ICM7218_15 Datasheet, PDF (5/11 Pages) Intersil Corporation – 8-Digit LED Microprocessor-Compatible Multiplexed Display Decoder Driver

ICM7218
FIGURE 2. MULTIPLEX TIMING (COMMON CATHODE VERSION)
sign (-), a blank (for leading zero blanking), certain useful
alpha characters and all numeric formats.
The four bit binary code is set up on inputs lD3-lD0, and
decimal point data is set up on ID7.
FIGURE 3. SEGMENT ASSIGNMENTS
Detailed Description
DECODE Operation
For the lCM7218A/B products, there are 3 input data formats
possible; either direct segment and decimal point information (8
bits per digit) or two Binary formats plus decimal point
information (Hexadecimal/Code B formats with 5 bits per digit).
The 7-segment decoder on chip is disabled when direct
segment information is to be written. In this format, the
inputs directly control the outputs as follows:
Input Data:
Output Segments:
ID7 lD6 ID5 lD4 lD3 lD2 lD1 ID0
D.P. a b c e g f d
Here, "Ones" represent "on" segments for all inputs except
the Decimal Point. For the Decimal Point "zero" represents
an "on" segment.
HEXAdecimal/CODE B Decoding
For all products, a choice of either HEXA or Code B decoding
may be made. HEXA decoding provides 7-segment numeric
plus six alpha characters while Code B provides a negative
DECIMAL 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
HEXA
01234567 8 9 A B C D E
F
CODE
CODE B 0 1 2 3 4 5 6 7 8 9 - E H L P (BLANK)
SHUTDOWN
SHUTDOWN performs several functions: it puts the device
into a very low dissipation mode (typically 10A at V_DD = 5V),
turns off both the digit and segment drivers, and stops the
multiplex scan oscillator (this is the only way the scan
oscillator can be disabled). However, it is still possible to input
data to the memory during shutdown - only the display output
sections of the device are disabled in this mode.
Powerdown
In the Shutdown Mode, the supply voltage may be reduced to
2V without data in memory being lost. However, data should
not be written into memory if the supply voltage is less than 4V.
Output Drive
The common anode output drive is approximately 200mA per
digit at a 12% duty cycle. With segment peak drive current of
40mA typically, this results in 5mA average drive. The common
cathode drive capability is approximately one-half that of the
common anode drive. If high impedance LED displays are
used, the drive current will be correspondingly less.
5
FN3159.3
September 15, 2015