PBD 3545/1
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•
•
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thermal overload
short circuit to GND
short circuit to VCC
open circuit
VIN
An output current less than 8 mA
VOUT
IOUT
VErr
might be detected as “open circuit”.
Output currents larger than 8 mA and
less than 2 A will definitely not generate
an error. The normal operational area is
shown in figure 5.
Also when the driver is inactivated an
Error indication can occur. That is if the
output is shorted to GND. In figure 6
short circuit to GND Error state versus
output voltage is shown.
*
>130° <120°
When the Error-detection function is
activated, the Error output is capable of
sinking 8 mA, supporting direct connec-
tion of an LED. The current has to be
externally limited by a series resistor.
Overload or Short circuit Open circuit
Normal
operation
Over
temperature
short circuit to GND
Undefined
level
*
Figure 18. Signal diagram.
Signal diagrams
The signal diagram in figure 18 shows
the input signal and the resulting output
signals for each error mode. For details,
se error table, figure 17.
+ 5 V
Load
5 kΩ
V
cc
R1
R 2
1 [21]
PBD 3545/1
Voltage reference
To logic
VIN = Input voltage. Active = HIGH.
VOUT = Output voltage.
5 [5]
Output
Input
TTL,
LS-TTL,
CMOS
IOUT = Output current from driver.
Thermal
protection
V
ERR = Error output voltage.
+
Short-circuit to
µP,
controller
Q
S
R
Error = LOW.
V
cc
protection
h
Short-circuit to
GND detection
PWR GND
(PLCC only)
4 [7]
Applications Information
Error
Open circuit
detection
Important application areas are:
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Programmable logic control
systems.
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Security systems.
Relay control.
Figure 19. Typical application. Pin numbers refer to TO 220 package.
parallel will improve high frequency
decoupling. Typical values range from
0.002 µF to 0.1 µF. In an application
having a highly stable supply and short
power leads to the driver a low leakage
electrolytic type can be used, which is
less expensive.
Hydraulic valves.
4. If several supply voltages are to be
used, prefere a supply having separate
ground leads. In this case the logic
ground and the power ground should be
connected together at only one point,
the ground pin of the driver.
Intelligent interfaces between
microprocessors and loads.
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Vehicle control systems.
Robot techniques.
Dashboard information systems.
Print head drivers.
Switch mode applications
3. Connect Input and Error via pull-up
resistors to the appropriate logic supply
level or VCC to obtain highest noise
immunity. Se figure 19. The resistor R1
limits the current into the Error indicating
pin. This current must not exeed 8 mA.
R2 is a pull-up resistor which improves
noise immunity at the Input. Pull-up
current should not exeed the sinking
capacity of the controlling device output.
The internal diodes are normally
sufficient for clamping of transients
caused by inductive load turn off.
External diodes may be necessary in
PWM/switch mode applications, and
when the terminals are externally
accessible and thereby exposed to an
electrically noisy environment. Recom-
mended diodes are BYV27/100,
BYV98/100, UF4001 or similar types
with a trr < 100 ns and IF ≥ 1 A.
High-current stepper motor drivers
with security aspects.
Transient protection
1. Keep VCC and GND leads as short as
possible.
2. Connect a filter capacitor close to the
circuit. Recommended filter capacitor
between VCC and GND is 6.8 µF, of
tantalum type. A ceramic capacitor in
7