MAX6850 MAXIM [Maxim Integrated Products], MAX6850 Datasheet - Page 7

• Manufacturer Part Number: MAX6850
• Description: 4-Wire Interfaced, 7-, 14-, and 16-Segment Alphanumeric Vacuum-Fluorescent Display Controller
• Manufacturer: MAXIM [Maxim Integrated Products]

4-Wire Interfaced, 7-, 14-, and 16-Segment Alpha-
Figure 2. Example of a Two-Digit-per-Grid Display
Figure 3. Digit Structure with 14-Segment Character,
DP Segment, Cursor Segment, and Four Annunciators
Figure 4. Connection of the MAX6850 to VFD Driver and VFD Tube
numeric Vacuum-Fluorescent Display Controller
MICROCONTROLLER
GRID 1
°C °F pH mW
DOUT
SCLK
CS
DIN
SCLK
CS
_______________________________________________________________________________________
MAX6850
GRID 2
VFBLANK
VFDOUT
VFLOAD
VFCLK
4 ANNUNCIATOR SEGMENTS
14-SEGMENT CHARACTER
DECIMAL POINT (DP) SEGMENT
CURSOR SEGMENT
VFDIN
VFCLK
VFLOAD
VFBLANK
VFD TUBE DRIVER
GRID 3
GRID/
ANODE
DRIVERS
GRID 4
out of phase with the cursor. The blink-speed control is
software selectable to be one or two blinks per second
(OSC = 4MHz).
DP segments can be lit or off, but have no blink control.
A DP segment is set by the same command that writes
the digit’s 7-, 14-, or 16-segment character.
The cursor segment is controlled differently. A single
register selects one digit’s cursor from the entire dis-
play, and that can be lit either continuously or blinking.
All the other digits’ cursors are off.
The designations of DP, cursor, and annunciator are
interchangeable. For example, consider an application
requiring only one DP lit at a time, but the DP needs to
blink. The DP function does not have blink capability.
Instead, the DP segments on the display are routed
(using the output map) to the cursor function. In this
case, the DP segments are controlled using the cursor
register.
The output of the controller is a 4-wire serial stream that
interfaces to industry-standard, shift-register, high-volt-
age grid/anode VFD tube drivers (Figure 4). This inter-
face uses three outputs to transfer and latch grid and
anode data into the tube drivers, and a fourth output
that enables/disables the tube driver outputs (Figure 6).
The enable/disable control is modulated by the
MAX6850 for both PWM intensity control and interdigit
GRID 5
GRID 6
GRID 7
GRID 8
7