MAX6922AQH+TD Maxim Integrated Products, MAX6922AQH+TD Datasheet - Page 10

• Manufacturer Part Number: MAX6922AQH+TD
• Description: IC DRVR VFD TUBE SRL 44-PLCC
• Manufacturer: Maxim Integrated Products

Specifications of MAX6922AQH+TD

• Display Type: Vacuum Fluorescent (VF)
• Interface: 4-Wire Serial
• Current - Supply: 1.65mA
• 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

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 dis-
charges 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.
Take care to ensure that the maximum package dissi-
pation ratings for the chosen package are not exceed-
ed. 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 (P
MAX6932/MAX6933/MAX6934 for static tube drivers
with the following equation:
where:
A = number of anodes driven (maximum of 32 with the
MAX6922/MAX6934).
I
(V
mum anode current I
A static tube dissipation example follows:
Determine the power dissipation (P
MAX6932/MAX6933/MAX6934 for multiplex tube drivers
with the following equation:
where:
A = number of anodes driven.
G = number of grids driven.
I
I
The calculation presumes all anodes are on, but only
one grid is on. The calculated P
suming one digit is always being driven with all its
anodes lit. Actual P
this P
into account interdigit blanking and any PWM intensity
control.
27-, 28-, and 32-Output, 76V,
Serial-Interfaced VFD Tube Drivers
10
V
ANODE
ANODE
GRID
CC
BB
______________________________________________________________________________________
P
P
((2.5V x 2mA/25mA) x 2mA x 32) = 60mW
P
= 5V ±5%, V
- V
D
= maximum grid current.
D
D
D
figure by the actual tube drive duty cycle, taking
= maximum anode current.
= maximum anode current.
H
= (V
= (5.25V x 1.5mA)+ (18V x 2.2mA) +
= (V
) is the output voltage drop at the given maxi-
I
I
ANODE
ANODE
CC
CC
x I
x I
BB
CC
CC
x A))
x A) + ((V
D
OUT
) + (V
= 10V to 18V, A = 32, I
) + (V
can be estimated by multiplying
.
BB
BB
BB
x I
x I
- V
D
Power Dissipation
BB
BB
is the worst case, pre-
H
) + ((V
) + ((V
D
D
) x I
) for the MAX6922/
) for the MAX6922/
GRID
BB
BB
OUT
))
- V
- V
H
H
= 2mA
) x
) x
A multiplexed tube dissipation example follows:
Thus, for a 44-pin PLCC package (T
75.188°C/W from Absolute Maximum Ratings), the maxi-
mum allowed ambient temperature T
So T
This means that the driver can be operated in this
application with a PLCC package up to the +125°C
maximum operating temperature.
The MAX6922/MAX6932/MAX6933/MAX6934 operate
with multiple power-supply voltages. Bypass the V
V
power-supply pins to GND with 0.1µF capacitors close
to the device. The MAX6932/MAX6933/MAX6934 may
be operated with V
supply is not required. For multiplex applications, it may
be necessary to add an additional bulk electrolytic
capacitor of 1µF or greater to the V
The order of the power-supply sequencing is not impor-
tant. These ICs are damaged if any combination of
V
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
because the input protection diodes clamp the signals.
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 cas-
caded at the full 5MHz CLK speed when V
When V
limits the maximum cascaded CLK to 4MHz.
CC
BB
T
V
P
J(MAX)
, V
CC
, and V
A
D
= +138°C.
= (5.25V x 1.5mA)+ (42V x 2.2mA) +
BB
= 5V ±5%, V
CC
((2.5V x 0.4mA/25mA) x 0.4mA x 20) +
((2.5V x 24mA/25mA) x 24mA) = 158mW
(MAX6922/MAX6932/MAX6934 Only)
, and V
I
ANODE
= T
<4.5V, the longer propagation delay (t
SS
75.188°C/W)
A
(MAX6932/MAX6933/MAX6934 only)
+ (P
SS
Power-Supply Considerations
= 0.4mA, I
BB
SS
is grounded while the other supply
D
Power-Supply Sequencing
x T
= 36V to 42V, A = 20, G = 12,
tied to GND if a negative bias
JA
) = +150°C = T
GRID
Cascading Drivers
= 24mA
CC
BB
A
is given by:
JA
is not operational
supply.
= 1 / 0.0133 =
A
+ (0.158 x
CC
≥ 4.5V.
DO
CC
)
,