mc14489b Freescale Semiconductor, Inc, mc14489b Datasheet - Page 7
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mc14489b
Manufacturer Part Number
mc14489b
Description
Multy-character Led Display/lamp Driver
Manufacturer
Freescale Semiconductor, Inc
Datasheet
1.MC14489B.pdf
(22 pages)
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a through h (Pins 1, 2, 4 – 7, 19, 20)
ly–matched current sources which directly tie to the anodes
of external discrete LEDs (lamps) or display segment LEDs.
Each output is capable of sourcing up to 35 mA.
independently control up to 20 lamps. Output h is used to con-
trol up to 5 lamps dependently. (See Figure 17.) For lamps,
the No Decode mode is selected via the configuration regis-
ter, forcing e, f, and g inactive (low).
drive segments a through g, respectively. Output h is used to
drive the decimals. Refer to Figure 9. If unused, h must be left
open.
Bank 1 through Bank 5 (Pins 9, 13, 15, 16, 17)
tance switches to ground (V SS ) capable of handling currents
of up to 320 mA each. These pins directly tie to the common
cathodes of segmented displays or the cathodes of lamps
(wired with cathodes common).
optimum brightness from the LEDs. A 20% duty cycle is uti-
lized.
MOTOROLA
Anode–Driver Current Sources. These outputs are close-
When used with lamps, outputs a, b, c, and d are used to
When used with segmented displays, outputs a through g
Diode–Bank FET Switches. These outputs are low–resis-
The display is refreshed at a nominal 1 kHz rate to achieve
Figure 7. a through h Nominal Current per Output versus Rx
NOTE: Drive current tolerance is approximately
15
20
35
30
25
10
5
400
800
1.2 k
WITH D23 = LOW, i OH IS CUT BY 50%.
BIT D23 = HIGH (BRIGHTEN LEDs)
Rx, EXTERNAL RESISTOR ( )
1.6 k
2.0 k
5 V SUPPLY
date the high currents with low EMI (electromagnetic interfer-
ence) and minimal spiking on the power lines.
POWER SUPPLY
V SS (Pin 14)
the chip’s V SS pin does not contain the Rx current compo-
nent.
V DD (Pin 13)
the serial interface is functional, this voltage may range from
3 to 6 volts with respect to V SS . For example, within this volt-
age range, the chip could be placed in and out of the low–
power mode.
6 volts with respect to V SS .
chip’s current drain. In the low–power mode, the current mir-
ror and clock oscillator are turned off, thus significantly reduc-
ing the V DD current, I DD .
2.4 k 2.8 k
Special design techniques are used on–chip to accommo-
Most–negative supply potential. This pin is usually ground.
Resistor Rx is externally tied to ground (V SS ). Therefore,
Most–positive supply potential.
To guarantee data integrity in the registers and to ensure
To adequately drive the LEDs, this voltage must be 4.5 to
The V DD pin contains the Rx current component plus the
15%.
3.2 k
3.6 k
4.0 k
MC14489B
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