20-Output, 76V, Serial-Interfaced

VFD Tube Drivers

6

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PIN

TSSOP

MAX6931

MAX6921

WIDE SO/

PLCC

NAME

FUNCTION

1–5, 10–19,

24–28

——

OUT0 to

OUT19

VFD Anode and Grid Drivers. OUT0 to OUT19 are push-pull outputs swinging

—

1–5, 10–19,

24–28

3–12,

17–26

OUT0 to

OUT19

VFD Anode and Grid Drivers. OUT0 to OUT19 are push-pull outputs swinging

—

9

2

DOUT

Serial-Clock Output. Data is clocked out of the internal shift-register to DOUT

on CLK’s rising edge.

6

6

27

DIN

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

edge.

7

7

28

Logic Supply Voltage

88

1

VFD Tube Supply Voltage

9

——

Filament Bias Supply Voltage

20

20

13

BLANK

Blanking Input. High forces outputs OUT0 to OUT19 low, without altering the

contents of the output latches. Low enables outputs OUT0 to OUT19 to follow

the state of the output latches.

21

21

14

GND

Ground

22

22

15

CLK

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

rising edge.

23

23

16

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.

Pin Description

SERIAL-TO-PARALLEL SHIFT REGISTER

LATCHES

CLK

DIN

LOAD

BLANK

OUT0 OUT1 OUT2

OUT19

DOUT

MAX6921 ONLY

MAX6921

MAX6931

Figure 1. MAX6921/MAX6931 Functional Diagram