iC-MFL / iC-MFLT
8-/12-FOLD FAIL-SAFE LOGIC N-FET DRIVER
Rev C1, Page 10/13
DETECTING SINGLE ERRORS
I(OUTx)
If single errors are detected, safety-relevant applica-
[µA]
tions require externally connected switching transistors
to be specifically shut down. Single errors can occur
150
when a pin is open (due to a disconnected bonding
wire or a bad solder connection, for example) or when
two pins are short-circuited.
−30kΩ
When two output of different logic levels are short-
circuited, the driving capability of the lowside driver will
predominate, keeping the connected N-channel FETs
in a safe shutdown state.
V(OUTx)
[V]
1
2
3
4
5
With open pins VCC, GND or GNDR iC-MFL switches
the output stages to a safe, predefined low state via
pull-down resistors or pull-down current sources at the
inputs, subsequently shutting down any externally con-
nected N-channel FETs.
Figure 6: Output characteristic at OUTx with open
GND pin
Loss of GND potential
If ground potential is not longer applied to GND, the
output stages are shut down and the outputs tied to
GNDR via internal pull-down resistors with a typical
value of 30 kΩ.
I(OUTx)
[µA]
150
I(OUTx)
[mA]
3.6
−30kΩ
V(OUTx)
[V]
1
2
3
4
5
V(OUTx)
[V]
Figure 5: Output characteristic at OUTx with discon-
nected VCC supply
1
2
3
4
5
Figure 7: Output characteristic at OUTx with open
GNDR pin
Loss of VCC potential
If the supply voltage is disconnected from VCC pin, the
outputs are tied to GNDR via internal pull-down resis-
tors of typically 30 kΩ which form a passive path from Loss of GNDR potential
the gate of an external switching transistor to ground. If ground potential is no longer applied to the GNDR-
A further increase of output current may occur due to pin, the output stage highside drivers are shut down
self-supply effects via the output of the iC, as indicated and the outputs actively tied to GND via the lowside
by the arrows in Figure 5.
drivers.
ICHAUS [ IC-HAUS GMBH ]
