Rainbow Electronics MAX6920 User Manual

General Description

The MAX6920 is a 12-output, 76V, vacuum fluorescent display (VFD) tube driver that interfaces a multiplexed VFD tube to a VFD controller such as the MAX6850–MAX6853 or to a microcontroller. The MAX6920 is also ideal for driving either static VFD tubes or telecom relays.

Data is inputted using an industry-standard 4-wire serial interface (CLOCK, DATA, LOAD, BLANK) for compatibility with both industry-standard drivers and Maxim’s VFD controllers.

For easy display control, the active-high BLANK input forces all driver outputs low, turning the display off, and automatically puts the MAX6920 into shutdown mode. Display intensity may also be controlled by pulse-width modulating the BLANK input.

The MAX6920 has a serial interface data output pin, DOUT, allowing any number of devices to be cascaded on the same serial interface.

The MAX6920 is available in a 20-pin SO package. Maxim also offers VFD drivers with either 20 (MAX6921/MAX6931) or 32 outputs (MAX6922 and MAX6932).

Applications

White Goods Industrial Weighing Gaming Machines Security Automotive Telecom Avionics

Features

♦ 5MHz Industry-Standard 4-Wire Serial Interface

♦ 3V to 5.5V Logic Supply Range

♦ 8V to 76V Grid/Anode Supply Range

♦ 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

♦ Small 20-Pin SO Package

♦ -40°C to +125°C Temperature Range

MAX6920

12-Output, 76V, Serial-Interfaced

VFD Tube Driver

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3061; Rev 0; 10/03

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.

Typical Operating Circuit

TOP VIEW

DIN

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

LOAD

CLKGND

BLANK

OUT6

OUT7

OUT8

OUT9

OUT10

OUT11

DOUT

MAX6920AWP

Pin Configuration

PART TEMP RANGE PIN-PACKAGE

MAX6920AWP -40°C to +125°C 20 Wide SO

+60V+5V

µC

VFDOUT

VFCLK

VFLOAD

VFBLANK

C1 100nF

DIN

CLK

LOAD

BLANK

MAX6920

OUT0 – OUT11

GND

120

C2 100nF

VFD TUBE

MAX6920

12-Output, 76V, Serial-Interfaced VFD Tube Driver

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Typical Operating Circuit, VBB= 8V to 76V, VCC= 3V to 5.5V, TA= T

MIN

to T

MAX

, unless otherwise 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)

BB.................................................................................

-0.3V to +80V

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

OUT_.......................................................-0.3V to (V

+ 0.3V)

All Other Pins..........................................-0.3V to (V

+ 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 .................................60mA

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

20-Pin Wide SO (derate 10mW/°C over T

= +70°C) ..800mW

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

Logic Supply Voltage V

Tube Supply Voltage V

Logic Supply Operating Current I

Tube Supply Operating Current I

High-Voltage OUT_ V

Low-Voltage OUT_ V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

All outputs OUT_

low, CLK = idle

All outputs OUT_ high, CLK = idle

All outputs OUT_ low

All outputs OUT_ high

VBB ≥ 15V,

= -25mA

OUT

VBB ≥ 15V, I

= -40mA

OUT

8V < VBB < 15V, I

= -25mA

OUT

VBB ≥ 15V, I

= 1mA

OUT

8V < VBB < 15V,

= 1mA

OUT

TA = +25°C 72 170

TA = +25°C 350 650

TA = +25°C12

TA = +25°C 0.53 0.85

TA = +25°CV

TA = -40°C to +85°CVBB - 2

TA = -40°C to +85°CVBB - 3.5

TA = +25°CV

TA = -40°C to +85°CVBB - 2.5

TA = +25°C 0.75 1

TA = -40°C to +85°C 1.5

TA = +25°C 0.8 1.1

TA = -40°C to +85°C 1.6

3 5.5 V

876V

= -40°C to +125°C 200

= -40°C to +125°C 700

= -40°C to +125°C 4.2

= -40°C to +125°C 0.9

- 1.1

= -40°C to +125°CVBB - 2.5

= -40°C to +125°CVBB - 4.0

- 1.2

= -40°C to +125°CV

= -40°C to +125°C 1.9

= -40°C to +125°C 2.0

- 3.0

µA

MAX6920

12-Output, 76V, Serial-Interfaced

VFD Tube Driver

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Typical Operating Circuit, VBB= 8V to 76V, VCC= 3V to 5.5V, TA= T

MIN

to T

MAX

, unless otherwise noted.) (Note 1)

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.

Rise Time OUT_ (20% to 80%) t

Fall Time OUT_ (80% to 20%) t

SERIAL INTERFACE TIMING CHARACTERISTICS

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 V

Low-Voltage DOUT V

Rise and Fall Time DOUT

CLK Clock Period t

CLK Pulse-Width High t

CLK Pulse-Width Low t

CLK Rise to LOAD Rise Hold

DIN Setup Time t

DIN Hold Time t

DOUT Propagation Delay t

LOAD Pulse High t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

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

VBB = 60V, CL = 50pF, RL = 2.3kΩ 0.6 1.5 µs

(Notes 2, 3) 0.9 1.8 µs

(Notes 2, 3) 1.2 2.4 µs

(Notes 2, 3) 0.9 1.8 µs

(Notes 2, 3) 1.3 2.5 µs

, I

∆V

CSH

CSW

C (Note 2)

(Note 2) 100 ns

3V to 4.5V 20

4.5V to 5.5V 15

= -1.0mA

SOURCE

= 1.0mA 0.5 V

SINK

= 10pF

DOUT

= 10pF

DOUT

3V to 4.5V 60 100

4.5V to 5.5V 30 80

3.0V to 4.5V 25 120 240

4.5V to 5.5V 20 75 150

0.8 x V

0.5

200 ns

90 ns

5ns

55 ns

0.05 10 µA

0.6 V

0.3 x V

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