage in 2.3 x RC
seconds. So, for example, a 15kΩ value for R dis­charges 100pF tube grid or anode from 40V to 4V in

3.5µs, but draws an additional 2.7mA from the driver
when either output is high.

Power Dissipation

Take care to ensure that the maximum package dissi­pation ratings for the chosen package are not exceed­ed. Over-dissipation is unlikely to be an issue when
driving static tubes, but the peak currents are usually
higher for multiplexed tubes. When using multiple driver
devices, try to share the average dissipation evenly
between the drivers.

Determine the power dissipation (PD) for the MAX6922/
MAX6932/MAX6933/MAX6934 for static tube drivers
with the following equation:

PD= (VCCx ICC) + (VBBx IBB) + ((VBB- VH) x

I

ANODE

x A))
where:
A = number of anodes driven (maximum of 32 with the

MAX6922/MAX6934).
I

ANODE

= maximum anode current.

(VBB- VH) is the output voltage drop at the given maxi­mum anode current I

OUT

.

A static tube dissipation example follows:

VCC= 5V ±5%, VBB= 10V to 18V, A = 32, I

OUT

= 2mA

PD= (5.25V x 1.5mA)+ (18V x 2.2mA) +
((2.5V x 2mA/25mA) x 2mA x 32) = 60mW

Determine the power dissipation (PD) for the MAX6922/
MAX6932/MAX6933/MAX6934 for multiplex tube drivers
with the following equation:

PD= (VCCx ICC) + (VBBx IBB) + ((VBB- VH) x

I

ANODE

x A) + ((VBB- VH) x I

GRID

))
where:
A = number of anodes driven.
G = number of grids driven.
I

ANODE

= maximum anode current.

I

GRID

= maximum grid current.

The calculation presumes all anodes are on, but only
one grid is on. The calculated PDis the worst case, pre­suming one digit is always being driven with all its
anodes lit. Actual PDcan be estimated by multiplying
this PDfigure by the actual tube drive duty cycle, taking
into account interdigit blanking and any PWM intensity
control.

A multiplexed tube dissipation example follows:

V

CC

= 5V ±5%, VBB= 36V to 42V, A = 20, G = 12,

I

ANODE

= 0.4mA, I

GRID

= 24mA

PD= (5.25V x 1.5mA)+ (42V x 2.2mA) +

((2.5V x 0.4mA/25mA) x 0.4mA x 20) +
((2.5V x 24mA/25mA) x 24mA) = 158mW

Thus, for a 44-pin PLCC package (T

JA

= 1 / 0.0133 =

75.188°C/W from Absolute Maximum Ratings), the maxi­mum allowed ambient temperature T

A

is given by:

T

J(MAX)

= TA+ (PDx TJA) = +150°C = TA+ (0.158 x

75.188°C/W)
So TA= +138°C.
This means that the driver can be operated in this

application with a PLCC package up to the +125°C
maximum operating temperature.

Power-Supply Considerations

The MAX6922/MAX6932/MAX6933/MAX6934 operate
with multiple power-supply voltages. Bypass the VCC,
V

BB

, and VSS(MAX6932/MAX6933/MAX6934 only)
power-supply pins to GND with 0.1µF capacitors close
to the device. The MAX6932/MAX6933/MAX6934 may
be operated with VSStied to GND if a negative bias
supply is not required. For multiplex applications, it may
be necessary to add an additional bulk electrolytic
capacitor of 1µF or greater to the VBBsupply.

Power-Supply Sequencing

The order of the power-supply sequencing is not impor­tant. These ICs are damaged if any combination of
VCC, VBB, and VSSis grounded while the other supply
or supplies are maintained up to their maximum ratings.
However, as with any CMOS device, do not drive the
logic inputs if the logic supply V

CC

is not operational

because the input protection diodes clamp the signals.

Cascading Drivers

(MAX6922/MAX6932/MAX6934 Only)

Multiple driver ICs may be cascaded, as shown in the
Typical Application Circuit, by connecting each driver’s
DOUT to DIN of the next drivers. Devices may be cas­caded at the full 5MHz CLK speed when VCC≥ 4.5V.
When VCC<4.5V, the longer propagation delay (tDO)
limits the maximum cascaded CLK to 4MHz.

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

______________________________________________________________________________________ 11

MAX6922

DIN

CLK

LOAD

BLANK

MAX685x

VFDOUT

VFCLK

VFLOAD

VFBLANK DOUT

VFD TUBE

MAX6922

DIN

CLK

LOAD

BLANK DOUT

MAX6922

DIN

CLK

LOAD

BLANK DOUT

Typical Application Circuit

Chip Information

TRANSISTOR COUNT: 3850
PROCESS: BiCMOS

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

12 ______________________________________________________________________________________

Pin Configurations

TOP VIEW

441234404142

43

5

21

24

26

25

27

28

22 2319

20

8

9
10
11
12
13
14
15
16
17

29

30

31

32

33

34

35

36

37

38

OUT18

OUT16

OUT29

PLCC

OUT30

OUT31

DOUT

VBBVCCDIN

OUT0

OUT1

OUT2

OUT17

GND

BLANK

LOAD

CLK

OUT14

OUT15

N.C.

OUT13

OUT4
OUT5
OUT6
OUT7
OUT8
OUT9
OUT10
OUT11
OUT12
N.C.

OUT19

OUT20

OUT21

OUT22

OUT23

OUT24

OUT25

OUT26

OUT27

7

39

OUT3

OUT28

6

18

N.C.N.C.

MAX6922

441234404142

43

5

21

24

26

25

27

28

22 2319

20

8

9
10
11
12
13
14
15
16
17

29

30

31

32

33

34

35

36

37

38

OUT18

OUT16

OUT29

PLCC

OUT30

OUT31

DOUT

VBBVCCDIN

OUT0

OUT1

OUT2

OUT17

GND

BLANK

LOAD

CLK

OUT14

OUT15

N.C.

