NE587 データシートの表示（PDF） - Philips Electronics
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NE587 Datasheet PDF : 9 Pages
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Philips Semiconductors Linear Products
LED decoder/driver
Product specification
NE587
AC ELECTRICAL CHARACTERISTICS
VCC=5V, TA=25°C, RL=130Ω, CL=30pF including probe capacity.
SYMBOL
PARAMETER
tDAV
Propagation delay (Figure 2)
tDAV
Propagation delay (Figure 3)
tW
Latch enable pulse width (Figure 4)
tS
Latch enable setup time (Figure 4)
tH
Latch enable hold time (Figure 4)
NOTES:
tDAV= (tHL+tLH)
TEST CONDITIONS
From data to output
From LE to output
From data to LE
From LE to data
LIMITS
Min Typ Max
135
135
30
20
0
UNIT
ns
ns
ns
ns
ns
TRUTH TABLE
BINARY
INPUT
-
INPUTS
LE RBI D3 D2 D1 D0
a
b
H
*
X
X
X
X
0
L
L
L
L
L
L
H
H
0
L
H
L
L
L
L
L
L
1
L
X
L
L
L
H
H
L
2
L
X
L
L
H
L
L
L
3
L
X
L
L
H
H
L
L
4
L
X
L
H
L
L
H
L
5
L
X
L
H
L
H
L
H
6
L
X
L
H
H
L
L
H
7
L
X
L
H
H
H
L
L
8
L
X
H
L
L
L
L
L
9
L
X
H
L
L
H
L
L
10
L
X
H
L
H
L
H
H
11
L
X
H
L
H
H
L
H
12
L
X
H
H
L
L
H
L
13
L
X
H
H
L
H
H
H
14
L
X
H
H
H
L
L
L
15
L
X
H
H
H
H
H
H
**BI
X
X
X
X
X
X
H
H
NOTES:
H=HIGH voltage level, output is “OFF”
L=LOW voltage level, output is “ON”
X=Don’t care
* The RBI will blank the display only if a binary zero is stored in the latches.
** RBO/BI used as an input overrides all other input conditions.
OUTPUTS
c
d
e
f
STABLE
H
H
H
H
L
L
L
L
L
H
H
H
H
L
L
H
L
L
H
H
L
H
H
L
L
L
H
L
L
L
L
L
L
H
H
H
L
L
L
L
L
L
H
L
H
H
H
H
H
L
L
L
L
H
L
L
H
L
L
L
H
H
L
L
H
H
H
H
H
H
H
H
DISPLAY
g RBO
**
STABLE
H
L
BLANK
H
H
0
H
H
1
L
H
2
L
H
3
L
H
4
L
H
5
L
H
6
H
H
7
L
H
8
L
H
9
L
H
-
L
H
E
L
H
H
H
H
L
L
H
P
H
H
Blank
H
L**
Blank
NE587 PROGRAMMING
587 output current can be programmed by using a programming
resistor, RP, connected between RP (Pin 8) and GND (Pin 9). The
voltage at RP (Pin 8) is constant (K = 1.3V). A partial schematic of
the voltage reference used in the NE587 is shown in Figure 1.
Output current to program current ratio, IO/IP, is 20 in the 15mA to
50mA range. Note that IP must be derived from a resistor (RP), and
not from a high-impedance source such as an IOUT DAC used to
control display brightness.
POWER DISSIPATION CONSIDERATIONS
LED displays are power-hungry devices, and inevitably, somewhat
inefficient in their use of the power supply necessary to drive them.
Duty cycle control does afford one way of improving display
efficiency, provided that the LEDs are not driven too far into
saturation; but the improvement is marginal. Operation at higher
peak currents has the added advantage of giving much better
matching of light output, both from segment-to-segment and
digit-to-digit.
August 31, 1994
533
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