CONNECTIONS TO VARIOUS DISPLAY READOUTS
LIGHT EMITTING DIODE (LED) READOUT
VDD
VDD
COMMON
CATHODE LED
COMMON
ANODE LED
≈ 1.7 V
≈ 1.7 V
VSS
INCANDESCENT READOUT
VDD
VDD
**
VSS
LIGHT–EMITTING DIODE (LED) READOUT
USING A ZENER DIODE TO REPLACE DROPPING RESISTORS
VDD
COMMON
CATHODE LED
VSS
GAS DISCHARGE READOUT
APPROPRIATE
VDD
VOLTAGE
VSS
* VZD should be set at VDD – 1.3 V – VLED. Wattage of zener diode
must be calculated for number of segments and worst–case
conditions.
** A filament pre–warm resistor is recommended to reduce filament
thermal shock and increase the effective cold resistance of the
filament.
MOTOROLA CMOS LOGIC DATA
VSS
VZD*
VSS
FLUORESCENT READOUT
VDD
DIRECT
(LOW BRIGHTNESS)
FILAMENT
SUPPLY
VSS
VSS OR APPROPRIATE
VOLTAGE BELOW VSS.
(Caution: Absolute maximum
working voltage = 18.0 V)
MC14547B
5