MAX6934AQH+D Maxim Integrated Products, MAX6934AQH+D Datasheet - Page 9

• Manufacturer Part Number: MAX6934AQH+D
• Description: IC DRVR VFD TUBE SRL 44PLCC
• Manufacturer: Maxim Integrated Products

Specifications of MAX6934AQH+D

• Display Type: Vacuum Fluorescent (VF)
• Interface: 4-Wire Serial
• Current - Supply: 2mA
• Voltage - Supply: 8 V ~ 76 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 44-LCC, 44-PLCC
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Configuration: -
• Digits Or Characters: -
• Lead Free Status / Rohs Status: Details

Table 1. 4-Wire Serial Interface Truth Table
L = Low logic level.
H = High logic level.
X = Don’t care.
P = Present state (shift register).
R = Previous state (latched).
clocked in are loaded. Therefore, multiple devices can
share CLK and DIN, as long as they have unique LOAD
controls.
The outputs are CMOS drivers, and have a resistive
characteristic. The typical and maximum sink and
source output resistances can be calculated from the
V
resistance to determine the output voltage drop at dif-
ferent output currents.
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 dissipa-
tion 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 mul-
tiplex ratio is given by:
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.
SERIAL
INPUT
DATA
H
DIN
H
L
X
and V
Determining Driver Output Voltage Drop
CLOCK
INPUT
L
CLK
electrical characteristics. Use this calculated
I
PEAK
SHIFT REGISTER CONTENTS
D0 D1 D2 … Dn-2 Dn-1
R0 R1 R2 … Rn-1
P0
H
L
X
_______________________________________________________________________________________
= (grids x 1600)
R0 R1 … Rn-2 Rn-1
R0 R1 … Rn-2 Rn-1
P1 P2 … Pn-1
X
X
Output Current Ratings
…
Serial-Interfaced VFD Tube Drivers
X
1/2
mA
Rn
Pn
X
INPUT
LOAD
LOAD D0 D1 D2 … Dn-2 Dn-1
H
L
27-, 28-, and 32-Output, 76V,
R0 R1 R2
P0 P1 P2
X
LATCH CONTENTS
X
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 dissi-
pate 530mW when shorted to an opposite level output
at a V
puts is to use diodes to prevent the outputs from sink-
ing 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 multi-
plexed tubes, the value of the resistor can be deter-
mined by the load capacitance and timing
Figure 5. Paralleling Outputs
X
… Rn-1 Rn
… Pn-1 Pn
…
BB
voltage of only 20V. A safe way to parallel out-
X
X
BLANKING
MAX6922
MAX6932
MAX6933
MAX6934
BLANK
INPUT
H
L
OUT0
OUT1
D0 D1 D2 … Dn-2 Dn-1
P0 P1 P2 … Pn-1
L
Paralleling Outputs
OUTPUT CONTENTS
D1
D2
L
R
L
OUTPUT
…
L
Pn
L
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