AMG-SM101 Datasheet, PDF (6/17 Pages) alpha microelectronics gmbh – Inductive Proximity Sensor IC

AMG-SM101
Inductive Proximity Sensor IC
5.7. Overload Protection Circuits
The function of this block is to protect the output transistor against destruction resulting from attempting
to sink excessive current into the IC or shorting the output of the IC directly to the supply rail. The
overload/overcurrent state of the IC is detected by comparing an internal reference voltage with the
voltage drop over an external current limiting resistor connected in series with the emitter of the output
transistor. The voltage threshold over the shunt resistor necessary to switch the protection circuit is
given in section 8.2. If the overload/overcurrent state is detected (threshold exceeded), the state of the
output is periodically sampled as long as the overload/overcurrent condition persists. In this state the
average overload current flowing through the load is much lower than its guaranteed value in the
normal operation mode, and the value of this overload current is given in Section 8.2.
Apart from protecting the output transistor the Overload Protection block is also responsible for
deactivating the output transistor shortly after the supply voltage was applied to the sensor. In this way
undesired transient behaviour of the IC output is suppressed.
5.8. Output NPN Transistor
The output NPN transistor is capable of sinking at least 150mA of constant output current. In the
overload mode the transistor delivers short current pulses used to test the state of the output and to
provide a small charge (or overload) current for capacitive loads.
6. Pinning
PIN#
1
2,3
4,5
6
7
8
9
10
11
12
13
14
15
16
17
Symbol
D_LED
OutN
RCL
NO/NC
CDET
RREF
CCL
GND
Vlin
VCC
OSCin
Description
Detect LED (1.2mA)
NPN output (open drain)
Current limiting resistor of NPN output transistor
n. c.
Normally open / normally closed switch
n.c.
Oscillation detector capacitor (CDET to GND)
Reference resistor
Current limiter sampling capacitor
n.c.
Ground
n.c.
Regulator blocking capacitor
Supply voltage
Oscillator input (LC tank)
AMG-SM101 Revision: B
06.11.12
© All rights reserved Page 6 of 17