OUT13

OUT4
OUT5
OUT6
OUT7
OUT8
OUT9
OUT10
OUT11
OUT12
N.C.

OUT19

OUT20

OUT21

OUT22

OUT23

OUT24

OUT25

OUT26

OUT27

7

39

OUT3

OUT28

6

18

N.C.V

SS

MAX6934

44

43

42

41

40

39

38

12

13

14

15

16

17

18

27

28

29

30

31

32

33

7

6

5

4

3

2

1

MAX6934

THIN QFN

OUT27

OUT28

OUT26

OUT25

OUT24

OUT23

OUT22

N.C.

OUT29

OUT30

OUT31

DOUT

V

BBVCC

OUT3

OUT4

OUT5

OUT6

OUT7

OUT8

OUT9

23

24

25

26

11

10

9

8

OUT21

OUT20

OUT19

OUT18

OUT10

OUT11

OUT12

N.C.

LOAD

CLK

GND

BLANK

37

36

35

34

19

20

21

22

DIN

OUT0

OUT1

OUT2

N.C.

OUT13

OUT14

OUT15

OUT16

OUT17

V

SS

36 V

CC

DIN

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

LOAD

CLK

( ) IS FOR THE MAX6933

35

34

33

32

31

30

29

28

27

1

2

3

4

5

6

7

8

9

10

V

BB

DOUT(OUT27)

OUT26

OUT25

OUT24

OUT23

OUT22

OUT21

OUT20

OUT19

OUT18

OUT17

OUT16

V

SS

OUT15

OUT14

BLANK

GND

MAX6932
MAX6933

26

25

24

23

22

21

20

19

11

12

13

14

15

16

17

18

SSOP

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

______________________________________________________________________________________ 13

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

PLCC.EPS

FAMILY PACKAGE OUTLINE:
20L, 28L, 44L, 52L, 68L PLCC

1

1

21-0049

D

REV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

D1

D

C

A2

B1

B

A1

A

A3

D2

e

D3D1D

D3

N

22.61

20.320.800D3

D2 0.890 0.930

REF REF

23.62

4.20

2.29

3.69

0.51

0.33

0.66

0.23

9.78

8.89

7.37

5.08

12.32

11.43

9.91

7.62

17.40

16.51

14.99

12.70

MIN

MIN

24.13

25.02

0.1200.090A1

REFD3 0.200

0.485

0.300

0.685

0.500

0.985

D
D1
D2
D3

D1

D

0.650

0.590

0.950

D
D1
D2
D3

0.450

0.390

0.695

0.656

0.630

0.958

0.995

REF

0.495

0.456

0.430
REF

0.050

0.385

INCHES

D
D1D20.350

0.290

MIN

A2
A3

B

B1

C
e

0.145

0.020

0.013

0.026

0.009

0.395

0.356

0.330

MAX

0.156

0.021

0.032

---

0.011

INCHES

A 0.165

MIN

0.180

MAX

3.04

REF

28

44

68

17.65

16.66

16.00
REF

24.33

25.27

12.57

11.58

10.92
REF

AC

AE

AB

10.03

9.04

8.38

MAX

N

20

3.96

---

0.53

0.81

0.28

1.27

AA

4.57

MAX

NOTES:

1. D1 DOES NOT INCLUDE MOLD FLASH.

2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED
.20mm (.008") PER SIDE.

3. LEADS TO BE COPLANAR WITHIN .10mm.

4. CONTROLLING DIMENSION: MILLIMETER

5. MEETS JEDEC MO047-XX AS SHOWN IN TABLE.

6. N = NUMBER OF PINS.

REFREFD3 0.600 15.24

17.53

19.05

19.94
D1
D2

D

0.750

0.690

0.785

0.756

0.795

0.730

52

19.20

20.19

18.54

AD

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

14 ______________________________________________________________________________________

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

SSOP.EPS

PACKAGE OUTLINE, 36L SSOP, 0.80 MM PITCH

1

1

21-0040 E

REV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

FRONT VIEW

MAX

0.011

0.104

0.017

0.299

0.013

INCHES

0.291

0.009

E

C

DIM

0.012

0.004

B

A1

MIN

0.096A

0.23

7.40 7.60

0.32

MILLIMETERS

0.10

0.30

2.44

MIN

0.44

0.29

MAX

2.65

0.040

0.020L

0.51 1.02

H 0.4140.398 10.11 10.51

e 0.0315 BSC 0.80 BSC

D 0.6120.598

15.20 15.55

HE

A1

A

D

e

B

0∞-8∞

L

C

TOP VIEW

SIDE VIEW

1

36

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,

Serial-Interfaced VFD Tube Drivers

______________________________________________________________________________________ 15

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

32, 44, 48L QFN.EPS

PROPRIETARY INFORMATION

APPROVAL

TITLE:

DOCUMENT CONTROL NO.

21-0144

PACKAGE OUTLINE
32, 44, 48L THIN QFN, 7x7x0.8 mm

1

C

REV.

2

e

L

e

L

A1AA2

E/2

E

D/2

D

DETAIL A

D2/2

D2

b

L

k

E2/2

E2

(NE-1) X e

(ND-1) X e

e

C

L

C

L

C

L

C

L

k

DALLAS

SEMICONDUCTOR

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

PROPRIETARY INFORMATION

DOCUMENT CONTROL NO.APPROVAL

TITLE:

C

REV.

2

2

21-0144

PACKAGE OUTLINE

32, 44, 48L THIN QFN, 7x7x0.8 mm

DALLAS

SEMICONDUCTOR

MAX6922/MAX6932/MAX6933/MAX6934

27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.