UDK2547EB Allegro Microsystems Inc, UDK2547EB Datasheet - Page 5

• Manufacturer Part Number: UDK2547EB
• Manufacturer: Allegro Microsystems Inc

Specifications of UDK2547EB

• Operating Temperature (min): -40C
• Operating Temperature Classification: Automotive
• Operating Temperature (max): 125C
• Package Type: PLCC
• Rad Hardened: No
• Lead Free Status / Rohs Status: Not Compliant

2547
PROTECTED
QUAD POWER DRIVER
NORMAL LAMP IN-RUSH CURRENT
CURRENT LIMIT
THERMAL HYSTERESIS
THERMAL SHUTDOWN
TIME
SHORT CIRCUIT
NOT TO SCALE
Dwg. WP-005A
Both conditions are sensed by comparing the input and output states.
Note that the FAULT output is operational only if the ENABLE input is
high. When a fault condition is sensed, the FAULT output will go to a
low state. An external FAULT output filter capacitor (0.1 F) is recom-
mended to eliminate erroneous switching.
poor lamp reliability and destroy semiconductor lamp drivers.
driver and lamp but use significant power either when the lamp is OFF
or when the lamp is ON, respectively. Lamps with steady-state current
ratings up to 600 mA can be driven without the need for warming or
current-limiting resistors, if lamp turn-ON time is not a concern.
is at minimum resistance and would normally allow a 10x to 12x in-rush
current. With these drivers, during turn-ON, the high in-rush current is
sensed by the internal low-value sense resistor, drive current to the
output stage is diverted by the shunting transistor, the output stage
operates in a linear mode, and the load current is limited to approxi-
mately 1.3 A. During lamp warmup, the filament resistance increases
to its maximum value, the output driver goes into saturation and applies
maximum rated voltage to the lamp.
stepper motors and other inductive loads can be driven directly.
The external diodes prevent damage to the output transistors by
suppressing the high-voltage spikes that occur when turning
OFF an inductive load. For rapid current decay (fast turn-OFF speeds),
the use of Zener diodes will raise the flyback voltage and improve
performance. However, the peak voltage must not exceed the speci-
fied minimum sustaining voltage (V
will attempt to increase. As described above, the drive current to the
affected output stage is linearly reduced (limiting the load current to
about 1.3 A), causing the output stage to go linear. As the junction
temperature of the output stage increases, the thermal shutdown circuit
will shut OFF the affected output. If the fault condition is corrected, the
output driver will return to its normal saturated condition.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
These devices monitor their outputs for open or shorted conditions.
High incandescent lamp turn-ON/in-rush currents can contribute to
Warming (parallel) or current-limiting (series) resistors protect both
When an incandescent lamp is initially turned ON, the cold filament
With the addition of external clamp diodes, bifilar (unipolar)
In the event of a shorted load, or stalled motor, the load current
SUPPLY
+ V
Z
+ V
F
V
OUT(SUS)
).